Deadrise on 13ft garvey style boat?

Discussion in 'Boat Design' started by Paul D, Mar 29, 2019.

  1. Paul D
    Joined: Jun 2018
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    Location: New Zealand

    Paul D Junior Member

    Hi everyone im hoping to get a bit of insight on boat design im interested in the power garvey stlye hulls mainly because of there stablability ,load carrying and there squarish nose bow thought it would suit a casting deck etc main use would be fishing and hunting with 2 people gear etc in our large river here where i live....

    Im planning on building one in the plywood stitch and glue method having built a plywood punt before ...the punts a 13ft slightly rockered flat bottom hull which i use a 5hp for, its a good drift boat but powers up stream pretty much at walking speed which can get frustrating hence my plan to build a planing hull....

    Ive considered building a simple jon boat design which would suit the shallows here ,but the river can get a small chop on at certain times and i thought a little bit of v in the hull may help..

    so one of the reasons for this post is how little deadrise or what angle of v in the hull would be suitable to handle a little bit of chop?... and still have a shallow draft etc....is say 10 degrees or less of deadrise a waste of time?...

    And also if i had ago at designing one myself ..(which i know there's a lot of good plans out there ..)...but thought for a small planning hull if i kept the back say 2/3rds maybe less of the boat flat( no rocker at the rear) and near the front a slight curve up to a pram style bow which i done on my punt obviously i would try to keep nice lines etc....and have a 10degree or less deadrise v at the rear thru to bow....sides flared slightly or plumb... ...transom angled back 15degrees for trim... hardwood keel.. running strakes etc etc

    Anyway for a simple 13ft slightly v garvey or v jon boat would it be unwise not to just buy plans ...or would it be simple enough to just design build one yourself?....it seems simple in my mind after building my last boat but I'm guessing I'm probably missing a few important facts about planing boat design....

    Anyway hopefully my questions aren't too confusing .....i have looked at alot of plans bateau etc...the one i like is sam devlin's cackler but i want to build a smaller lighter version maybe one that would plane on smaller hp... Cackler14Beauty.jpg

    anyway really appreciate any advice..
    Thanks
     
    Last edited: Mar 29, 2019
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    10 degrees would be good, no more.
     
  3. Paul D
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    Paul D Junior Member

    Thanks mate appreciate it....would anything less than 10degrees be a waste of time?
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    7-8 degrees might even be enough, and is a big improvement on flat. How much power do you anticipate ? 13 foot is probably a good size, and 10-15 hp would be easily enough to plane a light boat with two aboard.
     
  5. Paul D
    Joined: Jun 2018
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    Paul D Junior Member

    Im planng on about 10hp the tohatsu 9.8hp 2stroke motor its 26kgs and would still suit my punt i built....i thought the shallower i get the deadrise the easier it will plane aswell so if 7 degrees would work it may be the way I'll go....im planning on putting a sealed floor in aswell as decking the top of boat like devlins cackler design....the decking and floor will add weight so i may have to go to a 15hp outboard....was thinking of going the full width of the plywood for the bottom of the hull which is 1200mm (4ft)so cutting down the middle and giving it a 7 degree deadrise i will probly end up just under 1100mm of hull beam maybe havent figured it out yet...i may go wider just would need extra materials...
    Cherz
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

  7. Paul D
    Joined: Jun 2018
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    Paul D Junior Member

    Yea i like mark bowdidge designs the tropic 14 is a bit big for me the 12ft one is probably not bad ..im not sure what deadrise they are but a hull shape similar to that would be what im after..... the plans are the cost of 3 sheets of plywood although definitely worth it im on a budget lol....
    My boats probly not guna be that pretty but hopefully do what is needed
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    The deadrise is listed as 7 degrees for the 14 footer, 6 degrees for the 12 footer, I reckon a touch shallow, but only my preference. I think your beam is too narrow, I'd be working on 13 x 5 feet, for a more stable boat. You could plane OK with 10hp with a light hull, and not overloaded.
     
  9. Paul D
    Joined: Jun 2018
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    Paul D Junior Member

    If i keep the hull bottom at just under 4ft wide and flare the sides out a little would that give me more stability? ...i could go wider tho it will just add one more sheet of plywood maybe....i have a standard home trailer that i built a jig for a boat to go on its only 1270mm wide was trying to design my boat to fit on it aswell...i could modify it....
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    If you happen to want to carry a bit more load on occasion, the wider bottom will actually plane more easily.
     
  11. Paul D
    Joined: Jun 2018
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    Paul D Junior Member

    Thanks mate appreciate the advice .....makes sense ...i may just have to find myself a boat trailor or bigger home trailor ......is it ok to keep the width of the boat the same from transom to mid section of the boat then taper slower to bow....i see some designs taper in towards the stern transom making the transom narrower is this neccessary for any reason?
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    No, you can keep it like a box, but you need some slope to your topsides, or water will splash into the boat too easily.
     
  13. Paul D
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    Paul D Junior Member

    Thanks for your time mate no doubt i will have some more questions..cherz
     
  14. Paul D
    Joined: Jun 2018
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    Paul D Junior Member

    Would it help any with planing or anything with a transom like this...
    Screenshot_20190330-170254_Samsung Internet.jpg
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    No, you will just lose space inside the boat. That idea might have some merit if one-up, but with two persons, the other can sit forward to balance the boat. That engine in the pic looks like it would be hitting the boat before it got the full range of steering.
     
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