Exhaust Mufflers for 3607 Carver

[MakinTime]

Hi guys I was thinking about adding a clamp on muffler to the exhaust that comes through the transom. The straight exhaust with no mufflers gets a little loud on long trips so I am looking for ways to tone it down. I have been looking at the Gibson 4"clamp on muffler, or dumping my exhaust underwater in some way. Anyone have experience with these mufflers? Or with making turndowns to put it underwater? Thanks Tim

[km1125]

I have a 3607 too, with 350HP Crusaders. At one point, I bought a set of "Dappers"... at least I think that's what they were called. They were 4" diameter pipes with baffles in them. I put them in the flexible exhaust lines that run back to the thru-hulls in the transom.

I wish I had done some kind of before-and-after test. I had put them in over the winter so I couldn't really judge how much of a difference they made. I took them out because I thought there was too much back pressure... I had an exhaust hose pop off and I blamed it on them. It was probably just bad clamps though.

[Viper]

Are you talking about adding a muffler tip on the outside of the transom? If so, I don't have any feedback. The Centek inline Vernatone mufflers perform well if you have room to install between the engine bay and transom.

Underwater exhaust will require a muffler specifically designed for that. They typically have a dry exhaust relief above the waterline as well. They're okay but I always prefer to see at a glance that I'm actually pumping water. Also not crazy about a couple of large holes in the bottom of my hull. Having said that, while mine isn't underwater exhaust, it's not that easy to tell if I'm pumping or not.

My 3807 doesn't have mufflers either. It's on my bucket list but will be a bit of a challenge to incorporate. There isn't much room between the Y fitting and where the exhaust hooks up to the hull side. There is an exhaust pocket built/glassed into the hull that runs from the engine compartment to the transom so there is no way to install an inline muffler along that run. Also very little room in the engine bay for a lift muffler. Centek makes some smaller in-line units that will fit between the y and the hull side but the smaller you go, the less effective they are. Going to be a bit of a challenge to get a meaningful difference but I'll come up with something. May go with an exhaust hose insert type like this, they can be installed in a flexible exhaust hose and clamped in place.The good think is it doesn't matter if the hose is level or not which really makes a difference in my case:
https://www.wr-products.com/products/ggb-marine-exhaust-insert-competition-4-pair

[MakinTime]

Thanks for the responses... Ike that idea Viper I have never seen that type of muffler before definitely sounds like the easiest way no doubt. I was thinking about coupling them to the end of my exhaust tips for easy install this summer while the boats in the water still. Then this winter put them in line near the transom. KM do you know off hand what size the tips are that come out of your 36? I am thinking they are 4". Not going to get to my boat until the weekend.

[km1125]

The hose going back there is 4", so I would assume the outside tips are the same.

Those bolt-on mufflers look interesting. I wonder how well they work.

Those integral ones that Viper linked to are interesting also. I wonder if it would work better to put two 3" ones in each exhaust output downstream of the risers or a 4" one in the main somewhere after they are combined?

I've looked at some custom ones that would have two 3" inputs and one 4" output.. there are a few designs that would fit behind my engines above the shaft log but haven't explored it beyond looking at pictures.

[Viper]

The guys in Ontario that build the type of muffler I noted above build them to spec. You tell them what you have to deal with and they will design a system specifically for each application. They do a lot of high performance boats and I know the key there is minimal restriction requirements while quieting down the big horses so I'm confident in their ability to do the job. Still on the fence though, pretty hard to beat the muffling capabilities of a lift muffler. The problem is the lack of space.