Hull/Deck seam

[raquet]

I'm not sure if my 'new' boat is a classic but she is wooden and 40 years old so may count. This is my first venture into the joys of wooden decks and hulls - both in this case are marine ply - cold moulded for the hull and nice flat ply for the decks. The trouble is there are leaks the size of Niagara around the chain plates. I assume this is a point where there will be the maximum of movement in the join - certainly a high stress area. Any advice on how to fill/seal the join gratefully received. What products can I use on ply which will have enough flexibility and give to cope?

 

[Mirelle]

Hang on a minute? Are the chain plates internal or external?

 

[raquet]

The chain plates are internal - assuming I understand the question. They come up inside the hull and pass through the deck. I guess my boat isn't classic enough to have chain plates bolted on the outside of the hull! The area around the plates has clearly been filled with gunk before. The size of the hole in the deck varies a bit - I guess because on some plates leakage has caused some deterioration in the deck and the wood has been cut back. Obviously I would like to stop this before the deck become the minority area.

 

[Peterduck]

It astounds me that designers continued to specify internal chainplates when they are so famous for leaking; it's what they do best! The easiest solution is to move the chainplate to the outside of the hull and plug the deck hole with a graving piece. If there is a rubbing strip around the gunwale, then you may need to remove it in order to create a rebate to accommodate the chainplate.
Peter.

 

[oldharry]

Entirely agree with Peterduck: Internal chainplates on wood - no way! Bad enough on GRP. A temporary botch would be to use Sikaflex Polysulphide to fill the hole - has around 30% stretch before failure. But long term, they have to be outside. a cheaper Polysulphide forr temporary repairs can be had as a building sealant from the local builders merchant. 207 masonry seal works remarkably well in the marine enviuronment at half the price of Sikaflex. Dont use Silicone based mastic - it doesnt stick

 

[Woodlouse]

You may want to check the areas round the chainplates for rot before you spend too much on sikaflex.

 

[Roach1948]

Thats is precisely what I have done after huge problems with leaks. The problem you will find is that the old holes for interior chain plates will no longer fit once you move outside. The new holes could end up very very close to the old ones - but I got round this by moving the plates up an inch and by completely renewing the old backing pad in 12mm marine ply and expoxing in place. Good idea to check for rot - as I had rot under the toe rail which I only discovered by chance.

I have original designer's specs and low and behold, internal plates are the spec. Having them on the inside is more aesthetically pleasing on a sloop in my opinion - I constantly mull over whether I should leave them galvanised or paint white like the topsides - either way the move out was great as I have no more deck leaks.

 

[Woodlouse]

Paint them the same colour as the topsides. You'll barely notice them then.

 

[raquet]

Well thanks one and all. I think I'll try Sikaflex first and see how it goes. I'm also inclined to think that internal plates look better on some boats - mine is a comparative youngster at a mere 40 and the cold moulded ply hull looks so beautiful without bits bolted on - of course I may be just a little biased.

Maybe next year I'll think again if leaks persist.

 

[Mirelle]

They will.

Rarely have we seen quite such a show of unanimity on a subject!

By the way, check the whole length of your hull and deck joint, but espescially in way of the chainplates.

Cold moulding fails, when it eventually does, due to rain water penetrating down the voids between the laminates and starting rot. This of course gets in at the hul/deck join. Tap carefully all over the topsides and you will be able to hear a "dead" rather than a "ringing" sound in any places where you have a problem. The chainplate area is always a likely spot for trouble to start where the chainplates are internal.

 

[oldfrank]

Slow down - I've got internal shroud plates on a 70 year old Broads sailing cruiser. Yes, they are trouble...... but they do look good and it is possible to minimise the aggro. They're original, so it must be right. The first thing to do is to check the fit between the shroud plates and the beam shelf is as tight as can be obtained - to reduce any movement to the minimum. Wedge it up as tight as you can.

Nothing rots quite like rainwater. Take the shroud plates out and epoxy coat the area where any water may run down the inside of the hull - rot can develop between the shroud plates and the hull.

A flexible sealer is required to fill the area in the very tiny slot around the shroud plates - I used stickyflex.

You need to ensure that your hull flexes as little as possible - to reduce movement around the hole in the deck for the shroud plates. A bit of extra stiffening never goes amiss - an extra deck beam? or maybe you could attach the shroudplate to an extra piece of SS plate run down to a floor. It all helps to stiffen the hull. Yes they are trouble.... and all of this is extremely difficult on an old and flexible Broads River Cruiser hull. But it's worth it - looks like the soft underparts of dogs!

 

[oldharry]

[ QUOTE ]
Slow down - I've got internal shroud plates on a 70 year old Broads sailing cruiser. They're original, so it must be right.

[/ QUOTE ]

/forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif Really?! "Nothing but trouble" - doesnt sound at all right to me.

But then Broads boats are a bit different and special anyway (and not just cos I spent my honeymoon on one a great many years ago /forums/images/graemlins/smirk.gif) being designed for smooth water sailing without the flexing and stress a seagoing craft has to be able to take.

 

[oldfrank]

Stresses on Broads boats are different - not necessarily lower. Smooth water certainly saves falling off or crashing into waves. On the other hand; sailing between trees significantly increases rigging stresses. A Force four slam imposes higher stresses from a standing start than if a sailing boat were progressing steadily. My particular example carries a fifty foot mast and has a lifting cabin top. You won't find many rigs of that size fitted to an (effectively) open, seagoing, 35 foot hull.

As I indicated - it can be done satisfactorily and looks good - but it certainly isn't the easiest way to fix shrouds. Perhaps I should also have added that due to a dislike of scraping down a couple of acres of varnish every winter the boat is undercover by the 1st November - stripped out internally, with all the rig removed. Standing outside in the rain all winter will increase any problems.

Old Frank