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Thread: Rotten transom 22 classic

  1. #1
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    Rotten transom 22 classic

    Well.. Hate to say it, but I have a rotten transom... The other day a mounting screw made it's way out of the transom, causing the trim pump to lean. That's how I noticed it. So I got in there and turned the other screw to remove it and (unfortunately) it spun free inside the transom. No bueno. So I guess I'll have to pull the motor and drive?? The transom is hollow halfway down....

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    You will also find the aft sections of the stringers rotten, Donzi like most other manufacturers does not isolate the stringers from the transom wood with a layer of glass. When one goes so does the other, you will also find the transom plywood is 5" square chunks not solid pieces. You can preform your replacement pieces which was done on mine. You can go different way, two pieces of 3/4" or three layers of 1/2" both setups with a layer of glass between the pieces. Another point is when cutting your transom pieces cut them straight across the bottom eliminating the V section. Once the plywood is glassed in place build the lower V area up with glass then drill for your drain tube. Doing this way completely eliminates the possible weepage from the drain tube which seems to cause much of the transom rot as does the limber holes. Make a cut the back end of the stingers on a 45 degree angle 4" high, This cut off allows for water to get into the bilge with -0- restriction. The stringers should have one layer of glass on them before the are set in place, having the transom done and the stringers glassed will isolate them stopping any possible water migration. Far to many people redo these items just like the factory putting them in future jeopardy! A job done right will last the life of the boat.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

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    Quote Originally Posted by MOP View Post
    You will also find the aft sections of the stringers rotten, Donzi like most other manufacturers does not isolate the stringers from the transom wood with a layer of glass. When one goes so does the other, you will also find the transom plywood is 5" square chunks not solid pieces. You can preform your replacement pieces which was done on mine. You can go different way, two pieces of 3/4" or three layers of 1/2" both setups with a layer of glass between the pieces. Another point is when cutting your transom pieces cut them straight across the bottom eliminating the V section. Once the plywood is glassed in place build the lower V area up with glass then drill for your drain tube. Doing this way completely eliminates the possible weepage from the drain tube which seems to cause much of the transom rot as does the limber holes. Make a cut the back end of the stingers on a 45 degree angle 4" high, This cut off allows for water to get into the bilge with -0- restriction. The stringers should have one layer of glass on them before the are set in place, having the transom done and the stringers glassed will isolate them stopping any possible water migration. Far to many people redo these items just like the factory putting them in future jeopardy! A job done right will last the life of the boat.
    Thank you. So is the glass laid thick enough that I can cut out the wood from inside the bilge and not have to cut through the hull? I have one of those Rockwell tools. Would that do the trick? I'm hoping these repairs can be done without the need to re-gel the stern. Is that realistic?

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    Quote Originally Posted by Admeister View Post
    Thank you. So is the glass laid thick enough that I can cut out the wood from inside the bilge and not have to cut through the hull? I have one of those Rockwell tools. Would that do the trick? I'm hoping these repairs can be done without the need to re-gel the stern. Is that realistic?
    I used an air chisel / no problems ..........................

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    Getting ready...

    I'm prepping the garage to repair the transom. Hopefully I can "knock this out" before next spring. I guess it comes down to time and money. One question for all the guys that have been down to fiberglass in the bilge, how thick is the glass typically laid on the transom? Just curious.

    I plan on documenting the process here. I also would like to sell my 460 OMC and replace with a 454 merc in the whole process. Depends on $$$. King cobra may stay for another season unless I can find a bravo I can afford but first things first.. Rotten transom...

    Wish me luck!

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    Quote Originally Posted by Admeister View Post
    I'm prepping the garage to repair the transom. Hopefully I can "knock this out" before next spring. I guess it comes down to time and money. One question for all the guys that have been down to fiberglass in the bilge, how thick is the glass typically laid on the transom? Just curious.

    I plan on documenting the process here. I also would like to sell my 460 OMC and replace with a 454 merc in the whole process. Depends on $$$. King cobra may stay for another season unless I can find a bravo I can afford but first things first.. Rotten transom...

    Wish me luck!
    Not sure about the KC, but Merc has an exact spec for the overall thickness where the transom assembly is installed. Something like 2 1/4 or 2 3/16 maybe. I think people usually build up the glass over their coring to hit that spec. A few years back they gave a range, now they specify an exact thickness. If you go to the Merc website and find an engine/drive installation guide, it'll be in there. If you can't find one, yell. I have one on my laptop somewhere.
    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

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    Quote Originally Posted by Admeister View Post
    Thank you. So is the glass laid thick enough that I can cut out the wood from inside the bilge and not have to cut through the hull? I have one of those Rockwell tools. Would that do the trick? I'm hoping these repairs can be done without the need to re-gel the stern. Is that realistic?
    The outside fiberglass of the transom is probably around 3/8" so it is plenty thick enough that removing the rotten wood from inside the engine compartment is the correct way to replace the transom wood. I always used an air chisel to break out the stubborn sections. You will probably find some sections are completely rotted to sawdust and other sections might still be fairly intact so the air chisel really helps (much easier than chiseling by hand). You will need a grinder to prep the transom fiberglass before starting the rebuilding process.
    This would definitely be the time to replace your outdrive before cutting out the transom assembly holes in the fresh transom. You might want to get a professional to help you on the conversion process for many reasons including getting your x dimension as high as possible. Just some thoughts.

    1971 Donzi 18' 2+3
    1985 Eliminator 23' Daytona Offshore - Kevlar hull
    1988 23' Donzi CC F-23 with 250HP EFI Mercury OB
    1989 28' Team Warlock Offshore - single 548CID/600HP
    1990 23' Warlock Offshore - single 525HP
    Bill from Denison, TX - Lake Texoma

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    +2 on Bill's input. If you are thinking of replacing the drive do it now, not sure but I think the cobra is a larger footprint than a bravo. I didn't see the year of your 22 but as MOP said, your stringers are most likely bad too due to the factory layup process. I replaced stringers gussetts and shelves, and sistered a new engine bulkhead. Also, depending on the year, you should think about adding layers to the bottom. Using a bi-axel cloth and mat like 1708 about 7-8 layers equals 1/4" which is what I would have on the inside of the transom.
    - M
    1978 Magnum Starfire "MAYHEM"
    1994 Donzi 22 Classic 540/Blackhawk - Sold
    1982 Midnight Express 32 SS

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    I've been told the cutout for the King Cobra nearly the same as the Bravo I and that you only had to drill one new hole to do the conversion. ...I've thought about it but my King is pretty happy behind the 502 now that I've got rid of the obsolete OMC specific parts.


    Quote Originally Posted by MDonziM View Post
    +2 on Bill's input. If you are thinking of replacing the drive do it now, not sure but I think the cobra is a larger footprint than a bravo. I didn't see the year of your 22 but as MOP said, your stringers are most likely bad too due to the factory layup process. I replaced stringers gussetts and shelves, and sistered a new engine bulkhead. Also, depending on the year, you should think about adding layers to the bottom. Using a bi-axel cloth and mat like 1708 about 7-8 layers equals 1/4" which is what I would have on the inside of the transom.
    - M
    Jay Z.
    '93 White/Teal Classic 22

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    If you have a good King one with the hump it is nuts to swap to a Bravo, the King has proven to be stronger and more hydrodynamic IE faster with the same power.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

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    Nuts

    Quote Originally Posted by MOP View Post
    If you have a good King one with the hump it is nuts to swap to a Bravo, the King has proven to be stronger and more hydrodynamic IE faster with the same power.
    Yes it's a KC. Keep it??

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    Finally in the garage

    Got my garage cleared out this weekend and the boat is in with fans on it. I will start pulling the motor and drive soon. Question for you guys that have "been there done that"... would I save time in the long run if I pull the deck to pull the engine and replace the transom/stringer wood? or should I just leave it for now and only pull it if I need to get to the stringers under the bench seat? also wondering 'round about how much it costs to replace the fuel tank if I get that far into it. Thanks guys

  13. #13
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    Quote Originally Posted by Admeister View Post
    Got my garage cleared out this weekend and the boat is in with fans on it. I will start pulling the motor and drive soon. Question for you guys that have "been there done that"... would I save time in the long run if I pull the deck to pull the engine and replace the transom/stringer wood? or should I just leave it for now and only pull it if I need to get to the stringers under the bench seat? also wondering 'round about how much it costs to replace the fuel tank if I get that far into it. Thanks guys
    Pull the deck, the sooner the better.
    It's pretty easy to do and can be done in half a day, even by yourself.
    Once it's off, everything is so much much easier.
    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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    I started out like you did. Wet transom. Okay, I'll pull the drive, engine and replace. No big deal.
    Cut the top skin off of one of the stringers to see if they were wet too.
    I thought, "hmmm should be dry after a bout a foot forward of the transom".
    Not a chance in hell! Pulled the deck off and they were finally dry about six inches from the front.
    Scraped all of the soggy wood out out. I'ts nice to replace everything and fix/replace the poor build quality. I completed all of the work in one winter.

    Jeff
    " Just piercing the surface"

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    Pictures of the frame to pull the deck. I completed all of the work on the hull while it was still under the deck and sitting on the trailer. When it was finished, I pulled the hull off and rolled to the side to fix the low spots on the hull.

    Jeff



    IMG_0075[1].JPGIMG_0076[1].JPG
    " Just piercing the surface"

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