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  1. #1
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    Ply or Coosa?

    The lower portion of my 27 sport's transom has rot. It was quite evident when I could scoop out pieces of wood with just my finger alone through the drain plug hole. Should there have been a protective sleeve? seems it would've been a prudent thing to do - nor - did I see any evidence that they protected the area with a resin. I'm leaning towards replacement of the transom with Marine ply with particular care in those before troubled area's, but even though Coosa is 3x's the cost it might be worth it in more ways than money. Any thoughts???
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

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    Hey Scippy
    I had an hour conversation this week with one of the most respected boat builders ever about this exact thing in my 27 and he emphatically said marine grade plywood. That may create a stir from a few diehards here of "modern" materials but he uses some of the most high tech stuff out there and still does his trabsoms in wood He had lots of good reasons and he really does know what he'stalking about I'm redoing my whole transom and using wood
    Parnell
    Time forSweet Cheekz to find a new home

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    P, I've heard that before to a certain extent, but even better still when a experienced builder has many newer materials before him & still prefers marine ply for the transom. Coosa board does seem to be more forgiving then plywood especially if it were in the area of my drain hole plug.......lol - My total transom thickness is 2" (3/8" FG shell followed by 1-1/2" plywood followed by 1/8" FG...........the outter layup is amazingly thick, no wonder these boats are so heavy!
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

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    My stringers and transom were done by a buddy who was the head glass guy at Hustler, plywood has superior adhesion to glass over the foams. He did go on to say that the real strength is in the laminate. When he did my transom he eliminated the KEY cause of rot, this was done by squaring off the bottom of the plywood then building up the plug area with solid glass. He said there was structural no reason what so ever to fill in the V area with wood, that all it did was make it liable to fail again, he also isolated the stringer wood from the transom wood. Reason being the moisture wicks from the transom into the stringers then slowly creeps forward, while you are at it check the stringers more than likely they are wet. Mine were wet up to just past the engine mounts, he cut them out about an other five feet until he got dry dust when cutting. Then installed doubled stringers, added bulkheads and transverses added maybe 100lbs of structural soundness to my 22.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

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    There may not be a reason to replace the entire transom.
    Why don't you start by moving upwards from the drain area and see if it gets solid?
    If the rot can be localized and removed, why replace the whole thing?
    When you start cutting replacement pieces, use a penetrating epoxy, like System Three Clear Coat, on all the exposed end grain and it'll never rot again.
    BTW, MOP's solution is very good.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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    MOP's story is almost exactly what I heard from my guy escpecially the stringers and transom suggestion
    I like Georges idea too from a money, time and work standpoint if it can work My transom is so swisscheesed that there is no where left to drill any new holes. I have to replace the whole thing Scippy, do check it might be a nice suprise
    Parnell
    Time forSweet Cheekz to find a new home

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    Quote Originally Posted by gcarter View Post
    There may not be a reason to replace the entire transom.
    Why don't you start by moving upwards from the drain area and see if it gets solid?
    If the rot can be localized and removed, why replace the whole thing?
    When you start cutting replacement pieces, use a penetrating epoxy, like System Three Clear Coat, on all the exposed end grain and it'll never rot again.
    BTW, MOP's solution is very good.
    I agree..

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    Quote Originally Posted by MOP View Post
    My stringers and transom were done by a buddy who was the head glass guy at Hustler, plywood has superior adhesion to glass over the foams. He did go on to say that the real strength is in the laminate. When he did my transom he eliminated the KEY cause of rot, this was done by squaring off the bottom of the plywood then building up the plug area with solid glass. He said there was structural no reason what so ever to fill in the V area with wood, that all it did was make it liable to fail again.
    MOP, Eliminating wood in this "KEY" area makes soooooooooo much sense now.............thanks for helping me not repeat a mistake!

    George, I also like your idea to just replace what's rotten in the lower transom by moving upward & away from the drain, but I have 2
    TRS cutouts and would likely replace with bravo's.........something I forgot didn't mention.
    Also, regarding the layup to the drain plug area.........should I use alternating schedules of CSM & WR until thickness is achieved?

    P, With the elimination of those "Gussets -or- tank stringers" I now can order tanks with a capacity of 70+ gallons each..........nice
    gain's with not too much fuss.


    Jamie, How's that TR running?
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

  9. #9
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    [quote=scippy;573151]
    Also, regarding the layup to the drain plug area.........should I use alternating schedules of CSM & WR until thickness is achieved?[quote]

    You probably don't need to add more than 1/2" of 'glass.
    Using only 1708 Knytex alternating the orientation between +/- 45* and 0*/90*, it wouldn't take very many courses to get there.
    While you're at it, cut out the plywood in the area of the TRS cutouts. I think you could use a circular saw w/the blade very carefully positioned. Then it's easy to fill in the 'glass in the cutout area.
    Do you guys know about cutting a plug of glass (like in the area of the drive cutout) and burning it?
    If you do, when it burns out and cools, you can carefully take apart the various courses of glass and determine the original layup.
    Good luck.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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    Quote Originally Posted by scippy View Post
    Jamie, How's that TR running?
    It's not this year. I have been slowly taking it apart & freshening many things.. Hopefully I will get to enjoy it next summer.. Jamie

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    Quote Originally Posted by scippy View Post
    P, I've heard that before to a certain extent, but even better still when a experienced builder has many newer materials before him & still prefers marine ply for the transom. Coosa board does seem to be more forgiving then plywood especially if it were in the area of my drain hole plug.......lol - My total transom thickness is 2" (3/8" FG shell followed by 1-1/2" plywood followed by 1/8" FG...........the outter layup is amazingly thick, no wonder these boats are so heavy!
    I just reread this. My guy said use two sheets 3/4" marine plywood with layers of glass on all three sides which jives with the thickness now Magnum did a really nice job of building boats back then. Just an observation that hopefully doesn't piss anyone off but they made their boats much more stout than Donzi at the time Course they were bigger also, just sayin
    Parnell
    Time forSweet Cheekz to find a new home

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    Quote Originally Posted by Sweet Cheekz View Post
    Hey Scippy
    I had an hour conversation this week with one of the most respected boat builders ever about this exact thing in my 27 and he emphatically said marine grade plywood. That may create a stir from a few diehards here of "modern" materials but he uses some of the most high tech stuff out there and still does his trabsoms in wood He had lots of good reasons and he really does know what he'stalking about I'm redoing my whole transom and using wood
    Parnell
    I agree on using wood and was that builder Pete of Douglas Marine / Skater ?

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    Quote Originally Posted by OFFSHORE GINGER View Post
    I agree on using wood and was that builder Pete of Douglas Marine / Skater ?
    Hi Artie
    It was. Give me a shout when you get a chance

    Scippy Bill has good ideas and has been successful at it a few times Sound advice
    Parnell
    Time forSweet Cheekz to find a new home

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    Quote Originally Posted by Sweet Cheekz View Post
    Hi Artie
    It was. Give me a shout when you get a chance

    Scippy Bill has good ideas and has been successful at it a few times Sound advice
    Parnell
    Parn ,i will get with you sometime next week and have a great weekend .

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    Decided to remove the (cockpit/cabin) bulkhead wall from the 27 sport today..........I found a little rot in the corner where the wall meets the hull, but really not much. I was looking for any good reason for a while to due this. Now crawling in & out won't be half as bad. I was lucky to get the wall out in virtually one piece, it was just a little flimsey so I screwed 1x2's to support it for tracing out the new wall after the fuel tanks go in. After much thought, I decided on 2 aluminum fuel tanks, both 65" apiece, roughy 12" longer than the 53" stock originals. Both getting Rochester twinset fuel senders (a manual sight glass gauge on the tank plus electrods to a dash mount) ........In a couple of the pictures you'll notice I've been peeling off some loosely laminated fiberglass. I pulled a slight corner that was up and now I'm surprisingly off to the races!......I have two questions?.......(1) I've used a flat chisel to pry it up to this point, how far ahead do I keep prying it up?.....also, because I'm using a bit of force to pull it up with a flat chisel, should a normal layer of woven roving be that prone to separation?..........One thing for sure is, "This beats f**k'n grinding any day of the week!
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

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