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View Full Version : Dried out hulls and sheathing a wood hull



airborne1
05-04-07, 22:30
Heres a couple of questions which I would like experiences of and opinions on:
1. I have a wood hulled 25ft boat which has been waiting for my boatbuilders attention for so long that it has now compeletly dried out so that the seams have opened up. Some seams are so dried out that I can see through the gaps, even the filler has cracked and the caulking string is very dry.
Its been inside a shed in a boat yard for some 6 months and I would like any comments on how to tighten the seams up again so that I can start to anti-foul her using Copper-Cote (the packs are paid for and waiting to be used so I am committed to using it).
2. Has anyone ever tried sheathing a wooden hull with fibreglass cloth so that she will not leak in the future. If so, how do I tackle the open seams mentioned above. Do I need to sheath both the inside and outside of the hull after removing the existing filler and packing the seams with epoxy filler.

The background to this is so long that I won't go into detail as it would be too long and boring (some may say sad or a reflection on wood boatbuilders/repairers in this day and age)

Spuddy
05-04-07, 22:58
My understanding of the theory and the practice is that sheathing carvel boats is a disaster. The resin and mat hardly move but the planks will, so terrific stresses set up and sheathing will separate. The pockets so created will hold water ( fresh water from rain or atmosphere ) and encourage rot. Works well on ply boats if done properly I've heard, but then ply moves a lot less.
Some people might say, spline the seams and use epoxy but I wouldn't. Please don't fill seams with epoxy. The planks WILL expand when back in water and fastenings will be strained.
That's the extent of my knowledge. There's cannier people on here to reassure you about caulking and carvel boats plimming up.

ccscott49
06-04-07, 05:59
Sheathing an old hull, is a no no. You need to recaulk the seams and put filler in them, then get the boat in the water with a BIG pump, to pump out the inevitable flow of water into the boat, until the planks "take up" (expand with water) then the boat will have to be taken out again, filler removed, caulking hardened up and then re-filled, (quickly) painted and dropped back in the water. The caulking is not a DIY job unless you know what you are doing, the filling you can do yourself.
Splining is not the answer for this job, same as filling the joints with epoxy, it will strain the fastenings when the boat does see water.

Porthandbuoy
06-04-07, 06:43
And here's the hat-trick of bad news. Coppercote is an epoxy based, copper powder loaded, anti-fouling. The epoxy base will try to prevent your planking from getting wet, but it will fail as you cannot seal the seams. If you use this, or any other similar product, your boat will rot very quickly indeed.

The seams are likely to be well impregnated with linseed oil from the putty used as stopping on top of the caulking. This makes it extremely difficult to get glue, even epoxy, to stick; unless you rout out the seam back to clean wood.

An elderly carvel yacht relies on the planks swelling up when immersed, compressing the caulking, and making a seal. Again, if you use epoxy you will slow down this process and your boat will likely never "take up" and will leak like a sieve.

If your caulking is still in place and still "stringy" as opposed to having the consistency of potting compost, leave it alone. It's easy enough to put some more in once she's taken up and you can see where the weeps are. Too little is better than too much which, as you say, can strain fastenings. Note that epoxy will behave exactly like too much caulking!

ccscott49
06-04-07, 08:27
I agree with Mariposa, coppercoat is not for carvel planked boats, which are not splined and cascover sheathed from new. It will just crack when the planks take up and move.

oldharry
06-04-07, 08:39
[ QUOTE ]
My understanding of the theory and the practice is that sheathing carvel boats is a disaster. .... Works well on ply boats if done properly I've heard, but then ply moves a lot less.


[/ QUOTE ] Then I fear you have heard wrong. At least as far as Polyester resin sheathing is concerned. Its as bad on ply as any other wooden boat, because Polyester doesnt stick to wood long term in damp conditions.

What does work well if the ply is dry enough is epoxy sheathing done properly as in the West system. Cascover sheathing was very succesful too, using a water activated resin like Cascamite. But Polyester on any wooden hull is a big no-no, and even more so on a carvel one.

One popular system used in the 50s and 60s involved skimming a wooden hull with concrete. Probably about as effective as using tar and canvas, which was the other traditional way of squeezing a few years more life out of an old hull. But both these were very much 'last resort' techniques and only put off the inevitable for a few years.

EASLOOP
06-04-07, 09:45
IMHO caulking is not the 'professional only' type job a lot of people make it out to be. My boat, carvel built, was ashore for 12 years while I slowly refurbished/repaired/rebuilt large sections of the hull. One of the jobs was completely removing the caulking and letting her further dry out. Finally I completely re-caulked her, including the laid deck. I just took my time, care and caution while doing this job, making sure I did not over compact the cotton. I used multi-strand cotton paring out the right number of strands for the section I was doing. I looped the cotton pinching it in to position before going back and driving the loops of cotton into the seams. I NEVER hammered the cotton in, just lightly drove it with a caulking iron and ordinary wooden mallet. The compound was made of putty+white lead (above the w/l) or putty+red lead powder (below the w/l). She has been back in the water over the last three summers and ashore for the opposing winters. She takes about 12 hours each season to take up alongside the club quay before going out onto her moorings. Her first summer was in the mud at the club becasue she was taking up a lot after those 12 years but since then no apparant plank cracking or etc. Fingers crossed the same will apply on the 20th April. when she goes back in for her annual dunking.
As regards sheething - don't do it -. I read an account of someone who did trans-atlantic on a 28 footer that had a sheathed hull. While at sea looking over the side the owner noticed a very large sting ray following him. On closer inspection it transpired that the sheathing cloth had come unstuck and was actually threatening the boat!!

Good luck with your endevours

Niander
06-04-07, 10:49
Is this a carvel or clinker built boat? [planks or smooth hull]?

btw ...The background to this is so long that I won't go into detail as it would be too long and boring (some may say sad or a reflection on wood boatbuilders/repairers in this day and age)

id read it!

old_salt
06-04-07, 11:21
Hi Brian.
You say she's been inside a shed in a boat yard for some 6 months.
In time scales Thats nothing so she's dried out a little and you can see thought the seems DO NOTHING to her as regards the seems and outer hull unless it realy, realy needs it. You can remove any thing from inside that would suffer from water ingress and put her in on a sling or on a trolley and let her retake as mentioned above with a good pump to pump her out if needs be.
Another way would be to fill a 40 gall drum with sea or salt water and a sheet of Polly under her to catch and recycle the water and spray the outer hull.
Also you could put sacks well dampened in salt water on the inside of the hull done this way for about 2/3 weeks keeping them wet will help and if you can get the seems to close then painting and anti fouling may be an option open to you before putting her back in.
Or you could just put her in then when she has taken up pull her out and do your paint job and anti fouling again as suggested above.
But not the Cooper coat as explained above .
Good luck and please post some photos.
Cheers and all the best with her David.

Bajansailor
06-04-07, 14:35
There is a famous old Falmouth Quay Punt called 'Curlew' - her owners (Tim and Pauline Carr) gave her a new lease of life (when she was about 70 years old!) by cold moulding with epoxy a few layers of kauri pine sheathing on the outside of the hull (after first ensuring that she had thoroughly dried out).

She now lives at the Falmouth Maritime Museum - more info about her at http://www.nmmc.co.uk/index.php?page=Curators_Archive&choiceid=31

What is the Forum's view on sheathing an old timber vessel in this fashion?

Porthandbuoy
06-04-07, 15:21
[ QUOTE ]
T

What is the Forum's view on sheathing an old timber vessel in this fashion?

[/ QUOTE ]

I've been mulling this over today and was pondering the possibilities of strip planking over an old hull. Plane back to clean dry timber and soak in preservative. Then epoxy strip planks to hull, and each other, with temporary fastenings. I'd think you could get away with the thinnest of strip planks and end up with a strong and fair hull.

ccscott49
06-04-07, 15:34
I've seen this done on an old double diagonal watson lifeboat and it was very effective. But done for different reasons.
I guess the veneers would be thick enough to stop any movement in the planking of a carvel hull as well.
Basically a new cold moulded hull, with the old as stiffening and support!

old_salt
06-04-07, 19:03
[ QUOTE ]
There is a famous old Falmouth Quay Punt called 'Curlew' - her owners (Tim and Pauline Carr) gave her a new lease of life (when she was about 70 years old!) by cold moulding with epoxy a few layers of kauri pine sheathing on the outside of the hull (after first ensuring that she had thoroughly dried out).

She now lives at the Falmouth Maritime Museum - more info about her at http://www.nmmc.co.uk/index.php?page=Curators_Archive&choiceid=31

What is the Forum's view on sheathing an old timber vessel in this fashion?

[/ QUOTE ]

Now thats interesting my 1905 hull is carvel kauri pine.
Where did they get the kauri pine sheathing from.
New Zealand baned it's export in 1930 something.

Bajansailor
06-04-07, 21:07
I am just going on what the reports about her say - but I think they did this work while they were in New Zealand with Curlew.
The Carrs lived on board her for more than 20 years, and went around the world during this time, as well as spending quite a few years in Antarctica.

She is an amazing boat, and her previous custodians were pretty amazing sailors. I dont think she ever had an engine - they sailed her everywhere. All very traditional, no solar panels, oil lamps down below.

I remember seeing Curlew at Antigua Race Week in 1987, before the seperate Classics regatta started a few years later. She was racing against modern day cruiser racers - and left many of them far behind in her wake, while absolutely hammering them on corrected time.
Die hard racers were not amused to be trounced by an 80 year old engineless gaffer........ /forums/images/graemlins/laugh.gif

tyga
07-04-07, 03:04
I agree with the general sentiments above. I lived on a wooden junk for three years. She was lifted one year for antifouling and to have her varnish touched up. After just a few days ashore her bottom seams would open and she need 24 hours in the water (with a BIG pump) to take-up. Once she had taken up she was absolutely watertight below the waterline.

The key thing then was making sure that the topsides also took up. One owner I knew almost lost his boat (and his life)when failing to do this before setting out on an ocean crossing . Make sure the topsides are wetted-down regularly then set-sail (or head into rough water in a stinky) with care. In the days when we used to sail on the Broads in hire yachts with varnished mahogany hulls, hirers were told to wash off the topsides with the deck mop every day to keep the seams tight.

IMHO sheathing is like a face lift - it may look good for a time but ultimatly ends up with the old lady failing to keep the beauty that comes from aging gracefully.

Notwithstanding all the above I have read a book by an American boatbuilder who had developed a system of sheathing that appears to work and can be used on hulls that are beyond repair by conventional techniques. In his pre-amble he lists all the factors that cause "conventional" sheathing to fail. These are pretty much as given by posters to this thread. His technique was to apply the sheathing and then, while still tacky, fasten it to the timbers using an industrial staple gun and thousands of non ferrous staples. From memory he used a much heavier lay-up than convetional sheathing techniques so was effectively creating a new GRP hull using the existing hull as plug which would then remain in situ to provide strength and rigidity.

Even if this technique works I would regard it as a last resort to be used after all normal boat repair techiques had proved unsuccessful.

citibhoy
09-04-07, 20:18
The 1906 Fife Eva http://www.fundacionhispania.org/ingles/eva.htm

Has a mahogany (i think) sheathed epoxy hull. Snr Juan Belliure -juanbelluire.com speaks very good english and would im sure be happy to give a critique of the process.

I have no commercial connections regarding the above, except in so far as D. J. Belliure was most helpfull to this classic owner during an (extended) visit to Denia.

Mukes
10-04-07, 20:46
Bryher is Carvel built and was Epoxy sheathed when she was re-built in the 80s. When I bought her in 2005 I was very wary about this and had her surveyed by a known classic surveyor and asked him to pay particular attention to the soundness of the sheathed hull. 20 years after being sheathed and she came through the survey with flying colours. She is dry as soon as she is launched after being ashore for the winter and is low maintenance. I can't with any authority describe how she was sheathed but (I hope) she is proof of how it is possible.

Keith 66
24-06-07, 01:06
Sheathing a wooden boat in Grp or concrete is the kiss of death

Woodlouse
24-06-07, 01:56
Course you could do a Pen Duick. GRP on the outside, remove the wood on the inside and put the interior back how it was. Voila! Instant 100 year old GRP classic.

skenn_ie
14-02-11, 17:43
With a related problem ... that of waterproofing a timber hull when it is impractical to completely dry the wood, I asked under another heading ... does anyone know of a product which can seal/prime timber while it is still wet ? I have only 8 hours between tides, and it is impractical to get the boat completely out of the water.

DownWest
14-02-11, 18:06
Skenn,
Resoltech make an epoxy coating sealer/primer that can be put on damp wood (RE 1010) but, you would have to ask them if it is OK with salt water.

As for sheathing, several layers of veneer (i.e. a new hull) The idea of strip planking is a no-no, as the expanding carvel planks would split the strips, Veneers would be laid on the diagonal in at least two layers so would be strong enough. The advice above is best. Let her take up.

lesweeks
14-02-11, 20:55
My impression from talking to the Copper Coat guys at the recent LBS is that it's ideal for plastic & metal boats but not so brilliant on wood. Now they didn't actually say that, of course, but insisted that the coating must go onto clean, bare wood as the first, thinned, coat needs to penetrate the surface of the wood; i.e. all traces of previous finishes must be removed.
At that stage I lost interest having recently got my 'project' back to bare wood and then carefully primed!
How committed are you?

Seanick
14-02-11, 23:04
Sheathing a wooden boat in Grp or concrete is the kiss of death

Yup. So what have those very clever (and wealthy) people who run the class of Solent Sunbeams decided????

To allow the sheathing of the hulls to 'reduce maintenance'.

They seem to be ignoring the fact that it will reduce the fleet to compost in a few years.
I am relieved to hear that the Falmouth fleet will not be following suit.

One Sunbeam is currently being 'cooked' to reduce its moisture content to the Epoxy manufacturers requirement.

To win at all cost, and sod the future.

Keith 66
14-02-11, 23:28
To my everlasting shame i was once persuaded to sheath a carvel boat in epoxy & glass, it came out initially very well. Several years down the line & before she ever went in the water the keel had split lengthways vertically, a 6" by 7" lump of old oak is never going to stay stable no matter how much epoxy you put on. She ended her days being sawed up & burnt.
If she had been a horse i would have shot her.

I am currently restoring a very lightly built carvel sailing dinghy & the epoxy sheathing route has been suggested several times, it aint going to happen on my watch.

chinita
15-02-11, 10:58
Just for fun, and to allow me to maintain my own wooden boat, I did the one year course at the IBTC Lowestoft.

Most of the stuff in their sheds is in a similar condition to what you describe. Just about all of them will be re-caulked (the remainder being splined).

Caulking is not rocket science. It is physical, yes, and requires technique.

The College will tailor a short course for you - perhaps just a few days - to give you the knowledge and 'skills'. Why not give them a ring?

Personally, I would not consider sheathing of any variety. I like to see what is going on.

DownWest
15-02-11, 11:35
Over the other side of the pond, they have something called 'Seam Slick' AFAIR. The excess squeeses out as the planks take up. SeaNick might like to comment on it.

oldfrank
15-02-11, 20:20
Let's try and take this in easy stages. Sheathing an old hull is usually disastrous - and often only carried out for a few more seasons use at relatively low cost. Once water gets behind the matting it'll start to lift and the boat will rot quickly.

Splined topsides and sikaflexed bottom togther are fine ... but the sikaflex doesn't have an idefinite life expectancy.

It is possible to spline the entire hull and apply 3 (min) coats of epoxy - rollered on (without matting) and smoothed out with one of those spongey things on a stick. Paint is supposed to keep the water out and epoxy is just a very efficient paint. Use 217 hardener instead of the usual 216 - there's less of a bloom ... and when it's warmer you'll be able to get three coats on in day. You have then sealed your hull; water shouldn't penetrate and your days of moving planks should be over. You need to be very careful to ensure the entire hull is sealed (the keel is often the difficult bit - don't forget to tighten up the keel bolts). Subsequently you will have to be very careful about how much water you allow to stand in the boat - preferably none. Standing water will cause the planks to swell and give problems with the underwater splining - you can never fully stop the water running down the mast for example. This is entirely usable system - but you do have to look after it.

Seanick
16-02-11, 22:14
Over the other side of the pond, they have something called 'Seam Slick' AFAIR. The excess squeeses out as the planks take up. SeaNick might like to comment on it.

I have used Seamslick. Its handy to have in a pot on board for a weep, but its more expensive than linseed oil putty, which is quite good enough and has worked since time began.
Once a boat is back in good ownership and in the water on time then drying out is not an issue for most boats.

Seanick
16-02-11, 22:26
Let's try and take this in easy stages. Sheathing an old hull is usually disastrous - and often only carried out for a few more seasons use at relatively low cost. Once water gets behind the matting it'll start to lift and the boat will rot quickly.

Splined topsides and sikaflexed bottom togther are fine ... but the sikaflex doesn't have an idefinite life expectancy.

It is possible to spline the entire hull and apply 3 (min) coats of epoxy - rollered on (without matting) and smoothed out with one of those spongey things on a stick. Paint is supposed to keep the water out and epoxy is just a very efficient paint. Use 217 hardener instead of the usual 216 - there's less of a bloom ... and when it's warmer you'll be able to get three coats on in day. You have then sealed your hull; water shouldn't penetrate and your days of moving planks should be over. You need to be very careful to ensure the entire hull is sealed (the keel is often the difficult bit - don't forget to tighten up the keel bolts). Subsequently you will have to be very careful about how much water you allow to stand in the boat - preferably none. Standing water will cause the planks to swell and give problems with the underwater splining - you can never fully stop the water running down the mast for example. This is entirely usable system - but you do have to look after it.

I agree with most of the above. The issue of the Sunbeams is they are open boats, with usual paint and varnish finishes inside.

We have done some work on a 30sqM. She was epoxied in Germany in the late eighties. I have never seen a more perfect example of how to do it. The whole of the inside was coated in multiple coats of epoxy, The build up is good, about 2mm, and the finish like glass. All the steamed timbers were epoxied filleted to the planks and there are no chinks in the armour! Externally she was sheathed and faired.

I am not anti epoxy if it is done as above, but in most cases its half a job (ie external only) and is a quick fix for the short term. I liken it to putting high tech render on a house with subsidence.

Splining the topsides however is a great way to add strength and reduce maintenance. SCODS built at Burnes Shipyard over 50 years ago have enjoyed smooth topsides for years, only repainting to cover damage from mooring bouys or damage.