(and for the rest of you) I would've come across some passages in Ambrose's book that related to Hobart's Funnies...
Ambrose speaks about the strength of the British in science and technology. Did you know that radar and sonar were British innovations? I didn't! I do remember hearing about how Dad's T (built at Evansville) was one of the first to have radar...and it was very hush-hush. Most likely a very rudimentary form.
"Hobart's Funnies" were named for General Percy Hobart of the 79th Armored Division. Churchill (and others) gave him the job of figuring out how to get tanks onto the beaches to break the concrete fortifications of the Germans. "Swimming tanks" (aka "Hobart's Funnies" were the result. Two propellers working off of a main engine exactly as you noted. The waterproof, air filled screen made of canvas made the tanks look 'funny', but they seemed to work allowing some bouyancy. One thing it didn't mention was how quickly and how they dropped those canvas screens... anyone have any idea?
These were also adapted to be a "Crab" (not me without coffee...
) which detonated mines in it's path. Pretty versatile!
The chapter then goes on to talk about the pre-fabricated ports - Mulberries.
