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Old 05-01-2013, 09:38   #1
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The saga of my beneteau 49

I bought a new beneteau 49 in 2008 and have changed so far the engine twice because of water coming into the engine.
The first time , I noticed when I was sailing for prolonged periods of time on the same tack some difficulties in starting the engine. After checking the oil I found some water and decided to get a new engine as i was planning to sail from NY to the caribeans.
More recently again during a trip from NY to St Maarten, the skipper of the boat could not start the engine which was found full of sea water (again after sailing for a long time on the same tack).
I changed the engine again after adding a swan neck loop to the exhaust tube in before the thru hull.
Just recently as I was sailing for 3 hours on a starboard tack I noticed the same types of difficulties in starting the engine, and I am afraid that I have some sea water again coming in.
So I am at a loss, I had the boat inspected by a Yanmar technician who confirmed that the engine is installed properly.
Seems to me that the only source of water is the cooling raw water (and not the water from the exhaust) . So I changed the syphon valve in the raw water system in cas it was malfunctioning.
Any body has any suggestions on what I should do? The Beneteau people are telling me their boats are fine (mine is not!), so I am on my own on this one.
My boat is for time being at le Marin in Martinique, and I would like to be able to go and sail without worrying about sea water coming in .
Thanks for any help!
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Old 05-01-2013, 09:41   #2
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Re: The saga of my beneteau 49

Welcome to CF princessoftides. Sorry, I can't be of any help on this one, but I'm sure some others will have good answers for you. Best of Luck.
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Old 05-01-2013, 10:12   #3
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Re: The saga of my beneteau 49

So at this point you have an exhaust loop that is pretty high right? is it in the lazzarette? How high is it? It sounds like you have a vented loop on the raw water hose to the exhaust. Some people mount a small hose in lieu of the valve on the vented loop and take it to a cockpit drain. This provides a definite siphon break without the valve to fail and you can hear or see it in the drain to confirm cooling water. Also, if your exhaust outlet has a lip, put one of those power boat black rubber flappers on it. If you do all these things I dont see how it could have a problem. Does your engine inlet thru hull have a scoop on it? maybe that would be forcing water as you sail thru the engine eventually filling the exhaust and rear cylinder. (doubt it)
Do you have a waterlift muffler in the exhaust? If not, I suppose a long exhaust hose and a low mounted engine could combine to get some water out of the hose into the engine after being heeled for a long time.....
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Old 05-01-2013, 10:13   #4
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Re: The saga of my beneteau 49

You'd probably get better results if you moved this thread to the 'Engines and Propulsion Systems' forum...
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Old 05-01-2013, 10:23   #5
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Re: The saga of my beneteau 49

Thanks for your reply.
The exhaust loop goes all the way to the top of the rear lazarette.
I have installed a new and bigger waterlift muffler after I changed the engine for the first time, and added a black plastic flapper to the exhaust, but this did not solve the problem.
I am convinced now the problem comes from the cooling water. The best way to test it is to close the intake seacock when I shut down the engine and check if the problem occurs again. (I better remember to open it when I start the engine....).
Thanks for your help.
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Old 05-01-2013, 10:39   #6
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Re: The saga of my beneteau 49

Is it possible you are having difficulties stating the engine for unrelated reasons, then are using the starter for prolonged periods resulting in water ingress? I'm pretty sure you already know this, but if your engine fails to start within a few seconds, the raw water pickup should be closed, then re-opened immediatly after engine start-up.
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Old 05-01-2013, 10:42   #7
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Re: The saga of my beneteau 49

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Originally Posted by Princessoftides View Post
(I better remember to open it when I start the engine....).
Hang a note on the ignition key
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Old 05-01-2013, 11:04   #8
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Re: The saga of my beneteau 49

Is the exhaust on the starboard side, and did the water in the engine problem always occur on starboard tack? What point of sail were you on--upwind, downwind, or reaching?
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Old 05-01-2013, 11:11   #9
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Re: The saga of my beneteau 49

Ye, the exhaust thru hole in on starboard and the issue seems to occur when on starboard tack.
Thank you
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Old 05-01-2013, 12:05   #10
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Re: The saga of my beneteau 49

I always start my engine with the seacock closed. With freshwater cooling, with the cooling water inlet closed. As long as you open it once the engine starts, it is not a problem to start it with no cooling water. Oh, if you have a vented loop, check to see if it is the kind with the screw-in vent cap. Make sure it isn't shut.
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Old 05-01-2013, 12:17   #11
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Re: The saga of my beneteau 49

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Originally Posted by Princessoftides View Post
Ye, the exhaust thru hole in on starboard and the issue seems to occur when on starboard tack.
Thank you
If your exhaust discharge is under water while sailing and your exhaust hose does not have a vented loop, once you've shut down your engine, cooling exhaust gases in the water-life muffler could create a vacuum that could suck water into the exhaust line. As you report a loop high in your transome, it is, presumably, above your mixing elbow hence gravity would allow water to flow into the water-lift and, potentially, back up to your mixing elbow/engine. It may be that simply adding a fitting with a small vent line from the top of the loop in the exhaust hose to a small thru-hull in the transom (this is always above water) is all that you need to break the siphon. Note, however, that I would expect this to be a problem on more than just one boat if this is an issue that emerged shortly after delivery from the builder; and, it would be unlike Beneteau to allow such a condition to persist.

FWIW...
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Old 05-01-2013, 12:34   #12
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Re: The saga of my beneteau 49

I wonder, could it be, that cooling water intake is installed backwards?
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Old 05-01-2013, 12:57   #13
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Re: The saga of my beneteau 49

If you are on starboard tack, your exhaust would be well out of the water going to weather, and out of the water except for the occasional wave when reaching. If you have put a flap on the exhaust, the waves shouldn't be forcing water up it, and the exhaust loop under the deck should allow what little comes in to flow back as long as you are heeled less than 30 degrees. I've heard of transom exhaust boats having problems in following seas and having to put in gate valves, but you installation seems similar to my Bene 45, and I never had a problem.

If the engine exhaust is on the port side of the engine it would be a bit lower when you are on starboard tack, perhaps making the anti-syphon valve a prime suspect.

I'd suggest you close the engine thru hull and go for a long sail on starboard. The only problem is how to tell if the water is filling the exhaust system BEFORE it gets into the engine. All I can think of is to pull an exhaust hose off the waterlift (not easy underway), and see if water flows in from the back of the boat or the engine side.
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Old 05-01-2013, 13:48   #14
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There are quite a few of these boats around, I knew an owner of one who did not have this issue. Have you talked to Bene? Is there something different about this one from other B49s?
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Old 05-01-2013, 13:50   #15
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Re: The saga of my beneteau 49

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I wonder, could it be, that cooling water intake is installed backwards?
+1 on this. I recently repaired a Trimaran engine damaged for this very reason.
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