Did you know destroyers in the US navy fleet only have 3/8" thick steel, so while they are in the lead of a carrier fleet, if they are torpedo'd, the torpedo goes thru it with out exploding! Meanwhile the battle and carrier ships have thicker steel. BUT, a torpedo will explode and sink them! The US navy in WWII lost more destroyers due to typhoons than torpedo's! So having a frame that is not to strong or thick etc, might be an advantage at times. Also why PT boats were made of wood. Lighter, just as strong per say, but a torpedo would go thru them, potentially allowing said boat to get to the sub and destroy it!
So one can have, many types of materials to make a boat per say, sometimes the strength of it, as you imply by whether or not a bullet will go thru stop or equal, may be to either it advantage, or disadvantage. That fir would not explode a bullet, so you only have a round hole in hull to deal with, the steel on the other hand, would explode the bullet, sinking the steel boat!
Take that for what it is worth!
I just measured the hole in 3/8th plate made by a 30 calibre bullet. It measured 48 calibre, not exactly exploding the bullet, and not making a significantly bigger hole, when I have seen them expand at least as much, or more in wood.
I wouldn't put much faith in the math skills or judgement of anyone who believes that the energy needed to push a 180 grain projectile hard enough to go thru 23 inches of fir, can be contained in a wooden barrel. I saw a 3 inch shell hole in a sunken tug at Fanning Island thru the iron prop. Anyone there can dive on it, just off the village. You couldn't get that kind of energy from a wooden barrel.
It just shows how ludicrous the comments about the strength of wood made here really are.