Gentlemen, this is an excellent discussion and one which is really clarifying some important issues. The Luftwaffe and RAF drivers which come out of this are going to be interesting (Shane, I can see several points on which the British Aviation paper has to be amended. An example, with the consensus emerging here, Whirlwind really cannot die off as we thought it would. So that nightmare of a fighter again raises its ugly head)

Coastal Convoy

The point on German coastal movements is a good one. Even a small regional fishing port is able to handle breakbulk coasters up to about 200-300 GRT.

1GRT is 100 cubic feet of revenue-earning volume within a ship (passenger and hold).

A 'standard' Australian 'large coaster' was SS Poonbar (200' BP x 34'1" x 12'2" 909 tons), her forward hold was 28323 cu ft internal and 1062 on the hatches, aft was 19508 and 1012 respectively for 49906 total. The rest was passenger space.

Conversion cu ft to M3 is 100 cu ft = 2.831 Cu m.

So her cargo capacity was 1412 Cu m

A normal general breakbulk cargo was 50% density, so about 700 tons, but wartime cargoes tended to be denser (you'd expect 75%). Coasters tended to have 3 ton cranes and 10 ton derricks.

That's a minimum of about 350 truck loads for the normal small 1930s style truck (2 ton truck). So you can see the utility of even small coasters carrying 150 tons of cargo into small ports, or fishing boats c arrying 30 tons to a small jetty. Sure, it is only a local solution, but it helps to reduce to load on the railways.

So this is an obvious answer for supply to coastal German garrisons. Even fishing craft can be used, as these can deliver 20-50 ton cargoes to the smallest places, even to small private jetties!

You have just noted a very strong driver for small German coastal convoys.

OK, where from?

Gentlemen, here's where canals become very important. A German priority is going to be working the east-west canal systems (norther ones first Ostende, Dunkirk, Calais, then down to the Rhine-Marne etc etc.

The small seaports where the canals linking Germany to the Dutch, Belgian and French coasts are going to become the coastal nodes of this coastal small-ship convoy system.

Shane and Imah, I believe this gives the RAF light bombers a new bombing target set, and one where the light bombers can do quite useful work hitting locks and maybe even mining canals.

it also gives British coastal forces and their small submarines a valid target.

Cheers: Mark