Repair Shaft pockets from conversion

Discussion in 'Fiberglass and Composite Boat Building' started by rybo30, Mar 8, 2009.

  1. rybo30
    Joined: Sep 2008
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    rybo30 Junior Member

    I am in progress of a 100% rehab of a 30' Rybo Runner CC and changing from inboards to outboards hence I now have multiple below waterline holes, shaft pockets and rudder shafts to seal. I seem to have numerous concerns or looking for verification of my plans.

    Shaft pockets - I assume cut out completely (3" x 12"), fill with either plywod or composite, glass both sides; What fill is best, type of glass, sealant? do I need a larger backer plate on inside (screwed, glassed)?

    Thur hull holes ; Assume fill with plywood plug (type??) what is best sealant, glass both sides, do I need a larger backer plate in inside? holes are ~2"

    Rudder shafts; holes are ~1.5" with 4"x4" plates on top which seem to have warned glass below, should I cut out the entire section or just fill the hole

    General; What is best fill plywood? type, other woods, composite plastic
    Type of resin, type of glass
    Sealant for repair?
    Top backing plate?

    Have some other above water repairs, exhaust holes, air vents which I assume will be repaired in similar manner

    THanks for the advice in advance, if needed I can post pics of repair areas
    THanks
    Tom
     
  2. AroMarine
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    AroMarine Junior Member

    Tom are your pockets completeley in the hull or are they drop down below the waterline?
     
  3. PAR
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    PAR Yacht Designer/Builder

    Fill all of your hull shell holes to the same laminate dimensions as surrounding hull shell in the immediate areas.

    Rather then use chunks of wood, just grind back the edges of each hole to feather them back into the hull shell, then fill with fabric and resin until the same thickness of laminate is achieved. Fair and paint to finish it off.

    The reasons are many, but it basically boils down to simply not being cost effective in the short term or long run to add any other materials to the hull shell, other then laminate. You will not save an appreciable amount of fabric using wood, nor resin with these small repairs. It will also be easier and faster if you skip the wood portion and just use resin and fabric.
     
  4. rybo30
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    rybo30 Junior Member

    Pockets extend approx 2-3 inches both below the water line and inside the boat
     
  5. rybo30
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    rybo30 Junior Member

    Par

    THanks for the info yet I may have a 4" x 15" square hole - seems to big to fill with glass?
     
  6. PAR
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    PAR Yacht Designer/Builder

    I'm assuming your boat is a 'glass boat, in which case your concerns of too big to fill with 'glass seems, well, not founded, considering it's construction material is the same.

    A 4" x 15" hole isn't particularly big and 'glass would still be the best use of materials.

    If you're concerned about keeping this size repair reasonably smooth, during the 'glass lay up, then use some plywood as a backer. Cover a piece of plywood (that's bigger then the hole) with clear plastic packaging tape. This will prevent the resin and fabric from sticking to the board.

    Wet out all your hull shell edges with resin (I'd use epoxy just to make things easier and to get a better bond then the poly's), then pack in your fabrics. Wedge or brace the plywood into place on the outside of the hull. This will create a smooth surface once cured, that needs little fairing and more importantly prevent the goo and fabric from drooping down, sagging and other unwanted things.

    On the inside, continue filing the repair area with resin and fabric, until it's the same thickness as the rest of the hull shell in the general area.

    When this has cured, pop off the plywood and you'll have a nice smooth outer finish, that needs just some minor surface sanding and fairing.
     
  7. rybo30
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    rybo30 Junior Member

    Cloth rocommendations

    Par
    Any recommendations on type of cloth? Stagger different configutations on us only one?
    Thanks for the advice and this is the approach that I plan to take

    You seem very knowledgable so by chance do you have any first hand experience with the 30' Rybovich CC. I need to evaluate the transom prior to hanging a bracket with 1000# of engines. The transom seems to need additional support plus I seem to want to tie the transom into the stringers which currently it is not?
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I've worked on several Rybo's over the years.

    Yep, you'll need a fair amount of reinforcement on the transom. You'll also probably need to relocate tanks and a good bit of other stuff to adjust weight distribution.

    Transom reinforcement should be carefully worked out. Your bracket manufacture may have recommendations in this regard.

    A laminate schedule depends on several things, including resin type employed. The general idea is to provide similar laminate to surrounding areas.
     
  9. rybo30
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    rybo30 Junior Member

    Transom

    Are you talking about adding a full tramson 1/2 - 3/4" board on the inside? Do you beleive I need to tie such a plate to the stringers which are currently not attached to the transom?


    The current tank configuration is one 70 gal cenerline in front of consol and two side 70 gal tanks mid ship

    I obviosuly now have a large area to mount a tank centerline behind the console where the inboards were previously installed

    THanks for any advice with tanks and transom reimforcement
    Tom
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Well, it's helpful if we know what we're discussing here. What year and model Rybo are we talking about? Any optional equipment or personal desires that may affect the decision making processes? Previous HP and anticipated HP with the new outboards, etc.?

    Typically the stringers don't tie into the transom on inboard installations. The loading is predominantly on the bottom of the hull shell. With a transom or bracket mounted outboard, then load transfer to the bottom has to be insured, plus accommodation for the weight reallocation.
     
  11. rybo30
    Joined: Sep 2008
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    rybo30 Junior Member

    Rybo Runer

    She is a '86 30' Rybo RUnner, previously had 350 staggered/inline with remote v-drives. Planning on 250 -300 outboards on brackets. Plan to keep orginal tower on vessel other than that all is open. I currently have her 100% stripped to bare hull and have begun sanding/grinding the below water line holes. I have yet to cut out the shaft sockets.

    I understand the torque and thrust of the OB vs IB will be grossly different and need to sure up the transom

    THanks
    TOm
     

  12. rybo30
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    rybo30 Junior Member

    here is a pic- not great yet show my new hole to fill
     

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