General Quarters…Hit the Deck

USS INTREPID (CV-11)S24/00-redm 28 March 1944Ser: 051C-O-N-F-I-D-E-N-T-I-A-L

From: The Commanding Officer
To  : Commander Air Force, Pacific Fleet.
Subject: USS INTREPID – handling of after Battle Damage.

1. At 0011, 17 February 1944, Zone plus 12 Time, the USS INTREPID was hit, by an aircraft torpedo, just forward of the rudder post. The night was clear but dark. The resultant damage presented various problems which may be of interest in handling similar damage in the future.

2. At the time the torpedo hit the INTREPID was in a left turn using 15° left rudder and at 25 knots.

The detonation ruptured the bottom of the steering engine ram room and motor room, immediately flooded these two compartments and jammed the rudder. Propellers and engines sustained no damage. The crosshead and the rams of the steering gear were completely wrecked.

The rudder was severely distorted and the fin which fills in over the counterbalance of the rudder was blown off. The detonation opened a hole in the starboard side which extended from near the keel to above the fourth deck. The fourth deck in way of the explosion was completely missing. The third deck in the Chief Petty Officers’ country was pushed up to the overhead of the second deck, and missiles penetrated the hangar deck. Complete details of the damage are contained in the Action Report. The net result of this damage insofar as ship control was concerned was to create the permanent effect of approximately 6½° left rudder. The INTREPID had the advantage of having made the standardization trials for the CV-9 class.

One of the tests conducted was to lock an outboard shaft on one side, go ahead full power on the two shafts on the other side and determine the rudder angle necessary to maintain a steady course. This rudder angle during the trial proved to be approximately 6½°. After the torpedo hit it was found that the combination needed to maintain a steady course approximated the condition found during trials.

 The continuous backing, coupled with the hull damage aft, however, created so much vibration that numerous steam and water leaks began to develop in the engine rooms. The rapid increase of make up feed required began to approach the capacity of the evaporators and some other means of controlling the vessel became a necessity. It was then decided to tow the vessel with the seagoing tugs which had been made available. A 2½” wire was taken from the towing engine of the tug USS MUNSEE, and secured to the port anchor chain. The chain was veered to place the 60 fathom shackle on the forecastle and about 240 fathoms of wire was put out by the tug. This rig worked very well towing into the wind, with a good catenary. The tug worked up to 14 knots and the INTREPID made 5 knots for a net speed made good of about 8 knots. An attempt was then made to reverse the course. It was found that the tug could not pull the ship out of the wind. The tug immediately got in stays and worked back to a position on the port quarter in spite of stopping the INTREPID’s engines. A 2ndtug then passed a line to the 1st tug to assist in holding up the head of the tug. This tandem combination worked satisfactorily and the vessel was turned through 180° in about 1¼ hours. For the remaining three days of the wait outside Pearl, during the storm, the tandem towing arrangement worked very well, making good about 5 knots, the tug making turns for about 14 knots and the INTREPID’s engines stopped. The tugs would find a position of about 45° on the lee bow. In this connection it is worthy of note that the tugs used in this operation have their towing engine too far aft and their rudder appears to be of insufficient area. Tugs designed for towing heavy ships should have the towing engine located near the pivot point of the tug.5. Upon returning to the dry dock at Pearl a jury fin was installed to restore a fin area equal to that of the original rudder.

One hundred square feet of this fin was hinged. This hinged portion represented about one-fifth of the area of the original rudder. (See enclosures). It had a maximum angle of 20° right or left and was controlled by wire cables brought up outboard to the fan tail. The ends of the rudder cables were secured to three-fold wire jiggers, the running ends of which were taken to the after capstan.

 The large hole in the skin of the ship on the starboard side was filled in to reduce the drag on that side although the patch was not watertight.     6. It was the intention of the designers of the jury rig that the movable part of the fin would be used to overcome the effect of the wind and that steering would be done primarily with the engines. Upon sortie from Pearl, however, it was found that steering by engines was extremely difficult and the yaw to each side could not be reduced below an average of about 40°. The jury rig to the capstan worked so smoothly that the final combination, which proved very satisfactory, was to adjust engine revolutions to overcome the effect of the wind and use the jury rudder to steer. The effect of the jury rudder when hard over, appeared to bo equivalent to about 4° to 5° of the designed rudder. The yaw, using the jury rudder to steer, averaged from 10° to 15° on either side. Winds of 15 to 25 knots were encountered. The passage from Pearl was made at speeds of 14 to 16 knots without any further difficulty. The starting panel of the capstan is not designed for continuous service, such as that required for steering, but frequent cleaning of the contacters prevented shorting due to arcing. Special arrangements were necessary to provide lubrication for the capstan shaft, because the pump did not provide sufficient lubrication during the short starts and stops necessary.

7. Upon arrival at the Parallon Islands the vessel was met by four tugs and a line was taken from a single tug.

The vessel was towed to the entrance of the dredged channel over the bar at a speed of about 10.5 knots, the INTREPID making turns for about 7 knots and the tug making turns for about 14 knots. 150 fathoms of wire and 30 fathoms of the port chain were used.

The weather was perfect – no sea and very light wind. At the entrance to the dredged channel the ship slowed down and four additional tugs were taken alongside, two on each side. At slow speeds the ship was very difficult to control because of insufficient rudder effect. It was planned to arrive at the Golden Gate at high slack before ebb.

Due to local conditions the ebb actually commenced about half an hour earlier than shown in the current tables. The result was that the ship was caught in some very erratic tidal currents and at times was almost completely out of control.

 It was frequently necessary to use the engines at high powers to correct a sheer to the right or left. After passing under the Golden Gate Bridge the scope of the towing tug ahead was shortened to 100 fathoms. A towing speed of about 7 knots was used, which in certain places, gave a speed of advance of about one knot due to strong ebb current.CONCLUSIONS     8. The steps taken to maintain steering control of the ship as described in the proceeding narrative, were as follows:

(a) Trim the ship by the stern.
(b) Slow down, stop or lock shafts on one side.
(c) Move aircraft on the flight deck forward to act as a headsail
(d) Rig a sail between flight dock and forecastle, Additional canvas could have been rigged, with some difficulty, on the radio masts forward, from a stay leading forward from the island structure, or on palisades arranged fore and aft.

9. Further steps which could have been taken but which proved to be unnecessary during the INTREPID’s voyage are as follows:

(a)   Rig a paravane on one side. A paravane creates a very considerable pull on its towing cable and would materially assist in keeping the bow out of the wind, if rigged on the leeward bow.

(b)   Tow a small vessel (an escort destroyer or, preferably, a tug) with a short scope astern. This scheme was successfully employed in the Pacific some years ago in the case of a large passenger vessel that was unlucky enough to have lost her rudder, The towed tug, in this case, stopped her engines and used her rudder to steer the heavy vessel which provided the motive power.

Speeds as high as 18 knots were maintained. A little consideration will indicate that the tug’s rudder was put right when the heavy vessel desired

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