Raw water in the beilge whaen underway

[Nigbb]

Hi does anyone have any ideas please. Sessa c35 with twin D4, the engine beilge is bone dry when the boat is left sitting but just a 3-4hour ru we have raw water in the beilge, not lots, noy enough to activate the pump . I spoke ged it out and we are talking a couple of bucket full.
There are no obvious leaks on the engine raw water side.
Leg we serviced this spring with new bellows.
Any ideas?

 

[Bandit]

Have you thoroughly checked the coolers?

 

[Jamie Dundee]

Raw water pump leaking perhaps? I had similar, imperceptible drip at idle, 5 litres+ in the bilge after a trip out. Water was hitting the belts and spraying out so no direct leak evidence.

 

[Mr Googler]

Raw water pump leaking perhaps? I had similar, imperceptible drip at idle, 5 litres+ in the bilge after a trip out. Water was hitting the belts and spraying out so no direct leak evidence.

Is that the one George is rebuilding?

 

[philipdawsonladds]

Check the O rings on the strainers - these can leak if not sealed properly - only when under way

 

[Jamie Dundee]

Is that the one George is rebuilding?

Yep, he said he was doing another one and I guessed it was yours. I bought a new one from Repower so the original will be a spare.

 

[Mr Googler]

Yep, he said he was doing another one and I guessed it was yours. I bought a new one from Repower so the original will be a spare.

Not trust his work? ??

 

[Nigbb]

Raw water pump leaking perhaps? I had similar, imperceptible drip at idle, 5 litres+ in the bilge after a trip out. Water was hitting the belts and spraying out so no direct leak evidence.

Aha, OK need to have a real good close inspection with engine running.
Cheers

 

[Nigbb]

Check the O rings on the strainers - these can leak if not sealed properly - only when under way

Agh, OK didn't think of that, I guess there is more pressure when pushing on.
Thanks

 

[Jamie Dundee]

Not trust his work? ??

I changed the pump 18 months ago, kept meaning to send it away for refurb but never got round to it. Thought it was about time to get it done.

 

[lauriel]

Are you sure it's sea water? I had similar issue but found it was drinking water. Eventually discovered the 100 litre moulded plastic water tank had some horizontal splits higher up the sides. This tank was installed 30 years ago under the seat in the saloon. When moored no problem, when heeled to port no problem but heeled to starbord it leaked into the bilge.
Eventual fix was replacing the tank with a bladder under the vee berth.

 

[AndieMac]

Aha, OK need to have a real good close inspection with engine running.
Cheers

Yes, definitely do this while engine is running at operating/cruise speed. Wear ear muffs so you can spend time close to the engines for as long as you need to and use a torch to look into dark corners.
Is water being sprayed against bulkheads or upper hull areas?, this would indicate leaks after the raw water pump and under pressure.

 

[Nigbb]

Are you sure it's sea water? I had similar issue but found it was drinking water. Eventually discovered the 100 litre moulded plastic water tank had some horizontal splits higher up the sides. This tank was installed 30 years ago under the seat in the saloon. When moored no problem, when heeled to port no problem but heeled to starbord it leaked into the bilge.
Eventual fix was replacing the tank with a bladder under the vee berth.

Agh OK, yes it's definitely salt water.
Cheers Nigel

 

[Nigbb]

Yes, definitely do this while engine is running at operating/cruise speed. Wear ear muffs so you can spend time close to the engines for as long as you need to and use a torch to look into dark corners.
Is water being sprayed against bulkheads or upper hull areas?, this would indicate leaks after the raw water pump and under pressure.

No signs of any splashing or signs of it being thrown up by belt. Someone suggested the strainers seals which I will also check out,

 

[Nauti Fox]

I had a leak from a hose between the strainer and the water pump, at slow speeds it was ok but at cruising speed water came through where the wire coils in the hose had eaten into it.

 

[Portofino]

A recent ish thread turned out to be a soggy transom compressing when underway .The outdrive flange seals had silently failed over years .Water ingress softened the balsa , or whatever core material .It’s compression only occurs when the leg is pushing the boat through the water at a certain speed = sufficient force .= opens the seals as it’s getting squeezed = water ingress

Obviously this diagnosis drops at the bottom of the tree once the higher up stuff listed above , mentioned like pump seal plate , hose clamps , cooler corrosion etc have been eliminated first .

 

[Nigbb]

A recent ish thread turned out to be a soggy transom compressing when underway .The outdrive flange seals had silently failed over years .Water ingress softened the balsa , or whatever core material .It’s compression only occurs when the leg is pushing the boat through the water at a certain speed = sufficient force .= opens the seals as it’s getting squeezed = water ingress

Obviously this diagnosis drops at the bottom of the tree once the higher up stuff listed above , mentioned like pump seal plate , hose clamps , cooler corrosion etc have been eliminated first .

Mmm, thats looking quite likely because I have had the engines running at 1500 rpm at working temperatures and not a drip from anywhere.
Do you mean the big clamp rings that supports the back of the engine on the inside and carries the sterndive on the outside?

 

[Portofino]

Mmm, thats looking quite likely because I have had the engines running at 1500 rpm at working temperatures and not a drip from anywhere.
Do you mean the big clamp rings that supports the back of the engine on the inside and carries the sterndive on the outside?

Yes .Run them @ working cruise rpm say 3400 or something and see if water enters .In gear of course not N .So the transom is compressing.

 

[Hornet_UK]

I've just found this thread and have asimilar problem with my C35, was there any conclusion on the cause and solution to the problem?

 

[Nigbb]

I've just found this thread and have asimilar problem with my C35, was there any conclusion on the cause and solution to the problem?

Hi, I THINK I have found the problem but won't know for sure until we do the repair over winter when out of the water. I am pretty sure water is coming in via the trim tab hyd cylinder top mounts, I imagine that they have some sort of gasket which is opening up very slightly .
I drew this conclusion because we get the most water in when the trim tabs are down (hyd cylinder pushing against the hull) and we are at displacement speed with the boat dragging in the water. We get almost no water when at planning speed when the cylinder top is bearly in water .
As you have sent in the thread there was mention of transom and clamp ring being the problem however when I put this to guys that really know boats all said its highly unlikely so I wouldn't get to sidetracked by this, not impossible but very unlikely was the concensus.
If you sort yours soon I would be interested to hear, because I have learnt to work around it in the short term I won't be remedying until winter lift.
Regards Nigel