trailing edge

Not really, more like it seeping from a porous skin. See F15D 1/0055.
CPC Scheme - F15D FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS https://www.uspto.gov/web/patents/classification/cpc/html/cpc-F15D.html

 

Be aware that the optimum TE shape for zero leeway is different from that for usual windward leeway angles (3-10 deg). The info is in Hoerner's two volumes, Marchaj, Larsson etc. and is summarised in this extract from my yacht design book (apologies for quasi-advertising):

“For minimum drag at zero attack angle the trailing edge should be razor sharp. However, a razor sharp trailing edge produces less sideforce than one which is blunt i.e. one that has been cut off (Hoerner & Borst, 1975). These two conflicting performance characteristics become irrelevant in practice. A razor sharp trailing edge is easily damaged, and it is very difficult for antifouling paint to build up to sufficient thickness. A square cut off of 3-4 mm is probably a good compromise for most keels and rudders. If the foil is creating vibrations it may be worth making the cut-off at about 45° (Larsson et al, 2014). This may avoid the generation of a vortex street”

 

Thanks. I think the info you and others have presented sums up what is going on. I like the 3-4 mm. It seemed that a lot of people had the idea the 1/4 inch TE was written in blood. Obviously, not the case. Thanks to all.
Ron