1967 48' ChrisCraft Constellation Restoration

Discussion in 'Wooden Boat Building and Restoration' started by robster, Aug 12, 2008.

  1. robster
    Joined: Apr 2008
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    robster Junior Member

    Par, thanks for your honesty and willingness to have a productive conversation, and of course I am totally willing. I am sure we can learn some things from each other. at the moment I have taken a lot of time today to respond to all the comments and will get back to you later today with a more detailed outline of my composite process.

    Just to add here. I thoroughly respect and honor the craftsmen and many in my mind are "Legends" of wood yacht and ship design, such as a personal hero of mine, Master shipwright, Donald Mckay, of which I have studied intensely even until now, his methods of clipper ship construction. But he also used the cotton/water soaked caravel planked system, and is the very reason why all of his ships are now either burned up or at the bottom of the ocean, with none still in existence.
     
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  2. gonzo
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    gonzo Senior Member

    You started the thread saying that this was a restoration. That is defined by repairing and rebuilding to original standards. Later on you insult us because we post opinions and facts according to what you posted.
     
  3. robster
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    robster Junior Member

    gonzo, I apologize for the miss communication, and the use of the term "restoration", i can see how it could be miss-understood. I have actually taken the boat totally apart down to the keel and rebuilt it with new materials and process. most people think i am crazy and wasting my money. but I think that is up for me to decide. One of my motivations was to take and old design and rebuild it with new processes and materials and do some testing and comparisons so that we all can learn from them. maybe some of my processes will not work very well, but that is what experimenting and learning is all about isn't it. I am never one to stay "In the box" and therefore get beat up quite a bit for it.

    Also for starters. this is the penetrating epoxy I am using

    http://www.rotdoctor.com/test/penetration.html please check out their testing of the product.

    I soaked one of my mahogany planks with this stuff and let it sit out in the weather through the summer and winter for a whole year. it got sun baked, rained on, snowed on and frozen, experiencing temperatures from 100 deg down to below zero. the next summer after examining the plank, I noticed it did not change the structural characteristics of the wood at all and was still shedding water the same as when I first applied the epoxy on it.

    I tried other penetrating epoxy products that totally failed from the same test. so it proves that not all products are the same.
     
  4. gonzo
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    gonzo Senior Member

    An old guy friend of my always said that if you want it and can afford it, then it's not expensive. You are taking the planks out one by one and then re-installing them, right? Might as well set everything in epoxy and laminate the outside. It would be like any wood, composite hull and become a monocoque structure. Using epoxy and then a flexible adhesive seems counterproductive.
     
  5. robster
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    robster Junior Member

    Yes I took all the planks off the hull and most of the ribs, of course I had to do this a little at a time so that I would not loose the shape of the boat. what little structure of the boat that was left. I saturated it with penetrating epoxy first and continually put on multiple coats until it stopped soaking in, then I began to replace most all the ribs, batons and planking, soaking them with epoxy by heating them up first to open the wood pores and then soaking them in a tank of epoxy for one hour. after drying I saturated them again with West System Epoxy before installing on the boat. The reason why I used a "thin" coat of 5200 is to allow minimal movement of the structure so that it will not crack after years of vibration and flexing from wave impact. No matter what, a boat (Much like an airplane) needs to be allowed to flex so that it will not crack at the seams or worse, break structural components because it is too rigid. Just the vibration from the engines alone (as stated in an earlier post), will crack out epoxied seams.
     
  6. missinginaction
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    missinginaction Senior Member

    Excuse me, I have a question......

    How does one soak something in a "tank" of epoxy for an hour without setting fire to the shop?

    I'm really not trying to be a wise guy but this just doesn't add up, but then, what do I know.......

    :?::confused::?:
     
  7. robster
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    robster Junior Member

    No problem, actually a good question. First of all penetrating epoxy stays liquid after mixing for several days. I built tanks that were just big enough to put the planks in. Then i fill the tank with just enough epoxy to cover the board. And let it sit for 1 hr. Then take it out. After using up all that is possible. I clean out the tank before it sets up so i can start another batch.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Well this wasn't what I was hoping for when I asked for a schedule, but out of hand it's clearly way over the top as far as practicality, in a restoration or repair setting and not something the vast majority would consider. Given that, you've placed much too much faith (in my opinion in light of the testing results) in this re-badged Smith brothers product. I've tested this stuff, along with all the other major brands and they are precisely what their hazardous materials documentation suggests they are, highly diluted epoxy. In the case of the particular product you used, ~33% solids once fully cured. This isn't an especially impressive version of the DGBEGA molecule, particularly considering in it's usual form is a 100% solids product.

    The hot on hot process you briefly describe is only effective on the very first coating of epoxy. Subsequent coats, with a hot on hot technique will not draw in any differently then room temperature applied coats. This is simple physics as the pores are sealed in the first coat so contracting gasses in the second coat, can't draw in additional material. In the case of CPES and considering is gross porosity, there might be some additional "suck" in subsequent hot on hot coats, but I suspect the surface pores have a fairly high percentage of the solids, while the many vehicles have leached further into the substrate as they evaporate.

    The addition of the word "thin" to a coat of 3M-5200 makes a substantial difference in an interpretation of what's been done here. I still don't recommend this stuff below the LWL, but used as you have, which is thin and under the pressure of the mechanically fastened, faying surfaces, you placed it in as good a position to succeed as it can be. Under pressure during the cure, 3M-5200 does work in underwater situations, but this isn't the usual exploitation of this goo.

    Personally, I would have (and have in the past) just used good repair techniques and saved myself (and the client) a bunch of money. In your case, you where after something entirely different and the approach bears this out easily.

    Finally, your test board survived outdoors for a year with just CPES on it. Your sun must be much different then my sun, as we have UV down here that will char epoxy (regardless of brand or dilution rate) if left with direct sun exposure for a full year. Now I realize the great white north hasn't as direct an inclination angle as we southerners, but I would have suspected some damage without UV protection coatings. Not even the Smith brothers make these claims, though they've made some real doozies over the years, one of which forced them to change their product name. In fact, it was the claims of their product that caused the uproar and industry wide testing, name changes (they're on their third) and the general debunking that comes when multiple testings prove advertising hype to be just that.

    I hope you've embalmed enough of her Robster. Have you an idea of how thick the neat epoxy coating was, before you assembled? I would think this is key to success in your case, as CPES just doesn't work without a significant neat coating over it. This was one of the other things found in testing (among several interesting tid bits).
     
  9. robster
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    robster Junior Member

    Hello par, I apologize for not responding to you yet today, my earlier posts were just responding to gonzo. I had to go see a client and just got back.

    Yes I agree that what I am doing is not for the average person to try and neither am I promoting it to anyone, I am just explaining some of the things that I have done with this project in response to this thread. But what I am hoping for is for people to get ideas to advance the wood boat building technology so that wooden boats will be better preserved and more of them to be built.
    The testing that I have done with epoxy is from my own experience and am not trying to promote any product or trust any advertised claims. But I do know some things I have learned through personal use and testing of materials, although I am very open to any product that would outperform the epoxy that I am using.
    For example, I never could get penetrating epoxy to hold up under any testing by just brushing it on the surface of the board. after putting it out in the sun, the UV rays would just peal it off. It wasn't until I started soaking the boards by submerging them that I got satisfactory results. also you are very correct that penetrating epoxy will only soak in on the first coat, if left to set up, the second coat will not do any benefit. that's why I submerge the boards in wet epoxy and let them soak for an hour.

    As far as the West system epoxy, I apply three coats on the wood before installation. and drill all the fastener holes beforehand so that it will soak into the screw holes also. I would estimate that there is about 6 - 10 mills thick of epoxy on everything as I put it on fairly heavy per coat.

    As far as the weather, we get a lot more rain than you guys in the south and therefore a lot less sun. but I am not concerned about the epoxy on the surface getting damaged by UV rays as it will never be exposed to the sun in my application.

    One thing I did notice is this particular system I am using works well with mahogany but not so well with other wood material.

    Since we are on the UV subject, I do have a question for you. I am looking for a urethane or varnish that would be best for mahogany decking as I am experimenting with using mahogany or white oak for my deck planking, as it is much more available and economical than using teak. the planking will be going over 3/4" plywood deck.
     
  10. PAR
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    PAR Yacht Designer/Builder

    White oak will wear well, though likely to "fray" and raise a bit as it wears. Live oak will wear better and not display the bad habits of white, but it's heavier. Mahogany will wear moderately well in comparison and the dark color will be fairly hot in direct sun light.

    The urethanes preform better then the traditional alkyd varnishes. The two part polyurethanes will preform the best. This said the LPU's can be difficult to apply and get the "feel" of. There's even some water born LPU's now that are preforming better then single part urethanes, but all the alkyds included, have their good and bad points.

    Repairs are much more difficult on the urethanes, so you need to keep them in good shape or you have to strip the whole surface and start over. The multiple part formulations are the most difficult in this regard, as they are the hardest curing. Traditional alkyds are relatively easy to repair by comparison, but again you can't let the finish get away from you or it's hell to pay, bringing it back.

    Lastly, the alkyds have a lovely amber glow that everyone likes, but the urethanes don't, so formulators are using pigments to simulate the amber tint. Some brands do this much better then others. I've used them all and like the preformance of Bristol Finish. It's an LPU, but look good, with the right color amber, so the traditionalists think you've applied and hand rubbed a couple dozen coats. Don't skimp on the number of coats. 6 would be a bare minimum with 10 or 12 being reasonable. Double these numbers if spraying. A show winning finish will have a coat count in the upper teens if not the 20's!
     
  11. robster
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    robster Junior Member

    Thanks for the input, I'm going to use white oak and put lots of coats of the two part polyurethane on it. I'm going to try the Bristol Finish Two-Part Urethane Varnish System.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Thin the first coat by no more then 20% by volume (less then 15% is better), but all other coats apply at the strength you can, given any environmental limitations. Lastly, don't over sand, 280 is about as high as you want to go, naturally with the grain, so put down the DA or jitter bug. Most folks need a magnifying glass to see the scratches left by 220 grit with the grain. If you get into the higher grits (320, etc.) then there's not enough "tooth" for the coating to "key" onto and it's peel strength is dramatically reduced.
     
  13. Boston

    Boston Previous Member

    interesting reading guys
    cheers
     
  14. mikelake
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    mikelake New Member

    I am alittle bit confused by all of this so I have two questions. I own a 67 48' Constellation, and this is my first expierence with anything like this. I believe I have had some good help along the way.

    1. I did not need to replace any boards below the waterline but I did pull the cotton out of the seams and replaced it with new cotton and dolfinite bedding compound. Will this give a watertite seal when the hull swells up?

    2. What do you think about painting the hull above the waterline with latex paint so it can expand and contract?
     

  15. gonzo
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    gonzo Senior Member

    If the cotton was driven properly it will be Ok.
    Oil base paint allows enough humidity through to swell the planks. Latex, or better acrylic/latex, can work above the waterline. It has a life expectancy of about ten years on a house and boats usually get better maintenance.
     
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