Good evening all. We're thinking of creating a cover to try and drown out the sounds of our inboard-ouboard on Lili. Something like an upturned 100L Tupperware box maybe with some soundproof insulation. Anyone tried it? Any hints?!


No, but my inboard has sound proofing with a foil outer face. Just make sure whatever you fit is fire proof!
Nosey - Parker 325-26
philip linsell
Make sure you keep a good air supply to the well, exhaust gasses can build up and effect the engine running.
rascal superseal 26 ( seal 22 a long time ago)
Thanks Philip - that’s a good point. Will see if I can run a hose for the exhaust or intake away from the box
Does that help much?
I made sure the cover on my (Tohatsu) engine was pulled down tightly by the catch. This can be done by bending the metal tab on the cover.
Then I cadged some automotive sound insulation material of a friend who was building a camper van and stuck this around the inside of the engine cover essentially making it heavier and less prone to vibrate.
Not silent by any means but very much quieter.
Mike Ball
P235 No 36 "Juicy Blue"
philip linsell
My information is very old, it's many years since I had my 22. The outboard motor had a "piddle pipe" which is some of the cooling water squirting out from the leg above water level as a positive indication that the cooling water is circulating. Unfortunately this is driven by the exhaust gasses which build up in the well. the solution was to fit a flexible tube through the stern to discharge the water and gasses outside of the well. I have no idea if modern motors still have this feature/problem.
Thanks all

Tried to launch today but had to abandon as the motor wouldn’t allow me to switch between gears. Very frustrating and happened before but thought a service had sorted.

Having to put sound insulation (and sailing) plans on the back burner for now!

John Edwards
I ‘sound-proofed’ my last outboard with an insulating padding that was stuck to the inside of the outboard cover. Not overly successful and it remained very noisy to the point that I did not bother with the new engine. I would be very interested to know what and if others have done – other than to turn the engine off at every opportunity!
235/07 Diamond
2022-03-27T20:02:12Z (1,973kb) downloaded 12 time(s).

Some benefit with just a box, going to try insulation next...

(as you say, though, minimal engine use is probably the key!)
James Hamilton
I have also tried insulating the inside of the engine cover, with only minimal effect. My conclusion was the same as yours, probably only a sound proofed box (with the air intake coming from over the stern), would make much difference. Currently try to sail whenever possible.
Jim Hamilton (235 Sandy lady)
Thanks Jim

We were wondering about the air intake. Couldn’t quite work out how to externalise this - a thick hose through the engine cowling and new “box” I guess, but didn’t ideally want to drill a hole in the cowling. Also didn’t know whether just supplying fresh air under the cowling would be enough or whether I’d have to actually feed it to the air intake itself.

It actually ran pretty well for 20mins just under the box, but not a hot day etc.

Am I right in thinking that the exhaust comes out under the water line anyway?
James Hamilton
Yes, once it is up and going, the exhaust comes out underwater (makes reverse a bit inefficient on my engine however). During warming up, I do get some steam? through one of the water exhausts but this doesn't last long.
The air intake through the cowling is quite small, so I have allways assumed that all you needed was an aft pointing hole perhaps 1.5 to 2 x the size (allowing for the more convoluted flow path)
As I would expect sound to come out of this hole (in the box), It should perhaps be baffled or at least pointed aft so the sound waves are directed away from the cockpit.
I was thinking that you would not want to make a hole for the twist control (would let the sound out), so unless you have a Morse control, you would only use the 'box' for passages, and remove it in harbour, or possibly have a flap you could open for access.