Float Plane Pontoon Trimaran Boat

Discussion in 'Boat Design' started by Scotty Wisley, May 1, 2009.

  1. Scotty Wisley
    Joined: May 2009
    Posts: 6
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    Location: Papua

    Scotty Wisley Junior Member

    I am not a boat guy but I live on the island of New Guinea and am trying to figure out how to have good vacation time with my family here where there aren't many options. The ocean, reefs, beaches and surf breaks are one of the best assets but "getting there" is the nightmare. If we had a little boat we could make this happen. Money isn't plentiful. Main use would be for camping and recreation with 400-500kg on it.
    Looking around at my options I've got 1 pontoon off a float plane that I can use. It was designed to keep about 750kg off the bottom. but seems that floats are designed to sit real low in the water and then when power is administered they basically hydroplane and help the plane lift off. There is a small "step" right near the rear as well.
    My thot is to make a trimaran which would be 15 ft long and about 12-14 feet wide and mount a 15hp outboard on it. The pontoon weighs about 60lbs as is. It is about 2.5 feet high by 2 feet wide shaped like a big sausage.. fairly bulbous up front tapering down to nothing in the rear. I like it cause it has 5 sealed compartments that can each be pumped out. Seems pretty "unsinkable" to me and is very light and designed to hydroplane and it is free.

    I'd really like some input on this from those who know. Here are my thots. Please get out the red pen!
    Outrigger mounting.
    There are two well positioned mounting brackets that go through the pontoon for the wheel strut from the plane. They are postioned about 5 feet back from the front and 3 feet from the rear with me cutting off about 6 feet. If I anchored a 4-6 foot length of 3 inch pipe (Alum or Zinc coated) centered in each mounting bracket. Then with 2.5 inch piple inserted into this continue out to the outrigger. This will slide inside with a pin to hold it in position when on the water but able to pull the outriggers off when transporting or slide em in to narrow the boat. Rough width would be about 12-14 feets?
    The main hull would have good buoyancy but easy to roll. Outriggers then seem to me to be pretty key. Most easily available material is PVC and I was thinking of 4 or 6 inch pipe bundles of 3 pipes for each side with one on the bottom and two center above it. Idea being that when the boat gets up to plane the outriggers come up with it and minimize contact with the water but provides stability in turns or waves...I have no idea if this is enough. Not much of a math guy either. My thot was to mount the pipes so that the front would be 6-8 inches higher than the back thus minimizing the slap/smack I experience on the traditional outriggers here. This seems like it would also help the boat plane better. Wanted to use 3 in case I break/crack one. Other thot was compartmentalizing one into 3 sections.

    Deck. Was going to get a 4x8ft sheet of alum diamond plate, cut it in half and put 2x8 on the outrigger pipes on either side of the hull/pontoon making a 6x8ft deck.

    OUtboard. Mount on the rear outrigger pipe/deck to one side of the hull/pontoon. 15hp is already going to max out my bank account but would like to pull the kids on a tube/wakeboard.

    That is probably enough info to solicite some good input from those in the know.
    thanks much, this could do our family a lot of good...in saving us a nightmare or providing us with a great little vacation rig.
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