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Thread: Ply or Coosa?

  1. #271
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    Pete,

    When I lowered the floor on the Plum Crazy Sport. I just did the section that was under the 3 man racing bolster, and not the entire floor.
    I cut down the center string and then sandwich both sides of the center stringers with 3/4" marine plywood.
    I then build a floor box out of the 3/4" marine plywood and glass it to the two side stringers and floor, put two water drains in it. I also kept the storage hatches that were in the floor.
    When Roger Munn lowered the floor on the Jolly Roger Sport, he just cut and put in two boxes in the floor about 7 inches deep. and they sat between the stringers

    Thank you
    Jim

  2. #272
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    Love this thread Pete. I forget...what are your final plans?...how's it going to look?

    1974 Magnum 27 Sport
    1970 Donzi 18 2+3

  3. #273
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    Pete [or any other Mag restorers] have you found a deliberate cut in the corner behind the dash going up to the deck ? My Mag had this and is most likely the reason I had a deck crack. I re enforced both sides to be safe. Mine my have been built on Friday..or Monday. Great workmanship on your rebuild Pete.
    Mark
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  4. #274
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    Jim,
    Rather than having a couple drop down boxes to plant your feet into, I asked Parnell about the
    mechanical feasibility of lowering the whole cockpit sole by as little as 4" and as much as 6".
    by the way, we both felt the same way about the low freeboard in the sport and by lowering
    the "whole floor" (rather than the boxes) all occupants in the boat (not just the navigator & driver)
    would feel defintely "more in the boat"

    Aaron,
    I already have 2 Dart SB 427's long blocks...Marine kenetics is helping with the cams, but still aways
    off before dropping them in......my main task now is getting all the structural work done..being in the
    boat with the lower floor now the gunwale is at my hip rather than my thigh


    Mark,
    I had the same crack same corner, but it never migrated to the deck........could be some torque involved
    from the console weight twisting on it....only a few bolts and lightly glassed ......mine is a V windscreen
    more dashboard to hide the cracks.
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

  5. #275
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    [Rather than having a couple drop down boxes to plant your feet into, I asked Parnell about the
    mechanical feasibility of lowering the whole cockpit sole by as little as 4" and as much as 6".
    by the way, we both felt the same way about the low freeboard in the sport and by lowering
    the "whole floor" (rather than the boxes) all occupants in the boat (not just the navigator & driver)
    would feel defintely "more in the boat"]

    Pete here is my two cents. If you take all of the floor down your going to need much taller bolster stands than standard to get the back suport with the bolster. And my bolsters are made already so there no turning back. Are you plannig to lower the back seat so the rear seat pasengers are lower in the cockpit. ? I'm doing just the floor cut outs, as it felt great that way in my old race Mag. I know a deeper cockpit is good & that's what sold me on my past Mirage powerboats, & as my Sedan Mag has a deeper floor also. I look at the Mag sport as the big brother to the Donzi 22' classic, just get in & hang on..
    Mark

  6. #276
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    Mark I cut the back portion of the benchseat in half separated it & added 4"of coring and glassed it in.
    I also added 2" to foor height so your feet can reach the floor............I here ya about hanging on!
    Attached Images Attached Images
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

  7. #277
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    Pete

    With the 3 man bolster set up , I really never had any one in the back seat area, Back then I had Bilt Rite build the 3 man set up with drop seats and the bolster was bolted to the cockpit sides , so
    I could adjust the bolster height also

    Thank you
    Jim

  8. #278
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    Pete now that's how to lower the floor. The glass work on the back seat looks great. That 4" will make a big difference for anyone riding on the rear seat. Mark

  9. #279
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    Pete,

    I think you found a good middle ground on your seating. Before you posted the pics of the back seat I was going to suggest a cockpit floor design like my starfire (roughly a 45"x 48" lowered section under the forward part of the floor thinking that the higher floor height at the rear seat was right for the bench height. However, I realized that my deck height around the rear seat is probably 8" or so highter than your sport which would make the back of the seat stick up above the deck or have a short back. Lowering the whole floor and making the rear bench deeper is a good solution.

    - M
    1978 Magnum Starfire "MAYHEM"
    1994 Donzi 22 Classic 540/Blackhawk - Sold
    1982 Midnight Express 32 SS

  10. #280
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    building the cockpit/cabin bulkhead was a little difficult with the deck on, but it's built now.
    I made the template by using clear pine pieces .....(1"X 12"s and 1"X 6"s) scribing the angles
    then using epoxy to glue the pieces together.....looking for some advice here.....I intended to
    transfere the template to marine ply but thinking about just keeping the pine, seal and glass it
    over once with epoxy resin & 1708............What do some of the experts think???
    Attached Images Attached Images
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

  11. #281
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    Pete,

    Not an expert but a couple things come to mind. First, the bulkhead being multiple pieces of wood is probably not ideal but the one part that bothers me is the outward most seam, its right where the top of the bulkhead meets the deck fairing which is a high stress/flex area. I know Bud said this area is prone to cracking, maybe he will chime in. Secondly, look at the first picture I posted of my port side bulkhead without the liner. The hull has a strip of wood approx. 1/4" thick and 3" wide that is glassed in before the bulkhead is tabbed in, spreading out the support of the bulkhead.(no hardspot) I think this is more important than the seams in the pine.

    - Marshall
    1978 Magnum Starfire "MAYHEM"
    1994 Donzi 22 Classic 540/Blackhawk - Sold
    1982 Midnight Express 32 SS

  12. #282
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    It's very important that I not overlook anything here................thanks for the unbiased opinion.
    If I see it right, the wood strip your refering to (portside pic) isn't that the base rail for attaching
    the side compartment piece (liner) under the gunnel?
    1983 Cigarette 35' Mistress
    1976 Magnum 27' Sport
    1986 Donzi 18' Classic
    NEVER FORGET 9/11

  13. #283
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    Pete,

    In post #457, first pic. Look at the bond between the bulkhead and the hull. Its hard to see but running the length of the bond the hull is built up with a piece of wood coring that is about 1/4 or 3/8 thick and 3-4" wide glassed in from the chine up almost to the rub rail. Then the bulkhead is glass/tabbed onto this built up area. All of the bulkheads should be bonded in this manner if you look at them.

    - M
    1978 Magnum Starfire "MAYHEM"
    1994 Donzi 22 Classic 540/Blackhawk - Sold
    1982 Midnight Express 32 SS

  14. #284
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    Quote Originally Posted by MDonziM View Post
    Pete,

    In post #457, first pic. Look at the bond between the bulkhead and the hull. Its hard to see but running the length of the bond the hull is built up with a piece of wood coring that is about 1/4 or 3/8 thick and 3-4" wide glassed in from the chine up almost to the rub rail. Then the bulkhead is glass/tabbed onto this built up area. All of the bulkheads should be bonded in this manner if you look at them.

    - M

    Does the bulkhead/coring-strip joint sit in the middle of the coring strip, or is the bulkhead butted against the forward edge of the strip? (I'd think it was the former, but of course in the pics we can only see one side of the bulkhead.)

    For those following casually, here's the pic:

    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

  15. #285
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    I'm, personally, not a fan of using ply in applications like this. I'd much rather see a build-up of solid lumber.
    The main reason is the virtual elimination of any chance of rot. If the bonding is done w/a good grade of epoxy, and all the edges are sealed w/a thin penetrating epoxy, no water can enter the wood fibers. The next reason is a greater strength in compression from deck loads than ply can give you because all the wood fibers are running vertically, giving maximum strength in that direction.
    For similar reasons, I don't like ply stringers (i.e., w/ply, half the fibers are running 90* to the lines of stress and contribute nothing to the strength of the boat).
    I'd rather see someone use Coosa than ply. At least w/Coosa, everyone understands a reasonable amount of FRP is used to guarantee good strength and integrity, rather than using a minimum amount of glass on ply thinking you have enough strength.
    I'm not going to comment on the the particulars of this boat, 'cause I've never worked on one.

    I like it Pete!
    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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