First 25.7 lifting keel

[AngusMcDoon]

Which is why I said I'd like to see a comparison of bonding / glued surfaces - especially considering age and work fatigue - compared to stainless steel bolts in shear load...

There's no comparison for strength and reliability, but bonding is lighter and possibly cheaper / easier.

There will be no formal study of comparison between the two techniques. You know that. But here's some anecdotal evidence - my boat's hull/deck joint is entirely bonded with outboard flanges. It's lightly built too. Current log reading... 46,281 miles. No leaks. No fatigue failures. Do you have statistical evidence, by the way, that a bonded joint is weaker & less reliable, seeing that you've already said that you've not seen a comparative study?

A Sail magazine article on joint techniques says that it isn't cheaper or easier to do if done properly. Are they wrong, or is it another case of if it isn't done like that on your boat then it's just rubbish? If bonded joints are prone to fatigue failures why are they acceptable in aviation? Apparently even the love of your life, Harriers, have them. I expect they were designed by qualified engineers though, you know, graduates, chartered, that sort of thing.

 

[Neeves]

I'm interested in the solution for the long offering OP

Maybe getting the thread back on track again

If his deck is bonded - he could bolt it up (which seems to be the current suggestion?) but is it not better to remove the deck clean of old bonding components and then re-bond (with out without bolts?). sounds like a pretty significant task to me - or it there an easier way.

But going back to Harriers, and their like - I'd always assumed they were built from an aluminium alloy, like Airbus?, and surely stainless bolts may suffer from dissimilar metal corrosion? Why stainless - and not anodised 7075 aluminium - and then if weight is an issue for said yacht - why not alloy bolts, as on bikes??

Jonathan

 

[AngusMcDoon]

Are thé known for leaks between thé Hull and the deck and if yes how Can you curé thé leak.thanks

None of this discussion is helping you. Post some photos, inside & out, from above & below, and you'll get more helpful responses. I'm sure it's improvable, if not completely fixable.

 

[AngusMcDoon]

If his deck is bonded - he could bolt it up (which seems to be the current suggestion?) but is it not better to remove the deck clean of old bonding components and then re-bond (with out without bolts?). sounds like a pretty significant task to me - or it there an easier way?

If the bonding has failed it's almost certain to just be in small patches, not the whole joint. Getting the deck off is major boatyard surgery & £££, especially as most of the bonding will still be holding. The deck is not going to pop off any time soon. It might not even be the bonding. Maybe the bedding of the toe rail has failed & it's through screwed which is leaking.

For a boat that size and age almost certainly the solution will be some sealant somewhere, maybe some retrofit bolts if there's any evidence of larger areas of bonding failure, stop worrying about it, & go sailing.

 

[youen]

I sorry because its a second hand boat 10 years old l am surveying and found some moisture behind some headlinings in the saloon which begin to bé unsticked from the Hull in the saloon.Before Î own an Hallberg rassy and I am afraid to see how a Beneteau is built.On the forum these leaks seem to be quite fréquent

 

[AngusMcDoon]

I sorry because its a second hand boat 10 years old l am surveying and found some moisture behind some headlinings in the saloon which begin to bé unsticked from the Hull in the saloon.Before Î own an Hallberg rassy and I am afraid to see how a Beneteau is built.On the forum these leaks seem to be quite fréquent

Is it a boat you are considering buying? If yes, the answer is probably don't if it has this problem, as there are plenty more boats available. If you are doing a professional survey I believe that you have received by private message the professional view on how to fix it that you can report to your client.

 

[anoccasionalyachtsman]

A few facts.

Youen is looking at a boat which is for sale.

He's found moisture above headlining panels.

The hull/deck joint is NOT biscuit tin lid, it's screwed down onto a flange and covered by toerail/filler. Previous comments on repair don't apply.

It's far more likely that youen has found evidence of a leak in a deck fitting or windows.

We need to see pictures of where the moisture is before anyone can guess where it's coming from. Could youen go back and take a camera?

Beneteau have a long track record of building strong and safe boats, and this certainly isn't a reason to withdraw from the purchase. I am a bit of a fan of all the x.7 range, they are very good to sail, and much more fun than a Rassy!

 

[Neeves]

I think most people were trying to offer advice, based on very limited information, and were making a best attempt at being helpful.

Images would have helped immeasurably.

Not being, too, critical of Youen - its is impossible remember everything about everything when you view a boat (or a historic monument!) cameras are invaluable - and then take multiple images. No longer does taking a photograph need be restricted by cost of film and printing and if the owner does not like you taking pictures - walk away.

Jonathan

 

[Tranona]

A few facts.

Youen is looking at a boat which is for sale.

He's found moisture above headlining panels.

The hull/deck joint is NOT biscuit tin lid, it's screwed down onto a flange and covered by toerail/filler. Previous comments on repair don't apply.

Not sure that is correct. Agree not a biscuit tin but flanged. however, suspect it is just glued. Nothing wrong in that in principle.

Agree, though that leaks could come from anywhere, including partial failure of the glue. Before rejecting the boat worth identifying exactly where the water is coming in before deciding on what repairs are needed. He suggests that leaks through the joint have been reported so obviously a place to look. However, as we know actually finding leaks particularly minor ones that lead to dampness can be a frustrating business.

 

[ProDave]

As an aside, much better bonded joints are outboard flanges on both hull & deck. These do not require multipart moulds & clamping is very easy, just use a load of G clamps during assembly. The downside is that there is a flange sticking out round the hull, not desirable on most boats, but useful on the centre hull of a trimaran as it's what the trampolines attach to.

This is exactly what my boat has. Glued and bolted together. Even things like chain plates pass through it so additional clamping. And the entire outboard flange is encased all the way round the boat with a big U shaped rubber strip forming a big rubbing strake all the way round.

 

[greeny]

Sounds like the source of the leak has not yet been identified. The OP is assuming it's the deck/hull joint but it maybe/probably isn't.
More likely to be windows, hatches, deck fittings in my opinion but first one needs to find the source then discuss the remedy.
I own a Beneteau of the approx the same date and the hull deck joint is not any more flimsy or lightweight than most modern boats. It is bonded and screwed through, so i would suggest his will be similar. His a 27.5 mine a 323. If the leaks been there for a while he should be able to trace it by removing a few of the panels and following any water marks/staining. Water can travel a long way behind panels before it shows itself. More investigation required methinks before removal of complete deck is discussed.