Exhaust Rooster Tail!

[Fogg~Dogg]

With the boat trimmed perfectly even via inclinometer and "feel", my AE-28TE kicks up a mean rooster tail coming off the port side stainless steel exhaust fairing! I've worked all kinds of trim adjustments, weight balancing acts, people disbursement, and load management scenarios, but it still kicks up. If I lift up the port side via trim tabs, the underwater exhaust is no longer underwater, thus I get a very loud noise reading and smell of diesel. I don't seem to be loosing any speed over ground, but it does look pretty bad. In fact, that rear side of the boat gets fairly wet. I am wondering (a) Does anyone else experience this - and how do you deal with it? (b) Is there a speed cowling or fitting that would smooth out the flow over the gasket and stainless fitting? I'd guesstimate that the gasket and fitting are about 1/4-inch protruded out from the hull into the flow of water - thus the rooster tail. (I do know that when I was in airplanes, the manufacturers would smooth out the airflow in situations like this with moulded fairings thus reducing drag). Thanks.

[jumpjet231]

I have the same problem. I was going to try to smooth the edge out next year with a taper of black caulk.

[furball]

If tide/current is running from port to starboard I get a good size rooster tail as well. If the tide/current is running starboard to port, no roaster tail. Shows what a small edge can do in the water. I have never had it wet the back of the boat. It's never been that large. I wonder if it's caused by the leading edge or the inside of the trailing edge of the exhaust port?
Good luck and I hope you find an answer.
John

[RobS]

John,
Two very good points you mention there.

[Fogg~Dogg]

Thanks guys! I did hang over the rail to see if it was the leading edge or the trailing edge of the exhaust opening that was causing the problem. Couldn't tell without tank testing at $1,000,000! My only worry with adding a fairing is that any extension over the exhaust opening could cause a pressure wave to develop and make things even worse. I condidered, don't laugh, using a mock-up made of Play-Dough to see if it might work, and then have a final stainless piece cut and stamped out. That'll depend upon cost. Man, the things we look at in a "down-economy"!

[Jack28]

I put a bead of caulk in front of the exaust flange as someone suggested and it seems to have helped the rostertail. I just put it on the leading edge from the waterline around the bottom radius. I will look more closely next time I run the boat. JACK

[fuenstock]

I put a bead of caulk in front of the exaust flange as someone suggested and it seems to have helped the rostertail. I just put it on the leading edge from the waterline around the bottom radius. I will look more closely next time I run the boat. JACK

How did this fix help with the rooster tail? My boats being hauled out this week for new boat paint and considering doing the same to my exhaust( caulking to front edge of exhaust )to help with the rooster tails..

[Jack28]

The caulk fell out, I am not sure when. I plan to try again this winter, this time I will remove bottom paint where the caulk will go. JRG

[Denis]

Can you build a small faring attached to a small dowel that you could hang over the side while under way just to see if it helps? If it does then you can make one out of stainless or fiberglass and attach it to the side of the boat. Just a thought.

[DougSea]

Just a point of interest (maybe) but my older TE with the Penninsular has a molded exhaust port without the trim ring like the newer Yanmar's. It has a built in fairing on it's leading edge. I'll have to look around and see if I have any pictures of it. I don't have any issues with an exhaust rooster tail.

[jcollins]

I found a picture that shows the "fairing" on the leading edge. Not the best shot.

[fuenstock]

I Just picked up my boat from getting a fresh coat of bottom paint where I also had the shop feather in the front edge of the exhaust port to hopefully reduce the rooster tail it causes. While making my way back to my marina 4-5nm down the way I tried diffrent speeds and headings to see if the rooster tail had been reduced. The rooster tail was greatly reduced but, it's still there. Much smaller anyway, I don't see it being big enough to wet the transome anymore. The reduced rooster now shoots off to the side and low to the water instead of straight up the side of the boat.