4" Rubber hose on engine exhaust to under water

Ralph Johnstone · Aug 25, 2015

danstanford said:
Where the exhaust exits through the hull, there is a large diameter rubber hose attached so that the exhaust actually gets released under water. Because this big hose is longer than a foot and has about a 90 degree twist in it, it picks up weeds and must be adding a ton of drag on port tack. It seems quite quiet which may be why it is there, but I cannot tell if the exhaust is flowing water...

Can anybody enlighten me? Is it a standard item to be added, or was it factory?

Thanks, Dan

I think I'd be willing to pay money to see a picture of this 4" dia. hose as it penetrates the hull. It's definitely not factory as it makes no sense and may actually be a hazard if the PO was a little off kilter. As it's not factory, you want to make sure it's very, very solidly installed. Should it break off, you'd sink in a matter of minutes.

Both our boats are close in both size and year and I know that many Hunters like ours had underwater exhausts, most likely sound dissipation. It definitely works but presents problems in detecting raw water flow.

Please post a picture if possible.

Calif. Ted · Aug 25, 2015

Because this big hose is longer than a foot and has about a 90 degree twist in it, it picks up weeds and must be adding a ton of drag on port tack.

That REALLY doesn't sound like anything I've ever seen.

Ralph Johnstone · Aug 26, 2015

danstanford said:
I will take a picture and post it when I go to the boat this weekend. It is my thought that the large diameter does not penetrate the hull but is anchored on (pretty securely) to the hull by some kind of flange or bracket.

This set up is either a stroke of genius or just the result of a stroke on the part of the PO

.

Either way, we've got to see the pictures.

Ralph Johnstone · Aug 27, 2015

One Picture ......................

danstanford said:
Here goes. It looks like there must be quite a large metal flange coming out of the hull and this is hose clamped to that.

.............. a thousand words ............. my mistake as I thought that the 4" dia. hose was on the inside of the hull.

I'm going to say (based on 15 years experience) that the function of the 4" hose is to avoid having the exhaust filled bubbles from the outlet, backwashing up against the semi-submerged portion of the transom. If you'll notice when you're under way, the squat sinks the transom enough to submerge it by a few inches. Every spring, someone is hanging over the back end of our boat, scrubbing off the black soot from the exhaust.

The attached photo is how the exhaust looks as it comes out of the water with no cleaning. Scrubbed by the passing water while under way. The transom is a little dirtier.

I will say that the hose is probably quite effective in avoiding having the soot staining the transom BUT if you want it there with the problems you've detailed here .................

I've got to wonder how the exterior flanged section is attached to the hull. And, if it were hit by something, what would the effect be ?

quadrille38 · Aug 27, 2015

I don't know and could be off but I can't imagine the additional back pressure that created on the exhaust can be good for the engine. It seems like the added back pressure could cause engine performance issues.

Plus I'd be worried that the additional pressure would cause the water to back up in the muffler and up into the cylinders.

HMT2 · Aug 28, 2015

I think your boat is simply a he.

kloudie1 · Aug 29, 2015

Sailing one day close to Annapolis and saw a very spiffy and pristine traditional sailboat kinda motorsailing along with a 5foot long big rubber hose clamped onto the transom exhaust thru-hull. It looked strange and a bit rude to see that thing flopping around right on the water surface, belching water and occasional puffs of smoke.. We had a laugh looking at the lewd thing as we rounded Thomas Point Light! We guessed he didn't want soot on the pristine topsides..??

SEMPERAVANTI41 · Sep 4, 2015

Both the exhaust for the engine and generator on my 2007 41DS exhaust above the waterline. I believe this is a mandated requirement. Perhaps someone knows the actual regulation.

Sailor_Jeff · Sep 5, 2015

If your cooling water is not flowing, won't an alarm sound on your engine control panel in a few minutes before engine damage occurs?

Sailor_Jeff · Sep 5, 2015

If your cooling water is not flowing, won't an alarm sound on the panel after just a few minutes? Way before damage occurred? If not, can you install a flow switch and beeper on the water intake through hull?

seadaddler · Sep 5, 2015

290I had

I had a 2001 290 for a about 6 years and had no hose but I think
the hose was added to stop the black sooth from collecting all over the rear stern.
While I had the boat changed the mixing elbo and had the engine checked but no matter what I did the black sooth would collect on transom so just maybe
he had the same problem and this was the fix.
Nick

Ralph Johnstone · Sep 5, 2015

This May Help .....................

danstanford said:
There is a small elbow but even if it were flat I would still not be able to insure water flow in the exhaust because it comes out under water.

......................... for monitoring underwater exhaust water discharge.

http://forums.hunter.sailboatowners.com/showthread.php?p=1088183&highlight=aqualarm

woodster · Oct 19, 2015

i would not grind that off i would take it out through it as far away as i could and get the proper exhaust through hull fitting and replace it ...i understand you didn't put that on there ....but i will say that i detest cross eyed engineering (read rube goldberg)....that thing is not doing you a bit of good and is causing drag when under way like you would not believe and totally looking like a donkey's appendage ....sorry for the rant...but you get the picture

4" Rubber hose on engine exhaust to under water

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