Pontoon boat pilot house

Discussion in 'Boat Design' started by BobL, Feb 25, 2011.

  1. BobL
    Joined: Feb 2011
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    Location: Sevierville,Tn.

    BobL Junior Member

    I have a 24ft. pontoon boat and would like to add a small pilot house so I can get in out of the weather while cruising and fishing, and have an enclosed head. I use it now for fishing, mostly, and have removed all seats except 1 corner seat and the console. It has 2, 24 inch pontoons(round) and an 85hp motor.
    My main concern is weight and construction materials. Also, do I have to have it inspected after modification by the CG?
    Basically, it is 5 by 10ft, 61/2ft. high, and framed with metal, 20 gauge studs and tracks, using screws and MIG welding. The top is sheet metal on 24 in. centers. It has 2 side doors just aft of the helm. The bottom section is 1/4 plywood 35in. high, with plexiglass windows around the top section. The helm is 14ft. forward, leaving a 4ft. deck aft and 10ft. forward deck. The heaviest part is the top which I can easily lift myself.
    The window frames will be made of mahogany as well as the door frames and other areas around the windows and the helm. I'll use foam insulation inside.
    Sorry for the long winded description, but I'm wondering if it's feasible, and am I headed in the right direction. I plan to trailer it and the height from ground to top is 11ft.
    Any suggestions would be greatly appreciated
    BobL Sevierville,Tn.
    PS: It will be used solely on a lake.
     
  2. messabout
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    messabout Senior Member

    Bob; one of the things you might consider is windage on the pilot house. It does not take much area to cause a considerable force on the boat. If your lake is often windy you will find it annoying that the boat wants to go where it wants to go rather than where you choose for it to be while fishing.

    The most serious consideration is weight. I suggest that you do some research in this area. Take the boat and trailer to a truck scale. Have the boat and trailer weighed. Now take the boat to the lake and launch it. Take the trailer back to the scales and weight it. a little arithmetic and you have the weight of the boat, motor, and whatever gear that you normally carry. That is the starting point. Now do a serious analysis of the weight of the proposed structure and whatever might be inside it.

    Your boat will support roughly 4000 pounds when it is at the 12 inch draft condition. That is to say that the pontoons are half immersed. This is the absolute maximum that you should contemplate for reasons of safety and common sense. At 10 inch draft you will have about 3200 pounds of flotation, at 8 inch draft about 2400 pounds, at 6 inches somewhere in the region of 1600 pounds. Be aware that these displacement estimates are for two pontoons. At 8 inch draft each pontoon is supporting 1200 pounds, etc.
    keep in mind that a couple of robust guys (OK fat guys) at the side of the boat will depress that side by a noticeable amount. These displacement numbers are just ball park estimates that would seem to suggest that the displacement is linear with respect to draft. Not exactly so.

    It is prudent to avoid any weight condition that would immerse the pontoons beyond the mid point. You do the arithmetic and if the draft including the new house will be less than ten inches I'd say go for it.
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Consider a collapsible canvas enclosure, instead of a built up, hard walled arrangement. This is quite common with a head on a pontoon boat and could also be enlarged for a pilothouse on those occasions you need some protection from the elements. With something like this, you'd remain light weight and have the option of breaking it down for the open air feel when it's nice out. Lastly, you wouldn't have the windage of a big 'ol dog house at the back of your boat, getting pushed and shoved around by every hunk of wind gust that comes along.
     
  4. BobL
    Joined: Feb 2011
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    Location: Sevierville,Tn.

    BobL Junior Member

    Dear Messabout, Thanks for all the good information you sent me. I have done the math and came up with 2650 pounds, which includes a larger engine than I plan to use, but does not include the 2 fat guys. They will have to find another ride. The waterline with all the furniture, etc., which I removed, plus the 85hp engine, which I will remove, is 8in. at the midship point, without any of my additions.It looks OK weightwise. What do you think? BobL
     
  5. Boston

    Boston Previous Member

    sorry but I gotta disagree with the idea of telling the fat brothers to find another ride

    I'm no naval architect but there's a few things I have learned. You gotta figure for worst case scenario and that includes unexpected passengers like Mark and Hoyt, Some folks just insist on rocking the boat a little or at least set it listing some. You want enough reserve buoyancy to deal with the unexpected. Even if it means the occasional republican. Do not short your dynamic loads when considering righting moment, if everyone runs to one side to watch a commy pinko get eaten by sharks how does your vessel react.

    I used the maximum passenger load of 6 and figured for fat people 300lbs each and then I rounded up to a nice easy 2000lbs of shifting weight when I calculated dynamic stability.

    I'm sure these guys will mention Skene's elements of yacht design eventually
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It's even worse then the scenario above. If the same well fed group, standing on the roof of the new enclosed poop and wheel house, watching the fireworks on 4th of July, when a 16 year old with a tube top falls in and the top gets to the surface before she does. Hows your stability curve look with these puppies all on the edge of the pilot/poop house roof, not to mention a reasonable safety margin too.
     
  7. BobL
    Joined: Feb 2011
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    BobL Junior Member

    Poontoon pilot house

    Thanks for your thoughts and advice. The roof is 20gauge sheet metal and not designed to support anyone, so we can rule out out that possibility. As far as passengers, fat or otherwise, I really don't plan on any, other than an average adult. I'm 72 and my wife is 68. I'm planning this for quite cruises on a small lake. Given that scenerio, do you think I,m OK?
     
  8. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    Yes Your OK, but consider canVAS AND LIGHT ALUMINUM POLLS AS PAR SUGGESTED. sorry for the caps. They even make insulated canvas or vinil these days.
     
  9. BobL
    Joined: Feb 2011
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    BobL Junior Member

    Pontoon Pilot house

    Thanks for the reply. I considered canvas and plastic orginally, but the cost was out of reach. I'm on a budget here and was trying to keep it simple, using tools and materials on hand (I built musical instruments here in the Smokies for 35 years and have a pretty good shop, but no TIG welder for the aluminum). I guess I could use 1/4" wainscoting for the lower 35" and plastic around the top 36", with the metal top I have already built and weighs about 50 pounds. Any thoughts?
     
  10. Boston

    Boston Previous Member

    there is a product called polygol that might be perfect for a canopy if your thinking a clear top. Its lexan product and costs or used to cost about 60 a sheet, very light which is why I mention it
     
  11. messabout
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    messabout Senior Member

    Boston and some of the others are correct..."plan for the worst case scenario".
    I was being facetious about the fat guys but the notion is valid. The problem with cylindrical hulls is that at any point past half immersion the bouyancy per inch immersion diminishes. That is why you must be vigilant about the way the boat is loaded. If only you and your bride are on the boat, then there should be no problem. As long as you do not have rowdy parties with lots of people aboard you will be fine. Do not let that assurance lead you into a false sense of security.

    Given your woodworking experience, you will, no doubt, do a fine job of this project. And remember that everything you put on the boat does indeed weigh something. Amazing how the sum of a bunch of small parts can add up to more than you anticipated.
     
  12. SamSam
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    SamSam Senior Member

  13. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    here is a link and pricing for about any type and color of tarp/canvas you can imagine. Pretty cheap put over a wood frame and should be good for a few years if you store it in the winter.http://www.a1tarps.com/category.jhtm?cid=201
     

  14. BobL
    Joined: Feb 2011
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    BobL Junior Member

    Pontoon pilot house

    Thanks for the reassuring words. My wife has reminded me several times that I'm building a shelter for the boat, not an F5 mandolin. I've weighed all the materials I plan to use by the board foot, so I'm watching my weight, thanks to the information you and others gave me. Thanks to all of you! I have come up with an "off the wall" name for the vessel----"Res Ipsa Loquiter" If I'm not totally embaressed with it when I finish, I'll post a picture. BobL
     
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