According to the International Sailing Federation, and their Racing Rules of Sailing –
“Since both vessels are under engine power as opposed to sail, immediate disqualification shall be the penalty enforced upon both….”
Actually, I made all that up.
Who yields? Short answer, the plane. Something about ‘Why can’t you just put wheels on it and be like a normal plane?’
Sorry, made that up too.
Yetso's @ 48 North 
Oo you joker 😉
Rule number 12, you always knows the rules, even when if you have to make them up yourself! And I of course just follow along…. (Now that’s some blue Seattle water!)