Filling thru hull holes

Discussion in 'Fiberglass and Composite Boat Building' started by reelpleasure, Dec 4, 2013.

  1. reelpleasure
    Joined: Feb 2013
    Posts: 27
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Massachusetts USA

    reelpleasure Junior Member

    Hello, ALL,

    I have an older lobster boat with a solid glass. I am doing a refit/rehab/repower and need to fill two or three holes in the hull. Diameters are 3/4" to 1.5". The hull is about 3/4" thick. Gel coat on the outside, mat on the inside.

    I will grind out a concave circle on each side of the hole say 6-7 inches.

    The fill schedule will be polyesther lamination resin, 1 layer each of 1.5oz mat , 1708 and 2 layers of 1.5 oz mat on both sides.

    Does this sound about right for a hull of this depth ??

    Thanks, Bill
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    3/4" of an inch is quite a bit more then your laminate schedule. A single layer of 1708 is about .085" with a 50/50 resin/fiber ratio, so 4 layers of this is just less than 3/8". A single layer of 1.5 ounce CSM is about .05", so adding up the your schedule, which appears to be an outer 1.5 ounce CSM unit, followed by four 1708 units, eventually capped with another 1.5 ounce CSM, equals about .44" of laminate.

    I'd recommend you bulk up with three more layers of 1.5 ounce CSM, which will leave you just shy of the surface at .74" of laminate. I'd place the additional mat on the stitched side of the biax units to help the interlaminate bonds.
     
  3. reelpleasure
    Joined: Feb 2013
    Posts: 27
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    Location: Massachusetts USA

    reelpleasure Junior Member

    Thank you
     
  4. CEShawn
    Joined: Dec 2013
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    Location: United States

    CEShawn New Member

    Let me know how yours go... I need to replace two transducers this year and I'm in mass with a 35RP... I started to do mine last year but never got around to it. One tip I got, started it was to cut them into round pieces ahead of time and make them just a little bit smaller/bigger each time, sort of so they go on overlapping in a sense. The imagine my friend showed me was do it like a stack of coffee paper filters, just like that... was neat, but again didnt apply it...
     
  5. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    You could also use 600gsm woven roving in your schedule. as well as the CSM. Long as you have enough chamfer (with concave holes), you won't have a problem.
     

  6. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Chamfer should be about 8:1 minimum.

    For a 3/4" thick laminate, filled from both sides (so 3/8" is the short side of the chamfer) the long side is 3" Largest diameter is 6" + diameter of the hole.

    Construct a backing of some sort, to act as a mould, halfway the laminate thickness. A piece of made to fit plywood, covered in plastic works. (tape keeps it in place.)

    Fill the hole with glass plies (alternating CSM/woven roving or a combimat) of increasing size, as shown in the picture.

    In this picture there are 2 differences from my text:

    -chamfer ratio is too small
    -this is a one sided repair. I like double sided repairs better (less grinding work)
     

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