Best way to replace this transom - help

Discussion in 'Boat Design' started by WarrenW, Jul 19, 2007.

  1. WarrenW
    Joined: Jul 2006
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    WarrenW Junior Member

    I just aquired this boat today and the transom is rotted so the whole thing needs replacing. There are two braces holding the transom. There are no sheers or chines - the sides of the boat is just fiberglass.

    So once I cut out the transom, are the two braces and fiberglassing it to the sides going to be strong enough? Is there anything else I can do? It looks like the transom is made up of two or three layers of 3/4" plywood. I'll use marine ply of course.

    Also, does anyone know what make or anything about this boat is? Its 15' long - figure I could put atleast a 50 or 60 on the back.

    Warren
     
  2. messabout
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    messabout Senior Member

    The boat is an oldie dating back maybe as much as to the sixties. The tail fins are the tipoff to likely years of origin. I'd be a little hesitant to put a 50 or 60 on it even after repair to the transom. A 30 maybe.

    The knees that brace the transom are probably resting on some bottom stringers. The stringers may be below a ply floor so that you can,t see them. Stringers may be wood also, so there may be some rot in those areas. After installing new transom wood it will need some reinforcement. You may do that effectively by adding a horizontal board that resembles a seat. The seat will attach to the new transom and be fitted carefully into the sides. That item will be placed a few inches below the top of the transom such that the motor clamps or bolts will clear the board. Use epoxy everywhere that you attach something to something. Polyester does not work well for repairs of the sort that you are facing. do not brace to the stringers unless you are sure of their integrity.

    If you take pleasure from working on boats, then repair this one. If you just want to have a boat to use, then it will probably be more cost effective to find a used boat in safe condition and junk this one.
     
  3. SamSam
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    SamSam Senior Member

    I think someone cut out the whole transom and threw it away and then rigged up what you have. To handle 50-60 hp I think you will have build it up a lot more than it looks like there is now. Is the glass on the outside of the transom the original hull?

    Say you had a plywood transom 1 1/2 -2 inches thick. You'd have to encapsulate it with fiberglass 1/8-1/4" thick on the inside and outside and extending 6-8" or so along the sides and bottom, inside and outside, all faired in straight and smooth on the outside so you don't have any hook in the bottom.

    Normally the floor extends all the way to the transom and helps a lot to strengthen the transom. Usually the cap goes all the way across the transom also, forming a splashwell and adding another tremendous bunch of bracing. The braces and the horizontal stiffener above them are attempts to provide what the floor and cap usually do and something similar would probably be needed for that much hp.

    When its finished, you want as little rounding as possible on the corner where the transom and hull meet on the sides and bottom to facilitate the water breaking away cleanly from the hull at speed.

    I don't know if chasing down the registration # will give you any info on the make, Ga. doesn't care too much about names or numbers as long as they get some money. Try Googling 'classic fiberglass boats', here's one hit...

    http://www.fiberglassics.com/

    I like the fins.
     
  4. WarrenW
    Joined: Jul 2006
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    WarrenW Junior Member

    Thanks for your replies. I'm wondering if I should cut out part of the floor to check the bottom stringers? I cleaned the boat out today and the transom that is on there now was completely added. Someone must have put a new one in before and fiberglassed it in there. The transom that is there now is 2 plys of 3/4".

    Actually if I just cut the transom off in the back I should be able to see the stringers and the condition under the floor in the back. Then I will know if I need to cut out the floor and put in new stringers.

    As far as the work and cost, I don't mind it a bit. I had started building a boat from Glen-l.com called the Malahini 16' runabout. I got all the frames and transom done for it but had stopped. This boat was free that i got today and I love the style with the fins. I plan to work on it through till next year.

    So should I just remove the existing transom anyways so I can see whats under the floor?

    Thanks
     
  5. USCGRET/E8
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    USCGRET/E8 Senior Chief

    Boats that old didn't usually come with a floor. You walked on the top of the bottom actually. It looks like the transom and braces have all been added and need to be replaced.
     
  6. WarrenW
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    WarrenW Junior Member

    There is a floor in this one believe it or not. I didn't think there was either but it does have a floor.
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'm not sure of the model, but that is a 1958 - 1959 (possibly a 60, but not likely any younger) something, I've seen them before and think it's a Glass Craft Sportster. It's a heavy chopper layup over plywood and solid wood reinforcement structure (including the sole). Judging from the photos, the wooden components have had it and should all be removed and replaced.

    Two layers of 3/4" ply inside the transom is standard for most small outboard craft. In its day, the big motors were no more then 40 HP, which could drive the old gal to a reasonable full plane speed of maybe 30 knots. This was pretty quick in the late 50's.

    Frankly, other then the hull shell, nothing on the structure should be trusted after 50 years of neglect. The hull shell will likely be very thick and heavy by modern comparison, so you'll probably get some more life out of her. Don't be tempted to toss a big honking 90 HP out back, the hull was intended for around 30 - 40 HP (150 to 170 pounds of two stroke outboard) and will get pretty scary if much over powered. A modern four stroke will need to be sized with an eye on weight as well as HP.

    Splash wells were not common (nor required) in the 50's and the sole wasn't usually carried all the way aft. The sole typically ended a foot or so short of the transom, forming a small well, were the bilge pump and transom drain usual lived. Bordering each outboard edge of this well would have been two fore and aft (likely plywood) stringers, which enclosed the sides of the well. These stringers would have been tabbed well to the transom.

    If I remember this hull correctly, it came with a "splatter" type of interior paint job, with everything else being gel coat.
     
  8. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    A lot of work.
    I would separate top from bottom, brace it before so it doesn't deform
    See if transom ok or need to be replace
    Get rid of all wood
    Sand shell out completely from inside and redo with mat and epoxy
    But honestly may be use it as a mold or scrap it.
     
  9. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Clean it out some and take some more pictures. It looks to me like the floor stops at the front end of the braces. Does the raised floor actually go all the way back to the transom? If/when you start fixing it, take the whole transom out and throw it away, but first affix some braces across the cap from side to side so the hull holds its shape and the sides don't sag outward. The bottom back there will be weak also so you have to support it so it doesn't deform.

    You might want to put on a trailer first and look at the bottom to see if it is flat and fair with no dents from sitting wherever it has for however long. Trailer rollers or bad supports or maybe a rock if it was sitting on the ground can make big dents that aren't easily repaired.

    When stuff is growing out of the floor as in the pictures, odds are the floor and stringers are rotten also. If the deck is soft and moves anywhere when you walk on it, it's probably bad which means the stringers are probably bad too. It's a simple boat though so it shouldn't be too hard to do them.
     
  10. SamSam
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    SamSam Senior Member

    Here's the Glasscraft Sportster. The fins look a little different, but the size is about right. No splashwell or floor in the back. It did say what year it was. 1959

    [​IMG]
     
  11. WarrenW
    Joined: Jul 2006
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    WarrenW Junior Member

    Thanks everyone!

    The bottom of the hull is excellent. And after putting it in my garage, I got in the boat after cleaning out two wheel barrels of leaves :) and the floor was very solid all over. It did not give anywhere.

    I need to go ahead and pull off the existing rotten transom first. At that point will I be able to tell if the stringers under the floor are rotten?

    Your right SamSam, the floor goes up to the braces, then drops down some and then to the transom. I'll take some pictures tomorrow of it cleaned out so it will be easier to see. I just need to make sure the new braces will hold to the floor or I will just have to cut out the floor some and replace any wood under there. Its no problem if I need to do that.

    Warren
     
  12. WarrenW
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    WarrenW Junior Member

    You can see the braces and where the floor ends and drops to the bottom of the boat.

    Any suggestions on how to tackle this? Just cut out the transom and see what I have from there? Would I be able to tell if the wood that the braces are attached to is rotten? Remember, this is a 1959 boat! :)

    Warren
     
  13. WarrenW
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    WarrenW Junior Member

    I removed the two braces just now that was between the bottom and the transom. The part that the braces were connected to on the floor are like hollow drains. I can put my fingers in it so its not filled. My question is just using fiberglass and resin to hold the braces down good enough for the braces?

    I still have to remove the transom. It looks like the person that repaired this before wrapped fiberglass around the corners far. Is fiberglass that strong for holding the transom?
     
  14. WarrenW
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    WarrenW Junior Member

    I cut out the transom today and left some edge on the side that may help attach a new transom in. I was wondering if I could sandwich the new one in with metal sheets along with fiberglass and new braces. That should hold huh?
     

  15. mydauphin
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    mydauphin Senior Member

    Where you cut transom it doesn't look too bad. Is wood soft, moist or dry rot?
    May be sand it out and make it into epoxy sandwich with Aluminum plating on both side... It looks like transom may be old but still a good piece of lumber
     
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