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Thread: 3 Sheet Ply sailboat

  1. #1
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    Default 3 Sheet Ply sailboat

    I would like to build / design a 12ish foot sailing dinghy. I want it for inland water and estuary cruising. I have set myself a target of 3 sheets of ply, just because I know that is feasible. From the 3 sheets I would want the hull, foils and rudder. Built in buoyancy is not required as I will use beach rollers or expedition barrels for this. I want a boat looking boat not a brick, just for the aesthetics.

    My research has come up with the following: any ideas for other boats that meet this criteria would be greatly appreciated.



    I have plans for Selway Fisher Swapscott 12
    “The first Fisher Swampscott 12, with a length of 12ft and beam of 4ft 2 inchesand narrow tombstone transom and with 9mm bottom and 6mm planks (lightweight Gaboon ply), with 6mm ply for the seats etc, came out at just 66 lbs. in weight and took only 30 hours to build (including all marking out). She took just 2 sheets of 9mm and 2 sheets of 6mm exterior or marine ply plus a few lengths of Douglas Fir. Because of her light weight, she was easily car topped”
    http://www.selway-fisher.com/Other1013.htm

    And the Arch Davis Maine Peapod has a lot of appeal

    “The peapod uses three sheets of 8’ x 4’ x 4mm marine plywood for the planking, 1 sheet of 1/2inch plywood for the station molds, some lumber, epoxy resin, fastenings, and some hardware”
    http://www.archdavisdesigns.com/davis_peapod.html
    This can’t include ply for foils I am sure

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    Default Re: 3 Sheet Ply sailboat

    Richard Woods "Duo"
    http://www.sailingcatamarans.com/ind...sailrow-dinghy

    You can put your beach rollers on the outside.

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    Default Re: 3 Sheet Ply sailboat

    There is only so much you can do with 3 sheets, and Arch,s pod is a great looking example, i think.

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    Default Re: 3 Sheet Ply sailboat

    I can't resist to throw in one of my many half-baked design studies just to show what is possible with a given number of sheets. This arbitrary restriction may not make sense, but it is fun for me to max out the limits of this given number.

    A modification of Herreshoff's H-14 dinghy in the style of Russel Brown's PT 11. Two sheets for the hull -- a third one for whatever. This is not the latest version, but it gives an idea of the panel layout. LOA: 11' 6", beam: 50"









    Last edited by flo-mo; 07-04-2018 at 05:45 AM. Reason: Got LOA wrong - it is 11' 6" not 12' 6"

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    Well that went better than I expected
    My peapod design very roughly laid out on 3 sheet. The middle one would be the bottom panel and thicker ply, plenty spare for, thwart, board case and rudder stock.






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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by flo-mo View Post
    I can't resist to throw in one of my many half-baked design studies just to show what is possible with a given number of sheets. This arbitrary restriction may not make sense, but it is fun for me to max out the limits of this given number.

    A modification of Herreshoff's H-14 dinghy in the style of Russel Brown's PT 11. Two sheets for the hull -- a third one for whatever. This is not the latest version, but it gives an idea of the panel layout. LOA: 12' 6", beam: 50"









    Fully agree self imposing limits make to sense but it adds to the challenge and stops things getting out of control. That is a fantastic bit of design and Russel Brown is a total hero in my book. 2 sheets of 6mm would make a very light boat. Thanks for that

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    Default Re: 3 Sheet Ply sailboat

    Flo-mo
    I very much like your modified shell back dinghy http://flo-mo.weebly.com/two-sheet-boats.html Joel Whites Sheelback used three sheets in total with the bottom sheet like my peapod available for rudder blade, trunk sides etc etc. I think it looks like the H14 inspired design has a bit more free board and a more rugged boat. Herreshoff obviously liked his leeboards and so with a leeboard the extra sheet of ply is elimited.

    Quite like the idea of using a third sheet to make a simple double bottom (possibly partial) for buoyancy and dry righting after capsize but beach rollers seam a better idea.

    I am not sure if you offer you designs commercially but are you OK if I draw up my own version of the H14

    A Herreshoff, Brown, Flo-mo inspired design

    A Shellback size / style is what I have in mind as design. The first comment from this website inspires me

    http://theoarcruising.blogspot.com/2...ck-dinghy.html



    I cruised my shellback last year for over 2 weeks (North Channel & Rideau Waterway) and plan to do more this year. The wonderful thing about this boat is its versatility. Sail when it's windy, row when it's calm, car-top it singlehandedly to and from launch points. Removing the sailing component means you can't travel far when the wind picks up from the direction you wish to go. Shellbacks go well to windward. The sail not only provides propulsion (for free and it's lots of fun), but stabilizes the boat in rough water. Adding decks just complicates things... Harder to get to gear, less space to move around. I stow all my gear and food between the bow and center seat, and lash it to tie-downs so it won't go anywhere at high angles of heel (read capsize). The space between the middle seat and the rear seat is my living room. At 6'2", there's ample room for me to sprawl in the bottom of the boat while sailing, my head against one gunwale and my feet up over the other. A number of positions are available so I don;t get cramped. It's quite comfortable and very secure. Decking would simply makes this arrangement impossible. Similarly, floorboards are unnecessary... what value do they add? I lie in the bottom of the boat, which has only 1 mid-rib, and lack of floorbards makes it easy to bail out any water that comes aboard. When people say "simpler is better", it's for good reason. I cruise with a variety of other boats, all longer than mine, but espite its short waterline, my fellow cruisers admire the versatility and speed of the shellback. At just over 100 lbs, its easy to pull completely out of the water at the end of the day, something that they simply cannot do. For solo cruising, it's almost perfect. The only thing lacking is the ability to sleep aboard. That might be feasible, but would require floorboards to get rid of the bump caused by the central rib, plus some form of cover. I worked around that problem by getting a Marsh Hen... has a huge deck for sleeping on, with a dodger/tent... but it's a whole other class of boat. For simple cruising in remote areas where I can sleep ashore (i.e. no private land, cottages, etc.), and we have plenty of that in Canada, the Shellback can't be beat! Joel did an amazing job when he designed that boat. It's seaworthiness in rough water has to be experienced to be believed. Bobs around like a seagull!

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    Default Re: 3 Sheet Ply sailboat

    Hi tink,
    I do not sell plans of any of my designs. Feel free to use whatever may inspire you.

    Kind regards
    Stefan

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by flo-mo View Post
    Hi tink,
    I do not sell plans of any of my designs. Feel free to use whatever may inspire you.

    Kind regards
    Stefan
    Thanks Stefan,
    I am inspired ��

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    Default Re: 3 Sheet Ply sailboat

    A stitch-and-glue version of Joel White's Pooduck Skiff would also meet your requirements.




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    Default Re: 3 Sheet Ply sailboat

    Great ideas, thanks guys.

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by flo-mo View Post
    A stitch-and-glue version of Joel White's Pooduck Skiff would also meet your requirements.



    Thanks like that, what are the principle dimensions?
    Have been working in something more Pooduck size since my last post I think that the Shellback was a tad small for my needs and if you are going to go into the third sheet for sides of the board and other bits I might as well go a bit bigger.
    Have been going more like your H14 with the stem and transom more vertical to maximise water line length.

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    Default Re: 3 Sheet Ply sailboat

    The 3D-model I made to create the developed panels is based on the linesplan from Forty Wooden Boats. So the dimensions are those of the original design.
    LOA: 12' 10"
    Beam: 4' 6"
    Midship depth: 18"

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by flo-mo View Post
    Hi tink,
    I do not sell plans of any of my designs. Feel free to use whatever may inspire you.

    Kind regards
    Stefan
    Thank You for the duck punt plans. I used your panel and frame shapes to build the punt on my build thread, though I framed it like a traditionally built one, because I’m weird.

    Everything was a perfect fit.

    Peace,
    Robert

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    Default Re: 3 Sheet Ply sailboat

    Brilliant panel shapes Flo-Mo - especially the back half which looks to be a speedy bugger, indeed.

    These ever been built and sailed -very curious to hear a sailing report

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    Default Re: 3 Sheet Ply sailboat

    And this just sells the Pooduck to me

    https://youtu.be/KnEBACCkI-g

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by flo-mo View Post
    The 3D-model I made to create the developed panels is based on the linesplan from Forty Wooden Boats. So the dimensions are those of the original design.
    LOA: 12' 10"
    Beam: 4' 6"
    Midship depth: 18"
    I'm not sure how you do it but thank you very much. To get such a craft out of 3 sheets is a great achievement

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    Default Re: 3 Sheet Ply sailboat

    A Pooduck has weighty 12mm bottom and 9 mm sides...and those 3 sheets are the same cost as 4 sheets of 6mm, or 6 sheets of 4mm...

    Unless you're building this prototype for Ikea, you will be best served by spending time looking at your ramp angle, potential wave fetch, typical wind speeds etc to judge the best dinghy to build for your practical needs.

    If the sheet restriction is for a 'light car topper' (approx 20-30kg) I'd go long and narrow: close to a kayak's size and weight, probably a 15ft x 4mm ply Bufflehead with a small cockpit. Besides getting it on and off the roof, more waterline, less wavemaking resistance and a better arrangement of wetted area.

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    Default Re: 3 Sheet Ply sailboat

    Just because it's sthe boat I'd want to sail, my starting point would be the Beetle Cat. (Bolger's Bobcat being a chined derivitive.)
    Is wanting that much decking a deal breaker?
    -Dave

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by Edward Pearson View Post
    A Pooduck has weighty 12mm bottom and 9 mm sides...and those 3 sheets are the same cost as 4 sheets of 6mm, or 6 sheets of 4mm...

    Unless you're building this prototype for Ikea, you will be best served by spending time looking at your ramp angle, potential wave fetch, typical wind speeds etc to judge the best dinghy to build for your practical needs.

    If the sheet restriction is for a 'light car topper' (approx 20-30kg) I'd go long and narrow: close to a kayak's size and weight, probably a 15ft x 4mm ply Bufflehead with a small cockpit. Besides getting it on and off the roof, more waterline, less wavemaking resistance and a better arrangement of wetted area.
    Thanks, I like the idea of the size of the Pooduck but don’t see the need to go to those heavy scantlings. I am sure it would work fine with 9mm bottom and 6mm sides, plenty of similar sized boats have used lighter scantlings tha the Pooduck.

    I have a open canoe and that serves me well, this boat is to be more of a boat boat.

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    Quote Originally Posted by Woxbox View Post
    Just because it's sthe boat I'd want to sail, my starting point would be the Beetle Cat. (Bolger's Bobcat being a chined derivitive.)
    Is wanting that much decking a deal breaker?

    I to love the Beetle Cat, one concern I have is if it ever went over and turtled with the large beam it would be very hard to get back up. The beam also obviously adds lot of material and so cost and weight.

    Decking is in option and something I have thought about today. As a kid I was always amazed by Jack Holts Cadet, it has very wide side decks and so dry capsizes with ease. Such a cockpit on Pooduck derivative would make a really nice boat to camp on, tiny cockpit tent and you’re all set. Obviously it would need buoyancy for total disaster situations. I think if the deck had added benefits I could justify extra ply. I had also the crazy idea of skin on frame decks other that where the crew sit but probably going too far now.




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    Developed a CAD sketch from DelftShip model, hull only approximate.

    Quite like the idea of creating removable buoyancy from building insulation foam sandwiched between then big shed ply.




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    What I get up to
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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by tink View Post
    I had also the crazy idea of skin on frame decks other that where the crew sit but probably going too far now.
    Unsurprisingly, I think that's a good idea . . . and I have several boats with SOF decks. They work great, and both cost and weigh very little. You'll need a hard spot somewhere underneath to access the bow, if you can't just reach it from the cockpit.

    I'd probably build a sharpie from those 3 sheets, but that's just me. I do have a fondness for them.

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    Default Re: 3 Sheet Ply sailboat

    I like the direction you are going Tink.
    Along the sharpie direction is Graham Byrnes's Spindrift series. Lots of boat for the size. Larger panels might be harder to nest out of 3 sheets though.

    https://get.google.com/albumarchive/...I73geiNo9nN-gE





    Last edited by Matt young; 07-06-2018 at 07:32 AM.
    "Yeah, well, that's just, like your opinion man"
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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by Matt young View Post
    I like the direction you are going Tink.
    Along the sharpie direction is Graham Byrnes's Spindrift series. Lots of boat for the size. Larger panels might be harder to nest out of 3 sheets though.

    https://get.google.com/albumarchive/...I73geiNo9nN-gE





    Thanks for that, some nice detailing. Found the 12ft Amanda from the link which I really like.

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    This is where I got to today. Moved the mast aft a bit, the frame now forward of the board. Moved the board over to one side and added side tanks. The board goes through the bottom panel and there is still room to sleep in the aft section. Letting the design percolate and then look at widening the bottom panel and giving a bit more sleeping room. That is a big job as as to be done in DelftShip and imported into OnShape. There will be an adjustable and removable thwart for rowing.

    Kidding myself if this is a 3 sheeter, buoyancy bag / beach roller model next







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    Big rebuild required to fit in 60 kg 132 lbs buoyancy beach roller in, tomorrow’s job




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    Had the realisation that for such a hull form the round section of the buoyancy bag / rollers will:
    a) If high up result in a very swamped boat before they come into play
    b) If low down seriously reduce the area for sleeping - or storage by narrowing this area





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    What I get up to
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    Default Re: 3 Sheet Ply sailboat

    Looks like it Tink. Hey the Amanda and Spindrifts have a nice spot for the roller down in their chine. Maybe build that type Hull in plywood without the built in flotation. Do your seats out of light weight wood, and stick the rollers under them.

    Cheers
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    This is how far I think I can go with this hull form. Back to removable floatation in the bottom. One idea being make from Mixed Marshal Arts crash mats. Closed cell EVA foam 40mm and cheaper than ply. They use the same stuff for commercial boat floats and flooring. Did look ply double bottom but very inefficient. Can also fit canoe buoyancy bags to aid recovery.



    Going to explore the Spindrift form but don’t have access to DelftShip for a few weeks. Wanted something with more traditional American roots as single/double chine will look like a 1960 / 70s ply Holt type to un trained eye.


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    Some midships sections


    This one to scale



    Cube of 100kg 220lbs buoyancy and the panels developed on a sheet of ply, all to scale



    Obviously the close to a cube and using the existing hull uses the least materials.


    https://tinkboats.wordpress.com
    http://proasail.blogspot.co.uk
    What I get up to
    https://youtu.be/X9NZEyvpb_Y Streaker dinghy
    https://youtu.be/oni-3rJzxqQ Sail Canoe
    https://youtu.be/eW078PPgJak Proa

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    Default Re: 3 Sheet Ply sailboat

    There was a thread a while ago on recovery from capsize, one of the points that came up was stability when flooded.
    The thought was that some of the buoyancy needs to be spread around and at a higher level to enable the boat to be reboarded.
    The design immediately above with the blue cube would be very tippy also the design with just foam on the floor.

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by tink View Post
    This is how far I think I can go with this hull form. Back to removable floatation in the bottom. One idea being make from Mixed Marshal Arts crash mats. Closed cell EVA foam 40mm and cheaper than ply. They use the same stuff for commercial boat floats and flooring. Did look ply double bottom but very inefficient. Can also fit canoe buoyancy bags to aid recovery.
    That daggerboard looks to be a long way aft - how do the cla/coe/lead calculations play out.

    I've used closed cell polyethylene foam for buoyancy - https://www.kewell-converters.co.uk/...ethylene-foams
    Creationists aren't mad - they're possessed of demons.

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    Default Re: 3 Sheet Ply sailboat

    Quote Originally Posted by oldcodger View Post
    There was a thread a while ago on recovery from capsize, one of the points that came up was stability when flooded.
    The thought was that some of the buoyancy needs to be spread around and at a higher level to enable the boat to be reboarded.
    The design immediately above with the blue cube would be very tippy also the design with just foam on the floor.
    Thanks, something I am thinking about, in post 31 I showed buoyancy bags by the gunwale to help the stability for re-entering when swamped. I have learned that the had way getting a nasty cut above my eye when the opposite gunwale of my canoe hit me.

    The blue cube is not a proposal. I was just investigated what 100 kg of buoyancy looks like and how much ply it uses - I feel it shows how relatively inefficient it is.

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