Carvel hull repairs

[fishfetishist]

I have a 36ft broads cruiser on the Thames in Oxford UK. She is about to come out of the water and I anticipate some plank replacement on her bottom. The big question is <Should I leave gaps between the new planks. If so how wide?> My previous repair I did push-fit for two planks about 2ft long. Anticipated repair is possibly 3-4 planks wide. If push fit I suspect that when planks take up water they will swell and push adjacent seams apart.

 

[EASLOOP]

I have a wooden sloop that I have completely re-caulked. I did a lot of reading before I started and the following applies:
In a carvel hull the planks should be bevelled along their length - a caulking bevel. When laying against its partner the two bevels form a 'V' that should be open at the outside by 2 or 3 mm or so and closed at the inside. The cotton is driven into the primed seems (red lead paint is a good primer) and then payed with a putty and red lead mixture (below the w/l) and white lead above. If using Sika then prime the seam with a Sika primer and lay in the black stuff will into the seam. When she takes up the cotton will take the compression and seal the seam. Do not over caulk as you could end up splitting the plank edges. I used traditional materials and after 12 years ashore she has been in the water for 6 weeks and all seam leaks have stopped.

Good luck
John

p.s. I do not like Sika below the w/l as when the planks swell the sike bulges outward and cracks the paint on the seams.

 

[trouville]

if you calk then sikaflex is the last thing you need.!
Its a glue as well and will tear the wood when removing it. Polysulfide can be used but why not use cotten and putty? costs far less is far easyer to use and works very well indeed.

If you look at sikaflex used as deck calking, it usualy lasts 5 years less than polysulfide,as the wood albeit teak or oily pine rejects the less flexable glue sooner than the far more supel sinthetic rubber

 

[johnlilley]

If you are concerned about the moisture content compatability of old and new, jus leave the new planking close to the boat for a while before finally sizing to allow for a degree of similarity of moisture content. Leave in shadow or perhaps down below in the bilges where it should equalize to a degree. Probably about ten days should be long enough.

 

[EASLOOP]

Hi,
The only place I have used Sika is on the laid deck seams - and I am not convinced its the best for this application. I have also heard that Sika won't adhere to old wood well enough, hence I have used putty and white/red lead for the entire hull - and she is now tight as a drum.

I thought I might re-d0 the deck seams with something like jeffery's glue. Any thought on this?

rgds
John

 

[trouville]

i wouldent as it melts when the mediteranian sun touches it!

Lots of boats use sika polyurathane for decks as it quick easy and will remain leakproof for a year or two! That way the people that do it get more work later on!
Again the best deck calking is still a 2 component polysulfide which comes in 5liter packs and once mixed mush be used within the hour!! you need compressed air bulk applicator or hve to fill the cartriges and use them as only ship yards that do that every day can

There is happly one component polysulfide which works very well and when i used it on my old sloop to calk a laid teak deck lasted more than 5 leak proof years 2in the uk and 3 in the med before selling her

A boat next to me had her seams done with polyurathan and leaked the next winter but her deck wasent laid and so the teak was very thin!!

Good luck with the work!

PS now if you had a really good boat such as a Folkboat you could be sure of a leakproof deck by recovering proply with canvas!!!

 

[Mirelle]

Possibly teaching grandmother, but - shift of butts!

I hope you don't mind my shoving my oar in, but when renewing a number of strakes of carvel planking you need to be very careful to observe the shift of butts.

The planks contribute a good deal to the longitudinal strength of the hull, and if the replacements are shorter, so that the butt joints between lengths are not "shifted" as original, the structure can be seriously weakened.

The best practice is to replace entire planks as original. Since it is quite hard to get hold of long lengths of planking timber this can turn out quite expensive.

Some people say that it is OK to scarph shorter lengths in since the glued scarph makes up the strength. I am not so sure about this and I notice that some very good yards are equally unhappy about it.