Wood Boat Plans

Discussion in 'Boat Design' started by Sandy1, Mar 3, 2015.

  1. Sandy1
    Joined: Mar 2015
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    Sandy1 Junior Member

    Hello.
    I've been searching the internet for a couple months now, and have not been able to find a boat plan that meets my needs. Okay guys so here is my criteria. I would like the boats capacity to be 500 pounds, seat two people side-by-side, would like it to be under 9 feet long if possible, be the lightest possible construction, be stable up to 10 miles an hour and finally, I'd like to make it from wood. If any of you have ideas for me, or can steer me in a direction where I might be able to find information, that would be wonderful.
    Thank you advance!:)
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    I am not that surprised you can't find anything that answers that description. It is actually a tough contract, if the two sitting side-by-side are "average" size adults. Under 9 feet is tiny, and presumably one will be steering the boat, getting in the way of the other one not steering, and vice-versa !
     
  3. valter.f
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    valter.f Junior Member

  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    A 9' dinghy, traveling at 10 MPH is running at a S/L of 3, which is full plane mode, so it needs to be a skiff like hull. The Iain Oughtred dinghy listed above will not met any of the requirements, except length.

    500 pounds capacity isn't so tough, though given the typical 360 pound crew weight, this means a 140 pound boat, including motor, fuel, cooler full of beer, etc. Given a 60 pound outboard, 20 pounds of fuel, now we're talking about a 60 pound boat. Now a 60 pound 9' boat is possible and I have a 10' flat bottom design, that is 60 pounds when finished, though it's not a full plane hull form.

    Finding a full plane hull form in a 9' length, will be a tough search, though there are some possibilities. The basic problem is, boats of this length are generally used as yacht tenders or dinghies, which means they're designed to carry a hefty load, but not necessarily to plane off. Some can plane, though usually not very well and also usually at the speed it might be towed, rather then pushed with an outboard. This is the general role for a 9' dink, to carry skipper and crew, with their supplies and gear, to and from the mother ship and get towed behind same.

    Go over to Bateau.com and look at their "Fast Garvey 10" (> http://bateau.com/studyplans/GV10_study.htm?prod=GV10 <), which is a touch longer then your needs, but can take an outboard, will have some reserve capacity and can getup and scoot if you want.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Don't forget the lovebirds sitting side-by-side ! I can visualize this, sitting up the back of the 10 foot planing dinghy, on the same thwart....things will be barely manageable with the nose pointing upward alarmingly, getting completely out of hand when the throttle is opened. It can be done easily enough if the crew can bear to be separated by about 6 feet of so, lengthways.
     
  6. lewisboats
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    lewisboats Obsessed Member

  7. Sandy1
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    Sandy1 Junior Member

    Thank you all so much for your replies. All the information is very helpful. I've owned several boats but have never built one, which I'm sure is obvious to most of you. One thing I missed in my initial post was that I was planning on it to be "electric" powered, rather than gas. I envisioned the battery or batteries near the front of the boat. I was trying to consider proper weight distribution throughout the hull, such as seating being more centered as to encourage it being level not moving and easier to plane. For the motor, I was thinking a larger trolling motor with at least 80 lbs. thrust. I have no Idea if that's going to be anywhere enough power to achieve 10 mph. Not that the high speed is an absolute must. Thank you all again for you ideas and experience and appreciate it very much!
     
  8. lewisboats
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    lewisboats Obsessed Member

    I expect you won't see 10 mph unless you go with a very high thrust 24 volt motor. You'll pay for that with a lot of battery weight... 80-100 lbs worth if you want some endurance. The motor won't be any slouch either... 30 lbs or so? You'll sink a grand easy into the propulsion system what with the 4 gauge or thicker wire you want for the motor current load. I thought you wanted this light weight. Boat, motor and batteries so far will push you up close to 250 lbs.
     
  9. Rurudyne
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    Rurudyne Senior Member

  10. PAR
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    PAR Yacht Designer/Builder

    To go 10 MPH on electric, you'll need in the area of 3 KW's of energy (in the 350 pounds of thrust range), so a lot of power for such a small craft. A typical trolling motor will not get this done, mostly because they're proped to run at 3 MPH trolling speeds. Of course, you could reprop, but now you're just playing and fiddling, until you get lucky. The biggest commonly available trolling motors are in the 100 pounds of thrust range and usually 36 volts (three 12 VDC batteries at least). 3 groups 24's will weigh a minimum of 105 pounds.
     
  11. Sandy1
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    Sandy1 Junior Member

    Thanks for your ideas. They are very much appreciated. A lot to consider here. I definitely would like to stay with electric, so the bottleneck seems to be the weight displacement because of the short length, associated with the speed. I actually don't mind loading the boat with the necessary equipment when ready to launch, just so that it is light enough to move without the batteries motor and other accessories. I've even considered that I might take fewer batteries, if I took out the boat myself on a shorter outing. I realize that trolling motors are designed for going slow. I may need to reconcile that fact especially considering the length of the boat and how it would be less stable at high speeds anyway, (unless it was a single seater race boat). Again a lot to consider, overall size and length verses, shorter and more compact. Thanks again for all of your input!
     
  12. kerosene
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    kerosene Senior Member

    with electric speed, power, and weight will put you on a merry go round like a cat chasing its tail.
    You cannot have fast (and 10mph for small is fast) boat with electric. To be fast you have to have power and be light. To have power you have to add weight (batteries).
    Read a few electric boat threads in the hybrid section to get an idea.

    How long do you want it to run with batteries on one charge? absolute minimum.
    How much are you prepared to pay for the propulsion system? 5hp outboard is pretty cheap compared to electrics.
     

  13. PAR
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    PAR Yacht Designer/Builder

    3 phase and stay within the length of the extension cord's connection to the dock.

    Sandy, you're not the first to envision something like this and we've been trying for many years (decades) to get electric up and running, but the same issues keep creeping into the equations. We've made some advances in recent years, but range and weight are still the biggest problems, assuming cost isn't a concern.

    You could arrange something that will make the speed, say a DC washing machine motor, straight shafted to a outboard prop. You'll blast right up to 10 MPH, maybe more, but in a few minutes the 2 big car batteries will start to smoke.

    It might be possible to get one of the new Torqeedo outboards (electric) to push a lightly built, probably pretty narrow 9' boat to 10 MPH. The "Cruise 2.0R" is a 5 HP equivalent and costs $3,350. A gas 5 HP outboard will cost much less (the cheaper ones in the $1,000 range) and weigh less too. Name brand outboards will be much closer to 2k, but still considerably cheaper than a Torqeedo.
     
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