Never mind what Brian says ;o), they have gales daily in that English channel. I live on a wind swept coast myself. But I can see the use for a fisherman's where you sail John. Twiddling yer thumbs all day in calms, playing with extra canvas sounds like the thing to do. 1/2 a knot is not to be sneezed at either. I might be tempted to give it a go, what use is a schooner if you can't have fun stringing up all kinds of laundry?
But on JR schooner it looks like all the fisherman does is blanket the foresail, so not so sure.