Outboard silencers

[mark221263]

Hey Guys, read another listing on a site for an outboard siliencer. I've made one as follows that works fine and doesn't break the bank and keeps the neighbours happy. Thought I'd share the idea.

Get a piece of storm water pipe or other plastic pipe that fits neatly inside your prop.

Cut it to be about 350~400mm long and glue an end cap on one end.

Drill about 40 to 50 x 12mm holes in it starting from the capped end back to within 150mm of the open end.

Stuff it with shade cloth so it's reasonably well packed but not crammed super tight. Hold the shade cloth inplace with a couple of cable ties through 2 of the holes closest to the open end.

Now push the open end into the inner diameter of your prop and hey presto, $5 muffler.

I made one from 90mm storm water for my previous 70hp yamaha and now use a pipe of 100 sewer pipe for my 150hp merc.

Work a treat, cost bugger all and dont rust!

[bigbrian47]

i tried one of those silencers but couldn't keep it in place it came with an elastic strap
the supplier said they were no good on my stainless prop ::)
how do you hold yours in place when motor is running
cheers brian

[impulse492f]

Great idea Mark, what’s the difference in sound levels do you think?

Brian, I have the "large" unit 4596C (as per here http://www.biasboating.com.au/outboard_access.html ) which was slightly to big (the medium was way to small) for my 85 Suzuki (with SS 13 1/4 x 17 prop).

I needed to linish the edges of the silencer and the unit now fits like a glove, I don’t need to use the strap and can run the motor in low rev's.

I would say it cuts the noise by 60% and produces higher water flow through the main water discharge hole in the outboard.

[searaider]

impulse492f ,
mmmmmm , very interesting .

bigbrian47 ,
I tried on of the Bias silencers on my 150 Yammie & had to get a 2nd O'Ring off them to fit the S/S Prop .

Sealed in the prop fine , but with the silencer fitted I couldnt get water out of the TelTail .
I even started the motor & then fitted the silencer . As soon as it was fitted the water stopped flowing from the TelTail . :o :o

Took it back to Bias & they refunded my money .

Peter
Searaider 2 #

[mark221263]

H Guy's, I'd say my silencer cuts the noise buy about 40%. The main thing is you don't get that sharp 2 stroke bark noise.

It must not cause too much back pressure as there is no change to the water flow and I've never had t secure it in place. I've alwyas found a piece of poly pipe that was a neat fit and the prop tends to reduce silghtly in diameter so it tends to wedge inplace.

If it was a problem being loose you could make a large rubber band to go over the end of it and around the back of the leg from a bike tube or similar.

I'll try and list a pic tomorrow for those interested. Shame I cant post a sound file, one whit it on and one with it off. For anyone interested in a sound file pm me your email address and I'll email on through.

Cheers Mark

[ahoj]

Can someone send a picture of installed silencer? Thanks

Ahoj

[billfisher]

A wet hessian bag or rag over the exhaust will do the same.

[mark221263]

Here's a pic of the cheap version

[impulse492f]

Here's the BIAS version of the silencer

Pt 1 of 3

[impulse492f]

Pt 2 of 3

[impulse492f]

Pt 3 of 3

[wayneoro]

knock it off guys what sweeter sound is there then the cackle of a healthy 2 stroke

[bigbrian47]

thats the one i could'nt keep it on even with the strap bought it at the boatshow a few years ago
decided not to persevere so usually come home cold flush with the tap (keep the peace) run in the tank later
brian

[impulse492f]

knock it off guys what sweeter sound is there then the cackle of a healthy 2 stroke

The cackle from the mean neighbours wife from over the fence at 2am (she scares me :'()

But yes the sound of the 85 is sweet.

[gogecko]

So these are just for flushing? Will any of them work while Im running on the river at 4am?

[SeaHunt]

So these are just for flushing? Will any of them work while Im running on the river at 4am?

Just go fast :)

Wet rag works pretty good. I use an old teeshirt, tie the arms together around the back of the leg or is that the front? You know what I mean. ::)