Dud? Let me explain at a level a child should understand. You run the
engine -it gets hot. You turn it off. You raise the sails so the boat
heels and puts the exhaust under water. The engine cools and water gets
sucked in 'cos the siphon break valve no longer works...

get it?

Cheers

JAXAshby wrote:
Now tell us why you think you don't need an antisiphon valve. Vague
references to gas laws are required.


you can't siphon water uphill using the weight of exhaust gas going downhill.
dud!