Beneteau Antares leaking - toilet seacocks span double hull (inner and outer)?

[Pleinmont]

Hello all

I have a new leak from under the waterline (about 5litres an hour - not catastropic but enough to need pumping out daily).
Water is pooling under the floorboards at the front of my 760 then draining back into the bilges at the stern via the overflow holes cut for the cables.
Unfortunately parts of the boat are covered by the double hull (inner fixed to the outer hull with a 10mm thick void) so I can't always see the outer hull.

The toilet compartment is one of these areas and has 2 seacocks that seem to be fitted across the inner liner and outer hull.
I was always under the impression a seacock is tightened against 1 solid layer not 2?
Also makes it impossible to see if the fitting is leaking inside from the sea and dribbling down inside the void.

Water comes in at rest so definitely nothing to do with engine.
Stern tube area and bow thruster are dry
Through hull fittings in engine bay also dry and solid (2 inlets for engine and prop shaft and thru hull transducer in solid GRP).
No known damage or cracks in hull (not hit anything in last 3 years since owned it).
Rudder seal drips a little when underway but not at rest (always done this).
Dyed the freshwater tank pink and only a few drips from the pressure release have turned up pink after running it through H&C - so definitely sea water

I am planning to get the boat lifted in the next couple days and the only things I can think of are the 2 seacocks for the toilet just can't verify as out of sight.
Will be difficult chasing leaks once the boat is out.

Does anyone have any experience of fitting or leaking seacocks in this type of hull?
I'm surprised that these 2 fittings seem to be fitted across the double hull not just one solid surface.

Either way i am desperate to avoid spending a lot of money with the boatyard chasing leaks so keen to narrow it down before lifting!

Thanks

 

[Plum]

I have some experience of the 760. When I fitted new heads skin fittings there was no void between the inner and outer skins as they were solidly bonded with resin between, as were all the other seacock skin fittings. Have you tasted it to confirm it is seawater and not fresh? Leaks from almost anywhere will eventually finish up in that location so it could, for example, even be your anode studs (my studs nearly wasted away during lockdown after the anode completely depleted). Also, and I am aware of another 760 having this problem, under your hull, just below that forward section, is a lenth of stainless steel keel band that protects the hull when taking the ground. It's held on with stainless self tappers. On this other 760 one of those screws started leaking.

www.solocoastalsailing.co.uk

 

[Jamie Dundee]

I had a leaky seacock when the boat was launched, the water collected in the well for shower water under the wooden floor panel in the heads. As Plum says, there is no double skin on the seacock fittings. I’ve currently got both seacocks out and can confirm solid hull below.

 

[BruceK]

Also, and I am aware of another 760 having this problem, under your hull, just below that forward section, is a lenth of stainless steel keel band that protects the hull when taking the ground. It's held on with stainless self tappers. On this other 760 one of those screws started leaking.

Keel bands are notorious for this. If you have one remove it and fill all screw holes. If you really need a keel band get Keelguard or one of the plethora of rubber and adhesive types.

 

[Pleinmont]

Ah many thanks for the quick replies - that's massively appreciated. That's incredibly useful to know there is definitely no gap between the shower floor and outer hull!
I had always presumed it was solid GRP because of the skin fittings then doubted myself this week when the other sources of water were eliminated.

Keelband screws.... never considered this.
It is certainly underneath the compartment where the water is entering... will take this into account when she gets lifted.
I dry it out now and again a couple of times a year sometimes on sand/gravel so the band does get used to support the boat.

The only other thing I considered is whether water could enter into the hull voids where the stern tube enters the boat - there's no water in the sump below the stern gland but don't know if water could enter into the hull without coming out inside the bilge. You would hope this area is all solid GRP given the torsion and also the fact the skeg is attached here.
Bit unlikely but clutching at straws given there is literally no evidence of water entry from inside the boat other than what is turning up in the forward bilge whilst sat quietly in the marina (no rain either). Also the prop tube is well below the level of where the water is pooling.

Keelband is a good shout, many thanks

I would love some schematic drawings of my boat but I have not been able to find any - the manual is very thin.

 

[Plum]

Regarding my comment above about the anode studs. I have seen the hull anode fitted in two different places on the Antares 760 so I guess Beneteau changed the spec at some time. Mine is fitted next to the engine on the starboard side and at that place there is a void between the inner and outer skins so the inner skin should be cut away so the studs only tighten against the outer skin. If this is what you have, any leak at the studs will immediately run between the skins probably unnoticed until it shows up at the lowest point. So my money is on either the keel band or the anode studs.

www.solocoastalsailing.co.uk

 

[Jamie Dundee]

Mine is fitted next to the engine on the starboard side

As a matter of interest what is that connected to/protecting? The stern anode on mine is connected to the stern gear, I have anodes on the prop, keel and rudder and that’s the lot.

 

[Pleinmont]

Regarding my comment above about the anode studs. I have seen the hull anode fitted in two different places on the Antares 760 so I guess Beneteau changed the spec at some time. Mine is fitted next to the engine on the starboard side and at that place there is a void between the inner and outer skins so the inner skin should be cut away so the studs only tighten against the outer skin. If this is what you have, any leak at the studs will immediately run between the skins probably unnoticed until it shows up at the lowest point. So my money is on either the keel band or the anode studs.

www.solocoastalsailing.co.uk

Good point re the hull next to the engine - I can see where the inner skin has been removed closely around the stern gland seacock (starboard next to the engine). Looks coated (maybe epoxy) to seal the cut though and no water visible (will try blue paper towel round it next time i go (daily at the moment!).

Other than that I've not got any anodes attached directly into the hull (same as Jamie - two on rudder, two on skeg and a prop anode).
Again points to the keelband to check first.
Cannot see any ingress anywhere internally and definitely not litres an hour!

 

[Plum]

As a matter of interest what is that connected to/protecting? The stern anode on mine is connected to the stern gear, I have anodes on the prop, keel and rudder and that’s the lot.

My anode that is bolted through the hull on the starboard side next to the engine connects to the propshaft. On later 760s i have seen this anode fitted much further aft, which is a better position as it is closer to the prop. My prop mounted anode only last for 3 months so the larger anode on the hull provides extended protection (i hope!)

www.solocoastalsailing.co.uk

 

[Plum]

Good point re the hull next to the engine - I can see where the inner skin has been removed closely around the stern gland seacock (starboard next to the engine). Looks coated (maybe epoxy) to seal the cut though and no water visible (will try blue paper towel round it next time i go (daily at the moment!).

Other than that I've not got any anodes attached directly into the hull (same as Jamie - two on rudder, two on skeg and a prop anode).
Again points to the keelband to check first.
Cannot see any ingress anywhere internally and definitely not litres an hour!

Hmm. My sterngland seacock skin fitting is on the port side fitted through an area of double skin where there is no void between, like all the other skin fittings.

So, it appears there is not much consistency on the Antares 760 regarding whether there is a hull mounted anode or not and where it is fitted. If you don't have one that is one (two studs!) less potential leak.

www.solocoastalsailing.co.uk

 

[Jamie Dundee]

My anode that is bolted through the hull on the starboard side next to the engine connects to the propshaft. On later 760s i have seen this anode fitted much further aft, which is a better position as it is closer to the prop. My prop mounted anode only last for 3 months so the larger anode on the hull provides extended protection (i hope!)

www.solocoastalsailing.co.uk

Interesting. My prop anode had disappeared on haul out, although it had been there a month or so before. My hull anode on the transom connects to the rudder stock. Stern gland, engine and deck wash seacocks are all on the starboard side. Quite different from yours by the sound of it.

 

[Pleinmont]

Maybe they moved the seacocks to the starboard side in later models as easier to get to (only need to lift the first section of floor).
Agree on 3 month prop anodes - last no time at all

 

[Plum]

Interesting. My prop anode had disappeared on haul out, although it had been there a month or so before. My hull anode on the transom connects to the rudder stock. Stern gland, engine and deck wash seacocks are all on the starboard side. Quite different from yours by the sound of it.

Are you filling the screw recess in the prop anode with mastic ofter tightening the screw? If not, the anode starts wasting around the screw and falls off before it is fully depleted.

www.solocoastalsailing.co.uk

 

[Jamie Dundee]

Are you filling the screw recess in the prop anode with mastic ofter tightening the screw? If not, the anode starts wasting around the screw and falls of before it is fully depleted.

www.solocoastalsailing.co.uk

Didn’t know that trick, thanks for the heads up

 

[Plum]

Maybe they moved the seacocks to the starboard side in later models as easier to get to (only need to lift the first section of floor).
Agree on 3 month prop anodes - last no time at all

Sorry if this is not already obvious to you but the seacock on the feed for the propshaft gland achieves nothing. While working on my engine I knocked the hose tail on that seacock and discovered it was brass and it just crumbled into dust and water started pouring in. No problem, i thought, just close the seacock. The water continued to leak in! The water was coming out of the hose that goes to the stern gland which, of course, has no seacock. If that hose tail had failed when I was not on board, even if the seacock was closed, my boat would have sunk,!

www.solocoastalsailing.co.uk

 

[Pleinmont]

Are you filling the screw recess in the prop anode with mastic ofter tightening the screw? If not, the anode starts wasting around the screw and falls off before it is fully depleted.

www.solocoastalsailing.co.uk

Thanks - good tip. I had been advised to paint around the screw head with nail polish to make it last - assume it helped somewhat but not as long as i hoped.
I'll try the mastic trick next time - logically that would keep more water out of that recess.

 

[Pleinmont]

Sorry if this is not already obvious to you but the seacock on the feed for the propshaft gland achieves nothing. While working on my engine I knocked the hose tail on that seacock and discovered it was brass and it just crumbled into dust and water started pouring in. No problem, i thought, just close the seacock. The water continued to leak in! The water was coming out of the hose that goes to the stern gland which, of course, has no seacock. If that hose tail had failed when I was not on board, even if the seacock was closed, my boat would have sunk,!

www.solocoastalsailing.co.uk

Yes I'd thought that might be the case - bit worrying!
Should really have another shut off valve fixed on the gland itself.

 

[Pleinmont]

Well, the boats out the water now.

Keel band it is (well unless something else less visible has also failed!)
The keel band was missing and all the screws rotted out - there was some water coming in last month and then stopped so it was obviously hanging on like a loose tooth.
Then we went out Saturday for the day and the leak got much worse so presume the band just finally fell off on the last trip out.

Will check all the skin fittings just in case but fairly confident the missing band was the leak.
Thanks for your advice this week