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Thread: Now I'm getting serious....

  1. #61
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    Thanks Rick. Part of my solution will be to cut open the stringer bases and after drying completely, if necessary, then pack it full of glass filled polyester putty, or glass filled thickened epoxy. Then forming large radii of glass filled putty both inboard and outboard of both stringers, followed by a layup of glass across the entire bottom (not just between the stringers) and up the sides of the stringers.
    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

  2. #62
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    George I love the pictures and steps your taking. I also think radius is a stress relieving good idea. Rick, I would like to see pictures of Donzi's fix. Just remember when you strengthen on part it shows weakening in other areas. the trick is to make the weak part easy to fix or non existent for your use. I normally don't drive past this point. If it is too nasty for me I slow down. If people want to pass me I wait till I deem it is good enough to pursue, then I catch up. Discretion the better point of valor. This is a good post!
    Randy owner of Donzis since 1966
    High Performance props 3, 4, and 5 blade. Turbo and Stainless Steel props. Props for old Volvo drives.
    The reason congressmen try so hard to get re-elected is that they would hate to have to make a living under the laws they've passed.

  3. #63
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    gcarter
    Engine torque causes a greater load on the port side stringer/motor mount area.
    I reinforced the stringers on my 18 w/BBC with some aluminum plate (1/4"x4"x36"). Aluminum angle would be better. GEOO did the same w/Mighty Mouse. If "Blackie" is following the thread mabe he'll post some pics.
    Your pic when removing deck showed you do not have any "Floors" near the stringers. I am pretty sure my 95 22 has 2 "Floors" on each side fore and aft of the engine mounts. I put diamond plate over the "Sole"(see pic) so I cannot check for you
    I have had no issues with the 1995 22. Of course I drive really slow
    +1 w/Grizz and your plan with the radius. If you reinforce an area make sure you do not create a "Hard Spot", spread the load as evenly as you can.
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    riggerb@aol.com
    1995 22 Classic

  4. #64
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    Then forming large radii of glass filled putty both inboard and outboard of both stringers
    Good idea George. The guy that fixed my boat wasn't confident that Donzi's repair would hold up because it only addressed inboard side of the stringers. He felt the outboard side should be radiused as well.
    Why is faster never fast enough.

  5. #65
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    Hard spots

    do occur, just take a look....
    Unfortunately they come from the factory w/them.
    1) Port Side
    2) Stbd side



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    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

  6. #66
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    Looking at these pictures, first you'd have to assume these stress lines (I don't want to call them cracks) continue all the way to the transom.
    I was sort of surprised to find them on both sides. You can see exactly where the stringer is.
    My conjecture is they exist from the transom to the inner strakes where the load then spreads out and then causes the hairline cracks up the sides of the strakes for another couple of feet.
    Now I wonder how many other boats have the same indication of stress since we NEVER see under the gel?????
    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

  7. #67
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    That's what I would call a "Hard Spot"
    Gel Coat must be VERY flexible.
    riggerb@aol.com
    1995 22 Classic

  8. #68
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    George, where's the stringer(s) base in the pictures, directly above the hairlines? Is the base where the dark color begins?

    Someone mentioned a while back that hard spots will try to cut their way through the bottom of the boat. Do you think this is what is going on?

    RickR, like you state the newer boats have a panel glassed in on the outboard side of the stringer(s) to the chine area.
    RickS-E

  9. #69
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    Rick, you're right on all counts. The dark area is the stringers plus unremoved paint, filler, etc.
    I'm a little concerned about every one else's boats too. Has any one else ever removed the gel under their stringers? Could this be more common than we might think?
    One other note, forward where the strake starts, the strakes are filled with a filler that doesn't harden. It's still pliable. I think that filler acts as a shock absorber. Aft of the strake termination, there's nothing to absorb it, so we get the stress.
    Anyone want to chime in?
    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

  10. #70
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    Quote Originally Posted by gcarter View Post
    ...I'm a little concerned about every one else's boats too....
    Bingo


    Quote Originally Posted by gcarter View Post
    ...Anyone want to chime in?
    I'm also waiting for this. So what is the ultimate solution? A thicker laminate under the stringers before they are laid in? A cored bottom, again before the stringers are laid in? Isn't Mr. X coring the bottom on his 22?

    I hate to ask this, but is this boat design/lay-up being pushed beyond its limits at 450 to 500+ HP?
    RickS-E

  11. #71
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    Quote Originally Posted by RickSE View Post
    Bingo
    I'm also waiting for this. So what is the ultimate solution? A thicker laminate under the stringers before they are laid in? A cored bottom, again before the stringers are laid in? Isn't Mr. X coring the bottom on his 22?
    I hate to ask this, but is this boat design/lay-up being pushed beyond its limits at 450 to 500+ HP?
    First, I think it is being pushed a bit. But we haven't had any sink yet as far as I know.
    Next take a look at this page;

    Keeping in mind no boat has 0* deadrise, it's only an illustration. But let's go through the process of the 80's boats.......
    The hull was laid up and the stringers were fabricated outside of the hull along with the transverse frame which was nailed to the stringers. The stringers were laid into the hull and saturated glass was laid over them. With the section of the stringers being made from 1" X 12" pine and having square bottoms, there would be a void under the stringers and they would only touch the bottom on the outboard corners, i.e., a razor edge in contact w/the bottom. I've worked on three of these boats now w/o any variation. They all suffer from lack of support under the stringers (this is only my opinion).
    I particularly like the third illustration, keeping in mind that our stringers are wood and not composite. But if an attempt is made to fill the voids under the stringers, build up large radii inboard and outboard of the stringers, and do a multi part layup of glass on both sides along w/strengthening of the bottom, it should help tremendously.
    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

  12. #72
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    Here's a picture of the hull inside above the port strake and you can see the translucense of the 'glass where I sanded the gel off the bottom.

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    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

  13. #73
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    This morning I cut into both the port and stbd stringers.....the good news is that they were dry. The less encouraging news is that there were voids under both. I don't know how bad they are yet but they're better than the Minx which were more than 1/2" off the bottom on the inside of the stringers.

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    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

  14. #74
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    gcarter
    Do you think the stringers are flexing?
    On my current project (87 Supra/ski boat, stringer, sole and floor replacement) I plan on cutting the base, of the wood part of the stringer (2"x6"), at an angle. Then bedding in thickened resin.
    Looks like Donzi's solution was install 2 floors (braces perpendicular to the stringers), on each side, fore and aft the motor mounts on the later models.
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    riggerb@aol.com
    1995 22 Classic

  15. #75
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    I haven't seen any indication of stringer flexing on any of the Donzis I've worked on. But, when you think about it, why would they???
    IMHO, the weakest part of the assembly would be the stringer/bottom joint aft of the strakes.
    The transverse frame along with a couple additional gussets are all the reinforcement it needs.
    I think the floors are more for utility than strength. The down side to them is the voids become inaccesable.
    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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