OFFICIAL REPORT ENGINEERING REPAIRS
Enclosure to,“GENROY”S LETTER DATED 20th November 1942
No 2658/190)
“GLENROY”. TORPEDOING AND SUBSEQUENT REPAIRS.
15. Main Engines comprise of two sets of Burmeister and Wains, two stroke cycle double acting, Airless injection Engines, each having six cylinders, arranged in threes, with gear casing for chain drives to cam shaft and scavenger towers between. The diameter of the Main Cylinders is 620m/m. (24½) The stroke of the engine 1400m.m. (55”), diameter of crankshaft 485 m.m. (19”). The indicated horse power of each engine is 7500 and Brake Horse Power 6000. The weight of one cylinder unit with pistons, rods etc., is over 17 tons. The weight of the Scavenger Blower, mounted on the back of the engine is 21 tons. Two 7 ton cranes are fitted in the engine room above the cylinder tops.
16 Auxiliary Machinery – Description
Four Burmeister and Wain, two stroke cycle, single acting Diesel Engines of 450 Brake Horse Power driving 300 K.W. Compound wound dynamos, are fitted at the bottom level of the engine room. One Ruston and Hornsby Diesel Engine of 64 Brake Horse Power driving 40K.W. dynamo is fitted at the upper part of engine room for emergency. Thirty electric motor driven pumps, air compressors, refrigerator compressor are also fitted in the engine room mostly at lowest level. These vary in Horse Power from 1½ to 90, with twelve of them over 40 H.P.
17. All above auxiliary machinery, with the exception of the emergency engine, was submerged with main engines for four months to a depth of approximately …. Feet, with water level reaching to within four feet of top of main engine, the upper platform being awash. Following were also submerged: Large main switchboard and 5 sub-panels, many electrical instruments, 59 boxes of electrical of electrical spares, M section of D.G. Coil and all electrical mains etc.
18 Main Engines. The normal procedure for reconditioning of the main engine would be to remove the upper part of the engine casing and lift out the engine in sections for removal ashore where each part would have been stripped down cleaned and replaced. The crankshaft and bedplate could have been left in the vessel, but shaft would have been lifted and alignment checked after cleaning.
19. As lifting the machinery out of the vessel was impossible, it was necessary to dismantle and recondition it on board. Due to lack of space in the engine room, limited further by simultaneous work on Auxiliary Diesels and electrical machinery, only one engine could be dealt with at a time. Further to space to necessary positioning of the cranks, the cylinders had to be worked on in pairs, thus limiting the number of people employed on the work.
20 The engine room was pumped out on 27th March1942, approximately, and as water receded the stripping of valves, fuel pumps etc was commenced These pars were taken on the upper deck and immersed in large drums of oil to preserve them until they could be overhauled. Before dismantling of main engines could commence, it was necessary to recondition two electrical turning gear motors. These were done by Base Electrical Engineer’s Department. Meanwhile the engines were turned by hand ratchet, a slow and laborious business, but necessary if machinery was to be kept free. Some hundreds of lubricant and a quantity of penetrating fluid were used trying to prevent the rusting of working parts. In spite of these precautions the engines daily became increasingly difficult to move and by the time the turning motors were returned, it was only by overloading the latter 50% that the engines could be turned sufficiently for dismantling to be carried on.
21. Starboard Main Engine (April to September 1942)
It was decided to dismantle the starboard engine first, as, due to damage to one of the bearings of the port shaft, it was uncertain whether the shaft was bent. First one part, then another was disconnected to find where the stiffness existed. Main bearings, guides, connecting rod brasses were all slackened off. The thrust block was stripped and propeller shaft coupling broken. The huge scavenge blower, driven by chain from crankshaft was disconnected, but still the engine was most difficult to turn. Many days were lost PAGE MISSING FROM FILE
SECRET
From : Base Officer Alexandria
Date : 20th November 1942
To : Commanding Officer, H.M.S. GLENROY.
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With reference to your communication Ref. 2564/90 dated 22.10.42, herewith are my remarks in connection with the dismantling and reconditioning of the Main Engine and Auxiliary Machinery in H.M.S. GLENROY, for inclusion in your general narrative.
1. The situation that faced the Naval Base when the Engine Room was pumped out by 27th March, was how to recondition the Machinery for further use.
The Main Engines comprise two sets of Burmeister & Wain’s two cycle, double acting airless injection engines, each having six cylinders arranged in threes, with gear case for chain drive to cam shaft and scavenge blowers between. The diameter of the main cylinders is 620m/m. (24½) The stroke of the engine 1400m.m. (55”), diameter of crankshaft 485 m.m. (19”). The indicated horse power of each engine is 7500 and Brake H.P.6000. The weight of one cylinder unit with pistons, rods etc., is over 17 tons. The weight of the scavenger blower, mounted on the back of the engine is 21 tons. Two 7 ton cranes are fitted in the engine room above the cylinder tops.
The Auxiliary Machinery comprises of four Burmeister and Wain, two stroke cycle, single acting Diesel Engines of 450 B.H.P. driving 300 K.W. driving compound wound dynamos, are fitted at the bottom level of the Engine Room. One Ruston and Hornsby Diesel Engine of 64 B.H.P. driving 40K.W. Dynamo is fitted at the upper part of Engine Room for emergency. Thirty Electric Motor Driven Pumps, Air Compressors, Refrigerator Compressors are also fitted in the Engine Room mostly at lowest level. These vary in Horse Power from 1½ to 90, with twelve of them over 40 Horse Power.
All above Auxiliary Machinery, with the exception of the Emergency Engine, was submerged with Main Engine for four months to a depth of approximately 30 Feet, with water level reaching to within four feet of top of Main Engines, the upper platform being awash. Following were also submerged: Large Main Switchboard and five sub-panels, many electrical instruments, 59 boxes of electrical of electrical spares, M section of D.G. Coil and all electrical mains etc.
The normal procedure for reconditioning these very large Main Engines and numerous auxiliaries would be for the vessel to proceed alongside a wharf under cranes of sufficient capacity to remove the large weights involved, the removal of necessary engine casing and lift out the Main Engines and auxiliaries in sections for transport to a fitting shop for stripping cleaning and refitting as necessary. As no refitting shops of the capacity necessary for this work exist in Alexandria and no berths with cranes with the necessary capacity, it was proposed that the ship be towed away to a ship repair yard, where such facilities existed.
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Unfortunately at the time this was under consideration, the Far Eastern Situation prevented this procedure being put onto effect. At the same time, the first part of the problem i.e. saving the machinery from becoming completely rusted up after such a long immersion had to be tackled without delay, and it was decided to endeavour to do this in Alexandria with the very limited facilities that existed. One further consideration it was found that no berth alongside could be spared, nor on account of great pressure of the naval repair work in hand could Dockyard labour be arranged to undertake this very large job. At this point the Engineer Officer of the shi, who had already started the work of stripping as the water level in the Engine Room went down, In consultation with the F.E.O. and B.E.O., considered that as the work of saving the machinery would admit of no delay, and with what assistance that could be provided from the base, he would be willing to undertake the work on his own responsibility, and this procedure was agreed to. Arrangements were made with a local contractor to provide the Engineering Officer with as many Greek Fitter as he could employ on board, and the work commenced along these lines. That is to say, apart from contact provision of the necessary labour and the undertaking of the necessary shop repairs, as the engine parts were examined, the entire work has been done by the Engineering Officer and his staff. Due to the limitation of work space in the ship and the fact she was at a buoy for the first three and a half months, the work necessarily proceed slowly.
As all the electrics required reconditioning, and before the work of stripping the Starboard Main Engine could proceed effectively, on account of the constant necessity for turning the main engine, this work had to wait until the Turning Motors had been completely reconditioned, during which the time Fuel Pumps, Fuel Valves, Relief Valves were removed and taken on the upper deck and immersed in large drums of oil until they could be completely overhauled. In spite of the use of some hundreds of gallons of lubricating and penetrating fluid, which were used on the engine to prevent rusting of working parts, the daily turning by hand while Turning Motors were under repair became increasingly difficult and the resistance to turning by hand increased to such an extent, that attempts had to be abandoned at least a week before the first Turning Motor was ready for installation. When the turning motor was installed, it was necessary to disconnect first one part and then another to find where the stiffness existed. Main Bearings, Guides, Connecting Rod Brasses were all slackened off. The Thrust Block was stripped and the propeller shaft coupling broken. The very large Scavenge Air Blower driven by chain from the crank shaft was disconnected but still the engine was most difficult to turn. Many days were lost because the engine could not be turned into the desired position for dismantling the various pistons, rods etc. It was finally discovered that the main course of the trouble was in the crank shaft bearings. A further trouble was in the bushed guiding twelve large valve spindles. Some of these spindles had to be pulled out by using the tackles connected to the 7 ton cranes. Some idea of labour involved may be given by stating that the spanners required for working are of such a weight that they must be handled with blocks and tackle to slacken the nuts; 3 ton chain tackles are used to assist the 1 cwt. Ram against the spanner.
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Dismantling of Scavenging Blower was very complicated and seemingly impossible task, owing to the restricted space behind the Main Engine. By removing numerous 3 ft. diameter exhaust pipes and using dozens of Chain Blocks and heavy wire slings, the 2½ ton sections were lowered to the floor and piled on top of each other where the long business of cleaning and polishing was carried out. Meanwhile on deck, three large vice benches had been constructed and a large squad of Greek fitters and labourers under supervision of Engineering Officers were engaged in stripping, cleaning and re-assembling all parts sent up from below.
Starboard Engine was ready for basin trials by 8th October 1942. Port Engine in meantime had become too stiff to move and would be dealt with as necessary later during passage.
Auxiliary Machinery. – Nos. 2,3 & 4 Auxiliary Engines were simultaneously being overhauled. This work was in itself a major operation, for two engines had been running when Engine Room was submerged and Connecting rods were bent and Cylinders and Pistons damaged. Every minor part was required to be stripped and cleaned.
Auxiliary Pumps were all completely overhauled and electric motors for same removed to shore for reconditioning by Base Electrical Engineer.
Pipes and Valves. – A number of large cast iron pipes etc. were damaged by shock and these required removing and renewing or repairing. Vessel had to supply own light and power by means of a 40 K.W. diesel generator, later assisted by a second machine loaned to Vessel by the Base. One old Worthington Steam Pump was supplied by Salvage Department and fitted to existing Pipe lines in Engine Room for pumping of tanks and bilges and supply of water to fire mains. Steam was supplied from boiler in No. 1 Hold.
General Observations. – As has already been stated, the entire work has been carried out under the sole responsibility of the Engineering Officer of the ship. In my opinion, on account of the very large size of the work and the difficulties that had to be overcome throughout its entire execution made it a work of total considerable difficulty, I consider this very big repair job as carried out as unique in the history of large engine repairs, and for this reason I strongly recommend that the report in the way of which it was effected should be submitted to Their Lordships for consideration.
I consider also that this unique job could only have been carried out by exceptional men, and would further recommend that as the credit for its successful completion lies soley with Lieutenant Commander (E) A.L.Howard, D.S.C., R.N.R, the senior engineer, and with Lieutenant (E) D.J.Scott, R.N.R., the senior engineer Sub-Lieutenant (EL) A.Hosie, R.N.R., the senior electrical officer, that the services of these officers be submitted to Their Lordships for consideration.
(Signed) Cecil R. Hoare
Engineering Captain, R.N.
Base Engineering Officer