Happy New Year All!
Have Yanmar SD20 with folding prop on my 30" sloop, saildrive is 27 years old. No leaks, original seals...wanted to change seals
several times just because, yanmar dealer says not needed and
cited older units still going strong with original seals.
Am coastal sailor and would change seals if going offshore or if
did not know history of older unit.
Have gone bump in the night few times, one time sailing over a
substantial submerged tree with no problem. Saildrive sits somewhat protected behind keel, would rethink if more exposed
as could be on a catamaran.
Makes for very quiet motoring with no vibrations transfered to hull
and bilge is dry as no shaft seal
leakage and no critical shaft line
up. My install my be somewhat unique as motor is turned 180 degree from normal install and presents easy access for inspection of saildrive seals and gear oil.
Almost forgot, there are actually two robust watertight seals
that have a sensor between them that sounds an alarm if
any water ingress. Alarm has never sounded other than when I
remove and test. There is a 3rd exterior seal/rubber flap not
water tight on the bottom of the hull/ saildrive leg that keeps
One has to be careful about keeping raw water intake open and I have installed a 3 way valve to another thru hull if needed, i don't
need to use but am very careful about keeping bottom/saildrive clean.
All in all am happy with yanmar sd20 saildrive, which are still made today...can not speak to Volvo drives...and certainly aware
that many are not fans.
Maybe some will speak to their personal experiences with their
particular makes and models.
Beware of experts with no first hand experience/knowledge in all things small and large.
Hope this helps,