As RONs 30, 34 and 35s' boats were maintained and repaired primarily by the PT Base, Portland, comments relative to the various departmental problems and departmental observations will be covered under this one general heading rather that as a section of each squadron's history.
Ordnance -
37MM Aircraft cannon, M4.
This gun, although designed for use
in aircraft as a fixed mount, has been used successfully by PTs in the
Channel area against E-boats and other surface craft not subject to torpedo
attack. The gun is mounted on a 20MM Mark XIV pedestal assembly making
it a free moving, easily fired and controlled anti-surface weapon.
The boats in this command were fitted with (2) 37MM guns, one on either
side just forward of the chartroom. The assemblies were made from
Mark X assemblies with eight and one-quarter inches cut from the stand
so that the Mark Xs resembled the Mark XIV mounts. The legs were welded
to steel plates secured to wooden pads mounted on the deck. Loaded
with a thirty-round magazine, the weight of gun and ammunition is 306 pounds,
entire installation including deck pads is 760 pounds. Placing the
37MM aft just forward of the charthouse improves the stability of the gun
in rough seas and clears the bow of the boat so that a better view forward
is obtained.
In its original assembly, the gun tended to be butt-heavy and had a tendency to rise as most of the weight was aft of the trunion body. Lt. Commander Davis, USN, Commander PT Base, Portland, developed a modification which consisted of a machined left and right carriage. The counter-balance spring was used to overcome the butt-heaviness inherent in the mount. A plate was fastened to the right side of the gun so that it projected far enough to ride on the cam lever. The cam lever in turn was machined down to allow the recoil cylinder to elevate in the carriage. The assembly was then placed aboard an experimental boat and the cam path altered so that the muzzle of the gun was kept clear of deck obstructions. Two positive cams stops were installed. This provided depression and train stops yet allowed the gun to be deflected so as to fire into the water within 15 yards of the boat on the beam.
The altered gun mount will still permit interchanging 37 and 20M gun if desired and the time of change is approximately 45 minutes. Boats in this command have fired approximately 4,000 rounds of 37MM ammunition without an instance of strain to mount or boat having been noted. As the M4 37mm aircraft gun is no longer in production, it is recommended that test be carried out with the M9 guns in these forward mount locations.
Guns were mounted on Mark 10 20MM mounts cut down in height to resemble the lower Mark 14 mounts. Gun pads were placed flush against the forward end of the forward 40MM ready boxes. Neither positive nor cam stops were used to control the train of the guns as mounted for the tests. Both guns were able to fire freely in train on their respective sides. Limitations in train was caused by danger of hitting forward torpedoes when firing on the bow, hitting the 40MM when firing aft and in elevation the dangers in .50 cal. turret.
Several drawbacks to this gun arrangement were noted. The man operating the port 20MM cannot wear the usual kapok jacket and still train the gun on the horizontal plane as the space between the outboard edge of the the rear .50 calibre turret and the gunner's back does not allow space for freedom of movement. This defect could be remedied by supplying the gunner with a CO2 type of life belt.
On a beam firing approach the noise and blast from the aft .50 calibre turret would prevent the 20MM gunners from firing accurately; shock or powder particles might cause injury. The ready box, would affect the 20MM gunners in this position so as to destroy the effectiveness of their fire and perhaps cause personal injury.
Conclusion - The addition of 20MMs on either side of the Elco boats is desirable in combating surface as well as aircraft. The experiment conducted on the location of these mounts indicates that such location is undesirable. Mounting of similar mounts amidships is recommended although such mounts would necessitate the temporary removal of the two wing tanks so that bolts securing the gun pads and stands could be installed. Mounts in these location would negate the shortcomings of the experimental mounts farther aft and offer greater freedom of action, train and elevation.
Torpedoes - Mark XIIIs were used by PTs in this area. 42 torpedoes were expended by the Task Group, all war shots with the exception of a hot-run aboard the PT457 which caused no casualties to boat or personnel and one torpedo badly damaged as a result of enemy shell fire. The Task Group, having two torpedo circuses as well as its squadron's torpedo personnel had ample trained personnel to routine and service its torpedoes.
Flack Jackets - Subsequent to the first shrapnel
injuries suffered by PT personnel in this area, flak suits had been obtained
for all boat personnel. These suits, of the type used by air crews,
were
In the event of necessity of abandoning ship, flack suits of the type used by PTs are readily removed by a release spring. It is thought that these jackets should be used as standard PT equipment.
Electrical Gear -
Radar - The radar equipment on PTs
in this command has been highly satisfactory. Most sets have operated
approximately four-hundred hours. Several casualties occurred to
the old high speed type Motor-alternators. There were very few magnetron
failures and relatively few tube failures.
It is thought that the set could be materially improved by installing an antenna that is less directional in the vertical plane allowing for better perception of planes and an improved effectiveness against surface targets in rough weather when the boats tend to roll and pitch. Another great benefit would be derived if the accuracy of the first mile sweep was to be improved to allow torpedo attack by radar, which, with the present set, is not wholly practicable.
ABk - No failures occurred although these sets were given little use in the Channel area.
GEE or QH - This navigating unit (described in more detail under RON 2 activities) is of British design and not intended for PT operations. While the sets works well under calm conditions, the set is not rugged enough for continued use under rough water conditions in a PT. Attempts to improve reception, by relocating the antenna, were not successful.
Flux-Gate Compass - The transmitter has been the cause of most casualties due to its bearings being unable to withstand the severe vibrations and pounding of PTs operating in rough water areas. In the Channel area, because of the rough water conditions, the average life of the Flux Gate was less than four-hundred hours.
TCS5 and TCS11
- Chief cause of failure was the bearing in the M-G set. Proper
ventilation would alleviate much of this trouble as a lower operating temperature
would save bearing wear.
Transportation - Squadrons up to and including RON 33 were supplied with one truck and two jeeps. These items of transportation have been deleted from the allowance lists. It is thought that these items should be reinstated and increased to at least three trucks (2 - 1 -1/2 ton trucks and 1 personnel carrier) and three jeeps. It is virtually an impossibility to requisition these vehicles from another overseas outfit for they, even including motor pools, consider themselves to be already under stocked with vehicles.
Engineering Suggestions - Exhaust manifolds carried away at the lowest point. To counteract this, it is suggested that the weak section of the manifolds be bored out and a Monel metal sleeve inserted as a strengthener. Manifold drain cocks are inadequate and a better type should be used.
Fresh water pump seals were a frequent breakage. It is suggested that a substitute seal be made of fibre rather than of carbon.
It is suggested that a drain valve be installed in the bottom of the heat exchanger to facilitate cleaning when oil is being changed.
No provision is made for cleaning fuel tanks. This could be remedied by the installation of sumps and a pump.
The present type salt water pump on the auxiliary generator can not be rebuilt when worn out or broken. It is suggested that a pump of different construction be substituted.
Thermo bulbs set into the exhaust stacks would aid in preventing overheating.
The salt water scoops in RON 34 and 35 boats is still so constructed and placed as to create air locks in the center engine's manifold.
10/18/2000