Smallest ASW vessel to sink U boats?

The smallest Asw vessel I know of to sink a U Boat was an 82 ft sub chaser - CS13 of the Cuban Navy which accounted for the U 176 on May 15 1943 off Cal Sail Bank. There were a number of sinkings by 165 ft Coast Guard cutters (U 352 by ICARUS, U157 by THETIS), also 173 ft PC type craft accounted for several U Boats. Any other small craft credited with U boats? What about Civil Air Patrol aircraft? Most accounts list 2 U Boats as being sunk by CAP aircraft, but can not find any confirmation of what boats sunk in records.

This is the official oral tradition of the CAP, (I thought it was one), but I have never seen a date, time, place, and witnesses. It could be that this story was wartime propaganda, adopted as holy writ. To be sure, the CAP volunteers did a lot until enought military planes were available. IIRC these missions ended by early 1943.

Is it possible/probable for 75 lb. bombs to sink a U-Boat?

The British 205' long Flower class corvette sank a large number of U-boats, the first on 1 July 1940.

You need to remember in your statistical search that British and Canadian forces sank 67% of all German U-boats; the US sank only 22%. Indeed, 70% of all ASW aircraft based in the continental US never fired a shot in anger.

Not WW2, but during WW1 UB4 was sunk by HM armed smack Inverlochy* (about 50' on deck, if she was typical of her type): http://www.gwpda.org/naval/ub4.htm

In WW2 - don't /think/ there were any claims of U-boat sinkings by MA/SB before they were converted to MGB - though it's possible that one did manage it (MA/SB were, IIRC, 60'. Again, I don't /think/ there were any successes against U-boats by armed drifters (generally less than 80', but a number were sunk by ASW trawlers, most of which were significantly smaller than the big 165' cutters.

* Probably also the only sailing warship to sink a submarine.

Also in the Great War Q-9 the auxiliary sailing schooner 'Mary B. Mitchell' was credited with a couple of possible sinkings of submarines, but post-war analysis did not confirm their destruction.

It appears to be called 'Inverlyon' at that URL and not 'Inverlochy'.

Maybe not probable, but certainly possible.

The shock-wave generated by a well-placed bomb of that size may or may not have been enough to breech the pressure hull, but it's certainly enough to damage the places where vital equipment went through the hull - for example, the propeller shafts or dive-plane connections.

There are two lethal possibilities from a close hit like that: firstly, the leaks created might cause flooding that couldn't be controlled, sending the boat to the bottom. Secondly, vital equipment such as propellers or dive-planes could be damaged to such an extent that the boat would be unable to maintain depth and would also be

The 'Squid' anti-submarine spigot mortar had only 35 pound warhead but was capable of sinking a submarine. Of course Squids were contact fused.

Andrew Warinner This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

ITYM Hedgehog, which was the ahead-throwing spigot mortar throwing contact-fused bombs. Kill rate was ~15-20%, from memory. Squid was a three-barelled mortar throwing depth-fused bombs, with depth-setting and fusing taken directly from the ASDIC (sorry, can't remember the type number). Squid kill rates/attack were ~35-40% for ships with a single Squid, 60% for ships with a double Squid. Squid was lethal.

Floatplane launched from battleship HMS WARSPITE sank U 64 (type IX)in Narvik fjord with 2 100 lb bombs, one scoring a direct hit. British used 250 lb anti submarine bombs delay fused to detonate on top of a diving U boat. CAP (Civil Air Patrol) aircraft were at first unarmed, later many carried 100lb or 325 lb depth charges, depending on size of plane, jury rigged with a cable release. Some of the smaller planes had to saw off bottom fin of bomb to keep from dragging on ground.