I used to het pelican itch really bad so I used a suncream with insecticide in it and it worked well

Shifu said..
What the heck kind of water are you guys sailing in???

I suspect they are growing extra digits etc

So here are the two things I have been doing to prevent ringworm infections, 1) wash clothes with a detergent with color safe bleach and also Borax, in hot water, while making sure I do not overload washing machine, and 2) scrub chest, upper arms, top of shoulders with a dandruff shampoo before the session, and if I got my chest wet during the session do the same afterwards. Ringworm needs dead skin cells to grow, so scrubbing with dandruff shampoo removes food source and leaves behind an anti-fugal too.

Ringworm is a type of Tinea. Infection can come from many sources but swimming would be unlikely. Direct contact is a more likely source, Can be from contact animals, people, clothing e.g. hats, even shower floors. Seek advice from a medical professional.

Sea bather's eruption | DermNet NZ
Could be Sea bather's eruption. Details below.
dermnetnz.org/topics/sea-bathers-eruption

So far so good, no more ringworm even after being in water a lot recently. Just have to remember to keep scrubbing chest regularly with dollar store dandruff shampoo.

Oh, and also now washing tops I use while windfoiling in a detergent with color safe bleach, just wash/soak in a small tub in the sink since I do not do laundry that often (save up cloths for big loads).