The PT Boat Forum

Forum Category: PT Boats of WWII

Forum Name: PT Boats - General

Topic: wake test

Up at Melville in June 1945, PT-140 was outfitted with an experimental wake camouflage system that used dye to conceal the boats wake. Comparison tests were run with PT-315 to determine the overall effectiveness. Here are several photos of the actual piping and tank setup installed on PT-140 for the tests. The chemical compound was a mixture of soap and carbon black. It did have an effect on the wake but only at about 27 knots and the boats could only carry enough of the chemical to allow its use for about five miles.


Posted By: Frank J Andruss Sr | Posted on: Feb 18, 2023 - 5:39am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am

That's interesting. Thanks, Frank. Was the wake a bigger concern when sighted from the air or from the water? I would suspect the latter.

I could see the soap being used to "calm" the water since it would have some effect on the surface tension, but no idea what the carbon black would do. My Dad said that they never laid "smoke" in a continuous stream or tried to hide in it. Rather, they released it i a series of short bursts, so the enemy had trouble establishing their direction and range. I wonder if the wake dampening apparatus was intended to be used the same way, which might make even a five-mile supply worthwhile had it been effective enough.

Randy McConnell (Randall J. McConnell III)

Posted By: PRJM3 | Posted on: Feb 18, 2023 - 11:02am
Total Posts: 94 | Joined: May 25, 2009 - 2:47pm

Test's were conducted as the wake was always a huge problem from the air, although it too could be seen from the water, but not as much, as the boats operated at slow speeds while on patrol. Not 100% sure about the carbon black although I suggest it had something to do with the color on the water

Posted By: Frank J Andruss Sr | Posted on: Feb 19, 2023 - 4:38am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am

I thought that the wake would obviously be most visible from the air but by the time these tests were conducted Japan's military didn't have much airborne presence. According to my dad, the rules of engagement were if it was on open water in the daylight, the American planes were allowed to shoot at it. And if it was in the air at night the American sailors were allowed to shoot at it. Of course, there was obvious coordination for movements of major American ships, but the PTs were restricted to waters declared to be under Allied forces control for daylight operations. The situations of PTs being attacked by US planes while returning to base after sunrise are well documented. I know of two operations where RON 27 boats, including dad's 361, were involved in daylight open water operations, but they were both well-coordinated military actions. I recall from one of dad's books, possibly Squadron X, that PT wakes were an issue for night operations when spotted by land and water-based Japanese forces, but I also recall those were situations of photo-luminescent organisms in the water, and/or full moon conditions.

As to the wake reduction tests, I did look at the characteristics of carbon black and its use in water solutions. As I already knew, it just doesn't mix with water and that may be why a soap was used in the mixture tested. Beyond that, changing the color of the sea water is the only benefit I can see.

Randy McConnell (Randall J. McConnell III)

Posted By: PRJM3 | Posted on: Feb 20, 2023 - 10:40am
Total Posts: 94 | Joined: May 25, 2009 - 2:47pm

Randy I know you have probably seen these photos of PT-361 but maybe some of the members here have not, so I will post few.


Posted By: Frank J Andruss Sr | Posted on: Feb 20, 2023 - 1:17pm
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am

Thanks, Frank. I have the original prints of some of those pictures with the censor's stamp on the back. In the center of the stamp are the initials of the officer that cleared them, and it is frequently 'VK' - Vic Kodis. I know you were friends with Vic before he passed.

Many of those pictures I have not seen before, and I appreciate your posting them. In many cases I can tell that an individual picture is part of a series of pictures of which I have other ones. For example, the picture of the 361 in the foreground of several boats tied up with other ships in the background is from a trip up the Pasig River through Manila after the city was liberated. I have others of literally hundreds of sunken ships and boats along the river. My Dad is only in two of the pictures most likely because he was the one behind the camera.

The next to last picture is my Dad upon graduation from Midshipman's school and was taken by my grandfather, also named Randall. He, my grandmother and my Aunt Helen drove from Pittsburgh to NYC for the graduation ceremony.

The picture with crew members sitting on the foredeck with a dog is most likely the first crew of the 361. I have several pictures of that crew - or at least the ones still there when my father came aboard - and will see if I can match up any faces. My Dad was part of the second crew, with the third and last crew coming aboard towards the end of the war. Vic Kodis probably came in part way through the second crew and was in command of the boat when the war ended. Dad said that the crews did not change en masse, but rather one or two at a time as replacements over several months.

I finally got a new desktop computer that makes it easier to manipulate pictures and will try to post some in the enar future. A late New Year's resolution?

Randy McConnell (Randall J. McConnell III)

Posted By: PRJM3 | Posted on: Feb 21, 2023 - 12:35pm
Total Posts: 94 | Joined: May 25, 2009 - 2:47pm

Randy very happy that you could use some of the photos, and I appreciate you letting me know what some of them are. Vic was a wonderful man who I enjoyed visiting very much while he was with us. I always enjoyed his stories of his time spent on the 213 and the 361.

Posted By: Frank J Andruss Sr | Posted on: Feb 22, 2023 - 5:39am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am