Transom Replacement Planning Help Needed.

Discussion in 'Fiberglass and Composite Boat Building' started by thill, Mar 8, 2007.

  1. Up_in_Michigan
    Joined: Mar 2007
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    Location: Michigan

    Up_in_Michigan Junior Member

    "How do you put a heavy tooth on both inner and outer skins? How do you clean it? I can just see a cute little sand paper on a stick sort of deal causing you to invent new words to go with your cussing, just so you can get to the bottom of the transom (where you'll need the most strength) with some 36 grit."

    Par,
    This is the step I am at right now. I am using a router with a 3/4" carbide straight bit. Works well, but with the extreme high rpm, it can remove to much of the fiberglass if your not real careful.

    I am going to tone it down a little bit with a different bit, and see if I can just remove the excess particles of wood, and provide a tooth. The problem for us harry homeowners is, how much tooth?

    Was really hoping to see a professional's third party opinion, and hope that the manufacturer, and one of you guys on here can work out a test on some old boats. I don't think this will ever replace the work you do on high-end boats, but for those of us with the choice of trashing an otherwise good boat, and using seacast it may create work at some shops because it will cut down on costs (maybe?).

    getting the bulk of the wood out isn't that bad, but is time consuming the way I did it(no chainsaw).

    Good day all.
     
    Last edited: Mar 20, 2007
  2. Up_in_Michigan
    Joined: Mar 2007
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    Location: Michigan

    Up_in_Michigan Junior Member

  3. Up_in_Michigan
    Joined: Mar 2007
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    Up_in_Michigan Junior Member

    For anyone using the bit in the picture above, it is a carbide router bit, however I ended up using just a 3000 rpm variable speed drill because the router was just to much rpm for me, although was much faster if controlled better. This was used once the bulk of the wood was removed with wood spade bits, and straight bits. It was 20" to to the V at the bottom of my transom, and was very easy to clean using this bit. I did use the bit in reverse on the drill on the bottom of the transom mostly, just to make sure I didn't damage the fiberglass down there. Good day all
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'm not sure how good a tooth you'll have with a smooth edged, straight cutting router bit, other then the gashes it must make in the laminate as it bangs around between the skins. Maybe a rotary rasp type of cutter would scratch up the inside better, but it still isn't what I'd feel comfortable with. What about a healthy sized transom, that has 3 or 4 feet of depth to the bottom? Swinging 36" - 48" of extension and bit, even at reduced RPM, doesn't sound very controlled. Cost wise, a professionally done Seacast transom repair is about the same as a more conventional repair. I suspect they've priced their product in this vain for this reason (understandably so).
     
  5. fiberglass jack
    Joined: Dec 2005
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    fiberglass jack Senior Member

    i just love the way they tell you to use a chainsaw, one day some poor old sod is going to experiance the chainsaw kicking back and have a nice gash, remenber you need to rough up the glass if you get a lenght of wood and staple some corse sand paper to it and work it right it should help for a bond
     
  6. tri - star
    Joined: Feb 2007
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    tri - star Junior Member

    " Chainsaw.........??..! "
    This thread gets better all the time.....words fail me...
     
  7. fiberglass jack
    Joined: Dec 2005
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    fiberglass jack Senior Member

    thats what the seacast site says a chainsaw
     
  8. Up_in_Michigan
    Joined: Mar 2007
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    Location: Michigan

    Up_in_Michigan Junior Member

    The Transom has been poured, and is set, and already has the strength advertised. So far I have about $350.00 in this project, which is of course much cheaper than the sticker shock of the quotes to have plywood put back in.

    I think if I was in this business, and had to get to 4' or more, I would probably talk to these folks, http://www.advantage-drillbits.com/auger.html and have a bit either maunufactured, or experiment with those off the shelf until I found the most efficient manner to complete this task for production.

    The chainsaw would probably be ok for the softest part of the removal, but there is an obvious risk involved. Not sure I would use it because there are many other ways to get the rotting wood out.

    There are already businesses using this product, here is one up here in MI

    http://www.invisionboatworks.com/

    My background is 23 years in US Navy (retired now), mostly carrier Flight Decks (Aviation Boatswains Mate) with alot of experience with all manner of paint, non-skid, and various other coatings application, and removal.

    I have no dog in this fight except for a 38 year old small lake fishing rig, but can sure see some petty emotions involved, (some going back a few years), industry traditions with a little fear of change, and sprinkle it all with different levels of self importance depending on who's posting. Don't mean to offend anyone, just call it as I see it.

    I can't blame you all for trying to protect your trade though (if this is the case), and keep what appears to me at this point, an excellent product from taking business from you. (which I really don't think is an issue). Fiberglass is not something I like to mess around with, but in my case it was either trash the boat, or use this product, and maybe see a fiberglass artist to fix the damage the motor did when the plywood core rotted out. (the fiberglass part IMO really is the most skill intensive part of this project).

    I don't think I would want plywood of any type in my transom now though, even if the boat was worth it to have this done by a professional.

    You have some very good questions though, and can't blame you for asking for the technical data on strength/durability, longevity, application evironment needs, etc. This sort of reminds me of the Non-skid wars between the manufacturers, and contractors and who was liable if the Non-skid failed. Usually it was the contracotor, taking some short cuts in prep/application.

    One question I have though is:
    With the better composites available, why is wood still being used in fiberglass boats?.

    If a product such as coosa board is much stronger, and lighter, and is not subject to rot, why is it not being used in the first place during boat construction. I am sure it has something to do with cost, which is why I am even posting here. Good day folks
     
  9. thill
    Joined: Mar 2007
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    Location: Virginia, USA

    thill Junior Member

    Boat Information

    Par,
    Thank you for the guidance. I just got the boat back, engine running great. I removed part of the top cap of the transom, and also took a look at a thru-hull fitting hole. Happily, it has a full inner skin. What I observed is as follows:

    Total transom thickness at the top: 2-1/4" - 2-1/2" thick, (appears to be a bit swolen in the center) broken down as follows:
    1. Outer skin- @ 5/16" - 3/8" thick, hard laminated woven glass with gel coat.
    2. Core- Plywood, 1-1/2" thick. Very soft in places, particulary in center near where the engine is mounted.
    3. Upper inner skin, above the floor- 3/8", same as outer skin.
    4. Inner skin, below the deck- Approx. 1/2" thick, (thicker around transitions to sides and bottom) appears to be all matt or chopped fiber. It looks kind of "stringy" on the surface, but is surprisingly solid just underneath the surface, and resists probing with a knife. Seems to be nicely bonded to the hull.

    BOAT INFO:
    The boat is a 1987 Bayliner Trophy, model 2110.
    Deep V style Cuddy Cabin.
    Centerline length - 20' 8",
    Beam- 8'0",
    Weight including single engine- 2,825 lbs, (3,229 with twins)
    Fuel tank- single aluminum tank, 95 gallons capacity,
    Hull draft - 17".

    This boat is designed for twin engines, although mine was ordered with a single. (I have the manual and original paperwork) The engine I replaced the original with is an 150HP OMC, 17p prop, weighing around 400 lbs. The top speed of the boat is around 40MPH on flat water with this engine.

    Here is a picture of the exact boat from the rear:
    [​IMG]
    Here is a picture of the original brocheure, showing the standard twin engine configuration:
    [​IMG]
    [​IMG]
    (I have to take the pics and upload them, so it may be a little while before they show up)

    If there are any other details you would like to know, please let me know. I really do appreciate everyone's kind input and assistance.

    -TH
     
  10. thill
    Joined: Mar 2007
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    Location: Virginia, USA

    thill Junior Member

    Up in Michigan,
    Greetings, and thanks for posting your results and pictures of your work. I think I'm in about the same situation as you were. I happen to know basic fiberglass work, but I don't want to invest too much time in this particular boat. Looks like I'll need about double what you used.

    It seems you cleaned your transom out extremely well. Congratulations!
    1. About how long did it take you?
    2. Did you rinse it out with Acetone or similar solvent, or just blow it out?
    3. Do you have any pictures of the transom after pouring?

    And here is the big question:
    4. Does the Seacast core seem to be very tightly adhered to the skins? If you stick a knife where they come together, does the skin separate from the fiberglass? Or does it resist any attempt to separate the two?

    I believe the factory claims that the heat produced makes some kind of "thermo-something" bond, and that it's stronger than the original bond to the core, so I'm very curious if this appears to be accurate.

    So far, all of their claims appear to be proven true by experience, but I

    Thanks, and best wishes for a successful and long life for your boat.

    -TH
     

  11. thill
    Joined: Mar 2007
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    Location: Virginia, USA

    thill Junior Member

    Par???

    Par??? You still there?

    I posted the info you asked for. Have you quit on me? Is this a way of saying this boat isn't worth the work?

    I'm definitely still listening, if you are still talking.

    Thanks.

    -TH
     
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