rocker

Discussion in 'Boat Design' started by tdd4, Jul 26, 2011.

  1. tdd4
    Joined: Jul 2011
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    Location: st. louis, mo.

    tdd4 tdd4

    i am new so be gentle and give it to me straight........I have one boat in me so I designed; with much guidance from this site, a 13 foot punt based on the pole punt 36'' wide and 1x12 sides so, what I am concidering is pushing the apex of the rocker back towards the stern... I'm 235# and will be using a paddle and trolling motor how will this affect the trim and preformance. My wife is 130#
    Can I have a refrence onhow to decide seat position and rocker design?
    I apologize in advance for the basic and naive nature of this question but its where im struck .... oh and thanks
     
  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    At the risk of violating your request for gentlness I will comment on your proposed punt design. You did say give it to me straight.

    At the dimensions you have mentioned, the boat will be dangerously overloaded. A one by twelve plank, for the sides of the boat, will finish at 11.5 inches. You'll be suporting more than 500 pounds on 36" beam x 13 feet with too little freeboard.

    Most of the knowlegeable forum members will be pleased to provide friendly council. I will be the first to advise you, in all sincerity, NOT to design your own boat. There are many reasons for that advice, not the least of which is to have you avoid drowning yourself and your companion.

    Do build a boat but get some plans from a qualified designer. There are hundreds of them available and many of them are cheap and some of them are free. Start a search on the internet for those plans. You could start by trying Duckworks.com. There are many other good places to search. Just be sure that the design you select is by an established designer whose boats have been built and used successfully.
     
  3. lewisboats
    Joined: Oct 2002
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    Location: Iowa

    lewisboats Obsessed Member

    This is built of 1x12s for the sides...not a lot of depth to be honest. I sit on it not in it. You are looking at about 205 lbs of me right now in a 12 foot hull that is 42" wide aft and 36" wide forward made of 1xs and 1/4" ply. You would want 15" sides and 48" beam to have a reasonable open boat to carry 465 lbs and itself.

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    This one here actually worries me a bit...I didn't realize how much of me wasn't in the boat.
     
  4. frank smith
    Joined: Oct 2009
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    Location: usa

    frank smith Senior Member

    I would make it flat in the middle and curved up at the ends , as rocker can make it rock , or pitch . I once saw a small row boat modeled after a sharpie , it had to much rocker and ,when power was applied to the oars , the bow would just rock upward . So the minimum amount of rocker is best here I think . If the free board it to little , just add another stake. Do take the time to look at other designs as a guide . And as always ,wear your PFD .
     
  5. frank smith
    Joined: Oct 2009
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    Location: usa

    frank smith Senior Member

    lewisboats, nice boat , I'll bet it will move in a breeze . I dig the paint job .
     
  6. tdd4
    Joined: Jul 2011
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    Location: st. louis, mo.

    tdd4 tdd4

    messabout, im sure you gave it to me the way i aSked for it....thanks.
    i however am in too deep i have look hard at your planked boat with 1x12s
    i believe what i ill do is add height to thesides to 18 '' and then widen the boat to 4 ' keeping it square and plumb front and rear 12'' decks to more tan a trolling motor and oars...give up on the paDDLE ... MORE LIKE A HANDY PUNT
     
  7. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    You might take a look at the PDRacer. It is a short version of the one you wish to build. Google P D Racer and you can find the plans and a lot of commentary about this homely but fun little boat. It has some rocker dimensions typical of the use for which it is intended.

    Your punt, at 13 feet by 48" x 18", is now far more capable, safer, and more practical. Go for it. One question though. Why use 1 x 12 plank instead of plywood?
     
  8. brucehallman
    Joined: Jul 2011
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    Location: California

    brucehallman Junior Member



    I ran some quick numbers and (if I understand you) a boat 13 feet long, 3 feet wide with 1x12 sides would hold about 220 lbs with a waterline at 6 inches of displacement, assuming a boat weight of 50 lbs, that is 170 lbs crew weight.

    One way to increase this would be to increase the width from 36 inches to 48 inches. The other way would be increase the sides from 1x12 to 18 inches, or more.
     

  9. tdd4
    Joined: Jul 2011
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    Location: st. louis, mo.

    tdd4 tdd4

    The 1x12 sides add weight but match my skill sets and work area (ashamed to say) also the Idea came from at boat I saw that was built with two 2x12s sides and was 12 foot long. A monster but it was floating down the river ( Missouri ) It was 36 wides 24 inch sides. At any rate I drew up plans for a 22 inch sides and have
    shorten the LOA to 10' x 48'' with 3/8 in ply bottom after studying plans for a handy punt. The boat will be on the heavy side but will be be closer to a proven design which will put me, my wife and aging father at ease.... the next one will be plywood. Btw is there a simpler formula for determining weight capacity.. a rule of thumb if you will?
     
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