redoing vintage 23' pontoon and propulsion choices

Discussion in 'Props' started by scopx, Jul 19, 2021.

  1. scopx
    Joined: Apr 2011
    Posts: 2
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    Location: Piney Woods Texas

    scopx New Member

    Long Time Lurker-First time Poster

    First of all, no spring chicken here. Am trying to find some interest in something and have decided to push ahead (after many years of procrastination) redoing vintage 23' pontoon. However, if successful in refurb, vessel will not be a pond putzer.(?)
    After much pondering and sifting through all the junk around the place, have decided upon propulsion system and putting some numbers together as to placement striving to achieve optimal location for balance. (I never did like the smelly 2 stoke hanging off the back anyway.)
    As a pontoon is a displacement vessel, will also be converting to a semi-displacement, if not full planing. I decided against designs "steps" as there seems not to be much agreement about the safe use with a novice skipper. D0 think it would be a hoot, but thinking about handing it down to the GKs and their propensity to be on the edge has caused pause. (One grand-daughter has already bailed out of an airplane, and she's not yet old enough to drive!) I can just imagine her at the wheel of 200HP scooter.
    There will be extensive conversion of the flotation aspect which is and will remain mostly (non ferrous) 5052 if my reading is correct. Through the years have managed to accumulate skills in several areas, and welding happened to be one. However, its kinda like sex-its been a while and will have to refresh. There is a new pulse TIG unit sitting in the barn (for over a year) waiting for me to build a cooler. The parts are gathered up in a pile. (I have lots of junk.)
    Only recently determined/discovered that roofing/siding panels can be made in aluminum was well as steel in various configurations.
    My first choice of engine (on hand) was 4 cyl turbo diesel, but so old, and head parts hard to get in the U.S.A.

    Do intend to plumb the transmission lubricant through a cooling system as will be, at times, working it rather hard. And will be using 1st gear of 4 speed toploader of which the ratio is/will be 2.78 to 1. And get to upshift to 2nd (1.95 think) once in a while.
    Hope I live long enough to see it come to fruition.
    Comments Considered.
    Good Luck To All.
    TLee
     
    Last edited by a moderator: Jul 19, 2021
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    A belated welcome Scopx, and congrats on your first post!

    Re the pontoon, is it literally a pontoon, as in a rectangular monohull, or is it a pontoon boat, ie a catamaran with tubular pontoon hulls?
    Can you post some photos of what you are working with, and / or sketches of what you are hoping to end up with please?
     
  3. scopx
    Joined: Apr 2011
    Posts: 2
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    Location: Piney Woods Texas

    scopx New Member

    Thank you Bajansailor for your reply.
    It is actually 24' OAL boat, nose to tail with two 20" diameter round pontoons, with length to beam ratio of 3:1. (8') wide. Since posting, have looked at several CAD programs and downloaded one that hopefully can master. I will go away for a time and return when have put something meaningful and understandable together. Thanks Again
     

  4. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    OK, so it sounds like you have a fairly typical 'pontoon boat' in a catamaran configuration.
    You mention using a 4 cylinder turbo diesel - how do you plan to arrange the propeller shaft and propeller?
    Will the engine be sitting on the bridgedeck between the hulls?
    If so, how you then going to support the shaft?
    You mention that you 'don't like smelly 2 strokes' - but there is a reason why pontoon boats have outboard engines . They do the job, fairly effectively.
    Quite honestly, for your 24' pontoon boat, the best thing that you can do is to just put an outboard motor (or two even) on it, and then let your grand daughter loose on it.
    Forget about 200 hp though - she would still manage to scare herself silly with less than half that power.
    Re drawings, rather than trying to learn a CAD program, do you have any sketches on the back of a napkin, or on a piece of paper? They will do, to convey what you are trying to show. They do not have to be fancy.
     
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