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Thread: A cold molded overlay over carvel?

  1. #1
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    Default A cold molded overlay over carvel?

    I often see somewhat tired carvel yachts I like and wonder if it is possible to cold mold multiple layers of veneer over them .... it would stiffen them and probably solve a series of small problems.

    It's something the Carrs did to their Falmouth Quay Punt, ''Curlew'' when she was getting rough.

    I understand that the hull and the whole structure would need to sit in a shed for months to dry thoroughly before fairing and proceeding with a very messy job.

    Would anyone like to comment on how satisfactory the process and the likely result would be ?
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    Default Re: A cold molded overlay over carvel?

    Peter its not that difficult, just laborious. You do need to dry the boat out, then you need to spline it, then you burn/scrape/grind/sand all the paint off. Each boat is different, but you need to make sure the garboard is fully attached and the detail of how to add the veneers has to be thought out to avoid issues. Thicker veneers are better than thin and one layer might do on a smaller boat. Use plenty of goop and an air stapler, a layer of biax and youre good to go. Excellent result if done well.
    whatever rocks your boat

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    Default Re: A cold molded overlay over carvel?

    It would seem the best way of sheathing a wooden boat but i wonder what happens down at the keel? If you take the ballast keel off & glass over the rest fine you can keep the water out but otherwise water will surely get in down the centreline, then shrinkage movement etc etc?

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by Paul G. View Post
    Peter its not that difficult, just laborious. You do need to dry the boat out, then you need to spline it, then you burn/scrape/grind/sand all the paint off. Each boat is different, but you need to make sure the garboard is fully attached and the detail of how to add the veneers has to be thought out to avoid issues. Thicker veneers are better than thin and one layer might do on a smaller boat. Use plenty of goop and an air stapler, a layer of biax and youre good to go. Excellent result if done well.
    Extra floors or cast floors if there is any question would be the go. Cloth around the ballast or under is something I don't know, dropping it and at least checking the keel bolts would be mandatory.

    Thanks.
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    Default Re: A cold molded overlay over carvel?

    The down side is you have no more access to the carvels or the screws underneath.
    Gerard.
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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by keith66 View Post
    It would seem the best way of sheathing a wooden boat but i wonder what happens down at the keel? If you take the ballast keel off & glass over the rest fine you can keep the water out but otherwise water will surely get in down the centreline, then shrinkage movement etc etc?
    Precisely, something to take advice on!
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    Default Re: A cold molded overlay over carvel?

    This subject was all the rage during the earlier years of WBM, but I haven't seen it talked about for many years. I wonder how those boats faired over the years and why we aren't hearing about the process now.
    I was born on a wooden boat that I built myself.

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    Default Re: A cold molded overlay over carvel?

    Ive had 2 skinned boats, both still alive and very well, one was skinned 25 yrs ago, the other maybe 10. It's a perfectly valid technique to stiffen up an otherwise basket case boat. I'll probably end up doing it to my latest one too. Technique as per Paul G above.

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    Default Re: A cold molded overlay over carvel?

    Goggle just found this for me Rich http://forum.woodenboat.com/showthre...arvel-Planking
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    Default Re: A cold molded overlay over carvel?

    ^ Just so. Cuirlew is still going strong in the care of the Falmouth Maritime Museum.
    From the thread linked to another thread:
    There is an index to woodenboat at http://www.woodenboat.com/wbmag/idx/

    The result of the search quay punt curlew.

    Anchor: placement/Falmouth Quay punt CURLEW, 119:47

    Cold-molded hull repair: critique/Falmouth Quay punt CURLEW, 120:98

    Cold-molded hull repair: Falmouth Quay punt, CURLEW, 86:36

    CURLEW (Falmouth Quay punt): commentary on rig, photos, illustrations, 131:58

    CURLEW (Falmouth Quay punt): comments, 120:104

    CURLEW (Falmouth Quay punt): comments, photo, 119:47

    CURLEW (Falmouth Quay punt): critique of rebuild, photos, 120:98

    CURLEW (Falmouth Quay punt): history, photos, plans, repair, 86:36

    Epoxy: for cold-molded overlay/Falmouth Quay punt CURLEW, 86:36

    Falmouth Quay punt: CURLEW/history, photos, plans, repair, 86:36

    Falmouth Quay punt, CURLEW: comments, 120:104

    Falmouth Quay punt, CURLEW: comments, photo, 119:47

    Falmouth Quay punt, CURLEW: critique of rebuild, photos, 120:98

    Repair: Falmouth Quay punt CURLEW, 86:36

    Windlass: placement/Falmouth Quay punt CURLEW, 119:47 (woodenboat.com)
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: A cold molded overlay over carvel?

    Yes, that project was a success by any yardstick!
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    Default Re: A cold molded overlay over carvel?

    Curlew had to undergo some serious work in Falmouth. It might have been down to bad service after the Carrs let Curlew go, she was just left sat idle and uncovered for some time. I understand there was an issue with the sheathing, someone i know personally inspected it.

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    Default Re: A cold molded overlay over carvel?

    I know one very old Wianno Senior that was skinned with two layers of cedar must be twenty years ago now. Only old Wianno that doesn't leak to weather.

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by skaraborgcraft View Post
    Curlew had to undergo some serious work in Falmouth. It might have been down to bad service after the Carrs let Curlew go, she was just left sat idle and uncovered for some time. I understand there was an issue with the sheathing, someone i know personally inspected it.
    That is possible. The Carrs did not lay any glass sheathing over the new wood. Said that it was not a problem but the glue lines did print through.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: A cold molded overlay over carvel?

    I have always thought it would be faster to rip off carvel section by section from the bottom and re place with strip planking. A single layer.
    Have never done it.
    I do not like the idea of locking up old planks inside new. Of course, if the original planking material is excellent rot resistant material....
    I recon these heroic steps may only be taken with a good boat anyway.

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    Default Re: A cold molded overlay over carvel?

    Jespersons in Sydney, British Columbia have had notable success with this technique.

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    Default Re: A cold molded overlay over carvel?

    That's encouraging, they have a good reputation.
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    Default Re: A cold molded overlay over carvel?

    A friend who did it on an old 32ft boat. All caulking removed and replaced with solid splines. Goes without saying that ANY bad stuff was removed and replaced, including some frames and most fastenings, in his project. Overlaid with 2 layers of 4mm marine ply with a light sheathing....epoxy bonded. Another boat that has done many miles and hard service with no issues.

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    Default Re: A cold molded overlay over carvel?

    Why pull the fastenings ?
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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by PeterSibley View Post
    Why pull the fastenings ?
    Some where old iron or galv spikes and way past there best. If i recall, the boat was originally built in the early 1900s.What couldnt be pulled was double fastened.

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    Default Re: A cold molded overlay over carvel?

    There is another method you might consider before diving in. Koehler Kraft boatworks in San Diego use a method that is less radical but similar in performance to the over-skinning with veneers.

    The humidity swings in San Diego/Southern California are strong when the dry air from the desert starts flowing offshore. It can go from 60% to 5% in a matter of days. The topsides of carvel planked boats in San Diego are maintenance hogs if the owners are concerned with cosmetics. The topsides seams open up and close (depending on wood species and VG vs FG) with the swings.

    The methods I've witnessed are as follows:

    1) Wood the boat down completely
    2) Replace any bad planks
    3) Refasten as needed
    4) Setup a guide and run a fat 1/2" groove into the caulking seam on every plank
    5) soak the boat inside and out with CPES
    6) Soak fiberglass yarn in epoxy and fill each routed seam with this material
    7) Glass the hull using epoxy resin
    8) Fair the hull using compatible compounds
    9) Prime and Paint with 2 parts Urethane

    The intent of the process is to minimize vapor/moisture movement in or out and create a stable surface. The hull of course is gloss and appears like a glass boat.

    It won't be as strong as the cold-molding / re-skinning methods. The moisture isolation of the keel is still pretty much the same problem.



    Personally, I'd drop the ballast and glass over the keel timbers and deadwood to attempt to make once continuous "Skin" if rebuilding conventionally didn't make sense.

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    Default Re: A cold molded overlay over carvel?

    Thanks all.
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    Default Re: A cold molded overlay over carvel?

    Reasonably common approach here.
    One thing I don't see mentioned is the change in the waterline after adding all that displacement. Something to remember.

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by John B View Post
    Reasonably common approach here.
    One thing I don't see mentioned is the change in the waterline after adding all that displacement. Something to remember.
    Often the case, the thickness of the skins make up for the extra weight as increased area......so no change in waterline.

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    Default Re: A cold molded overlay over carvel?

    I think I read somewhere that the increase in volume offsets the increase in displacement so boats having this kind of treatment float close to original waterline.

    Interesting discussion. Why not just repair traditionally? Other than the well-known and familiar negative issues with carvel hulls, one positive is longevity from proper repair. My boat is 70 years old. If I want to give her another 70, I will think carefully about doing something that is not easily reversible or repeatable. The further you bury important structural components like keel bolts and floors etc, the harder to dig them out.

    I always imagine a plastic bag full of wood and metal hanging in the water, with a few pinholes in the bottom, when thinking about veneering a traditionally built hull with anything - wood and glue, glass and glue, or whatever. It may take 20 years to turn to mush, but once it does, reversing it seems improbable. Plus I have inspected scores of amazing pedigree boats that are basically worthless due to being skinned over with the best of intentions and sometimes a lot of effort and expense. Maybe more than a traditional repair would have been.

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    Default Re: A cold molded overlay over carvel?

    I've never seen a good boat ruined by sheathing. I've seen quite a few dying boats where sheathing hasn't helped.

    I think the issue is waterproofing. Carvel boats aren't strictly waterproof - they need the planking to get wet to take up. But I think sheathing is all about waterproofing so I'd use whichever approach will ensure a waterproof hull. I've heard plenty of people suggest that you can't waterproof a wooden hull by sheathing but I know from experience that that's just nonsense - there are loads of examples of sheathed, waterproof, wooden hulls.

    I'd use a couple of layers of veneers, sheathed with glass/biaxial or I'd use a couple of layers of biaxial. Either way you get a stiffer and more waterproof hull. I'd also check out Alan Vaitses' book on structural sheathing with vinylester. Let me know if you want to borrow it and I'll bring it to Hobart along with your cookbook.

    Rick

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    Default Re: A cold molded overlay over carvel?

    Interesting, not what I was told, certainly the boats I've seen that have had it done look extremely bouyant. One had a whole lot of extra ballast added , but that was also due to over weight spars and extra sail area. Difficult to quantify.
    Certainly most of our unglued multi skin boats get saturated over a season or two , and when they go back in after a dryout they sit higher, so that could account for it too.
    Of the boats that spring to mind, one guy was just sick of leaking ( a notoriously low wooded boat that definitely was improved with the new freeboard) and the other was a basket case set for the dumpster,... or get skinned.
    Jessie Logan was the basket case. 1880.


    Matua was the other.. She's from about 1905 through 10 or so , I forget.
    I think she was skinned with macrocarpa and had a layer cotton fabric over. That was back in the '80's or early 90's if I took a guess.
    She was so freakin low ducks used to step down to her. I was curious to see her so went looking last christmas while we were up North.
    Last edited by John B; 11-08-2016 at 05:20 PM.

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by Jim Oppy View Post
    I think I read somewhere that the increase in volume offsets the increase in displacement so boats having this kind of treatment float close to original waterline.

    Interesting discussion. Why not just repair traditionally? Other than the well-known and familiar negative issues with carvel hulls, one positive is longevity from proper repair. My boat is 70 years old. If I want to give her another 70, I will think carefully about doing something that is not easily reversible or repeatable. The further you bury important structural components like keel bolts and floors etc, the harder to dig them out.

    I always imagine a plastic bag full of wood and metal hanging in the water, with a few pinholes in the bottom, when thinking about veneering a traditionally built hull with anything - wood and glue, glass and glue, or whatever. It may take 20 years to turn to mush, but once it does, reversing it seems improbable. Plus I have inspected scores of amazing pedigree boats that are basically worthless due to being skinned over with the best of intentions and sometimes a lot of effort and expense. Maybe more than a traditional repair would have been.
    Jim, I appreciate your concerns but the CURLEW example sticks in my mind. If you think of a dried out carvel hull as a building mold , laminate veneers over it ,then apply glass cloth over everything, back bone included so that it stays dry all should be well.

    The glass cloth is something I really like the idea of . We have teredo worms here that you wouldn't believe. I may post pictures when I buy a bit more download.

    Quote Originally Posted by RFNK View Post
    I've never seen a good boat ruined by sheathing. I've seen quite a few dying boats where sheathing hasn't helped.

    I think the issue is waterproofing. Carvel boats aren't strictly waterproof - they need the planking to get wet to take up. But I think sheathing is all about waterproofing so I'd use whichever approach will ensure a waterproof hull. I've heard plenty of people suggest that you can't waterproof a wooden hull by sheathing but I know from experience that that's just nonsense - there are loads of examples of sheathed, waterproof, wooden hulls.

    I'd use a couple of layers of veneers, sheathed with glass/biaxial or I'd use a couple of layers of biaxial. Either way you get a stiffer and more waterproof hull. I'd also check out Alan Vaitses' book on structural sheathing with vinylester. Let me know if you want to borrow it and I'll bring it to Hobart along with your cookbook.

    Rick
    Rick, I have Alan Vaitses' book here, thanks for the offer. I have quite a lot of timber here suitable for sawn veneers.
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    Default Re: A cold molded overlay over carvel?

    I would think that if you go this way the one ought to do a similar job to the deck/ coachroof and seal the deck hull joint.
    Otherwise fresh water will get in a sealed hull and rot inside out.....

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by Jamesh View Post
    I would think that if you go this way the one ought to do a similar job to the deck/ coachroof and seal the deck hull joint.
    Otherwise fresh water will get in a sealed hull and rot inside out.....
    Yes that's very important, so important its a given as far as I'm concerned , and yet I still read about people who fudge around with pretty stuff while they have the killer of wooden boats just rotting them from the top down. Deck to hull, coamings to carlin, hatches, staunchions.
    I know people who have followed the 'tradition' approach unsucessfully and they get wet in their bunks in the rain.
    As a counterpoint, my 1907 boat had its decks glassed over in the 1960's. We ran her for 25 years and that particular misery was not on our list of issues. Now as far as I am aware , she is the only boat of her type and age here that has her original decks and deck beams. All the rest have been re decked.

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    Default Re: A cold molded overlay over carvel?

    Great new ideas here.

    The OP asked about how satisfactory the process is. I think the process of working with wood is better than working with fiberglass. But that's just me.

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by RFNK View Post
    I've never seen a good boat ruined by sheathing. I've seen quite a few dying boats where sheathing hasn't helped.

    Rick

    I think this is an important distinction. Many have attempted to "fix all the problems at once" by sheathing a hull, without doing all the extra leg work of actually fixing the real problems. This often ends up being a Band-Aid that gets a few more years out of a boat, but ultimately won't save it.
    There's the plan, then there's what actually happens.

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    Default Re: A cold molded overlay over carvel?

    Quote Originally Posted by wizbang 13 View Post
    I have always thought it would be faster to rip off carvel section by section from the bottom and re place with strip planking. A single layer.
    Have never done it.
    I do not like the idea of locking up old planks inside new. Of course, if the original planking material is excellent rot resistant material....
    I recon these heroic steps may only be taken with a good boat anyway.
    This seems like a reasonable alternative.

    My 2 cents. Well, that may be overstating the value. Cleaning a hull with a pressure washer will be a thorough, if rather messy inspection for rot.

    Having just cleaned up some decks and other wood with a pressure washer, the things do find and rapidly erode rotten wood, loose knots, surface oxidation and anything else that isn't nailed down. The rotating nozzles do a lot less damage than the plain small jets. Any place the washer blows through caulking or rot will spray crud all over whatever is behind the spot, so the interior will be in need of some work afterwards if it isn't already.
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    Default Re: A cold molded overlay over carvel?

    So why not just glass it with a few good layers then gel coat it?

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    Default Re: A cold molded overlay over carvel?

    Because glass tends to not like salt water bleeding out of old saturated wood, and more often than not there aren't enough glass layers to fix underlying structural problems . The boats I'm aware of have delamination issues. The exception is one particular boat that had so much glass added that her wood hull was famously described as 'being a passenger'. In other words , the glass was to such thickness that could have made a hull by itself.

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