Leak near centre board case

[mat]

As a follow on from my previous thread regarding a repair to my Mirror I have further investigated the problem. There is a bubble (approx 5cm x 5cm) in the top layer of plywood adjacent and in front of the centre board casing on the floor of the boat. Nothing obvious on the undersurface of the boat.

My plan is to take off this top layer of ply with a stanley knife +/- chisel and then put the boat on some saw horses. Then dribble some water into the floor of the boat at the leak site to see where it come out on the outside.

Is this a reasonable approach? Any other ideas?

Obviously I need to fix the problem from both sides and mostly on the outer side.

[Daddles]

Dunno about putting water into it. I'd start by stripping the paint around the outside of the centre board. You'll have to anyway and I think you'll find it fairly easy to see where the leak is. But I'm a novice at looking after old boats so what would I know?

Richard

[journeyman Mick]

Mat
if you put water in you'll have to wait for it all to dry out before you can make any repairs. I reckon you'd be better off doing some exploratory surgery to try to find the leak.

Mick

[graemet]

Hi Matt,
Mick is right, if the leak is coming through delaminating ply, you don't want to wet it any more. I would cut out any loose plies, dry the remainder out as much as you think necessary with a hot air gun and then do it again (you can't have it too dry!) , and soak epoxy into the cracks. Then seal the lot with some fibreglass reinforcing from outside as well as inside. Then have a good look at the top of the centrecase to make sure that there is no movement sideways. Most leaking centreboard cases result from flexing sideways. There is a huge force on a centreboard when sailing closehauled in a stiff breeze, just try and lift it up a bit even in a light wind without easing the sails!
Cheers,
Graeme

[bitingmidge]

Another nasty spanner in the works.

Years ago (when Mirrors were first built) we used to use this magic two pack stuff called polyester resin. Unfortunately with age, the resin goes brittle and fibreglass adhered to the stuff can easily be lifted.

I don't want to be all doom and gloom here, but have a poke around the taped joints as well, if they are really easy to lift, you may as well accept that you need a major re-build (with epoxy), pull it apart bit by bit and get on with it.

Generally it's a lot easier than it sounds.

If all is well, I wouldn't bother with water, I'd just tape the outside of the joint with masking tape, and dribble epoxy round the keel. All bubbles and cracks will be magically filled!

Cheers ;)

P (good luck too!) :D

[mat]

The problem I have on the outside is finding the entry point of the leak. Because the problem is adjacent to the centreboard case one possible entry point is inside the centreboard case. Dealing with the issue on the outside opposite to the delaminating ply may not necessarily fix the water leak entry point.

Thanks for all the replies :)

[mat]

I've found the leak where the two ply boards join at the bottom of the vee just in front of the centreboard case.

Any hints on using epoxy?? In particular stopping it running when glassing on a non flat surface.

[Daddles]

I'm going to assume there is a gap between the boards. If not, you may be able to skip a step.

Turn the beastie upside down. Obvious I know but I keep finding myself in impossible positions because I'm too lazy to do this.

Mix unthickened epoxy - ie, no filler ... yet.
Brush it well into the joint. The idea is for the unthickened goop to soak into and to get as far into the joint as possible.
If there is a gap, thicken the expoxy to peanut paste thickness - yeah, that thick. When you lift the spatula out of it, it should form a crest that stays put.
Use the spatula (you know about tongue depressors don't you? Cheap and ideal) to push and press and coerce and force as much of the thickened goop in to the gap as possible - note, I'm assuming you're just dealing with a gap, not a flapping board.
Use the spatula to smooth it all off. If a board is flapping, don't thicken it as much and then use weights to press the board into the correct position.
More unthickened epoxy - coat the whole area to be glassed. If it's just a joint, glass tape would do the job.
Press the tape onto the joint and use your brush to thoroughly wet the tape with unthickened epoxy - you'll know you've got it right when the weave of the cloth 'disappears'.
This will run a bit so be on hand to pick it up with a brush. You can lay some of that thin packing tape around the repair. The expoxy will run onto that and get lifted off with the tape. A good move around any joint - produces a much cleaner joint.

Note, do all of this in one hit - ie, don't wait for one coat to dry before doing the next. The idea is to get a good chemical bond between each of the coats. Mind you, you have something like twelve hours to get that chemical bond so if you have to go in for dinner it doesn't matter. But I'd do it all in one hit. It sounds like a lot of farting about but it's pretty straightforward once you get into it.

That's how I'd do it, without seeing the job. Now you'll tell me I've completely misunderstood the problem but it's how I'd fix a gap between two otherwise intact boards. It's also similar to what I'll be doing this arvo on Henry - I stripped the paint off his hull and have realised just how good a job the previous bloke did of covering up thirty years worth of scars, knocks and rot.

Cheers
Richard

[mat]

Thanks Richard

Sounds like you're on the mark. Will start the attack tonight.

Someone suggested to put the final coat of epoxy on a second and third occasion firstly tilting the boat so one side is horizontal to prevent running and then on the third occasion tilt the boat the other way so that side is perfectly horizontal. How does that sound to you?
I understand that once the first coat of epoxy has cured you have to at least scuff the surface to get the next coat to bond.

[Daddles]

Someone suggested to put the final coat of epoxy on a second and third occasion firstly tilting the boat so one side is horizontal to prevent running and then on the third occasion tilt the boat the other way so that side is perfectly horizontal. How does that sound to you?
I understand that once the first coat of epoxy has cured you have to at least scuff the surface to get the next coat to bond.

Sounds like a lot of mucking around to me. Do it all in one hit. I've taped seams that were vertical. Yes, you do get run off but if you put plenty of packing tape on the downhill side, it comes off with a pull of the tape. And it's by the centrecase - hell, how much of a down hill angle could it be.

If perchance you do a coat after the first has set, you have something like 12 to 24 hours to do the second coat before you have to scuff it - you will still get a chemical bond. The next day is the ideal time to sand it too because it's hard enough to sand but soft enough to come off real easy. Leave it for a week and it's like iron. If you don't get onto the next day, yes you need to sand it to give a mechanical bond - something for the goop to bite into.

What you do have to watch is amine blush. This is a white, waxy coating that can occur (doesn't always - I've yet to see it). Just wash that off with soapy water and let it dry.

If you don't have the right fillers and are only filling a small hole, sawdust works - just shove a bit of ply onto your sander and collect the dust. Matches the wood too, unlike the white fillers that West provide. Botecote has coloured fillers. But if all you are doing is this one repair, you may not need to buy an expensive bag of power. But I'll happily take any excess from you :D

I've just bogged up Henry's bottom. Lots of nice white patches and fillets, like the bit on the corner of the transom where the two bits of ply just don't quite meet, leaving a hole the dog'd fall through if I didn't bog it, let alone water. I'll hit her with the sander tomorrow to get some shape into things. Bung on some tape and I'll be looking at the worst decision in the boating world - what flamin' paint to use. It's the old 'I want it to last but I don't want to spend a million dollars and yes, I do need a good primer despite what it says on the tin'. With any luck, she'll be sailing come January ... but we do need to remember who's doing the work, or not doing as the mood may be.

One of the really interesting parts of scraping Henry's bum was pulling off a strip of fibreglass and getting a very strong whiff of must. That's right children, putting glass over rotting wood doesn't stop the rot, it just gives it room to breed. But my repairs are designed to keep her in the water for a couple of years, then I'll think about extensive restoration or sale. That's the theory. Hah!

Cheers
Richard

[graemet]

Hi Richard,
I've been using Wattyl's Paracryl IFC which is a two part isocyanate free industrial coating which is designed for outdoor use and is UV stabilised. It has the advantage that it is recoatable without needing major preparation. I was able to spray it with my Vactric (see my earlier post), and got it direct from Wattyl as it is not a hardware shop line. They even had some going cheap which had been mis-tinted and was just the colour I wanted. It has been out in the weather for years and still looks good.
Cheers,
Graeme

[Daddles]

Now THAT's interesting Graeme. I'll see if I can get some. We've got Wattyl shops here.

Richard

[mat]

Richard

Thanks for your comprehensive replies. I did attack it in one go. Got a bit of a run but scraped it up at it hardened. I have put some fibreglass tape along the join for about 50cm or so. At this part of the bow there is a bit of slope.

I know what you mean about the painting as this will be the next stage.

I bought the mirror fairly cheaply to let the children get some experience but also not to worry about a few prangs. The cost is now starting to mount as I put on better rigging, pulleys etc and then theres the paint.

[Daddles]

I bought the mirror fairly cheaply to let the children get some experience but also not to worry about a few prangs. The cost is now starting to mount as I put on better rigging, pulleys etc and then theres the paint.

What's the definition of a boat? A hole in the water that you have fill with money. :D

Why does everything cost so darned much. Even doing boats on the cheap makes MG ownership look like an exercise in sanity. :eek:

Building boats is better though. Where else do you get to use dangerous tools to fashion toxic substances into a craft that can sink and drown you. :eek:

Glad I could help Mat. Have a good Christmas and get those kids wet. ;)

Richard

[sinjin1111]

If your still interested. E-mail me and i can give you my number. I used to build mirrors for a living.
Sinjin.
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