An Old Worn Out Boat, Prime Candidate for Cold Molding?

Discussion in 'Wooden Boat Building and Restoration' started by WhiteRabbet, May 10, 2022.

  1. WhiteRabbet
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    WhiteRabbet Junior Member

    It has been suggested on another thread discussing Cold-Molding vs. Fiberglass Sheathing that I start a new thread discussing my particular situation.

    The situation:
    50' Motorsailer. White oak stem, keel, and frames. Frames are appx. 2 1/4" square. Steam bent, except in stern where hard curve such that is reinforced with silicon bronze straps, and some in the very stern were laminated. (Per original construction specifications). Hull and Deck strapping - silicon bronze. Mahogany planking (not sure the thickness, would be able to determine if necessary but not immediately). Laminated spruce deck beams. Teak deck and pilot house. Boat has been sitting on the hard for 2 years now.

    The hull strapping is like a big 'X' on the side of each hull. The original construction specifications: "Three silicon bronze straps each side...notched into frames and screwed into frames and planking... The straps are to be riveted to the chainplates..."
    - The most forward of these straps anchored to the keel at the bow of the boat. These straps were cut away from the keel at this point to make space for a bow thruster that was installed later.

    There are a handful of broken frames - broken clean through. But many more that are starting to break - that have small-ish cracks at the moment. Replacing/repairing the broken frames would involve tearing out most of the interior of the boat. As well as taking out the generator. Also there is a section of frames behind the fuel and water tanks that are inaccessible. These I believe were installed before the decks were laid and are not going anywhere.

    There is also the matter of the stem, which has a crack in it from a collision.

    There are also a few planks that have been cut shorter in previous repairs, or in a couple cases, have soft spots that would be much easier to do the Dutchmen before sheathing than replacing all.

    All in all, I don't want to gut the boat and fix traditionally. I'm not going to. It's just too much. That leaves the potential option of sheathing. Now, I have read repeatedly and been told by boat builders that I need all sound frames and stem before I can think about sheathing.

    But this goes against so much else that I have heard.
    - Take for example the the Carr's Curlew, which they sheathed because it was a tired worn out boat otherwise destined for the scrap heap. I would imagine this means that it had a handful of issues with its framing and planking...
    - Or the old worn out fishing boats that get glassed to give them some more years of service. I have talked to both an old fisherman with a fleet of boats that has had his boats glassed, the guy he hired to do the glass jobs, as well as others in the area that attest to this guy's glassing method working for these old fishing boats and that many of them are still in service decades later. This guy said you don't have to worry about some broken frames.

    But as I visualize it, if you were to sister the broken frames... you would reinforce the broken part of the frame: you would tie the whole thing back together. The frames are holding the planking in place. If there is a break in a frame, that is an area where the planks are not held together as firmly - they are then only held together by the surrounding structure.
    But if you sheath the entire hull. Do you not tie ALL the planks together? It would seem that this outer "exoskeleton" would certainly tie the planks together in the spots where the frames are compromised.

    Is there a flaw to this thinking? If so, what is it?

    As for the stem, I have seen a video of a smaller boat, where the stem had a section far worse than my case and they cut it out, and laminated a new section over it, and then glassed the hull.

    This is question 1. And if so, would it reinforce the hull and planking such that the hull strapping would be reinforced as well? Or would the strapping need to be re-anchored to the keel at the bow?

    Question 2: If it can be agreed to some decent level of consensus that some method of sheathing would accomplish this, the next question, aside from which method would work best (So far, I gather cold molding for weight/buoyancy considerations), is this issue that after a hull has been sheathed, "the wood cannot be allowed to get wet" or else it is said by many voices on various forums as well as a shipwright I spoke with, that if the wood gets wet, it will swell and break the bond with the inflexible epoxy sheathing. And so, all the interior of the hull must be sealed also. This is equally impractical in my situation, as once again it would require removal of the interior including the immovable tanks, and the engine and generator, etc...

    Inevitably, water is going to get in the bilge.

    How did the Carr’s cold mold the Curlew then? I imagine they did not gut their entire boat either…

    Also, it would seem that even if water was kept out of the bilge, you would have to drop the lead ballast and glass under it as well - and in every way fully encase the existing hull in order to avoid having water cause expansion in the dried-out wood.

    The methods of cold molding I've read about terminate at the keel rabbet. And so would seem leave the wooden keel exposed to water... That I would assume would take up and expand when put in the water... Not clear why this isn't a problem...

    Another question about rigidity. It seems you want to stabilize the hull so it doesn't move when attached to a rigid layer of epoxy or you will have delamination.

    The method I have seen is to rip the seams and epoxy in wooden splines.

    But is a video on OffCenterHarbor.com of Eric Blake’s (thin) glass job of his boat Charlena. There, rather than ripping the seams and epoxying in wooden splines, he just fills the seams with “really flexible” epoxy. He said he did this to “allow for the inevitable movement of the original structure will have.” How does this make sense? It seems to be the opposite philosophy as to the method of filling the seams with wood. Would this flex not run the risk allowing movement that could cause de-lamination?

    Similarly, this guy who apparently has had success glassing many working boats in the chesapeake over the last several decades told me that his method does not involve ripping out the seams and filling them. He said he just leaves the caulking in place, puts a coat of 5200 and then three layers of glass with polyester resin. How could this work??

    Finally, what would be the best approach for my given situation? It would seem the option listed by Rumars in the other thread I mentioned: "Thick fiberglass sheathing. We are talking about minimum one inch of glass, usually in polyester. This creates a new monocoque glass hull, the old wood is just a liner on the inside, it can rot in peace until it dissappears on its own. The 5200 was used as a barrier coat over the wet wood, to allow the resin to polimerize correctly. Fishing boats had no time to dry out, just scrape away most of the paint, isolate the wood and start laminating."

    I wonder also though could you cold mold just the same over 5200 thereby getting the structure needed without added weight and changing the waterlines?

    And if so, would the boat actually need to be wet and properly expanded before doing this process, rather than dried out, as it is now?

    Thanks
     
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  2. fallguy
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    fallguy Senior Member

    The problem, in my humble opinion is that this is a bandaid on gangrene. I apologize for chucking a figurative grenade, but you are onto the issues.

    The reason is simple. Let's say you do a fine job of sheathing the entire hull exterior. It is encapsulated with epoxy and enough glass that the exterior is perfect.

    You still have a structurally unsound interior. And worse. You have an internal skeleton that can get wet on the inside and never really dry out the conventional way. This means that any old areas of dry rot are going on the expressway to mush. The wood swells and epoxy glass perfect work delams. Let's say the third time the boat gets wet, one small area the size of a nickel delams. Intro to erosion 101. The spot gets water pressures and delams more, leaving your perfect work susceptible to continued delam.

    I am putting my foam boat in a slip on current that will have a dock wheel. I'm worried about the dock wheel delaminating my hull if I bump.

    The concepts of a wood hull and an epoxy sheathed monocoque are nearly polar opposites. The epoxy sheathed hull is essentially waterproof inside and out. It doesn't move much and if it does; it does within limits or breaks. The wood hull is designed to move! When the planks swell, they seal the hull.

    My brother has a Windward 15 sailboat. The boat is ply on frame and sheathed on the exterior. It is a nice boat, but I'll never understand why they put ply on frame members that are not fully encapsulated; especially the plywood side. Someday, those will rot on the bottom and need repairs. I already replaced the luaun decks with okume and lightly glassed the deck.

    Epoxy won't bond properly to a wet boat.

    @Rumars is very wise. But. It is wholly impractical to put 1/2" of glass on a 50" hull laying rightside up. I suppose it could be done laying her on her side, but this to me is a hack approach.

    As a person who has scrapped a couple boats, I empathize with your situation. But I really think the conventional repair makes more sense. A half inch of glass and resin with a gelcoat is really heavy as well. 40 pounds per yard, say 50 yards, 2000 pounds, plus gc, fairing, overlaps, oi vey. I think you'd be ahead on hours gutting, repairing and remodeling the inside..

    I must be honest here as well. A fiberglass hull is tabbed to bulkheads, so skinning the thing is insufficient afaik. If it goes to mush inside, in theory, the skin could fall off. (In theory)

    Sorry, but conventional repair makes more sense to me; despite your wishes to not.
     
    Last edited: May 10, 2022
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  3. fallguy
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    fallguy Senior Member

    Don't these West System bottom jobs encapsulate the entire plank on the bottom only? Then bond the planks with 5200?

    I'd look into West System bottom before I'd consider glassing that beast.
     
  4. WhiteRabbet
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    WhiteRabbet Junior Member

    Hi fallguy, thanks for responding. I have some questions about some of the things you said:

    “The problem, in my humble opinion is that this is a bandaid on gangrene.”
    - On what timeline? Is it fast moving, or more like a geologic gangrene?

    “You still have a structurally unsound interior.”
    - Why? If imagine a loose structure being tied together with an encapsulating shell, it makes it so much stronger in my mind... There are a few weak points in the structure, but the rest is sound. By tying it all together, with say a - hypothetical 1” thick layer of fiberglass sheathing - would this not rigidify and solidify the whole structure to a significant degree? I dont see how it cannot. It would at least do so to some extent, that seems self-evident. Is it a sufficient extent, and if not, why exactly?

    “And worse. You have an internal skeleton that can get wet on the inside and never really dry out the conventional way.”
    - This point I dont really understand. What does “really dry out in the conventional way” mean? We are talking about a hull that is normally wet, swollen with water, with some seawater in the bilges. So when does this wood need to dry out? I don't get it.

    “The boat gets wet, one small area the size of a nickel delams. Intro to erosion 101. The spot gets water pressures and delams more, leaving your perfect work susceptible to continued delam.”
    - This is why I am asking about applying a layer of 5200. Because these working boats surely aren't keeping their bilges dry, nor are they coating the inside of the hull in some sealer. I was inside one of them and this was not a concern. And I’ve talked to them about it. They aren’t worried about having some salt water in the bilges.

    “The epoxy sheathed hull… doesn't move much and if it does; it does within limits or breaks. The wood hull is designed to move! When the planks swell, they seal the hull.”
    - Being designed to move and being designed to swell and seal - seems like two different ideas. Once the planks are swelled, and are so tight against each other that they seal the hull from water penetration, how much movement is actually happening? The less would seem the better, a tighter hull underway. If the hull was wrapped in a rigid sheathing, this would also tighten down the existing structure, would it not reinforce everything? Would it not presumably reduce the movement in the hull. The forces would seem to be dissipated a bit differently, no?
    How much are they moving after being encapsulated…

    “Rumars is very wise. But. It is wholly impractical to put 1/2" of glass on a 50" hull laying rightside up. I suppose it could be done laying her on her side, but this to me is a hack approach.”
    - It is not that impractical - I have observed a crew lay up a 90’ buy boat right next to my boat in the yard. I watched the process. It is far more practical than tipping such a large boat on its side. A skilled and experienced crew seems to have little trouble and makes relatively fast progress.

    “A half inch of glass and resin with a gelcoat is really heavy as well. 40 pounds per yard, say 50 yards, 2000 pounds, plus gc, fairing, overlaps, oi vey.”
    - For a boat that weighs 59,000 lbs, doesn't seem that significant when you consider added displacement, or the fact I've removed probably 1000 lbs of unnecessary junk.

    “I think you'd be ahead on hours gutting, repairing and remodeling the inside.”
    - Not a chance - doing as you describe would take exponentially longer.

    “A fiberglass hull is tabbed to bulkheads, so skinning the thing is insufficient afaik.”
    - This wooden boat has a number of bulkheads are fastened into the frames. From the construction specs: “ In addition to the main structural bulkheads, the partial thwartship bulkheads, in the way of lockers and toilet rooms port and starboard, shall be same thickness as structural bulkheads and shall be fashioned to the frames and beams in a similar manner to act as diaphragm knees.”

    “Sorry, but conventional repair makes more sense to me; despite your wishes to not.”
    - It is not my wishes. I have come to this after an incredible amount of time rooting for your alternative. It just isn't realistic. A conventional repair doesn't actually seem to make sense. Not without an extraordinary budget, and a lot of time. To build a boat like that from scratch today is… years, and millions of dollars. And that's what you would inevitably be doing if you started taking the boat all apart. Thats what happens when you go that way. Or the project doesn't ever get finished. Plenty of cases of that. And the boat never makes it back in the water despite the good intentions to save her for posterity. It's completely impractical for my purposes. I'm talking, can I get 15 reliable years out of it? They are glassing these working boats that are going into heavy weather, being worked hard every day, and they are still going after many years…after decades… Before the gangrene sets in? When will that be? What about cases like the Curlew? Where the Carr’s went on cruising with her for decades… And the reason they did it I read was "to save her from the scrap heap. I imagine she must have had a few minor structural issues herself. What kind of timeline are we talking about here?
     
  5. Ike
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    Ike Senior Member

    I have to agree with Fallguy. Sheathing a wood boat that has the problems you describe in fiberglass is really just extending it's life for a few years. If you really want the boat to be around for more than that then fixing it the traditional way is best, but I realize it is labor intensive, expensive, and takes a long time on a boat that big. I have seen a few boats that have used cold molding to sheath the hull . It has certain advantages. It actually makes the boat float higher and it is wood which expands and contracts just like the hull under it. But those broken frames and stem need to be repaired because the boat will still do the twist and tear itself apart. Again, it is really just a bandaid.

    Didn't you have a couple of other threads where you asked essentially the same question?
     
  6. WhiteRabbet
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    WhiteRabbet Junior Member


    A west system bottom appears to be what I was calling cold molding. It is interesting to see that they are done with a 5200 layer, as so far I had only seen them with epoxy bonding to the planking directly. And was wondering if this was possible.
    But, it seems either way - with fiberglass cloth or with strips of wood, the questionable factor is neither - its the inflexibility of the epoxy.

    The concern with using rigid epoxy to seal a traditional bottom is that is destined to crack and leak.
    And then, when moisture is trapped behind it, rot can eventually destroy the encapsulated wood.

    But what if the sheathing is of sufficient thickness to 1. Reduce this movement, 2. could a layer of 5200 in between as a kind of flexible buffer absorb this remaining movement? And if it does eventually crack and salt water encroaches will this necessarily rot the wood? It doesn't seem that rot can live submerged in salt water, from what I have read.


    >>> And aren’t there any slightly more flexible or forgiving epoxies out there?? That wouldn't just crack, but rather allow some amount of flex?
     
  7. AlanX
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    AlanX Senior Member

    The purpose of the cross-strapping is to provide shear resistance as carvel planking does not provide much (it any at all).
    The planks can slide relative to each other without the cross-strapping (at least on larger boats).
    Cold-moulding and/or fiber-glass sheathing will likely provide sufficient shear resistance such that the current diagonal-strapping will be redundant.

    While I understand the observations are real, I am not so sure of the proposed failure mode(s).
    Looking at this problem as a composite laminate, the hardwood core and FRP skin are not very compatible.
    The wood (wet or dry) will fail before the FRP:
    • Wood (American Mahogany) MOE 8700 MPa
    • Wood (American Mahogany) MOR 84 MPa
    • 30% v/v E-Glass FRP UFS 270 MPa
    • 30% v/v E-Glass FRP EF 14700 MPa
    As MOE/MOR (0.96%) is less than EF/UFS (1.84%), the wood/FRP boundary could de-laminate if the FRP layer is fully stressed or the wood is weaken by high moisture content. Note: I am not talking about a thin FRP sheathing for wear resistance here in this analysis.

    So if your looking to structurally sheath the hull I would only consider cold/moulding (subject to other limitation to be considered later).

    So now is later!

    Structural considerations:
    • I will ignore material strength differences between the planking and the cold-molding plywood.
    • By adding the cold moulded sheathing you have effectively "fixed the position" of the planking and effectively increased the hull plating thickness.
    • It could be argued that now the frames can include the some of the hull plating in their section modulus calculations.
    • The increased effective hull plating thickness and increased effective frame section modulus could allow spanning of a broken frame.
    • Only by doing some calculations will you know how much of an improvement you will get.
    It is not hard to do the calculations but you will need:
    • LWL
    • BWL
    • Tc (vertical distance from the water line to rabbet)
    • Displacement
    • Max speed
    • Frame spacings
    • I think we can ignore the longitudinal member spacings at this point of time.
    • Hull thickness
    • Frame dimensions
    Regards AlanX
     
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  8. Rumars
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    Rumars Senior Member

    I'll try to answer some of your questions.
    First, let's talk about how the repair is done traditionally. Steam bent frames do not require the removal of the interior, they are installed by sliding them in from above or below. You remove the coverboard and garboard, remove the broken frame (or not if you sister), then slide in the hot frame and screw from the outside. The stem (and other centerline timbers) are repaired by unscrewing the planks from it, scarf in a new piece, rescrew and caulk as needed. Floors do require some interior removal, but since they are low in the bilge it can often be accomplished by removing only the sole.
    While this may restore the local structure, it doesn't mean it will always cure the underlying problems. One of the big problems of wooden boats are the fasteners, they can deteriorate (even non ferrous ones) or the surrounding wood deteriorates. The result is a boat in need of refastening, either by adding new ones or replacing the existing with the next size up. This can be more expensive then even the best cold molding.
    Traditional wooden boats therefore have a limited life expectancy before major repairs are needed. When this is reached the decision to repair is usually driven by economic calculations, not technical ones.

    The non-traditional methods all adress this problems differently. We must always decide for ourselves what is considered a success. If a boat had the usual approx. 20 years life expectation and the sheating gives it another 20 years at 1/4 of the cost of a traditional repair, is it a success or a failure? Normally it should be viewed as a success, but in yachting circles its often viewed as a failure. That's because some of this methods while doubling the life at a low cost also double or triple the cost of the next major repair, thereby often guaranteeing it will not be done. You hear "don't buy a sheated boat", and it's usually good advice, but exactly this sheating has allowed said boat to reach its age. There is no free lunch, there comes a time when the current owner must pay the money saved by the past owners, if he wants the boat to survive.

    Thick fiberglass is totally independent of the wooden structure. The only thing that still has a structural job are the bulkheads and maybe the floors, they keep the boat sides apart. The fiberglass shell is usually stiff enough without relying on the wood.
    Thin fiberglass is exactly the opposite, the stiffness comes from the wood, the shell would collapse without it. The glass imparts strength to the wood as long as it adheres to it, but the boat will not function without sound wood because the glass is not stiff enough.
    How thick or thin the glass must be therefore depends on the underlying wood. A basket case can only be fixed by a thick glass layer. The stiffer the wood the lighter the glass can be. To achieve this stiffness the planking is often glued together beforehand. The caulking seams are often frayed and contaminated, so instead of laboriously raking and cleaning by hand, the seam is widened by machine exposing good fresh wood for the glue to bite into. Splines are used to save glue, but using thickened epoxy alone is perfectly acceptable. Sometimes wide planks are additionally cut and glued back together, blurring the lines between narrow carvel and strip planking.
    Cold molding is something between thick and thin glass. The veneers are thick enough to provide some stiffness but not as strong as fiberglass of the same thickness. Centerline timbers, floors and bulkheads must be in good shape and strongly adhered to the planking, while broken frames can mostly be ignored. Cold molding is normally finished with a thin glass layer for abrasion and worm resistance. This also seals the timbers that were not molded over, like stem and deadwood.

    Next point is adhesion to the underlying wood. Wet wood will not glue, a barrier coat is necessary. Polyester does not bond very well to wood, often additional mechanical fasteners are used in the first layers of glass. Epoxy glues very well to dry wood, adhesion is not a problem.
    If the plank is strongly adhered to a thin glass layer, the glass can fracture. If the plank is weakly adhered to a thick enough glass layer, the wood can separate from the fiberglass.

    Last point for now, the deck. Without a truely watertight deck the whole exercise of sheating (whatever method, even ferro) is for nothing. A sheated boat should not have a continuously wet bilge. Some water gets inside from spray, your rain gear, shaft seal (you should have a separate tray for that) or whatever, fine, your bilge pump takes is out immediately and the wood will naturally dry to ambient moisture levels. To make sheating a success the inside should be dry and nicely ventilated.

    Next post I'll detail some of @WhiteRabbet options.
     
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  9. Rumars
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    Rumars Senior Member

    The options for this specific boat as I see them, and of course my opinion is worth what you paid for it.

    1. Thick glass. The thickness is not necessarily uniform, when I say 1 inch I mean average, this could mean 2 on the centerline, 1.5 underwater then tapering to 0.5 at the sheer. This is a very safe option, it's safe even with half the wood rotten and broken. Another advantage, it requires the least amount of prep work, only removing the existing paint. The next major repair will consist of converting the boat to a full fiberglass one. How far away that is, depends, I would expect a solid 20-30 years even with the current deck. With a truely watertight deck and good ventilation and care it could be much more.
    I expect such a job to be done by a professional crew, so I won't talk about the pitfalls or costs. But, it can be done by the owner with very careful planning.

    2. Thin fiberglass. Here I am talking about a maximum of 1/4", probably half of that average. The prep work is much more, after paint removal the boat should be faired. Broken or rotten timbers should be fixed and their connection to the planking assured (extra screws for hood ends, floors), keelbolts checked (the glass won't hold the ballast), etc. Splining is optional (debatable) if most of the frames are good, short sisters are advisable (laminated or HDPE) for the broken ones. The success depends on the overall boat condition before sheating, if the fasteners are mostly still good it can last 20 years. A leaking deck will greatly diminish that number, it's much more important then for option one.
    The next major repair will be a full wooden boat rebuild, less likely to happen then for option one.
    This has the potential to be the least costly option since it can be done entirely by the owner.

    3. Cold molding. Prep work is paramount, splining (or similar) and then fairing is mandatory, as is tight deck and all rot removal prior to sheating. I would expect 3×4mm or 2x6mm veneers. Epoxy is mandatory, if you want to glue the first layer with 5200 you have to also use screws or nails. Properly done such a repair does not have a defined lifetime expectation, it all depends on subsequent care, just like any other wooden boat.
    Cost is hard to quantify since access to veneers varies so much. Professionally done I expect it to be more expensive then #2.

    4. Traditional repair. If refastening is needed this can become costly, I would expect a 100 000$ quote. Without refastening it's not so bad, but the only way it's cheap is if you can do the work yourself or with your friends.

    The deck is another pitfall. Does it have a plywood subdeck or is it a true laid one? How worn is it, meaning how much meat do the bungs still have? How are the spruce beams? How is the house fixed to the deck? This all decides how to repair it when the time comes, and unfortunately the time always comes. Unfortunately, because while sheating a hull is pretty straightforward, the deck is very time consuming.

    Wich option you take depends on your expectations. Do you want to keep the boat more then 15 years? Want it to be worth something when you are ready to part with it (sell or scrap)? Any major offshore sailing plans? Are you a good woodworker with an existing machine park?
     
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  10. fallguy
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    fallguy Senior Member

    Top of the line epoxy is now selling at about $1 an ounce. Cheaper brands might be less, but still gonna be very expensive.

    The devil in these is all small details. Like for option one, structural support integration. There has to be some. Engines can be on mush? A wet bilge will rot faster if it is encapsulated because the boat can never dry out well, even hauled. If rot is already present, then this is the bandaid on gangrene, okay? It will never dry and rot will go fast on all rotten bits. If the boat is now hauled for her problems, the rot is probably dried and stopped, but encapsulate or cold mold and it all starts if the boat takes water from deck or hull.

    I will say one thing about boat economics. The way I would make my decision is based on the value of the boat in good condition. So, say the boat in good condition is worth 100k to keep it simple. Scratch what you have into it today as time served, if I may. So, you can spend up to $100k on the repairs to break even.

    Boat economics is always bad. What you do NOT want to do is spend $100k on a boat that you can buy for $50k. Because noone cares that you spent $100k on it. You can go buy that 50k boat instead of the $100k repairs. And believe it or not, this happens all the time. I took twoboats to the scrapyard this way. Not worth the value of the repairs when done.

    My main point and I'll stay on it. Fixing the boat with alternate means and burying rot is a terrible idea.

    but Rumars is your best bet

    If the economics are there, I'd fix the boat the old way, or west system or something like it.
     
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  11. fallguy
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    fallguy Senior Member

    I'll only briefly respond to this query. The 5200 is a flexible bond. Planking can be sealed with epoxy, then the seams sealed with 5200. A permanent bottom. The bad thing is the frames gotta be good. Epoxy does not do well applied wet or in major flexible needs. Well, sort of, Epoxy has good elongation to failure, but the problem is where and how. A piece of wood when it swells, moves radially and away from the center. So, the ends of the board move greatly; the middle of the board not at all. If the end of the board
    'Grows' 1/8", then the epoxy bond there is under significant strain and elongation significant as a % of that small zone. Sealing the planking in epoxy makes the plank no longer take water and no longer move; the seam or connection in 5200 allows some movement between hull a/o planking.

    I only know a wee bit about West System bottoms. Never did one, just heard about it.

    Stick with Rumars. I'll offer what I am sure about or qualify what I can.
     
  12. fallguy
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    fallguy Senior Member

    I think you at least ought to understand the root cause of the stem failure before you go deeper into options. Is it rotten or what horrors allowed it to break?

    EDIT: sorry, I see a collision caused it

    I would think you could repair the section with epoxy and laminated built up sections. I can't spec it for you. But I would like to believe say a 3" wide stem could be repaired by laminating properly sawn timbers of about 3/8-1/2" with epoxy. My approach would be to assess the broken section. Say it is 24" and sheared in the middle. I'd start by supporting the boat with temp framing. Then cutting out the section and piecing it in with lap joins about 1/2" and something attainable in the space, but preferably 2" minimum steps. So, the middle piece would be 1/2" @ 24" and the next 28" each side of it and the next 32" each side until you lap the outside. Of course, my math doesn't work, but you get the picture? Sawing to be done to minimize the likelihood of grains shearing off an end... You would use chisels and oscillating tool for cutting each step in the existing stem. On the outer piece, I'd go as long as practical on unpainted wood for the join. The epoxy joins should be done as professionally as possible. Neat epoxy on all raw wood first, etc.

    Give us some idea of the damaged and good dimensions and let @Rumars remark. I am actually doing a repair similarily, but It is a much smaller boat and I plan to lay the repair pieces flat to the hull and step them the other way, if that makes any sense at all. The shortest 'veneer' will be against the planking and the longest piece to the outermost part of the repair. Napkin sketches would help us give you better advice. My personal opinion is that full replacement is not needed. But assumes not too terrible...

    Also, a picture of any kind at all would help because maybe I have the plane wrong in my head.
     
    Last edited: May 11, 2022
  13. Rumars
    Joined: Mar 2013
    Posts: 1,379
    Likes: 719, Points: 113, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

    Well fallguy, you are right, sheating is ultimately a bandaid on gangrene. The question is how much time you can buy with it. There are also boats that are to far gone for sheating to be of any use in the first place, those are the ones where the rot is to widespread to begin with. I also always advice that even if anyone decides to sheath, fixing the wood first is the better way to do it. My estimates of life expectancy of a sheated boat seem high, but they are for boats that are mostly rot free, dry and suffering only from fastener problems. If those conditions are not met, all you get from sheating are a few years before they turn to mush. Ultimately any sheated boat that was not designed for it from the onset will suffer that fate, careful maintenance will only delay the inevitable.
    I don't particularly like the method, but done correctly on the right boat, it does provide a useful life extension. After that it's usually the dumpster, and the moment one puts polyester on a wooden boat the value drops to zero, regardless of how nice the interior is, or how good the systems are.

    One thing I can add, there is nothing cheap when you have a 50ft carvel boat. One either has the needed money or not, there is no middle way.
     
  14. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    If you put 1/2" of glass on that hull, 60 yards of 1708 for example only is 1500 pounds of glass. 1500 pounds of glass requires 1500 pounds of epoxy for hand work. This is 167 gallons of epoxy. The cost of epoxy alone will be about $20k. I used about 300 gallons for my build, high waste rates for vac bagging, so not all in the boat, but just to give you a rough idea...I am close
     
    WhiteRabbet likes this.

  15. rangebowdrie
    Joined: Nov 2009
    Posts: 146
    Likes: 55, Points: 28, Legacy Rep: 10
    Location: Oregon

    rangebowdrie Senior Member

    I remember reading the extensive article about Curlew that was in WoodenBoat mag when the process was first done.
    Alan Vaitses was also doing work on sheathing carvel boats with glass ~ the same time, he's passed on, but he wrote a book about his procedures that you still might find.
    Another source for info would be "Jesperson": Jespersen Boat Builders / Custom Wooden Boats / Eric Jespersen /Boat Repairs Sidney BC (jespersenboats.com), they did work like you propose "back in the day".
    The archives of WoodenBoat are replete with pages of similar discussions.
    Here is one: A cold molded overlay over carvel? (woodenboat.com).
    No easy ways, sucess still requires a "dry" boat. Trying to "cover-up" a wet boat with existing rot issues is a recipe for disaster.
    A previous post mentioned "deck leaks", absolutely, fresh water coming thru deck/deck structure leaks is probably more destructive to a boat over the long term than saltwater coming in from a leaky caulking seam.
    PS. Perhaps I misinterpreted the above post by Fallguy, I would imagine that a 1/2" of glass over a 50' boat would require a HUGE amount of product.
    I'll say this "tongue-in-cheek": Get out the chopper gun,,,,.
     
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