Silent choice question
 

I'm considering buying a 1995 Fountain Sportfish with Silent Choice. Seems quieter at idle but not so much running. I've owned an Albemarle 24 and a Carolina Classic 28 with exhaust through the out drive. They were much quieter at idle and running. Why isn't the Fountain quieter with exhaust going thru the out drive?

Mainly because none of the exhaust diverters will close off 100%, at most its about 90%, so there is always some going out above the water.

Silent choice question
 

Is there an easy way to divert all the exhaust through the out drive?

I don't know the boat, what motor(s) or how the above water exhaust exit, but guess the easiest would be to plug the above the water exits.

Could also remove the diverters and install regular elbows. Would still probably need to close off the tips so water doesn't come in.

If you have B3 drives I would be sure it has an exhaust tube on the drive and not a exhaust hose

Silent choice question
 

Thank you for your kind reply. It has a 2009 Bravo 1 drive with a 2018 new 454 engine. How would you plug the above water exits?

I would remove the exhaust tips, cut some 4 1/4 plugs out of 2 layers of 3/4 plywood, then use epoxy resin and the plywood to plug the holes. Then mix some gelcoat to match and finish the hull.

An easier method, as before remove the diverters, and install elbows to the Y pipe. Then find someone that can weld stainless and have the tips welded closed. So you can still see the tips but they no longer function. This way when you sell it, if the next buyer wants to put them back in, it would be easy to change back

I would not run with any type of silent choice in the thru prop mode above 3000rpms.

Are they straight tips out the back or mufflers???

Silent choice question
 

They are straight tips out the back. Why not use Silent Choice above 3000 rpm?.

Silent choice question
 

They are straight tips out the back. Why not use Silent Choice above 3000 rpm?.

You are more likely to get water reversion, especially if the engine has been modified.

Are the tips baffled? Pics would help.

Above 3000rpm, the exhaust pressure is working against the system trying to divert it through the prop = killing the solenoids/ cause components to fail prematurely.

You have to look at it as a performance,through-hull design that can go quiet for idle/ no wake zones - not the opposite

What they said for above 3000rpms.

I would swap out the straight tips for muffler tips or add muffler inserts to the tips.

Thanks for all the comments and suggestions! How much sound reduction comes from muffler tips or inserts?

most advertise 4-10% reduction.... most are oriented to keep below legal max limits at idle as the base standards (80-90db)

https://www.offshoreonly.com/forums/...r-inserts.html

For optimum performance you don't want the exhaust to go thru the prop, but the motor still does fine going thru the prop, just going to loose a few hp at top end

4-10db reduction. A 10db reduction reduces the noise level you can hear by more than half.

I have to disagree completely. I ran for 16 years plus with Rex Marine sound selectors closed 90% of the time and never had a reversion issue. Reversion is more likely with poor exhaust design, massive cam overlap, and at or near idle rpm. Above 1000-1200 rpm there is no time in the reversion pulse to go up stream. I know the Rex Marine unit was bullet proof and could care less if it was closed, open or partially open at any rpm.

I've got the old 4 wire CC and the solenoids are in the relaxed/off position when it's exiting the prop.

I've always heard that running >3k RPM (for extended periods) with exhaust going thru prop can overheat the drives; more so if engs have been significantly modified. Anyone know of this is true? Sounds plausible to me.

Unsure of that but Merc does say use the exhaust tube and not the hose for a B3 drive, but not talking about a modified motor

Same here . I'm sure that's the standard way they're wired up .

Right, so it makes no sense that switching to open pipes after 3k saves parts.

This was the recommendation directly from Corsa (Marine) when we had to replace a NLA solenoid and rewire on a 502 Donzi