Is he on a power boat or a sail boat? if he was on a power boat he probably stimulated her too fast, and needs to start slowly, like running the engine in the marina, then pracitice going in and out of the marina, then going for a small very slow ride(2knots max) and go up from there.
If he has a sail boat was he leaning really heavily? was it very windy? the noise from the sails may have caused her to freak out. if he's in a sailboat he should motor out slowly and quietly a few times(no sails) then motor out then just let the sails loose and let them flap away in the wind (probably best to do this on a windless day) and slowly tighten them up and stopping when she tenses up and wait for her to calm down. lots of treats and toys and praise when she acts confidant. One of my dogs was terrified of the boat until he leaned that he go to go swimming and see 'seapuppies' aka sealions.
Good luck.
If he has a sail boat was he leaning really heavily? was it very windy? the noise from the sails may have caused her to freak out. if he's in a sailboat he should motor out slowly and quietly a few times(no sails) then motor out then just let the sails loose and let them flap away in the wind (probably best to do this on a windless day) and slowly tighten them up and stopping when she tenses up and wait for her to calm down. lots of treats and toys and praise when she acts confidant. One of my dogs was terrified of the boat until he leaned that he go to go swimming and see 'seapuppies' aka sealions.
Good luck.