----------------------------------------------------------------------- Page 15

Figure 5
Figure 5: Main induction valve bonnet.
(Note 1-inch steel pipe which jammed under valve disk.)
----------------------------------------------------------------------- Page 16 Work on the first tunnel, at frame 46, was started on October 22. The divers available had all done most of their diving in chasing lost torpedoes and were consequently experienced in using a washing hose for digging out buried torpedoes. Tunneling was therefore the thing they knew most about, and no special difficulty was anticipated. A 2.5-inch fire hose with a 4-foot pipe nozzle, at a pressure of about 40 pounds, was first used. The progress for the first day gave reason for optimism, but thereafter continued trouble was encountered. Instead of the soft mud in which the divers had ordinarily worked, and which washed freely with a hose, it was found that under a thin layer of hard sand and mud, there was a bed of hard blue clay mixed with some sand in which the submarine was buried. The consistency of the clay was such that a moderate water pressure had no effect on it. It was found impossible to raise the pressure on the 2.5-inch hose, as the diver was unable to withstand the reaction of the hose and lost control. After the first day's work, it was found imperative to raise the pressure to cut the clay. To permit this, the last length of fire hose was replaced by a 50-foot length of 1.5-inch wash deck hose with a pipe nozzle of the same diameter, and with this reduced size the diver was able to hold a pressure up to 70 pounds, which would cut the clay when the nozzle was held close against it. With this nozzle work was continued throughout the fall. Another unpleasant discovery was the fact that the clay and the sand were so heavy that, unlike mud, they refused to stay in suspension when cut and settled again in the tunnel within a foot or two of the nozzle. This feature was aggravated by the small size of the water jet, which was unable to set up any appreciable current in the tunnel as it advanced under the boat. As a result of this, the diver was compelled, after cutting ahead a little, to turn his nozzle and wash all sediment backwards out of the tunnel. Consequently only a small portion of the diver's time on the bottom was spent in actual cutting ahead. Finally weather conditions through October and November were such that diving was ordinarily impossible more than two days in succession, after which two or three days might elapse before diving could be resumed. It was found on returning after each storm that the bottom currents had either partly or completely filled the tunnel with heavy hard-packed sand, which had to be washed out before any new cutting was possible. The above factors, complicated by an insufficient and a decreasing force of divers, prevented driving a tunnel through during the fall operations. Several times success seemed near, with the divers approaching or even touching the keel, but each time bad weather caused a suspension, and practically all work had to be done over again when tunneling was resumed. After the first three diving days, sufficient knowledge of the troubles existing in sealing up and in tunneling was gained to make it evident that the 10 experienced deep-sea divers would not be able to finish the job before winter set in. An attempt was made to bolster up the force by using some of the shallow-water men, sending them down in company with more experienced divers. This policy was tried out on October 28, but the results were unfortunate. The first man sent down failed to orient himself and did nothing. The second man apparently was paralyzed with fear, fell off the submarine, and was found wandering on the bottom after having fouled the lines of another diver. This second man contracted a severe case of bends that night from which he nearly died, and which kept him in the hospital for over five months. A third shallow-water diver sent down late that day wasted the dive of his partner, who was compelled to put in his entire dive, keeping his mate from being washed away by the current or fouling his lines, and consequently accomplished nothing himself. The experience of this day proved conclusively that the diving course at Newport does not fit a man to dive in work of this kind. In confirmation of this fact, it was noted that of some 20 shallow-water divers present, none desired to work on the job, all apparently realizing fully their lack of training. As there was now neither time nor opportunity for training these men, it was felt that time did not exist for the small number of experienced men present to complete ----------------------------------------------------------------------- Page 17
Figure 6
Figure 6: Channel strong back securing motor room hatch.
----------------------------------------------------------------------- Page 18 the job; by the middle of November this was seen to be a certainty. However it was determined to do as much as was possible while the weather permitted. To seal off the motor room, Eiben and Wilson entered from the engine room and closed all necessary valves including the ventilation valve. Later they closed the motor room door and sledged down the dogs. To discharge the water, the drain valve in the forward bilges (pl. 1) of the motor room was opened, there being a nonreturn valve on the bilge suction. In the engine room a valve bonnet on this drain line was removed so that water could be forced from the motor room to the engine room but not in the reverse direction. To admit air, Kelley and Anderson removed a bolt through the top of the motor room, tapped out the bolt hole, and secured a 0.75-inch connection for a blowing hose. To prevent blowing open the motor room hatch under internal pressure, an external strong back was made and bolted down over the hatch, as shown in Figure 6. On November 7, the air was put on the motor room to test it out. Considerable water was expelled, when air started to blow out the ventilation main in the superstructure. Inquiry of the "S-51" survivors disclosed the fact that the drain valve on this line in the motor room was defective and could not be effectively closed, though they had not previously reported this trouble. To remedy it, the motor room door was opened, the drain line disconnected, and the valve (1.25 inches) sealed with a pipe plug. The door was resecured after considerable difficulty, on November 15, and on November 18 another attempt was made to blow the motor room. After the water had gone down a few feet, the air started to escape through the ventilation valve, which was reported by the divers to be chattering like a relief valve with the air being released in gusts. This valve was closed and secured by the internal locking gear, but this locking gear, even when set up to the limit, was unable to hold the valve on its seat against a few pounds pressure. Nothing further could be done with this compartment during the fall operations. The second compartment attacked was the C.O.C. To seal this compartment required the substitution of two salvage hatches for the regular hatches in the conning tower and the gun access trunk, as the original hatches were unable to hold an internal pressure. There was further required the closing of numerous valves inside the C.O.C. and the closing of the two doors leading to the battery room and the engine room. As a preliminary, the hatch on the gun access trunk was opened as previously described. The hatch on the conning tower was open at the time of sinking. Handling the salvage hatches presented a new problem. Each hatch was made of steel plate 1.25 inches thick, with a heavy strong back and bolt running through it, and with a long length of 4-inch suction hose attached to the underside about as shown in Figure 7. Each hatch weighed around 700 pounds assembled. After a rehearsal on the "S-50" it became evident that the hatches could not be suspended from the surface while the divers endeavored to install them, as the up-and-down motion was too much to allow the divers to work. It consequently became necessary to provide a means on the submarine boat over each hatch for handling it. For the conning-tower hatch a heavy oak timber provided with an eyebolt was secured over the bridge where it plumbed the hatch cover and the hatch itself was handled by a half-ton chain fall secured to the eyebolt in the timber; using this rig the conning-tower hatch was hooked onto the chain fall after it had been lowered in the bridge inclosure and was installed and set up by two divers, Frazer and Smith, in one dive. Having secured the conning-tower hatch, another long oak plank was attached across the timber already in place over the bridge, with the end of the new timber projecting forward of the bridge enough to plumb the top of the center of the gun access hatch. With this rig in place and the chain fall ready, the hatch was lowered from the surface boat, guided down by ----------------------------------------------------------------------- Page 19
Figure 7
Figure 7: Engine room salvage hatch.
Practice on "S-50". (Note 4-inch hose.)
----------------------------------------------------------------------- Page 20 a line secured to the side of the gun access trunk. As the hatch neared the submarine it was dragged over by the divers, who entered the suction hose into the trunk and fed it down until the hatch was landed when the surface line was let go by the divers. The chain fall was then hooked into the strong back bolt and the hatch was thereafter handled from the chain fall by divers. Considerable difficulty was encountered with this hatch in getting it adjusted, on account of the slope of the submarine boat, but this hatch was also successfully installed by Frazer and Smith in one dive. However, it appears that the exertion of handling this heavy weight while plumbing the hatch was such that Frazer strained his heart and it was discovered that further diving by Frazer was out of the question. (Gun access hatch, fig. 8.) With both hatches in the C.O.C. sealed up, the next attempt was to close the doors. Two divers entered the battery room and went aft along the passage to the crew's quarters toward the forward C.O.C. door and found the passage blocked by mattresses and bunks. An attempt was next made to enter the C.O.C. through the after door from the engine room. The first pair of divers who tried this entrance were unable to squeeze through. The second pair of divers on the same attempt had to quit because four underwater lamps burned out on them during one dive while inside the submarine boat. A third attempt to enter this door, made by Wilson and Eiben proved successful. The two men got part way in the C.O.C., cleared away a bunk which had washed into the C.O.C. from the battery room forward, and then found a clear though congested passage through the remainder of the C.O.C. By working forward they reached the forward C.O.C. door, which was found jammed with wreckage but which was cleared and closed by the divers. The necessary valves to seal up the C.O.C. were next closed by the same pair of divers. On a previous dive the divers noted that one of the air banks showed about 2,000 pounds of air in the C.O.C. An attempt was consequently made to open all the Kingston valves in the main ballasts, using the master controller in the C.O.C. to operate the air motors at the individual valves. The divers opened the master control, but none of the air motors functioned. As a result of this the Kingston valve for No. 3 port tank was opened by hand from the C.O.C. and the Kingston valves for ballast tanks 4 and 5, port and starboard, which were accessible from the engine room, were opened by hand from the engine room. None of the gear for operating the Kingston valves on the remaining ballast tank were accessible from the inside of the boat, due to wreckage. Having opened the Kingston valves on port ballast tanks 3, 4, and 5, on the next dive Wilson entered the C.O.C. again and adjusted the valves on the air manifold so as to blow down these three ballast tanks, using the ship's own compressed air. Another diver was stationed outside the submarine to observe the discharge from the Kingstons. Air was turned on all three tanks at once and the gauge inside the boat started to drop in pressure immediately. The diver outside noted that a stream of muddy water was being discharged from the Kingston in each one of the three tanks. The tanks were blown for about 30 minutes, when the air on the gauge inside the ship dropped so low as to render further blowing inadvisable. All air valves were closed and the diver came out. None of the three ballast tanks had commenced discharging air, so none of them were dry. It was estimated that all of them were from one-half to two-thirds blown down. A rubber hose was found through the after door of the C.O.C. running from a connection in the engine room to the ice machine located under the deck in the C.O.C. As this hose prevented closing the door, it was cut by the divers and gagged on both sides of the cut. The divers then closed the after door on the C.O.C. and dogged it down. A hose for blowing the C.O.C. was secured to the connection provided on the salvage hatch already installed and air was turned on the C.O.C. After building up a pressure of 3 or 4 pounds in excess of the bottom pressure at the point of discharge, air started to blow ----------------------------------------------------------------------- Page 21
Figure 8
Figure 8: Gun access salvage hatch in position.
(Note air connections.)
----------------------------------------------------------------------- Page 22 in gusts from the C.O.C. It was evident that in spite of being locked from the interior the ventilation valve in this compartment was operating in the same manner as the valve in the motor room. As this occurred at about the same time - that is, late in November - nothing could be done during the remainder of the fall operations. About the middle of November divers worked in the engine room on the fuel-oil manifolds, setting the valves and rigging air connection to blow the contents of the fuel-oil tanks, of which there were two groups, one forward and one aft. The after group of oil tanks were blown first, the contents being discharged through a hose led to the surface. It was found that the after group contained nothing but water, all of which was blown out until air was discharged. The connections were then shifted to blow the forward group, which was done a few days later. From the forward group of oil tanks there was discharged first water, then oil, and finally water again, until air was discharged. Late in October an attempt was made to lower the first pontoon. Divers passed reeving lines of 21-thread manila under the stern of the submarine, which was clear of the bottom. On these as guide lines there were hauled heavier manilas and then two 1-inch wire lines. The pontoon was to be lowered with a 15-fathom shot of 2.5-inch anchor chain hung from each hawse pipe, each chain being held at the top of the hawse pipe by a heavy bolted clamp similar in design to those used on the "F-4". The wire hauling lines were secured to the lower end of each one of the chains. The pontoon was to be lowered from the surface, using a 6-inch manila line at each end. Flooding of the pontoon was started as in previous practice with these pontoons on the "F-4" and the "U-111". The pontoon sank until it was practically awash, when it tended to submerge one end first. Some time was spent in juggling with the vent valves and the air connections on each end of the pontoon in an endeavor to level the pontoon and make it go down horizontally. This was not successful, as whenever the pontoon was made heavy enough to submerge as a whole one end always dropped first. As no more time was available for holding the pontoon at the surface, the weather getting worse, the pontoon was finally permitted to flood until it had negative buoyancy and was then lowered over the side on the 6-inch lines. As the pontoon went down a few feet it grew heavier and it became quite evident that the 6-inch lines could not hold the weight. To prevent the lines from breaking, an endeavor was made to pay them out fast; but in spite of this, first the line on the after end and then the line on the forward end of the pontoon broke in quick succession; later it was found that the pontoon had descended to a depth of about 50 feet when this happened. The pontoon thereafter fell freely to the bottom. Fortunately the "Falcon" was being held clear on one side of the submarine and the pontoon landed away from the submarine about 50 feet on the starboard quarter. The hauling wires with which it had been expected to guide the pontoon in position against the submarine had slacked off and fouled themselves around the submarine. After some days' work these wires were finally cleared and the pontoon was blown dry and brought to the surface. It was evident that the methods previously used in lowering and handling pontoons in shallow were not applicable in the open sea. The "Falcon" proceeded to Narragansett Bay where, in shallow water, using another pontoon, an attempt was made to lower evenly. It was again demonstrated that as soon as the pontoon had taken in enough water to submerge, between the loss of external water plane and the free water surface inside the pontoon (the pontoon at this time being two-thirds full of water), it retained no longitudinal stability, and the slightest inclination toward one end or the other would cause that end to drop and the water on the inside to flow to that end and make the pontoon go down one end first. Two solutions seemed possible; one was to allow the pontoon to flood completely at the surface and provide means of lowering it which could stand the full load of ----------------------------------------------------------------------- Page 23 40 tons. The second was to discover at what point the pontoon had taken in sufficient water to reduce its internal free water somewhat and consequently its lack of stability. If the pontoon were held reasonably level by the lowering lines, one end would not have a tendency to float up while the other end dropped and took all the load. It was felt that if such a condition could be found the pontoon could be flooded to that condition, the flood valves closed with the pontoon slightly submerged, and the pontoon then lowered. After some calculation and considerable experiment in Narragansett Bay, it appeared that with a negative weight of the pontoon of 10 tons the internal free water plane was sufficiently reduced to make the pontoon reasonably stable provided it was not permitted to exceed a moderate inclination. To handle the weight of 10 tons there was required a large factor of safety for dynamic conditions and for the probability of exceeding the designated weight while flooding. It appeared that nothing less than a 12-inch manila line would be satisfactory. By this time it was too late in the season, however, to do anything further about lowering pontoons alongside the "S-51". Meanwhile the mate to the first pontoon lowered, which had been moored to the buoy near the wreck on the day of lowering the first pontoon, was torn away by a bad storm and washed ashore about 30 miles away on a beach in Buzzards Bay. An independent expedition was sent out on the "Sagamore", which after some difficulty managed to pull the pontoon down the beach and float it again, where it was taken back to Newport. After the middle of November the weather became so bad that diving was possible only at infrequent intervals and the water became extremely cold. From the 21st of November until the end of the month diving was impossible altogether until the 30th of November when an attempt was made to dive. On this occasion, of three divers sent down two had to be hauled up because their air hoses froze up with ice from the moisture in the air being pumped down to them and completely cut off their air supply. At the same time only 4 divers out of 10 who started the job were still in good condition for work. It appeared that operations could not be continued successfully. An attempt was made to hire civilian divers to augment the force, but only three men were found who were willing and qualified to work on the job, except those of the wrecking company which had handled the rescue operation originally, and the latter were not employed. Considering the unsuitability of the weather, the impracticability of being able to work more than 1 day in 10 or 15, and the lack of divers, it was decided, on December 6, to suspend operations for the winter and all vessels of the salvage squadron proceeded to their usual stations. The mooring buoys were removed by the Lighthouse Service and two marker buoys, one can buoy and one lighted buoy, were left to mark the position of the wreck. The pontoons were left moored to the docks at the torpedo station, Newport. Before the shallow-water divers who were attached to the "Falcon" temporarily were detached and sent to their permanent stations, all of them, about 20, were put in the recompression chamber on the "Falcon" and the pressure was run up to 80 pounds, being the equivalent of about 180 feet depth of water. As a result of this pressure test, it was found that 12 of the men were capable of standing the pressure and appeared suitable material for deep-sea divers. The diving personnel on the "Falcon" scattered to their regular stations with the exception of the few men who were kept at New York to overhaul diving equipment during the winter and with the exception of Chief Torpedoman Kelley, who was retained as an instructor for the diving class which was immediately started, using the 12 men just selected. During the months of December and January these men were given daily work in a diving tank at the navy yard, New York, where they were required to use air tools of every description and do various jobs under water on pipe joints, cutting out rivets, and handling weights, the idea being to make the men thoroughly familiar with tools under water and to get them into ----------------------------------------------------------------------- Page 24 the habit of working under water without conscious effort as regards the proper adjustments of their diving rig. In the meanwhile a series of experiments was also carried on looking toward the development of a practicable under-water cutting torch, the torch previously available for use by the Navy having failed to operate on every occasion during the fall operations when it was tried. The torch experiments were carried out under the direction of Lieut. Commander Edward Ellsberg, who at the same time took the diving course with the other shallow-water divers. Meanwhile considerable attention was given to the method of rigging the "Falcon" for lowering pontoons, and a careful mathematical investigation was made of the stability conditions of a pontoon while being flooded on the surface and while being lowered. At the end of January the members of the diving class were considered sufficiently trained and were sent to the south to join the "Falcon" again for the purpose of actually diving in deep water. Unfortunately, the operating schedule of the fleet was such that during the first month that these men were aboard the "Falcon" no opportunity whatever arose to permit them to dive. As a result of this condition the men were all returned to the navy yard, New York, about the middle of March, where their training in the tank was resumed, followed shortly by diving in the basin of the navy yard where, on account of the mud bottom and the opacity of the water, diving conditions were somewhat harder than in the tank. About the middle of April the diving squadron was reassembled at the navy yard, New York, and all equipment which had been landed was taken aboard. All divers were recalled from their permanent stations and rejoined the "Falcon". The total diving force with which the expedition was equipped at the start of the spring operations was 25 men, of whom 10 were the original divers, 12 were members of the new diving class, 2 were divers from the fleet not previously available, and 1 was the yard diver from the navy yard, Boston. The "Falcon" sailed from the navy yard, New York, on April 23, 1926, and proceeded to Narragansett Bay, where the next three days were spent practicing on sinking a pontoon in deep water. It was found that the calculations were correct and that a pontoon flooded down to a negative weight of 10 tons could be lowered slowly to the bottom, held at any depth desired, and finally placed in any position required before actually landing. The total time taken in lowering the pontoon could be indefinitely extended, and in practice a pontoon was held for periods of over 30 minutes. By marking the 12-inch lowering lines with distinctive marks, at each fathom of their length, it was possible to maintain the pontoon in a horizontal plane at all times during lowering. To accommodate the wire hauling lines which were required around the submarine, the bulwarks of the "Falcon" were cut away in two places on each side and new steel chocks made on the "Vestal" were installed. At the same time all members of the new diving class were given an opportunity to dive in 130 feet of water and work on the pontoon as it was landed on the bottom. The new divers all passed this test in deep water satisfactorily with the exception of one man, who had trouble clearing his ears and who was unable to stay on the bottom as a consequence. The underwater cutting torch was also tested out on the bottom in deep water satisfactorily, a steel bar 3.75 by 3.75 inches in section being rapidly cut. Having made sure that practicable means of lowering pontoons was available, the "Falcon" sailed on April 26, 1926, from Newport for the scene of the wreck. Arriving at its approximate location it was found that the two marking buoys which one week before had been sighted in proper location and close together were now separated by a distance of over 5 miles. As the weather was hazy at the time, it was not possible to determine by sights of lighthouses on the horizon which buoy was correct, if either of them was. An attempt was made to get radio compass bearings from stations in the vicinity, but these plotted about 3 miles away from each buoy. Assuming that the more northerly buoy was probably correct, sweeping was started by the "Falcon" in its vicinity, but no results were obtained that day. ----------------------------------------------------------------------- Page 25 The next day the "Vestal" arrived. With clear weather it was possible from the high bridge on the "Vestal" to sight three lighthouses and get an accurate fix of the northerly buoy. Compared with the original fix of the wreck obtained last fall, the wreck appeared to be about one-quarter of a mile west of the position of this buoy. Sweeping was consequently concentrated in this area, using grappling hooks. Late in the afternoon of the second day, one of the grappling hooks made a hard strike and a diver descending the grappling line found himself on the deck of the submarine. The grappling line was immediately cast loose from the grapnel and made fast to the submarine, after which the "Falcon" replanted the moorings in the same locations as during the fall operations. An inspection of the submarine boat showed no change in position from that when last sighted in November. The vessel had not settled any deeper in the bottom nor changed her list or trim, nor had there been any silting up around the hull. There was a slight marine growth over parts of the hull, but no great amount. Diving was prevented by rough weather during the next few days, but on the 30th of April, 1926, the weather was fair and the "Falcon" took position for lowering the first pontoon on the port quarter of the "S-51". Divers passed two small reeving lines under the stern on which were hauled through heavier manila lines and then a pair of 1-inch wire lines for hauling. These wires were secured to the lower ends of a pair of chains suspended through the pontoon hawse pipes, the chains being held on top of the pontoons by bolted clamps. Unfortunately, just after the pontoon went awash and before the flood valves had been closed, a splice in the wire strap holding the forward lowering line opened up under no special strain, and as a result of this accident the pontoon tore free and sank to the bottom, end on. As before, the "Falcon" was holding herself a little clear to port, so the pontoon in landing hit the bottom about 30 feet outboard of its designated position. The next day this pontoon was lightened up on the bottom by blowing out some of the water and was then hauled over to its position against the port quarter of the submarine. The wire hauling lines, having pulled the chain under the submarine, were rove through the hawse pipes of the second pontoon on the surface and this pontoon was then lowered on the two wires as guides. This pontoon was sunk somewhat lighter than intended, with the result that it landed alongside the submarine standing on its end rather than horizontally. As a result, one of the chains unrove through the hawse pipe. The matter was rectified by lightening the pontoon and bringing it to the surface, after which it was resunk. The second time it went down evenly and landed in the horizontal position as intended. The torch was then used for the first time in actual work on the job. The chains were hauled through the pontoon hawse pipes for a predetermined amount after which a stud in the link just above the hawse pipe was burned out of each chain and a nickel steel toggle bar 40 inches long and 3.75 by 3.75 inches in section was slipped through the chain and locked in position by a long half-inch bolt on each side of the chain link. (See fig. 9.) When this had been completed, the lowering lines were cast loose and the hauling wires were burned free of the chain and taken up. Meanwhile work was recommenced on the forward tunnel at frame 46, using the same size hose and nozzle as during the fall operations. A special inclinometer was made and taken down by one of the divers to measure the heel of the ship. A measurement was taken just forward of the conning tower and it was found that the "S-51" was listed over exactly 11.5 degrees to port. Work was now commenced on lowering a pair of pontoons on the bow, and reeving lines were passed under that part of the bow which was clear of the bottom. The forward reeving line, however, slipped out three times from under the ship owing to the rise of the forefoot. To remedy the situation Chief Torpedoman Kelley went down with the torch and reaching down 2 feet through a hole in the deck burned in half the wire holding the mushroom anchor. This ----------------------------------------------------------------------- Page 26
Figure 9
Figure 9: Bow pontoons. (Note nickel-steel toggle bar through link,
locked in position by 1/2-inch bolt each side.)
----------------------------------------------------------------------- Page 27 dropped the anchor from its place under the keel forward until it rested on the bottom, and in this position its shank, which still protruded into the hawse pipe, formed a trap behind which the next reeving line was passed and which prevented any further slipping out of the reeving lines. A pontoon was then rigged and lowered on the starboard bow in the same manner as those at the stern, and later in the same day another pontoon was lowered on the port bow. This was the first instance in which two pontoons were lowered in one day. These pontoons were secured by the divers in the same manner as those at the stern. During a storm early in May which came up during the night while the "Falcon" was lying moored over the submarine, one of the tugs, the "Iuka", drifted down on the "Falcon", and in getting clear the "Falcon" was compelled to cut most of her mooring lines, while the "Iuka" fouled her anchor in the bow pontoons on the "S-51" and was then forced to slip her cable. As a result of this, when the storm cleared considerable work was necessary to clear the fouled anchor and chain, to replace the descending lines which had been carried away, and to recover the lost mooring lines. On May 11, 1926, after the longest dive made, up to that time, 2 hours and 20 minutes, Eadie and Wilson working from opposite sides of the submarine both managed to drive their tunnels down to the keel of the submarine. Eadie pushed his foot under the keel to the other side to which Wilson secured a small line which Eadie hauled back with his foot and the first line was thus passed. A second reeving line was then pulled through, tied to the first line, and the two lines cleared of each other. On this same day 16 divers made a dive, being the maximum number of divers who went down on one day during the entire operation. On the next good day preparations were made to sink a pontoon on the port side abreast frame 46. Manila lines, 4-inch, were rove through the tunnel as hauling lines for the 1-inch wires. The wires were hauled down and secured to the chain hanging from the pontoons at the surface as usual. However, when all was in readiness and the 4-inch lines were hauled in to pull the wires through, one of the 4-inch manila lines was cut in half by the starboard bilge keel of the submarine when apparently running freely and without strain. The remainder of the day was spent in an endeavor to recover an end of this line but unsuccessfully. Meanwhile the weather changed and in a heavy sea the pontoon alongside became a serious menace and had to be cast loose from all lines and towed away. The next day it was found that one wire reeving line was fouled on the bottom and had to be cleared. To replace the line which had been cut it was necessary for the divers again to work through the tunnel and push a new line through, this time with a small pipe 8 feet long as a lance to carry it through under the keel. After some difficulty this was accomplished and a new 1-inch wire was rendered through. About 7 p.m. work began on sinking a pontoon on the port side. The pontoon was lowered successfully and was held at a point about 30 feet above the bottom, where the chain should have started to render through under the keel; but in spite of the maximum pull that could be given on the hauling wires by the "Falcon", the chain failed to render. Two heavy manila hawsers, 6-inch and 8-inch, were then secured to the wire hauling lines, and the ends of the hawsers sent over to the "Iuka", which was anchored about 100 yards broad off the beam, with the idea of getting a flat hauling lead which might make the chains render more easily under the keel of the "S-51". The "Iuka" heaved on both lines with her quarter-deck winches but without result. A diver was sent down to inspect conditions on the bottom and found the pontoon in its proper position about flush with the deck of the submarine and with the two wires on the opposite side of the submarine leading out flat and taut toward the "Iuka", but no chain was through under the keel. The diver came up and the "Iuka" then started ahead on her main engines gradually working up to full power, but in spite of this she was unable to haul the chain through. 45129-27--3 ----------------------------------------------------------------------- Page 28 The "Iuka" then slacked off the 6-inch manila line to get her entire hauling strain on the 8-inch line. After about five minutes under these conditions, the 8-inch line parted, throwing the entire strain suddenly on the 6-inch line, which also parted. As nothing more could then be done, the pontoon was lowered the remainder of the way to the bottom. During the following two weeks various methods were tried to haul the chains under the keel, including the placing of tapered wood blocks under the keel as fair leaders. Various attempts were made to clear the first link from the keel with crow-bars and several more attempts to haul the chain, using the "Iuka" to haul. In every instance whenever a strain came on the chain the first link would be brought hard up against the angle of the box keel, which hung about 16 inches below the hull, and the chain would then bind securely and could not he freed. Owing to the close quarters, a diver having to work in a small tunnel and in an extremely difficult position, the divers were never able to clear the chain. Finally, after the last attempt at hauling had resulted in tearing the quarter deck winch out of the "Iuka", it was concluded that a different method would have to be used, and the pontoon was brought to the surface, together with the chains. Having done this, the position of the wire hauling lines through the tunnel was carefully checked, after which the chains were removed from the pontoons. The eye of the first wire hauling line was shackled in to the end of one of the chains, using a Boston design detachable link for a shackle. Over the end of the wire was then fitted a special steel cone which gave a smoothly faired surface from the 1-inch wire around the outer diameter of the first link, with no angles to catch on the box keel. With this rig the first chain was independently lowered and passed through the tunnel under the keel without difficulty, where it was equalized with the same amount of chain on each side of the hull. The second chain was lowered in the same manner. There being no pontoon to contend with at this time, the divers were able to work on the bottom while the chains were being lowered and to guide the chains through the tunnel. Having secured the chains, they were then held up as shown in Plate 3, and a pontoon was lowered on the port side until it was about 20 feet clear of the bottom, in which position a pair of divers went down on the pontoon, checked its location, and then rode the pontoon the rest of the way to the bottom. Here the divers cast off all lines and inserted and secured the locking hers. The mate pontoon, meanwhile, was brought out from Newport and was lowered and secured the same day. This method of handling the chains and the pontoons was seen to be considerably superior to the manner in which the pontoons had been handled before - that is, with the chains lowered with the first pontoon. The reason for the original rig was that the only means of securing the chains in the hawse pipes of the pontoon was by means of a steel clamp made in two halves, weighing about 300 pounds, and secured by four 1.5-inch bolts. Such a rig was extremely difficult to handle and probably could not be secured without auxiliary rigging in the way of chain falls or lines to the surface. In shallow water, where a diver could work all day, such means were available. In deep water, where his time on the bottom was very limited and extreme exertion was likely under the heavy pressure to affect him unfavorably (as actually happened in the case of Frazer), it was considered best to cut this work in half by securing the pair of chains to the first pontoon by making up the clamps on the surface, leaving only the work of clamping the chains to the second pontoon. However, when the use of the torch made possible the removing of studs and the insertion of a locking bar at any desired point, it became possible to eliminate the clamps. This was first done only in the case of the second pontoon of each pair, but was obviously applicable to both pontoons, and the further use of clamps was wholly discontinued. It might casually have appeared that all studs might have been burned out on the surface originally, but there was considerable danger in such a practice of the chain kinking up if the studs were missing while the chain was being handled under the submarine boat, and as such a kink would insure ----------------------------------------------------------------------- Page 29 the parting of the chain in a load, it was considered safer to burn off the studs where wanted, rather than taking a chance on burning out a large number to insure getting an open link on the hawse pipe. Early in the spring operations, on May 11, 1926, work was started to seal off the ventilation main leading to the C.O.C., the engine room, and the motor room. The motor room was first attempted, as the ventilation main leading to this compartment could be most readily reached of the three compartments. The deck of the submarine just forward of the motor room was removed, and the deck beams covering the ventilation main were then burned clear by Chief Torpedoman Kelley. Work was then started on unbolting both flanges of a section of this 12-inch main for the purpose of blanking it off on the motor room side. After some days all the bolts were removed from the after flange, but several of the bolts in the forward flange were practically inaccessible due to their location close alongside the engine air induction valve. After several attempts by divers to get at these bolts, it was determined, after an inspection by the salvage officer, that there was no need to unbolt both flanges. Consequently, a wire line was tied around the pipe near the unbolted flange and on heaving from the "Falcon" the pipe was torn out of the ship, the forward flange breaking off the pipe while the unbolted flange came clear. The joint left in the ship was then scraped clean by divers and a new blank flange, which was immediately made, was securely bolted on. (See figs. 10, 11, and 12.) After blanking off the ventilation main to the motor room, air was turned on to blow it dry, and divers reported a good stream of water being discharged through the nonreturn drain line into the engine room. After blowing about half an hour, a stream of air bubbles came to the surface over the forward end of the motor room. A diver's examination showed that a butt in one of the upper strakes of the shell on the starboard side was open over a sixteenth of an inch (the vessel was single hull throughout the motor room) and a steady stream of air was escaping from a length of about 2 feet at the upper portion of the butt. It was evident that the leak was due to defective workmanship originally, as there was no evidence of damage or strain in that vicinity. Apparently a poorly fitted and wide-open butt had been made tight by splitting the edges of the plates and bringing the feather edges of the two plates together. Between corrosion and an internal pressure part of the feather edge had now given way, causing a bad leak. To remedy this, Eadie and Eiben were sent down with strings of lead wool made by twisting together lengths of fine lead fuse wire. They calked this lead wool into the open butt until the space between the two plates was completely full, using ordinary hand wood calking tools for the job. Eadie then took a standard air-driven chipping and calking hammer and, using a fuller, proceeded to recalk the plates themselves in the usual manner. This calking job was complicated by the fact that each time the trigger was pulled the stream of air escaping from the hammer set up such a cloud of bubbles in the water that it was no longer possible to see the work clearly and the diver had to be guided by his sense of touch and general skill. When the air pressure was put on the compartment, the part of the butt which had been recalked was found tight, but new leaks had developed over the remaining length of the butt (as is usual even in surface work) and Eadie was compelled to recalk the entire butt with the air hammer. This effectively stopped all leaks in this location. In this calking job, the surface air pressure was kept at 150 pounds. The net pressure at the hammer was between 80 and 90 pounds, taking account of hose friction. On examination of this job later with the vessel in dry dock, the calking could not be distinguished from the other calking done while the ship was building. Air was again turned on the motor room and the water driven down a few feet farther, when another stream of air bubbles appeared, this time near the stern of the submarine and aft of the motor room itself. On a diver's examination of this new leak it was found that about ----------------------------------------------------------------------- Page 30
Figure 10
Figure 10: Section of 12-inch air supply line to motor room,
removed by divers.
----------------------------------------------------------------------- Page 31 10 feet from the stern there was a large dent in the top of the boat in way of the tiller room; in this dent one rivet was completely pulled through the shell and the adjoining rivet was partly pulled through. Air was escaping freely from these two places. The tiller room was a small compartment abaft the motor room, connected with the latter by a manhole about halfway down the bulkhead. It was evident that this manhole was open (which was not known definitely before) and that the air in the motor room, having driven the water down to the level of the top of the manhole, was now escaping via the tiller room leaks. To seal the leaks, a lead plug was cast to the size of the open hole and fitted with a tapered oak cone driven into its base to act as an expander. When this plug was inserted in the hole, the wood plug brought up against the frame bar inside, and resulted in spreading the lead plug inside the hole while the lead was being hammered down by the diver outside. The result was a firmly secured flush lead plug which was entirely tight and proof against jarring loose or being torn away by towing lines during later salvage operations. To seal the partly pulled rivet (the rivet itself was solid and in no way loose) the diver drove soft pine plugs into the open parts of the countersink so that the wood was firmly jammed in; then trimmed the wood off flush to prevent lines from tearing out any of the wood filling. This rivet showed pinhole leaks afterwards through the pine, but they were of no consequence. The reason for the dent in the shell was never definitely discovered. The location was far removed from all collision damage and could not have been a result of the submarine hitting the bottom. It is believed that one of the vessels engaged in the original rescue operations dropped anchor over the "S-51" and that the anchor landed on the stern, dented it in, and bounced clear. The work of sealing the motor-room leaks was completed early in June, and the pressure again applied; No further leaks appeared on the outside of the vessel in the vicinity of the motor room, but when the water level inside had been forced down to the point where it reached the shaft stuffing boxes in the bulkhead between the engine and the motor rooms, air started to escape in considerable quantity through the stuffing boxes into the engine room. At this point, the motor room was about two-thirds dry. It was only by sending all the air the "Falcon" could supply into the motor room that it was possible to drive the water lower; the moment blowing ceased, the air below the shaft lines would escape and the motor room refill to this level. Inquiry of the officers on the "S-50" brought out the information that on all submarines it was impossible to keep interior shaft stuffing boxes tight as the vibration due to the close proximity of the engines quickly wore the packing to a considerable clearance. No attempt was made to tighten up the stuffing boxes, as they were practically inaccessible to a diver; further it was considered that when the engine room was sealed up and blown dry, air leakage around the shafts would be of no consequence. If, however, on this job the engine room, instead of the battery room, had been the bilged compartment, this leakage around the shafts would have been a serious matter. Having sealed up the motor room ventilation valve by blanking it off, consideration was given to the same procedure for the ventilation valves in the engine room and the C.O.C. The main engine air induction valve, having had its bonnet previously removed in the process of closing the valve, was quickly sealed from the outside by bolting a steel strong back across the valve body and pressing a heavy oak block firmly down on top of the valve disk to hold it on its seat. The battery exhaust valve which discharged into the engine room and the ventilation supply valve which opened into the C.O.C. presented different problems. Both valves were closed by their internal locking gear, but it was now known that this was ineffective. It appeared possible to get at a section of the battery exhaust main in the superstructure and ----------------------------------------------------------------------- Page 32
Figure 11
Figure 11: 12-inch supply pipe to motor room
sealed by cover plate installed by divers.
----------------------------------------------------------------------- Page 33 blank it off, though with more difficulty than in the case of the motor room. The line to the C.O.C., however, was so covered by other pipes and buried inside the structure of the periscope shears as to be practically inaccessible for blanking off from the exterior of the boat. A start was made on removing the deck over the engine room, to get at the battery exhaust main at the same time as work was proceeding on unbolting the ventilation main to the motor room. The latter operation, while successful, took so much time that work was suspended on the engine room and a search made for methods requiring less diving. It was noted that each one of the compartment ventilation flapper valves had a 1.25-inch drain valve screwed into its body just above the flapper disk. In the case of the motor room, such a drain valve had previously caused considerable trouble by leaking and had to be plugged. It now appeared that through these drain-valve openings a cement mixture might be injected into the ventilation-valve bodies on top of the closed flapper valves, which on hardening would permanently seal the valves closed. To carry out this scheme, a special elbow, to get into a confined space, was made on the "Vestal" to suit the drain-valve connection in the C.O.C. This was tried on the "S-50". The door from the engine room to the C.O.C., which had been closed during the fall operations, was undogged and reopened after some difficulty (the gasket stuck). Eadie, Wilson, and Eiben then proceeded to install the cement connection, but found conditions on the "S-51" sufficiently different to prevent installation, as less clearance existed on the "S-51". After modification, the fitting was finally installed, but with great difficulty, as the water in the C.O.C. was so black from particles in suspension and from dead water throughout the winter that, even with a submarine lamp, vision was possible not over 6 inches, and the work had to be done by sense of touch in a cramped space. Conditions were so bad that the lamp itself was invisible unless held within 6 inches of the diver's faceplate. Meanwhile experiments were being carried out on the "Vestal" to determine the best cement mixture. The primary requisite was to obtain a cement that would harden under salt water; the secondary problem was to obtain a cement mixture that would flow freely through 250 feet of 1.25-inch-diameter hose, pass through a number of valves and fittings, and that would still not be too liquid to set firmly. Several brands of standard Portland cement were experimented with, but their hardening qualities under salt water, except in very thick mixtures, was extremely poor. A special bauxite cement, furnished by the Atlas Lumnite Cement Co., was tried and found to be extremely satisfactory. A neat mixture of two parts of this cement to one part of water by volume was found to be thin enough to insure flow, while its setting properties under salt water were excellent. The use of Lumnite cement in this proportion is strongly recommended for all future salvage jobs where cement is required. For injecting the cement, the "Vestal" made a steel tank tested to 200 pounds, with a quick-opening handhole on top for filling, test cocks on the side for determining the cement level, and a discharge connection tapering from 3 inches to 1.25 inches at the bottom. Using 200 feet of hose leading to the bottom of the sea into a piece of 12-inch pipe, a full-scale experiment was carried out on the "Vestal" to test the apparatus and the mixture, the cement being forced out by 150 pounds of air pressure on the tank. About five hours after injection, the pipe was hauled up and the cement was found already to have set moderately hard. It was kept submerged in salt water and by the next day had set solidly. The hose and the apparatus were taken to the "Falcon", where the divers ran the hose inside the submarine and connected the last short length to the fitting on the C.O.C. ventilation valve. When all connections had been made, the cement was mixed on the "Falcon", and two charges forced through, being about four times as much cement as was required to fill the valve body. The divers then uncoupled the hose section near the C.O.C., sent up the remainder of the hose, and a few days later closed and dogged down the door to the C.O.C.

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