I just finished reading Stephen Ambrose’s book “D-Day”. Fascinating stuff.
One thing that interested me was how they waterproofed the vehicles used in the landings. There are many first-hand accounts from soldiers who were on vehicles that drove off their landing craft into water deeper than the vehicle itself and kept on driving right up onto the beach.
I’m not talking about vehicles designed to be amphibious (like the DUKW), but things like Jeeps and tanks (even without flotation skirts).
How would you modify a vehicle to do this? We’re talking total immersion. Obviously you need a big tall snorkel, but could you then just seal the engine compartment? Keep in mind that the vehicle doesn’t have to stay underwater for long, maybe just a few seconds until it’s got hood above water level. How about the electrical system, I understand that non-diesel engines will just die if submerged (even if snorkeled).
No photos were included of modified Jeeps and so forth, just descriptions of them in action.
You need a watertight tube from the surface to the carburetor for intake air and a long exhaust pipe. The electrical system can be waterproofed without too much trouble although seawater makes it more difficult since it’s highly conductive.
And you also need to take Stephen Ambrose and probably the people he talked to with a grain of salt. As far as I remember from Cornelius Ryan’s The Longest Day the only vehicles to attempt landings in the initial assaults were some tanks with balloon floatation. None of the made it as I recall.
As far as the assault forces were concerned, they carried with them everything they needed, or thought they needed, since transport on the beach was going to be in damned short supply until a beachhead could be established.
Don’t get me wrong. Thousands of vehicles were landed on Utah, Sward, Juno and Gold beaches on D-Day. However they were landed across the beach and not from off-shore. Very few, if any made it to Omaha beach that day. Sites on the net say that only 100 tons of the planned thousands of tons of supplies were landed on Omaha beach on D-Day, and no vehicles until very late in the day after the German’s had been cleared from the hills above and landing craft could run up on the beach.
One last (I promise) note. Here’s the dope onwaterproofing compound. My reading of Ryan’s book indicates that it turned out to be largely precautionary but in advance you have to figure on not being able to put the vehicles directly ashore.
There were at least some swimming “DD” (Duplex Drive) tanks that made it through the water to Sword Beach on D-Day:
Here is a memoire from a DD tanker (“The Day I Became a Man: Sherman Tank Crew and D-Day”):
The British and Canadian beaches (Juno, Gold, and Sword) saw Hobart’s “funnies” (including the swimming tanks) used to great effect, whereas the Omaha Beach-bound DD’s were launched too far offshore, and only 5 out of 64 made it to the beach.
Of course, German defenses at Omaha were also far more brutal than at the other beaches.
A recent documentary suggests that the reason the Omaha DD tanks sank was that they were a little off course, making for the beach at an angle while aiming for a particular landmark. They were parallel to the waves and the side-to-side rocking swamped them. If they had stayed perpendicular to the waves, most would have probably made it.