I've wondered about this ever since the 1/35 scale PT-596 came out.

How were these later mark PT boats able to effectively a launch a torpedo by 'rolling' it off the side? I would think there's a great chance the torpedo's aim was off, depending on how i hit the water.

Looking at this image (ponch17, I hope you don't mind if I user one of your recent builds' image) I have a hard time seeing how this could be launched with a high degree of probability of hitting its' target unless the PT boat was very close to it.

That's an interesting question. i see what you're saying, but i don't know if it would make a huge difference in aim. whille i'm sure the slightly higher forward speed out of the tube would make a cleaner landing in the water it could also mean it would be a little off target from where the boat was facing since it was at a slightly different angle. i would guess they'd have to compensate for the difference in angle. but for the ones rolling off the sides of the boat, they simple fall off in the same direction as the boat. it would still have some forward momentum due to the speed of the boat, so...hmmm.

of course this is all just a guess.

Bill

Ahoy Mates,

I hope Garth chimes in on this one, he can probably give you a few of the technical details, but it was my understanding that the torpedo was turned on with the props spinning and the boat was on its' run to the target, once at optimal range a crew member pulled the lever to release the cables that held it in its' cradle and it rolled off, hit the water and took off. It had a higher speed than the boat and once in the water the boat turned away to avoid as much counter fire as it could.

Elimination of the rather weighty and complex torpedo tubes was a prime consideration, not to mention having to grease the torpedo. Not only was this a rather messy operation, it also left a slick in the water that led right back to the boat. Witout the weight of the tubes and all the gear needed for their operation, the boat was a lot quicker, of course as sailors will, they soon made up for that with the added weight of some more arms in the forms of various gun mounts and added ammunition.

The technique was actually arrived at by some PT Boat skippers who were involved in a conference on what type torpedo would be best to use and the design first sketched out on a cocktail napkin in a bar, some drinkin' thinnkin' obviously involved.

Hello Michael, the Mk.XIII torpedo used on the roll-off type racks was the same as those dropped from Naval aircraft, such as the TBF Avenger. If a fall from a hundred feet or more didn't hurt them, being rolled off of a PT wouldn't. The cables were used as a safety measure to prevent accidentally dropping a torpedo. They were removed before combat. The torpedo rack has two hinged parts on the bottom that held the torpedo in place, they were released by the lever to launch the "fish" overboard. You can see them in the photo just behind the cables. I have seen one photo of a boat with the older, longer torpedo, usually fired from a tube, mounted in a roll-off rack. so I guess they could also be launched that way. I hope this answers your question. Al

Another important consideration in eliminating the torpedo tubes carried by the early boats was that they required an "impulse" (gunpowder) charge to fire the torpedo from the tube. The flash from the charge at night gave enemy gunners a fine aiming point--not a good thing!

Hi John, also the powder charge would sometimes misfire due to the humidity, causing the torpedo to not completely leave the tube, and occasionally welding itself to the inside of the tube. Al

Thanks, all for the responses.