PT boats were (as with their name, Patrol Torpedo) meant to patrol around and ambush targets. Yes, they were made of plywood, but to hit a tiny, fast-moving thing like that was hard, and light flak rounds were fairly ineffective even against that. They are not meant to "front-line" ships, they are meant to flank or harass. Torpedoes are possibly the most dangerous weapon a ship could possess. But because they can't fire their torpedoes in game, PT boats are more nuisances than anything else.

But one DG shell and the thing should be history. (sinking. because the water going in the hole.:hmm:)

From a Schnell Booter here. With a few placed 37mm or 20mm the pesky plywood preditor should be quickly converted into rapidley combusting av gas and debri. What worries me is when somebody gets the 50 cal modded right. 2 sets of the twin 50s, which is what was common to all PTs, hosing me down would likely take out all my crew on deck, shutting down the gunfight no matter what boat I am on.
CL

Well one shell from a pt boat causes damage. I wouldn't think of it that way.:hmm:

Don't bother with PT boats. Just forget about it. They have little tonnage and renown

About the 20mm flak gun can pierce the PT-boat issue: I think the 20mm gun can do it, but it misses often since the U-boat is a very unstable platform and the PT boat is very agile with low silhouette. Also, the enemy fires on the gunner, who is exposed as well

I think they've got 37mm AT gun, aircraft autocannons and rockets as well in the later part of WWII. As you know, rockets is one of the major factors causing the demise of U-boat, and GWX3 has modelled that as well. The autocannon and AT gun can easily pierce the thin hull of subs since they are built against much better armored tanks

The 40mm shell weights only 2 pounds, for both QF 2 pounder and Bofors 40mm

Even if you destory the PT boat, it is frutile if your boat is destoryed in return.

Well, it may not, but remember the autocannons (20mm, 37mm and 40mm) fires extremely quickly, with several hundred rounds per minute, against the massive hull of a submarine

strange i had read 4.7 ish lbs for a 40mm shell.

perhaps they are talking about the entire round from the projectile to the shell casing and all?

I guess you are right. The projectile weighs 2 pound while the round weighs 2kg (i.e. 5 pounds)