Saw for Angle-Cutting Floor

Discussion in 'Fiberglass and Composite Boat Building' started by Islander11, May 6, 2011.

  1. Islander11
    Joined: May 2011
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    Location: Lake Champlain, VT

    Islander11 Junior Member

    I've been reading this forum for years, but this is my first post. Thanks for all the helpful content, especially all the boat repair pictures. I'll try to add some of my own...

    I'm about to start a gas tank/floor replacement on my '88 21' Seebold Eagle. It had a cracked gas tank, and upon ripping the floor out, also some relatively minor rot.

    I need to cut some plywood out of the floor in a few spots. I'd like to angle it at 45deg and splice in replacement pieces. Some of the locations I'd like to cut get close to the edge of the hull. My 7 1/4 circular saw would need to be 6" plus from the hull at 45deg. A cordless saw is less, but still a few inches.

    Does anyone have a favorite saw for cutting 3/4" plywood at a 45deg in tight locations? I'm thinking it would need to be a small diameter blade.
     
  2. HakimKlunker
    Joined: Aug 2009
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    HakimKlunker Andreas der Juengere

    Try a router.
    But 45 degress seems not enough to me. Normally you chamfer in a ratio of 1:8 or more.
    Other option: You cut 90 degrees, add a framing under the plywood all along the edges and make a sort of hatch.
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Agreed, a 45 degree cut will fail very quickly, even with epoxy, unless you use a butt block under it. If you use epoxy, then 6:1 tapers can work, though 8:1 is the usual recommendation. An 8:1 taper on 1/2" plywood is a 4" wide, sloped joint.

    The Fein MultiMaster or a similar tool could do a very precise job for you, though so could skillful use of several tools, such as a jig saw, angle grinder, reciprocating saw, etc. If you set you circular saw blade depth to only the thickness of the plywood sole (floor), you wouldn't hit anything underneath. Leave at least a 3" edge (preferably more) around any tabbing to the hull shell or other structure elements, so you can taper and tab the new sole back down.
     
  4. Islander11
    Joined: May 2011
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    Location: Lake Champlain, VT

    Islander11 Junior Member

    Thanks for the info on recommended cutting angle. Knowing that a 6 or 8:1 taper is required, I will plan for blocking instead. I can do that fairly easily...

    This turns out to be the least of my problems. After poking around, my stringers and a bulkhead are rotted. So I'll have a lot of other questions...
     
  5. HakimKlunker
    Joined: Aug 2009
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    Location: Thailand

    HakimKlunker Andreas der Juengere

    Islander, it is quite typical to start with some 'minor rot'.
    My last case ended up in removing the complete interiour and decking as well.
    This is not meant to discourage you, but better have a good look all around. It may save you some time later.
     
  6. Dean Smith

    Dean Smith Previous Member

    whats wrong guys have you forgot what a panel or crosscut saw is for? draw your line choose your angle and rip into it. :confused:
     
  7. HakimKlunker
    Joined: Aug 2009
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    Location: Thailand

    HakimKlunker Andreas der Juengere

    Dean, you embarrassed me. Of course there are non-electrical solutions
    :)
    There must be a shortcut in my brains...
     

  8. Islander11
    Joined: May 2011
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    Location: Lake Champlain, VT

    Islander11 Junior Member

    Yup...I'm paranoid about other rot also. One bit of good news was that as I was removing the bad stringer on the starboard side, it got progressively harder as I moved aft, enough that I'll need a wood chisel to square off the end at the aft bulkhead. I tried poking that bulkhead with an ice pick and it feels solid.

    Also the motor mounts and stringers around them are solid, as well as the transom, even around the drain plug hole. The difference is most of those structures are in open air, where the rotted areas were under wet carpet and the rear bench seat.

    So there may be more work to do, but for now I can't find any wood showing significant softness.
    I hadn't considered that option either...will use it if the need arises. But I think I'm going with vertical cuts and blocking instead of trying to taper it.
     
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