Recomendations for new transom material?

Discussion in 'Metal Boat Building' started by 85 starcraft, Jan 20, 2007.

  1. 85 starcraft
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    85 starcraft Junior Member

    Today we removed the old transom from our 21 ft. 1985 starcraft aluminum- hulled boat. The wood was starting to rot. When we extracted the transom we found that it was of 1 5/8" plywood ( marine?), 12 inches high by about 70 inches long.

    Having done all this work, and having much to do to reinstall new transom material, I pose the following question to the gurus here: What is the absolute best transom material to use as a replacement? Marine Plywood vs. monolithic lumber vs. some kind of composite vs. foam core? And why?

    Thanks for your help!

    Carl
     
  2. PAR
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    PAR Yacht Designer/Builder

  3. 85 starcraft
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    85 starcraft Junior Member

    PAR: Yes I'm new, and I'm not a professional boat-builder, but before posting the above question I did spend several hours searching this site's forums in an attempt to find an answer, or at least a consensus of opinion. Having read the transom-material debates in various forums re foam core materials vs. marine plywood vs. poor old Seacast [ pun intended], I concluded that marine plywood is clearly favored by at least a plurality of the pros here as being 'tried and true' and having known qualities, despite it's Achilles heel [susceptibility to rot]. Even so, there appear to be a number of boat builders who do seem to use composites and core material in "smaller boat" transoms with very good results.

    In light of the above, and given that my boat is an all-aluminum hull and only 21 feet in length, I thought it reasonable to narrow my search by posting the above question on this sub-forum-- "metal boat building"-- in hopes of eliciting opinions from folks watching this particular subforum with experience, opinions and a willingness to provide advice to someone who is [re]building a metal boat. Can you see my thought process here?

    I certainly did not mean to cause the 'inner circle' of Senior Members to roll it's collective eyes with an "Oh, no. Here we go again!" reply to my question.
    If the question is stupid because it's been answered or debated before ad nauseum, is it too much trouble to at least point a newbie in the right direction? If there is no good answer to the question, how hard would it be to just say so?

    Sometimes it's easy to forget that we all have to learn everything we know. Beginning from scratch.

    Respectfully,

    Carl
     
  4. marshmat
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    marshmat Senior Member

    I think at least part of the reason for PAR's frustration was that there is no right answer to your question. In the end, no known material will do what you want (strong, cheap and durable); rather, it's a matter of trading off cost versus longevity... and since there's no right or wrong answer, and certainly no 'absolute best', you'll be hard pressed to get a straight answer out of anyone. Unless they're trying to sell their own product of course.

    I look at your problem this way. The original wood, probably without much protection (not like we have today at least), lasted 22 years. Modern plywood, with modern sealants, should last at least as long. By then you'll have either sold the boat or passed it on to the kids. Why change what works already?
     
  5. PAR
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    PAR Yacht Designer/Builder

    I meant no offence, just that as Matt has suggested, it is a difficult question to offer definitive answers to.

    In spite of draw backs, it's very difficult to match plywood's physical properties. This is why it's used so much in this structural element. Pound for pound, effort for effort and dollar for dollar, it's good stuff and most materials/methods will be hard pressed to compare at a similar level.

    There are a number of engineering possibilities, most of which can be justified in some fashion, but the comfort level in working the method, price, and availability, make plywood had to dismiss.

    An inert material would make life easy to deal with, when faced with a new transom, but then life takes a hard left and you're looking at the cost of a fancy core process, fairing exotic fabrics, etc.

    In the end, you have to pick your own poison, depending on the particular qualifiers you've placed on it.
     
  6. 85 starcraft
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    85 starcraft Junior Member

    Thanks, I'm going with plywood. Problem there is shipping costs; all the good stuff [e.g. Okoume BS1088] seems to come from the West coast and i'm in Atlanta.
     
  7. bilgeboy
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    bilgeboy Senior Member

    Yup.

    The search function could also broaden your horizons.

    Search all posts by Par, and you could write a book on boat repair.



    This message paid for by Seacast TM.......:)

    Mike
     
  8. 85 starcraft
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    85 starcraft Junior Member

    Thanks Mike.

    Believe me, I Have been using the search functions. For hours. And have found a wealth of info. And I have read enough of PAR's post to appreciate his status as a boat-building guru. My "newbie mistake' was thinking that I was pitching my transom material question solely to those into metal boat building/rebuilding on the metal boat building forum, which I presumed would be a much smaller group with a narrower focus; I was hoping there was a firmly held consensus there. I would not have intentionally posted such an open ended question for "general broadcast". My bad.

    That said [and back on topic], I have decided to err on the side of being conservative and going with plywood [I'm thinking Okoume BS1088 at this point] and am searching for local suppliers in North GA/ Atlanta. I have located Southern Crown Boatworks at http://www.southerncrownboatworks.com/, but they specialize in wooden boat projects. Am still hoping to tie up with someone who does/knows aluminum hulled boats and is willing to give me some tips or advice.

    Thanks for the reply.

    Carl
     
  9. PAR
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    PAR Yacht Designer/Builder

  10. tja
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    tja Senior Member

    Tja

    Check with a good local marina to see if they have XL Panels made by Green Wood products. They make 3/4in. x 4ft x 8ft plywood that is preasure treated then kiln dried to 13 persent moisture. This product is used by many major boat manufacturers and is guarrented for life not to delaminate or rot for life or they will replace the wood along with any labor costs involved. One sheet will cost about $85.00 They have never had to replace any product to date. Good luck. Tom.
     
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  11. August Ice
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    August Ice Junior Member

    Hello Im new to this site. I recently bought a used 16' Mirrocraft boat with a 75 hp suzuki motor... We took it out and after a few times out the transom began pulling away. We were filling with water.

    Ive just removed all the rotten wood from the transom and the floor of the bow and under the dash. Ive been reading this article that seems similar but my transom needs to support a 75 hp motor. I ordered Okoume 1080 marine plywood but now Im reading up on how flexible this kind is and used for the hull and bow.... Is this the right kind of plywood for the support I need or should I get Maranti 1080? Or can anyone think of something that would be more supportive? I plan on wrapping it in fiberglass and have an aluminum sheet behind it for support (at least in part) The transom wood should
    be 2' X 6'. Id greatly appreciate any help from you experienced boat builders.

    Janet
     
  12. August Ice
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    August Ice Junior Member

    I found a plywood supplier with reasonable prices in No. Yarmouth, ME "Fat Andy's" Im not sure if this would be helpfull.

    Jan
     
  13. alan white
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    alan white Senior Member

    Hi Janet,

    Okoume is fine. The most important thing is to seal it well with epoxy (you can get epoxy at Hamilton Marine in Portland).


    tja,

    Pressure treated plywood question: Are the XL pamels recommended for use as is on aluminum boats?

    Alan
     
  14. August Ice
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    August Ice Junior Member

    Thank you Alan Your advice is highly appreciated. It turns out I also have to replace the deck and seats in the bow as well as part of the floor under the dash where there is a walk through windshield. I was thinking of Rhino lining it to make it washable after going out on the ocean. rather than putting carpet back on... Do you think Rhino lining appropriate or should I epoxy that as well?

    Janet
     

  15. alan white
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    alan white Senior Member

    I don't know if Rhino has an epoxy based or polyester-based resin, or if its polyurethane. I would guess epoxy or polyurethane, and if so, not a bad alternative to carpet, which I feel belongs in a living room and not on a boat. The surfaces the "lining" is applied to should be sanded and clean.
    Expensive, I imagine, and so it had better be a good product with a guarantee. I'm not too familiar with Rhino-lining on boats or trucks.

    Alan
     
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