I am installing a Vetus Waterlock exhaust for my Beta 60, my engine injection point of the cooling water is 23cm above the water line. The Vetus manual calls for 15cm Min so all looks well. However looking at my Beta manual it looks like there calling for 30cm Min above the water line, I should mention this a power boat not sail so no heeling involved here, don't see a need for a Anti syphon valve but would like a second opinion.
Thanks for the advice. I should mention that when raw water leaves the heat exchanger it goes to the V Drive for cooling and back up to the exhaust elbow, some where along this run I would like to put in a T with a 3/8" hose to my PSS shaft seal. Would this create a need for a Anti syphon valve? or maby there is a better way to get raw water to the PSS.
Now that I have the rest of the info I recommend that you must use an anti siphon valve. Fit the T for the PSS seal in the down hill run from the above waterline anti-siphon valve to the exhaust elbow.