Idle speculation about 'party boat' pontoons

Discussion in 'Boat Design' started by troy2000, Jul 16, 2012.

  1. troy2000
    Joined: Nov 2009
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    Location: California

    troy2000 Senior Member

    Around here we have a lot of what are commonly called 'party boats.' Unlike the east coast, where the term seems to refer to commercial boats hired out for fishing and recreation, party boats in this area are privately-owned pontoon boats about 20 to 24 feet long, that are typically used for family outings. They usually have cylindrical pontoons with rudimentary pointed bows, over-sized outboards, and displace an amazing amount of water when underway.

    Years ago I was rummaging through one of John Gardner's books on traditional boat building. He showed a set of plans for what he called a semi-dory: a boat with fairly traditional sailing dory lines forward, but a wider, flatter bottom aft. The idea was to accommodate a modest outboard motor, without the boat squatting and plowing (bear with me; this isn't a non sequitur:D).

    I thought at the time that if I took his semi-dory lines and shrank them down to half width, then stretched those half-width lines to twenty feet or better and lofted a pair of plywood pontoons, I'd come up with a boat that couldn't possibly be any more expensive or less efficient than the average pontoon boat around here. Seems to me it would push a lot easier, have a shallower draft, and be more stable to boot.

    Any thoughts?
     
  2. Edwardn
    Joined: Oct 2010
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    Location: Manitoba Canada

    Edwardn Junior Member

    Hi Troy

    This boat is listed as a 20ft Apache Royal Pontoon Boat, to me it is more a catamaran as my impression of a pontoon boat is like you mentioned, cylindrical pontoons... anyways I thought it may give you some ideas.

    Regards
    EDD
     

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  3. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    There are many reasons for using the flat or perhaps slightly vee bottomed pontoons. They will make a boat that is notably superior to the round pontoons. The round pipe type is better only in the construction stage. After that it's all downhill for the pipe type. Round ones will need more power, thus bigger engines, thus higher fuel consumtion, for the speeds the users seem to demand.

    Rectangular hulls will have much better reserve stability than the round things too.
     

  4. drailton
    Joined: Jul 2012
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    Location: Vietnam

    drailton Douglas E. Railton

    One of my associates in the marine industry and myself took to modifying his pontoon boat to increase efficiency. He had a 24’ party boat with a pair of Mariner outboards (I don’t recall the HP). The first thing I did was to cut out a triangular piece of the pontoon that was about 16” wide at the transom tapering to a point about 15’ forward of the transom making the planning area. It worked! We went from 14kts to 25kts on our fits attempt. The problem was that the pontoons did not dry off at speed throwing an immense amount of water into the air and under the deck. Solved that problem by making about 2” wide lifting strips mounted at about the 4 and 8 o’clock position. At the end of the day, we had a 30kt party boat. One big problem, the pontoons and the rest of the boat was not designed for the loads that are imparted into the structure at those speeds. Pontoons deformed, cracks in decking and other areas appeared within a year. But we had the fastest party boat in that part of Louisiana. Lots of fun doing it. Slight vee bottom or a shape similar to seaplane pontoon stepped planning surfaces would be great for party boats.
     
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