Sheathing a folkboat?

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cherrie

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Hi! I have a 1960 Folkboat that sinks every spring when we launch it. It has so many gaps and dries out every winter. In addition there are 6 ribs that need replacing and some wekness by the mast foot. I was wondering whether sheathing would be an idea? I know that it may be frowned upon, but the alternative is a major re-planking.
If sheathing is viable, then can anyone recommend any books on the subject? I have several questions already such as, Would sheathing sort out the structural problems (e.g. the cracked ribs) or would these need to be fixed anyway?
 
Sheathing will not remedy broken ribs. You need to put doublers or 'sisters' in alongside them to bring the hull back in to shape, and to restore the strength. The weakness round the mast foot needs seeing to as well, and sheathing is unlikely to make any difference.

IMHO you need to bite the bullet and get the boat repaired properly.

Sheathing? _ what with? If GRP then forget it - it will destroy the boat double quick. Polyester does not stick to wood, allows water ingress which provides ideal rot conditions. Epoxy systems may be possible but will be at least as expensive as doing the job properly, and will require the hull to be dried out to a very low moisture content - around 15% to ensure proper adhesion. That will cause mayhem with your old timber, and once it starts to get moist again it will move further than the epoxy sheath will allow causing all sorts of problems, and quite likely to do more harm than good.

Just a question - have you tried re-caulking the planking? The leaking may be simply the caulking has failed and needs replacing. Assuming she is carvel built that is, and not clinker. A carvel hull will have been built deliberately with gaps between the planks to allow for swelling, and these need to be properly caulked. If she is clinker, then the fastenings are probably loose and she may need re-fastening as you do not caulk clinker.
 
Sheathing would be the equivalent of a Band-Aid on a broken leg! First you have to fix the ribs, then you have to re-caulk the seams. The 'wetness near the mast-step' needs further investigation. The region of the mast-step is the most highly-stressed in the whole hull, because when sailing the mast is pushing downwards on the keel, and trying to open the garboard seam. If you are not experienced at caulking, get someone who is to show you how, or to do it for you. It is very easy for a newcomer to get it wrong, and damage the plank edges.
Peter.
 
The best way is to remove the deck and all the internal furniture. Turn it upside down and take a mould of the external profile.separate this off and lay to one side.

Make up a mould of the internal profile in the same manner . lay to one side.polish the external profile mould so that it is cosmetically perfect, lay on the gelcoat and then a continuous series of high modulous carbon fibre tows say +5 degrees, -5 degrees, +45 degrees, - 45 degrees, -5 degrees and +5 degrees. Build each rib and stiffener the same with a nomex core, ditto Keel but double up on the skins



Then laser scan the profile of the internal profile and crossload this to a 5 axis milling machine and set it to rout the voids betweeen the fillers so it will exactly match the inside of the internal oulded skin you have made as well.

Replace the keel with depleted uranium so you can lower the c of g

Hopefully all this will enable you to eliminate that evil stuff known as wood.

I could probably do the job for you for a mere £5 million plus tooling and expenses. /forums/images/graemlins/smirk.gif
 
How long is the boat out of the water each year, and how well sealed is the planking? You've ogt to give the boat a chance to stabilise. if the timber takes up and seals the gaps eventually each year, then the problem is caused by taking the boat out of the water each year. There's no way anyone is persuading me to have our hillyard out of the water for more than two weeks. She's well sealed, but all the loading is different, the hull will start to change shape and the planking will dry out. You can do various things to mitigate all these effects, but it will still happen to some degree. If she's dry and seaworthy by the end of the summer, can you leave her in over the winter?
 
Ditto all of this.

Don't sheath. Fix the ribs: this can be done by laminating new ones in place and is not a hard job, tools are nearly all found in everyone's shed. Also, recaulk.

The wetness at the mast step maens that the seams are flexing a bit too much, but remember, all wooden boats are supposed to leak a bit, so think about how much the boat leaks here.

It may be that the broken ribs are near the mast? Fix these and recaulk. You may need to build a slightly bigger "ring" frame (best done in laminate) where you frame right round thee inside of the hull at the mast. This stops the mast and keel moving in relation to each other. A combination of all three and the job's a good'un.

Oh, and once again- don't sheath. Kinder all round if you sell the boat to someone who wants to do the work. Would you sheath a sick horse in epoxy or shoot it?
 
[also folkboat]I also need to sister some ribs in the bilge by laminateing after i have laminated i presume i need to put in screws from the outside ?
how far apart would you recomend the screws are spaced?
 
Well I'm no expert, but as a rule its two fastenings per plank, certainly for a folkboat where I suppose the planks are 2.5 or 3" at their widest.

I always find making a template from scrap cardboard (keep those flatpack furniture boxes somewhere dry) are excellent for this. cutting blocks to fit the stepping of the inside of the hull before adding the laminate strips is a good idea. And you'll need quite a few G clamps.
 
Just in case you are unconvinced by the arguments here is my experience. I am currently in the process of removing sheathing from my recently acquired 1930's kreuzeryacht. The planks surrounding the chain plates on both sides have been rotting away unseen. From the outside the rot is hidden by the sheathing and from the inside, hidden away by fittings and stripping. The rot certainly escaped the notice of a surveyor. Below the waterline is a similar story. My own inexpert view is that sheathing is a recipe for disater. Your yacht may look fine on the outside whilst inside she is festering away unseen. I certainly wouldn't have wanted to be in a blow with those chain plates holding up my mast.
chain+plates.jpg
 
Sheathing a wooden boat is virtually signing it's death warrant. You are saying, I am going to be the last owner of this boat. I want it to look nice for about 5 years, and then I don't care, it can go for scrap or on a bonfire.
 
You might want to look at the Wooden Boat Forum, this has been discussed ad naus. A few successful jobs in the past are often quoted, but all the experts are V. negative. Same as here. Fix it properly or you will regret it later and won´t be able to sell it either.
Andrew
 
If you want big sheets of cardboard, seek out a pushbike retailer. The bikes come encased in large sheets of cardboard and the retailer usually has a skip out back full of them. They have to pay to have it removed so are delighted if you will take some away.
Just ask them not to fold the sheets before disposing.
 
Thanks to all of you who have posted a reply so far. The concensus is pretty overwhelming and I'm convinced - I'm dropping the idea of sheathing! I guess I had only read the success stories.
A number of you raised questions and I'll try to answer those. Firstly the question of leaving the boat in the water. The issue here is that the boat lies on the south coast of Norway where there is a danger of ice during the winter. Next year will be even worse due to the fact that we are moving to Oslo where it almost always freezes in the marinas. So basically I have to have the boat out of the water from october to april. The only bright side is that the temperature is low.
Another question was about caulkin. My folkboat is clinker built so I will have to replace all the fasteners to stop water seeping in between the planking. There are some sizeable gaps in the planks themselves but they close up well. But between the planks there is a constant seeping in some places.
One of you asked if the broken ribs where near the mast foot and therefore possibly the cause of the wekness in that area. The answer to that one is no, they are not related, the broken ribs are further back.
I think I can summarise the advice as follows: Make plans to get on with it: New ribs alongside the broken ones, strengthening around the mast foot, replacement of badly split planking and redo most of the fastening. Agree?
So my follow-up question is ... are there any good books on how to do the above? I'm competent with most things but it's great to study the subject before you start and try and avoid mistakes.
Once again I appreciate all the contributions (and the humour!)
 
Nick by now you will have realised the problems ahead of you. If your FB "dries out" to some extent after being back in the water for couple of weeks you may not have to replace your fittings. My FB is carvel and leaked like a "seive" for several days but we stayed and "manned"the pumps. She had been out of the water for 5yrs? But I have a friend who has a clinker FB and if left unattendended it used to leak badly ...but now before going back into the water he uses a flexable filler. After a couple of days he goes round inside wiping off the excess filler. Works well for him. Good luck with your FB.
Mike
 
Nick, I also have a clinker Folkboat. Last year when I took her over she had beeen ashore for about 18 months and did apparently leak quite a bit for the first week or so in the water. This year I lifted her out in December and put her back in about the middle of April; the electric bilge pump was running every 10 minutes or so to start with but after 12 hours that was down to every 20 minutes and after 24 hrs about every half hour. After a month it's now down to about once or twice a day as far as I can tell. If yours is leaking as much as you say when refloating then she may well need some refastening.
 
There is a technique whose name I cant remember for older clinker boats which involves pinning a 1/4round wood batten same thickness as the exposed plank edge, on sealant down the lands of each plank, effectively sealing it. Tried it once myself on a leaky old clinker rowing boat - surprisingly effective, but spoiled the appearance a bit - much less than sheathing though!

Common practice for elderly clinker working boats, and clinker ex ships lifeboats coming towards the end of their days until GRP took over.
 
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Well I'm no expert, but as a rule its two fastenings per plank, certainly for a folkboat where I suppose the planks are 2.5 or 3" at their widest.

I always find making a template from scrap cardboard (keep those flatpack furniture boxes somewhere dry) are excellent for this. cutting blocks to fit the stepping of the inside of the hull before adding the laminate strips is a good idea. And you'll need quite a few G clamps.

[/ QUOTE ]

Hi planks are about 2" wide and its carvel so no steps inside[so that makes it easyer]...do i need to put a screw though each plank into the new sisterd rib from the outside?
 
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do i need to put a screw though each plank into the new sisterd rib from the outside?

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Yes, that's the whole point. You want to make the new rib an intergral load bearer with the rest of the hull. As such, it ought to be fastened at each point, not only into the keelson, but also the beam shelf and at each point along the rib at each plank. If the planking has already had screws through it, it would be best if you moved the new rib along slightly to get fresher timber.
Remember that the strength of a wooden hull is the sum of its parts and no one part should take any excessive load.
 
Agreed - don't sheath.

Suggest you don't sister the timbers either. Remove and replace - either steamed or laminated. I wouldn't screw a timber if I could possily avoid it - in circumstances such as not being able to get a hammer to the end of the nail.
But you need a friend - and a dolly! OF
 
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