Tramp lacing points

Discussion in 'Multihulls' started by paxfish, Dec 3, 2014.

  1. Canracer
    Joined: Aug 2009
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    Location: Florida

    Canracer Senior Member

    Wow, that pod must bounce around like crazy when motoring in a chop. Or does it have hard attachment points to crossbeams. I can't see from the picture.

    Looks like it might be connected to the forward beam, and there might be a connection to a beam under the tramp.
     
  2. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    Thanks Guys. Farjoe, there are two bolts permanetly embedded in crossbeam. Then two nuts holding the forward end to those bolts.

    The aft part of the pod rests on top of another crossbeam, and is bolted down.

    Here is another perspective:
    [​IMG]
     
  3. farjoe
    Joined: Oct 2003
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    Location: med

    farjoe Senior Member

    i would appreciate some photos of the connections and the beam dimensions
     
  4. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    Correct - It is bolted to both beams and doesn't bounce at all...

    Farjoe - The beams are aluminum mast sections. I don't know the dimensions of each beam offhand, but they are pretty beefy. The bolts up front are probably 1/2" diameter stainless bolted into the mast section. The plans call them out as "captive" bolts. So I presume the head of the bolt is inside the beam.

    What are you trying to figure out? Maybe I can help...
     
  5. farjoe
    Joined: Oct 2003
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    Location: med

    farjoe Senior Member

    Basically I have a 7.5m cat with an outboard hung on the rear beam. Also I have one big tramp of similar material to yours between the mast and the rear beam which is very bouncy.

    I would like to emulate your solution because i think your solution has the following advantages:

    1. centralises the weight for less pitching.
    2. Prop spends less time outside the water.
    3. Engine is more protected against following seas.
    4. Less easy to steal engine.
    5. Smaller tramp sections for more rigidity underfoot.

    Disadvantages would be more weight and less space to pitch a tent on the tramp.
     
  6. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    I gotcha - Yeah. So if you think you have the buoyancy in the bows to allow you to move the weight forward, you might be able to build a pod.

    This one is about 8 feet long and weighs about:
    75 pounds pod
    105 for the 9.9 engine
    40 for the fuel tank
    50 for the battery

    So figure 275 to 300 pounds moving forward. Think about that leeward hull when you're sailing at 20 knots - can it handle moving weight forward?

    As info, my motor ventilates sometimes also despite its 25" lower unit.

    I might suggest using composite rather than plywood. A sheet of 3/4" marine ply is twice as heavy for the same strength. Mine is 1/2" ply around the perimeter, a couple of 1X2 cedar stringers on top, all coated with 6 layers of 6 ounce glass and epoxy. Cost for Carbon core sheets is + 50% over marine ply., and I would use it if I were doing a complete rebuild.

    The pod itself is cedar strip construction just like the hulls of the boat.

    I can jump up and down on the pod without problem.
     

  7. markstrimaran
    Joined: Dec 2014
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    Location: usa

    markstrimaran Senior Member

    making progress I see.

    I have started glassing in my tramp mount and was curious how much to over kill it. I know craziness self engineering. Basically I have a 1/4 thick 3 X 4 angle of solid glass. With a 2" of .15" fiberglass pipe It spans 9.5 feet with a steel support in the middle.
     
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