E27 Exhaust Under Water

[mordust]

While underway in our E27 using the Atomic 4 and moving at 4+ knots, the stern would squat so much that the exhaust was underwater a good bit of the time. Enough so that after the day's sailing there was a line of motor residue horizontally across the stern an inch or so above the exhaust outlet.
The boat sits even and the waterline appears normal at the dock.
We do not have any water in the water system tank under the v-berth.
It was just my wife and I in the cockpit (tiller version, so not sitting all the way back).
Waves on Lake Erie were mostly 3 to 4 footers, quarter following seas.

How much squat is normal?
How bad is this for the motor?
Has any one else had this problem?

Thanks
Bob Greene

 

[Loren Beach]

This might be an Unintended Consequence of the having a 30 (?) hp engine in a boat that only needed about 15.
IIRC, all the boat builders bought a 'standard' hp A4 engine and put it into every hull up into the high 30's.

Larger boats ended up with a good fit for power and smaller hulls had more than they needed.

Can you motor at 5.5 to 6. kts without squatting the stern? Given your DWL, the boat will not likely motor much faster than that anyway. (?)

Do you have a graph with hp compared to rpm for your engine? What rpm are you at when motoring at 6 kts? 5.5 kts?

Jeff should be checking in with better information.

Loren

 

[Christian Williams]

For what it's worth, my exhaust is in the water at a fast motoring speed as the stern squats. I tend to back off, as the boat feels like its climbing a hill. Also goes underwater running in a seaway under sail in the normal course of rolling, pitching and so on.

 

[Jeff Asbury]

Jeff should be checking in with better information.

Loren

Hmm?. I suppose when I have been motor sailing in big seas that may of occurred on my boat. I don't often pay that much attention to what's happening back there unless I am strictly motoring. Then I want to make sure waters coming out of the exhaust for sure. My first thought would also be how many folks are in the cockpit. I recently had 3 heavy Guys and 2 Gals onboard and we were sitting pretty low at the stern, but I did not look at the exhaust. Also, how much stuff do you have hanging off the stern rail, in the port lazarette and back in the quarter berth?

Might the exhaust on your boat be located in the same place as mine. I have a little Yanmar, my boat never did have a A-4 as far as I know.

 

[mordust]

Nothing out of the ordinary in the lazarette or quarter berth. Nothing hanging off the stern rail. Half a tank of gas.
Just me and my wife aboard.

My exhaust is about the same place as yours.

Bob Greene

 

[Jeff Asbury]

Nothing out of the ordinary in the lazarette or quarter berth. Nothing hanging off the stern rail. Half a tank of gas.
Just me and my wife aboard.

My exhaust is about the same place as yours.

Bob Greene

Well the A-4 is heavier than my Yanmar which is only 180lbs. Is there a lot of water in your sump keel bilge? Ya got me. My boat does not rest right on her lines, and is higher in the bow by a couple of inches. Sorry I couldn't be of bore help. It could be worse like the Catalina 30's that list to port.

 

[Second Star]

Exhaust Underwater

FWIW my 28+ sits like the photo of CUCAMUNA above and sails more or less the same. However under power she squats much like you describe. It will always squat under power as the prop is well below the waterline, angled to provide upward thrust across the centres of gravity and flotation. The more power applied the more the bow is lifted and stern driven down just like an outboard on a dingy. The amount that the exhaust is underwater is pretty small; consider how far an outboard motor exhaust is underwater compared to the engine.

 

[dt222]

My exhaust location is much like Jeff's and I have an A4. I also often have a line of residue above the exhaust after motoring so I must be squating also. I don't think it hurts the engine. With the routing of my exhaust system it would take some extreme conditions for a lot for seawater to return all of the way into my manifold.

Don

 

[Gregoryulrich]

I was messing around with my GoPro this past weekend on my way to anchor in Paradise Cove. We were making between 4 and 5 knots. You can see how far under the stern sits. One of the PO's put that clam shell over the exhaust. It hasn't seemed to affect performance so I've left it on. I assume it's to prevent following seas from entering the exhaust pipe while under sail.

https://vimeo.com/111576884

 

[Bill Sanborn]

My E29 does the same. I have always set my motoring speed so the exhaust is just above the water. This also happens to be about the speed I can sail in sorta calm water with well trimmed sails. This is just under 5 knots.

I think that sailing speed is a good indication of efficiency. Motoring at top sailing speed should be easy on fuel and engine.

IMHO that last 1/2 knot you can squeeze out while motoring is expensive.

Combining the above with Moyers adjustable high speed jet for the carb and motor sailing when possible can vastly increase the motoring range.

 

[mordust]

Great video. I guess from what I'm hearing that this "squatting" must be normal and probably of little consequence.
Thanks everbody!

Bob Greene

 

[Jeff Asbury]

Okay I was able to watch the video now. Great job and quality. Well I must say I don't think my E-27 sits that low in the water when under power. I will have to try and make my own video next time I go out. My engine (Yanmar 1GM10) is much lighter than a A-4 at only 180 lbs. Also my exhaust port is a higher than that one.

Granted I'm on a mooring here in this video I dug up from last Memorial day at Catalina, but it shows a good shot of the exhaust. http://youtu.be/iNffOq-DY_8

 

[celtic sea]

Ya, funny my E27, 1973 rests a couple inches high in the bow at the dock. Not sure why, always has and no problems. Looks pretty kool.
John
Celtic Sea
Atomic 4