At least in my head the PT boat class of world war two has everything to make a big, slow warship tremble. They were much faster, more manoeuvrable, hard to hit and cheap to field in big numbers; all of these and nothing to say of their torpedo capability. The torpedo, while not thors hammer could sink or cripple even the mightiest vessel with a single hit. Now obviously that is an overstatement considering the long list of war and merchant ships alike needing repeated hits to sink them, but war is anything if not a game of numbers and I don’t necessarily see them stacking up.
So the question begs, what was the humble PT’s short fall? I understand that the PT boats had because of their size only a limited amount of room to store munitions, in this instances, torpedoes (something like an average of 3 - 6). But surely a mobile squadron of PT’s could easily dish out enough fish to sink anything and all for a cost much less than a big destroyer or carrier ship normally required to do so. I can’t help but think of a morass of ants constantly chipping away at the bigger enemy, individually crushable, yet mathematically invincible.
Now I’m not saying the tactics of the time were wrong or that there wasn’t a reason why the Japanese admiral of the day didn’t consider the American PT boat to be rather like the tiny mosquito filled with the most deadly malaria. There has to be a reason or collection of reasons. Was it that the submarine could do all of the same things at less risk/lives lost? That the PT boat was simply to fragile, even in good number, to get within firing range of a decently sized enemy vessel?
There is something without doubt, I’m just too scrooge like to see it.
I was under the impression that the PT boats were reasonably successful. They were relatively inexpensive to build and effective in battle.
They did suffer a similar problem as the early subs. The torpedoes we had at the beginning of the war were total crap. I quoted some of the problems below. They eventually improved the guidance system but I don’t know if the PT boats got the better torpedoes.
Maintenance wise these boats were a problem post war. Plywood hulls are only going to last so long. They need constant cleaning and fresh marine varnish. Even then they’ll eventually rot. I’d imagine they were also much more dangerous for the small crew. A plywood boat was a great idea in wartime, and a liability in peacetime. They had similar quick boats during Viet Nam. John Kerry was the captain of a Swift Boat and it was an issue in his Presidential election. Swift Boats, PT boats are the same idea. Cheap to build, very fast, heavy armament and a small crew. If things go wrong you won’t sustain heavy causalities.
I’ll just note that the plywood construction of PT boats is not that stuff you buy at the Home Despot. It’s a common means of boat building where planks are overlaid in varying directions to create a very strong shell. The PT boats hull was several inches thick.
I need to clarify this. The crew of the PT boat might get wiped out. But that’s a very small number of men compared to other classes of boats that might have hundreds or thousands of sailors on them.
There is a movie about PT boats called We Were Expendable. That’s no exaggeration. In the early,desperate days of WWII these small crews joined PT boats knowing the risks. A PT boat crew was about the same size as an Infantry squad. They took the same kind of extreme risks as the Infantry guys.
What I was trying to say - I’ve understood that one of the flaws of the PT boats was that they really weren’t much faster than the ships they were going up against, and in some cases were actually much slower. Effective against slower transports. But the big boys (carriers, battleships, cruisers) didn’t have much to worry about, at least where sheer speed was involved. I’d say the biggest advantages they had was small size and rapid accelaration.
Very high vulnerability to air attack is another obvious problem. Carriers may be vulnerable in theory, but they can attack PT-boats from out of their range and then withdraw before you can attack them, or even find them for that matter.
Made out of wood to free time in shipyards for larger vessels. Initially equipped with older, often defective torpedoes. 75% didn’t have radar. Crews often not fully trained (probably a problem going from small navy to huge in a hurry).
Under the best of circumstances, the largest effective weapon range of the PT was probably 5 miles, which is the extreme limits of the Mark 14. Potentially a bit more if the target of attack was straight on. The range of a WWII destroyer was twice that due to is gun range. Battleship range is 20+ miles and aircraft carriers hundreds of miles.
As is true in the military in all aspects, from tanks to planes to ships to rifles - if I can reach out and touch you before you can reach out and touch me, I win. Range is everything and the PT boats didn’t have an effective standoff weapon.
Also, performance must have degraded pretty badly in any kind of chop or bad weather. They were basically fair-weather warriors.
Although there’s no doubt the PT boats were fast, a little-understood factor in ship speed is hull length at the waterline. Apparently it’s easier (more efficient) to move a longer hull through the water at a given speed.
There’s a lot of technical detail involved, and I should caveat that PT boats at combat speed were planing hulls rather than displacement hulls – planing hulls are substantially less affected by the “hull speed” limit of displacement hulls. However, at combat speed PT boats consumed fuel at an awesome rate – and outside of combat, at lower speeds, I expect they’d function as displacement hulls. Net result – when traveling long distances, they were slower and/or used more fuel than a longer hull like a destroyer. Combined with their poor performance in heavy seas, this limited their utility.
Here is one reasonably understandable discussion of hull length’s effect of speed:
As mentioned above, they didn’t use Mark 14 torpedoes. From Wikipedia:
Interestingly, their range went down (from roughly 9 miles to a little over 3 miles) with the later-war torpedoes, which were also slower. They eventually added rockets with about 6 miles range, though.
PT boats were cheap and largely didn’t compete with other weapons systems. But the central fact remains. They lacked range and an effective standoff weapon which limited their effectiveness.
The PT boats weren’t exactly blue water vessels. Adequate when operating from shore or between islands in an archipelago, not so great for the middle of an ocean. And rather than risk having a swarm of them take out a cruiser, battleship or carrier the countermeasure would be to send in smaller vessels like destroyers or cutters to deal with them. This switched the “cheap enough to lose” argument back to the other side: smaller vessels could engage PT boats with a favorable us/them loss ratio.
An ongoing debate today is whether a mosquito fleet armed with the latest anti-ship missles could attack a carrier group with an advantageous loss ratio. Missiles have much better range than any torpedo.
Hiding in an archipelago or sneaking inside a port unnoticed are probably the only things it does better than an aircraft. And it does those better than a submarine only if it is a shallow area. So it doesn’t sound like an ocean weapon.
Now, the German S-boats (somewhat bigger than their American counterparts and thus more seaworthy) were rather successful: sank 101 merchants, 12 DD’s, 11 minesweepers, and assorted other victims. Allied heavies didn’t as a rule traverse the Channel so the S-boats didn’t exactly have much opportunity against them (but they did damage 2 cruisers).
PT boats were not made of plywood; they were made of mahogany.
They could be most effective when lying in wait for other ships (especially supply ships). Tactics were developed so that the PT boats would hide among islands where the Japanese ships were passing as a supply route, then ambushing anything that passed with a quick hit.
They were not good for any direct attack, especially in daylight (and nearly all PT boat raid did take place at night). If spotted, the Japanese had far more firepower and could sink the PT boat before it got into torpedo range. They could also ram the PT boats and while that might get you elected president, it was not good from a military standpoint.
Reading some “silent service” history books mention that most [U.S.] torpedo hits occurred at ranges under 2000 yards (roughly 1 mile).
Enemy ships speed and course are estimations (at least until radar with a trained operator is installed). Small errors in these estimations make a big difference at longer ranges.
A PT boat closing to within 3000 yards of an alert destroyer is asking to get swatted. 4 and 5 inch naval guns have a range in the neighborhood of 15000 yards, although hits at that range are difficult. The rate of fire on those guns is 15 rounds per minute, so they can smother a target area.
PT’s are ambush predators. Great in restricted passages, or reduced visibility. Good for close to shore patrolling, like interdicting barges that the Japanese used to shuttle supplies around in.