I must admit I know a few matelots who seem to be scared of going to sea and suffer from seasickness. As soon as they have to go to sea they get sick...good place to start a cull in these present redundancy days.
Only come across one case. 1st time at sea had to be flown off cos of a nose bleed(bad). 2nd time another nose bleed, boat Tx. was checked out nothing found and was going to be trouped for self inflicted injuries, thought he was shoving things up to make it bleed.
Confined onboard and it happend again, the Doc checked his blood pressure and it was off the scale. Swift draft.