3" thru hull exhaust too loud, want to tone it down

[tfret]

Thanks for all the generous help guys. This has been very helpful for me.

 

[JASinIL2006]

Pulling the motor really isn’t a big deal...

 

[tfret]

I've decided for simplicity, I'll start out by doing the 90* turn down trick to see what that gets me. I think I'll tack weld a baffle disk with large center hole and multiple outer holes to the exit as well for additional on-plane muffling. This is a relatively easy modification that I can easily remove if I want. Concerning how far down to go with the tip, if I run a straight edge off the bottom of the hull, how much clearance should I have to the tip of the turn down? I don't want them to drag when driving over wakes etc. Maybe an inch?

 

[alldodge]

how much clearance should I have to the tip of the turn down?

Your guess is probably as good as ours, no one has tried to get that close to the bottom of the hull. My guess is it should work

 

[Bondo]

Ayuh,.... Ya just want the tips a couple few inches below the waterline at idle,.....

Go to deep, 'n the motor may not start because of the back-pressure,.....

 

[QBhoy]

Depends how much you can spend. Corsa marine have a captains call solonoid switchable system that might fit.
I have it on the boat. Straight through for the fun factor and silent when coming into the marina late at night

 

[tfret]

So I looked this weekend and yeah, totally impossible to install the Y pipe without pulling the engine. And I don't really have what is needed to do that. I have found some good 3" stainless short 90's that should suffice as turn downs to get me under the water at idle anyway. My straight throughs are 3 1/16" OD. I'm not sure how to connect the 90 to my straight. Lowe's has a 3" rubber adapter with hose clamps on both ends for coupling 3" PVC pipe together. Thats the only thing I can think of. Any suggestions from what other folks have done.

 

[alldodge]

Either Tig welding, drill and use some screws, or use some short pieces of hard walled exhaust tubing and clamps

 

[tfret]

I’d like to try the turn down approach with some 90 fittings installed where my flappers currently are. But I want to put shutters inside them to prevent back flow. Mine is 3” so the ID is about 2 3/4” wide. I’m having a difficult time finding an off the shelf part for this. My thru hulls are low on the water line so I’m afraid not to have shutters. Any suggestions on what I could put inside the turn down for this?

 

[alldodge]

Probably need to change your tip, or get something custom made. Last one in this link has internal flappers

https://www.cpperformance.com/products/exhaust/exhaust-tips.htm

 

[tfret]

My original thru flanges have what’s left of shutters in them. The cross piece is all that’s left. So I know at least back in the 80’s someone made a shutter for 3” thru exhaust.