Exhaust Design

Below is a typical sailboat exhaust installation. The waterlock silencer (muffler) is the collection point for water in the exhaust system when you shut the engine down, and as such needs to be the lowest part of the exhaust system. You need a drop of about 9” from the exit of the exhaust elbow (X on the drawing below) to the inlet of the waterlock muffler. If you are unable to accomplish this then we suggest using a high rise exhaust elbow which will raise point x up by the required amount.

If you are using a plastic waterlock muffler or a fiberglass one, then we suggest a minimum of 12” length of hose between the exit of the exhaust elbow and the entry point of the waterlift muffler. This allows enough time for the water in the exhaust system to cool the gases down so you do not have any muffler problems.

  • Note 1 Siphon break here for engines installed near or below water line.
  • Note 2 Loop in exhaust hose should rise approximately 18” above waterline.
Anti-Syphon Valve
Anti SyphonValve (Vented loop) For 7/8” & 1” hose
Highrise Extension Elbow
Highrise Extension Elbow
Cross Over elbow
6" and 8" High rise

Here are pictures of our waterlock mufflers we carry in stock.

waterlock mufflers
waterlock mufflers

Base width 5.5”
Base length 12.75”
Muffler height (excluding outlet connection) 7.5”

for use on engines up to Beta 38 only.

Other mufflers are available and very often, installers will choose one to fit in the space over the manufacturer. As long as the muffler has the adequate capacity to protect the engine while sailing, you would be fine.