Thank you, Michael, for this excellent information - and for going the extra mile.

I understand your reservations about overall accuracy but, even so, if I add in some assumptions of my own, say, a 50:50 split between power and sail for unspecified fishing vessels; and arbitrarily count prizes and damaged as 'lost' then I come up with:

Total: 7,241 ships lost (70% powered, 30% sail), of which
Merchant: 6099 (71.3%, 28.7%)
Fishing: 841 (50.1%, 49.9%)
Naval: 284 (100%, 0%)
in which I have left out the 17 hospital ships as being unclear as to merchant or naval.
In any event, adjustments in the tens will have little effect on the top-line percentages.

So, can we say that, within a margin of a few percent, based on today's figures, three out of every ten ships sunk by U-boats in WW1 were sailing ships? This seems to me an important conclusion.

I would hope to include a few lines to this effect in my story on 'Little Mystery' (UC-61) unless you have objections? Then there is the matter of attribution. Do you have rules on material lifted in this way?

Also, I was reading this week Basil Greenhill, The Mariner’s Mirror, ‘The Rise and Fall of the British Coastal Steamer’, Vol. 27, Issue 3, 1941, pp 243-259. In it, p. 256, Greenhill, says:

'During the war there were a sufficient number [of coasting schooners] for convoys to be made up of schooners alone, and such convoys were escorted by armed vessels of their own class. Very many were sunk, others fought successful operations with submarines, and some were borrowed for conversion into Q ships. The wartime losses among the sailing coasters were actually very considerable, the Stephens fleet [of Fowey, the owners of 'Little Mystery'] lost ten vessels in the year 1917 alone, but nevertheless very many survived and these, together with the vessels taken over from the enemy, schooners bought from Holland during the shipping boom, and a few newly constructed ships, must have made quite a considerable fleet ready to resume normal work after the cessation of hostilities.'

And in support, by chance, yesterday at TNA I found an Admiralty letter for May 1917 detailing the success of the first schooner convoys to France in the coal trade (TNA, ADM 137/1393, French Coal Trade, p. 27), including an armed schooner seeing off a u-boat.

Perhaps, the trend was a little more bumpy than I at first thought.

Best wishes
Chris