why on a yacht, though? i have a similar problem. shy bladder plus tense pelvic base. maybe even somewhat increased prostate (i don't know). so peeing is always something i need a little privacy for. but everytime i'm scuba diving plus out with a boat it's like my prostate is locking up completely. extremely weird and uncomfortable feeling. on those small boats there is never a toilet but there are sneaky options that in theory should work but don't. so i'm wondering if the wavy motion might have something to do with this problem.