Re: [BCC Forum Post] Jeremy and Nica: Muffler (for Sabb) & Exhaust Fittings


The Sabb G engine does not use a water lift muffler. Instead the exhaust
hose acts as the water lift muffler but I will need to read the engine
manual before I can tell you how far the hose should droop below the engine

When we run the engine at 1,600 rpm, the prop pitch lever is no more than 35
degrees from top center. If you over pitch the prop, the engine will
overheat and/or smoke. Max cruising rpm is 1,800 and the manual specifies
the engine rpm should not exceed this setting. Engine valves go out of spec
more frequently than specified in the manual, hence the valves should be
adjusted periodically. The engine will run with a 1/4" gap between the
rocker and valve stem but lacks power and sounds as if it is about to fall
apart. This engine was designed to run, regardless and still be passed on
to the next generation of fishermen.

The specified hose diameter for the G-engine is very close to 2".

Iduna’s transom does become just a little dirty but never very sooty. I
suspect you are overloading the engine and spurting carbon particles out the
exhaust. Because you use an auxiliary impeller water pump instead of the
Sabb diaphragm pump, the engine may be running on the cold side, resulting
in incomplete combustion.

You may want to consider installing a Sabb/VDO engine rpm meter and
purchasing an engine owner’s manual for from Sabb America.

If you like, send me a private message with your phone number and I will
telephone you after 19:00 hours tomorrow using my free cell phone minutes.
Let me know what is the best time to call.

Fair Winds,


Hi Rod,

Thanks for the prompt reply. I do have the (excellent) owner’s manual which indicates the drooped hose run. Note that this manual is available from Sabb as a PDF at:

My engine is largely below the waterline - so I route the exhaust hose like an “S” layed on its side. I have short hot stack swan neck coming up out of the silencer; I have a water injection tee on the downward leg; then hose going down and aft; the hose then makes a loop up to the under side of the deck before coming down to the exhaust fitting at the transom.

I do have a belt driven impeller pump, but I have a valve system to limit how much water I put through the engine - the rest goes through a bypass hose.

I’m headed down to the boat tomorrow - hope to finish painting the nonskid this weekend.



Thanks for the link to the pdf owners manual file. I measured the Vetus
exhaust hose we installed in IDUNA. The I.D. is 45 mm (1.77") not 2" as
previously stated. Based on your post, it sounds as if you have routed the
exhaust hose correctly. We do have a Vetus anti-siphon gooseneck between
the exhaust through-hull fitting and the exhaust hose. This was in place
when we purchased the boat and prevents (hopefully) water from flowing back
into the exhaust hose when a wave slaps the stern. Your cooling water
bypass flow control reminds me of my chemical plant days when I developed
processes and implimented them into the plant operations - fun stuff.

Fair Winds,


----- Original Message -----
From: “BCC Forums”
Sent: Friday, May 27, 2005 12:37 AM
Subject: [BCC Forum Post] Jeremy and Nica: Re: [BCC Forum Post] Jeremy and
Nica: Muffler (for Sabb) & Exhaust Fittings