I’m sure there’s a “You can lead a Horse to water…” joke in there somewhere.
But you can’t make him sink?
I belive it…many years ago, my brother and some friends were out in their boat, about 1 mile offshore (fishing). My brother spotted something swimming-it was a small brown do. The moved over and pulled the poor dog in-he was exhausted. They took him to shore and he ran off-none the worse.
Not that that’s not cool - it is - but come on, they have buoyancy and a built in snorkel.
Well, I’ve never heard of a donkey on a catamaran before but you’re saying SBHP is experienced in this & probably has procedures for equine rescue??? 
I wish Jim Morrison was still around to comment on this.
Do tell.