Optimum size for the gap between planks

[airborne1]

If I replace two planks in my wood hull, does anyone know the optimum width for the gap between planks on the inside and the outside of the hull. Alternatively, is there an optimum angle for the edge of the planks to allow inserting the caulking string

 

[nmiller]

Hi
There should be no gap on the inside, when built the planks will have been cramped up tight. As to the outside, about 3mm - 4 mm on 25 mm planking, or if appropriate for aesthetic reasons, the same width as all of the others.
Nick

 

[Seanick]

Agree with the above. If you look at the top edge of a plank, and divide it into thirds, the inboard third should touch the plank above, the second third will house the caulking, and the outer third will be the stopping (putty).

 

[Victorious]

[ QUOTE ]
and the outer third will be the stopping (putty).

[/ QUOTE ]

Putty.
Ive seen Red or White lead ( to great grandads recipie or bought ready mixed) with added ,white sprit, grease, fuel oil, engine oil, linseed oil, boiled linseed oil, paint, varnish. . . . . . . . .
P38
Window putty.
Pitch is fun /forums/images/graemlins/smile.gif

As far as I know, all the boats floated.. and may well be still afloat
So which IS actually best can be a heated argument in a few boatyards.

Oh and also there are some modern "goop" whos name I will not speak
which has ruined a boat or two...

/forums/images/graemlins/smirk.gif /forums/images/graemlins/smirk.gif /forums/images/graemlins/smirk.gif

 

[airborne1]

Thanks all, I always thought that the bevel should extend the full width og the plank. Makes sense I suppose
Anyone tried Sikaflex as a stopper?? and exactly what is the purpose of the stopper. Is it just to fill the gap or stop the caulking being pushed out??

 

[old_salt]

Re: Optimum size for the gap between planks

It all depends on.
If the boat has been out of the water for any length of time.
How much has the original planks dried out, and if the new planks are wet or dry, in that I mean are they fully seasoned or or they green.
I am sorry but there are so many variables if you want a very precise answer.
In my particular circumstances my boat has been out of the water for some 20 years so some of the gaps have opened up to about 5/16" of an inch or more.
I have lightly caulked them, by that I have NOT filed the seam with a "tightly" packed caulking,
I have Guesstimated and that is about the only word for it the amount the planks will expand when they take up when she is put back in the water letting the caulking be the right amount.
My boat has had all new ribs and fixings and that puts a bearing on it as well the new ribs and fixings are stronger than they would be if still the original ones.
So if you are caulking up with original ribs and fixing you will need to be careful of the amount of caulking you put in the seam.
My personal is if the gaps are over large and due to the boat laying ashore for some time, then a little less than you would think is required and lightly, and be prepared to add if needs be if she does not fully take up.
You will only have the true answer when you put her back in. Of cause if ALL IS NEW Then "just butted up" on the inside is the way to go.

I hope this helps cheers David.

 

[pyrojames]

Used Stikyflex once. Then used linseed oil putty/Antifoul mix, or red lead. Stikyflex isn't really that great underwater.

 

[Bajansailor]

The favourite way of doing it here on the timber fishing vessels is to have the planks fitting pretty tightly, then whacking in some cotton, and then stopping it with WEST epoxy mixed with colloidal silica or saw dust.
The epoxy falls out after a while, but it is then cheerfully replaced.... I have tried to tell boat owners that it is not a good idea to have a 'half and half' approach like this - either be 100% traditional, or 100% modern, and glue everything together.
Nobody listens..... and then they find that half way in between is a recipe for headaches....... and still do it the same way next time....

 

[oldgaffer1]

For underwater seaming work I am a great fan of Davis Slick Seam. This is a waxed based compound which sticks like the proverbial to a blanket. Can be overpainted and is soft enough to expand and contract with the planks. Much better than Sikaflex IMHO, especially if the plank edges are damp. Available in the UK from a few sources.

 

[Seanick]

[ QUOTE ]
exactly what is the purpose of the stopper. Is it just to fill the gap or stop the caulking being pushed out??

[/ QUOTE ]

The stopping protects your cotton/oakum, and gives you a smooth hull to paint. It may also keep some water out too. Red lead putty is quite good enough for any boat. Its supposed to go hard after a couple of years as this gives the hull some rigidity and allows you to get a good finish above and below the water line. Putty may be criticised for being to hard and not allowing planks to swell. This situation only occurs when the boat has been abused and has been launched late or painted the wrong colour. A boat that is in its normal environment requires friction between the planks to prevent wracking of the hull and movement on the seams. This is achieved by close fitting planks, caulking cotton well driven and compacted to form a seal, and a little putty for the above reasons. Red lead putty is normal linseed oil putty, which itself is made of whiting (chalk dust) and linseed oil. Fine for windows, but one adds the lead powder to reduce its tendancy to crumble with age. Below the water line more linseed oil may be added to make the putty softer and more sticky, or grease, a little oil or whatever is to hand. On the topsides one adds Gold size, which is very similar to varnish, to make the putty skin over and allow painting to continue. If you finish a topside seam a little low (say1-2mm) you can prime, then fill over using an easily sandable hard filler, yes polyester is fine, but not epoxy, as this is so hard it is tends to stand proud if the surrounding paints. Its also slow and unnessercery. Prime over the filler, before u/coating etc etc