Does a Bukh DV10 need a silecer?

[LittleSister]

Our project boat is fitted with both a water lock and a silencer. Is the latter necessary? (On our other boat with a Beta 14 there is no silencer and the exhaust is not at all noisy, but that's a twin cylinder rather than a single.)

 

[chewi]

mine only has a water trap.
that's all it seems s to need.