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  1. #1

    Default what fiberglass materials to use for transom replacement?

    Hey fellas, looking at doing my first transom replacement. I kind of know the process and am descent with fiberglass but never did a boat. I am wondering how much poly resin, what type of cloth and other items I may need to replace the transom boards back in on my 16' nordic crestliner runabout? Any help would be appreciated.
    Thanks
    Nigel

  2. #2
    Lieutenant Commander Cadwelder's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Marine grade plywood (there are other choices) and polyester resin. CSM and 1708 are the materials of choice here on the forums. For your transom only, I'd guess three gallons.
    A good brand of engine is one that runs

  3. #3
    Supreme Mariner oops!'s Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    ok....here we go.


    as far as plywood marine grade is allways the best....but is not allways avalable locally.
    exterior grade plywood is allmost the same as marine, the big thing you want is the glue.....it needs to be waterproof....this is found in the exterior grade (not osb).

    i have found that at least one peice of 1 inch thick, works fantastic for flatness.
    you will need to make up the thickness of your transom however you can.
    1x1 inch plus 1 x 3/4 inch....ect

    you will need 2 gals of resin...minimum
    i suggest standard unwaxed polyester.

    8 yards of 1.5 oz csm
    3 yards of 1708 biax
    a small bucket of milled fibers...(powder)
    small bucket of 1/4 inch short strand.
    1 can of acetone
    1/2 liter MEKP

    as far as tools...
    you need several mixing sticks.
    i prefer a egg mixer on a drill.
    a mekp mixing cup...(plastic shot glass)
    a few ice cream pails (i like proper measuring buckets)
    your fuzzy roller with several rollers
    fiberglass resin roller
    several bondo spreaders.

    there ya go
    cheers
    oops
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  4. #4

    Default Re: what fiberglass materials to use for transom replacement?

    thanks guys for the info, I will be using a piece of 3/4" acx plywood and laminate it together with a 1/2" piece. Now should i Completely coat the wood transom with fiberglass before installing?
    Thanks

  5. #5

    Default Re: what fiberglass materials to use for transom replacement?

    also where is a good place and/or website to get the supplies from?
    Thanks
    NIgel

  6. #6
    Lieutenant Junior Grade TruckDrivingFool's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    I and many others have use uscomposites but depending on where you are shipping can add up. I'm just about done with mine (roughly 77"x25") and had many of the same questions. So far I've about 4.5 gals of resin but this my first time doing FG so I would say my waste is about 3/4 to a gal. Plus I had a redo on making my lamination, so I'd guess it about 3 gallons of resin. and I've go through 4yrds of 1708 and not sure on the csm (due to the remake). If you go through US Comp I will warn on the hardener if you use the plastic shot glass that comes with it, read the cc measurement and not the ounce as they suggest in their pamphlet. I've been using 5cc per pint and 10cc per quart and getting 20 minutes before it kicks in the pot.

  7. #7
    Petty Officer 1st Class DeepBlue2010's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Here is some info to help you catalyzing your resin
    A) 1 cc = 1 milliliters (So you can just replace cc by ml in your calculations as I did below)
    B) 1 US fluid ounce = 29.57 milliliters
    @ 1% catalyst/resin ratio
    You need about 0.3 milliliters of MEKP per ounce
    For a pint (16 ounces) you need (16*0.3) = 4.8 ML ~ 5 ML ~ 5 CC
    If you choose to increase your catalyzing ratio to 1.5 for instance, you just repeat the calculations (it will be 0.44 milliliters per ounce in this case). Be sure to read the recommended ratio on the resin you buy. Stay closer to the lower range; it will give you more time to work without compromising the curing process.

  8. #8
    Supreme Mariner oops!'s Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Quote Originally Posted by DeepBlue2010 View Post
    @ 1% catalyst/resin ratio


    If you choose to increase your catalyzing ratio to 1.5 for instance, you just repeat the calculations (it will be 0.44 milliliters per ounce in this case). Be sure to read the recommended ratio on the resin you buy. Stay closer to the lower range; it will give you more time to work without compromising the curing process.
    sorry.....this is incorrect.

    the correct ratio of mekp to resin (ANY POLY RESIN) is 1.7-2.5 %

    some of the mekp manufacturers claim you only need 1% resin to mekp ratio........this is a very weak mix and will crack.

    i use 2% on every thing...including gellcoat.....it is very safe and strong.

    if you need more working time.......ask for a ddm, instead of a mekp. the ratio for a ddm is still 1.7-2.5%
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  9. #9
    Lieutenant Junior Grade TruckDrivingFool's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Not to hi-jack but,

    oops! - That means I should think about upping my mekp to at least 7.5cc per pint and 15cc per quart. Correct?

  10. #10
    Supreme Mariner oops!'s Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Quote Originally Posted by TruckDrivingFool View Post
    Not to hi-jack but,

    oops! - That means I should think about upping my mekp to at least 7.5cc per pint and 15cc per quart. Correct?
    sorry bud i work in metric.

    try using that system....its much easyer.

    for 100 ml......you use 2 ml of mekp.
    for 500 ml you use 10 ml of mekp.
    for 1000 ml you use 20 ml....

    really simple
    The Hull Extension Thread
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    IN MEMORY OF Our friend SpinnerBait_Nut LESTER WRIGHT July 31, 1953 - Nov 26, 2008 RIP

    IN MEMORY OF Our friend Tashasdaddy Robert (bob) Griffis. October 27, 1948
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  11. #11
    Lieutenant Junior Grade TruckDrivingFool's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    2 per 100 easy enough I'll give it a try thanks.

  12. #12

    Default Re: what fiberglass materials to use for transom replacement?

    well thanks a lot guys for the mixing info and all other info. It really helps a lot. I will be starting a new thread within the next few days on the work where I'm sure I will have more questions. Thanks again, it's very appreciated
    Nigel

  13. #13
    Petty Officer 1st Class DeepBlue2010's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    oops, as always, I appreciate your input and recommendation. Just to clarify, I wasnít suggesting any specific mixing ratio.
    Quote Originally Posted by DeepBlue2010 View Post
    Be sure to read the recommended ratio on the resin you buy. Stay closer to the lower range; it will give you more time to work without compromising the curing process.

    Which is the same as you did with your suggested ratio (1.7%-2.5%) catalized @ 2%.
    I choose 1% simply because it is the simplest example for the calculations and you can easily apply the same methods using any percentage. However, I didnít know that 1% is not an acceptable ratio even if it was recommended by the factory. I am glad I read your post before I start mixing for my boat. Thanks
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  14. #14

    Default Re: what fiberglass materials to use for transom replacement?

    MEKP = Methyl Ethyl Ketone Peroxide and according to Florida's hazardous waste management guide for Fiber-Reinforced Plastics it "May be explosive" Can cause blindness and affects the central nervous system....among other things....I understand lots of things can be dangerous, but this MEKP sounds extremely dangerous 8O !!!

  15. #15
    Senior Chief Petty Officer
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    Default Re: what fiberglass materials to use for transom replacement?

    you mix it at down here at 2 in 90 degrees at 90% humid and you'll be throwing away hot buckets. 1.5 is more than enough. If you live in that Tampa Bay Area you are welcome to bring it over and we will have it done in a day. You supply the materials. If not PM me and I will walk you through it.

  16. #16
    Supreme Mariner Woodonglass's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    Hopefully, since he started this thread on July, 3rd, he's already done with the transom, and all of this is a MOOT point. He started a NEW thread and lives in Minnesota. He has NOT started on the transom yet. If you're interested you can check him out here...

    http://forums.iboats.com/showthread....22#post3364022

  17. #17
    Cadet
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    Default Re: what fiberglass materials to use for transom replacement?

    Not to hyjack the post by why poly resin instead of epoxy resin?

  18. #18
    Supreme Mariner Woodonglass's Avatar
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    Default Re: what fiberglass materials to use for transom replacement?

    That's what the boat is MADE out of. Epoxy will work, but at twice the cost. No NEED to use it, but you can if you want.

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