Zodiac Hurricane to loud (through hull)

[Tylervg]

I have a 1995 Zodiac Hurricane with an AD41 turbo diesel in it. I use the vessel for a whale watching charter. It's hull cooled so the exhaust is through hull. At idle the exhaust is underwater but when I start to get on plane the exhaust is out of the water and extremely loud. Is there any type of exhaust I can bolt on the hull and quiet down the boat? any help would be greatly appreciated.

[clloyd]

Here are shots of two different Willards with two types of exhaust setups.

The one has exhaust going directly to a downpointing nozzle on the Konrad drive, this I assume is similar to your etup. Underwater when idling, pointing Down at the water stream flowing under the boat when planing.

This is my setup and frankly I'm more concerned that the exhaust manifold is not high enough to guarantee no water intrusion, espec when at anchor fishing, etc. and engine not running.

The second setup uses a waterlift muffler and exhaust is above waterline. The waterlift is interesting and I'm wondering whether this is older or newer setup on a Willard if anyone knows, please tell me.

I would think it should also be quieter, Not easy to find room for however.

[ncp]

I could be wrong here, but I believe that most Willards with the muffler have Merc outdrives. The reason being that Merc outdrive are made for the exhaust to come through the propeller hub. But, since that would cause to much exhaust restriction with a large Cummins, they T the line with a small line going though hub and a larger exhaust line exiting at the waterline. Since the waterline exhaust can be loud, they add the muffler. Just my hypothesis!