This report provides some interesting personal and background information and a detailed description associated with the docking of the Nathanael Greene (SSBN-636). After a break in Service of 5 years, and because I had previously been the Deputy Dockmaster of AFD 60 from 1976-79, I was offered the opportunity to resume my career to fill a rather sudden and unexpected vacancy on the dock, so returned to Faslane in April 1984 for a second period as the Deputy Dockmaster. In mid-August the Dockmaster was out of area on leave and I was asked if we could dock an American SSBN in AFD 60. Apparently the Nathanael Greene had lost her propeller somewhere in the Irish Sea and was creeping back to the Clyde areas at about 3 knots using her secondary propulsion motor, a transit of about 5 or 6 days. The U.S. docking facility in the Holy Loch was already fully committed and they needed a suitable alternative close at hand, could we help? AFD 60's next planned docking was over 2 weeks away, so provisionally, yes we could.

The Nathanael Greene was similar in design and dimensions to our own Polaris boats so if it would fit our SSBN 'docking cradle' we would be able to help but first we needed the submarine's docking plan to confirm this. Unfortunately this was onboard the boat so was not available but a generic set of 'class' drawings was held at the Holy Loch and were sent over. The good news was that the outer diameter along the parallel length of the hull was identical to our boats, so the centre-line and side blocks forming the major part of the docking cradle would fit. The not so good news was that the change of shape up to the bow and stern was significantly different to our boats and caused a few headaches ~ there needed to be an incremental increase in the height of the centre-line blocks over the length of the bow section by up to 8 inches and for the stern section by 12 inches. This would ensure that these blocks fitted the hull and were able to bear the loading of the submarine. After measuring the differences in hull diameter forward and aft from the class docking plan, we then increased the depth of packing under the specially shaped capping for each block and were able to create what seemed like a good shape. Then just to make life even more exciting, the day before the docking, we were advised that there was an optional sonar array the boat might have fitted in way of the keel just aft of the bow ~ under the circumstances we had no option but to leave out a centre-line block; in the event it turned out that this particular sonar array was not fitted but better safe than sorry.

Prior to any docking or undocking in AFD 60 the normal procedure was to visit the boat with accurate scale models of both the dock (with capstans and bollards positions) and the appropriate class of submarine, in order to run through the procedure for the benefit of the Commanding Officer and to instruct the Casing Officer with regard to the movement of wires, ropes etc ~ this was vital as any misunderstanding in handling the wires or ropes could lead to losing control of the submarine, which, within the very narrow confines of the floating dock could prove to be very embarrassing. It was not possible to have this pre-docking meeting for the Nathanael Greene as it was being brought directly to the dock by tugs as soon as it arrived in the Clyde. It is worth mentioning at this point that the Casing Party for a RN boat was a Seaman Officer plus 6 ratings, usually 4 forward and 2 aft. The submarine would be at damage-control state condition Zulu (emergency stations) with the remainder of the crew closed up to minimize flooding or damage in the event of an accident. However, the U.S. navy do things differently, as we soon found out.

At about 0630 on the day of docking an SSBN, AFD 60 would be flooded down to 'deep sink', an evolution that took about 90 minutes. The dock was ready when the RMAS tugs Deerhound and Elkhound brought the Nathanael Greene to the entrance of AFD 60, when the wires from the dock's number 1 and 2 capstans were passed over to be placed onto the forward cleats as shown on Graphic 1. As the docking officer, I can be seen on the top of the dock 'valve house' wearing a black bowler hat ~ a historic tradition borrowed from the naval dockyards. Also, at this time, the first pair of nylon rope 'springs' were connected in order to help control lateral movement and act as brakes to gently slow the boat if necessary (Graphic 2). Apart from those below on watch the remainder of the crew were on deck, also, the boat's hatches were open to allow for the easy escape of those below if an 'incident' occurred, all of which seemed like a recipe for confusion.

The procedure to bring the submarine into the dock would be to use wires from No's 5 and 6 capstans at the far end of the dock to pull the boat slowly into the dock, whilst wires from capstans 1 and 2 at the dock entrance and then wires from capstans 3 and 4 amidships on the dock would be used to maintain the lateral positioning. The previously mentioned pairs of nylon rope 'springs' were also available to help control lateral movement but more particularly to act as brakes to gently bring the boat to a halt if necessary. Trying to stop the submarine by using the capstan wires would usually result in a broken wire, which is time wasting as it has to be replaced and could be embarrassing. Tugs remain at the stern to keep the boat aligned as it is being drawn into the dock and would be released once the wires from 1 and 2 capstans had been transferred aft and have control of the stern. Graphics 3, 4, 5 and 6 show the Nathanael Greene at stages of being moved steadily into AFD 60.

Once the submarine was fully in the dock and 'centred' over the docking cradle, the dock's pumping system was used to bring AFD 60 up under the submarine, which was trimmed down 12 inches by the stern, therefore touching the blocks aft first and then forward, at which point pumping ceases. Then royal navy divers were brought in to do a 'swim through', checking all the dock blocks and therefore assessing the fit of the boat in the cradle. For the Nathanael Greene this was excellent (much relief all round) so we moved on to the next phase, pumping up the dock a further 2 feet to put some weight on the blocks and then passing the shore-power cables to the boat. During this time the divers remained in the water, connecting flooding bonnets to specified salt water inlets and discharges to provide cooling water to/from the submarine's various vital systems. Once shore power was confirmed the boat's C.O. was told he could shut down the diesel generators ~ normally a straightforward procedure for UK boats ~ but US submarines apparently do things differently. To avoid any possible strains to the generator's crankshafts, that might be caused by stresses in the submarine hull, the marine engineer officer wanted the submarine to be afloat. One does wonder about the flexible mounts fitted to the generators, plus the fact that the hogging/sagging indicator on the dock was always maintained within strictly prescribed limits to reduce any hull stresses in the submarine to a minimum. Suffice to say, the CO realised our docking procedures were completely safe and told his engineer to shut down the diesels. With everybody happy the dock was pumped up to normal freeboard, the final services were connected and nuclear safety checks completed. What the U.S. personnel found so amazing was that the docking had been completed so quickly ~ from arriving at the dock entrance at about 0800 we were up and dry by 1230. Although this was the usual timing for one of our boats, the American dock in the Holy Loch would apparently routinely take 12 hours and up to 24 hours for a docking. However, that said, I believe that the new ship-lift facility at Faslane (that replaced AFD 60) can also take up to 24 hours for a docking! But that is another story.

Prior to the arrival of the Nathanael Greene at Faslane, the naval base engineers had obviously offered the Americans every possible support they may need, this included teams of scaffolders to erect staging around the stern ~ but all help was declined! Everything but everything needed for the boat's time in dock was flown in from the States; this included the scaffolding and scaffolders, engineers aplenty and various project managers and scientific types. It was quickly established that the shaft had broken, resulting in losing about a third of its length along with the propeller. I believe a spare propeller was available from the Holy Loch but the new shaft had to come from the States, however, the replacements were quickly obtained and fitted. Repairs were completed in about 12 days and the Nathanael Greene was undocked on 3 September 1984 (Graphic 7) and sent on its way rejoicing, as they say.

As a result of this incident, I believe that checks were subsequently carried out on the shafts of all U.S. and UK nuclear submarines and apparently incipient cracking was discovered in a number of other boats.

As an item of interest, I have included a photograph taken when visiting the area in September 2013, of AFD 60 flooded down to 'deep sink' with a nuclear submarine entering the dock.