3 ft. wide sailboat using pdracer rocker

Discussion in 'Sailboats' started by Gabe, May 11, 2015.

  1. Gabe
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    Gabe Junior Member

    image.jpg

    I couldn't resist narrowing the pdracer to three feet. It's fast and fun. Best of all it fits in my stationwagon.
     
  2. messabout
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    messabout Senior Member

    PDR at 36 inch beam would be quicker that its fat sister one would think. Keeping it right side up might be a bit more problematic though.

    I have actually threatened to build one with 40 inch beam that could fit into the back of my Honda Element.

    Tell us more about your experience with the skinny PDR Gabe. I'm interested. How much sail are you flying, how much wind speed, etc
     
  3. captngraybeard
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    captngraybeard New Member

    what size sail and type
     
  4. Gabe
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    Gabe Junior Member

    image.jpg
    My sail is 40 sq. ft.(8x10) heavy duty poly tarp. Freeboard is 11"
    I used 2 sheets of 3/8 and made 2 transoms and 2 bulkheads(airtight fore & aft) from the deck cockpit opening. 3/4 inch chine and titebond 3 treatment on the edges. So far so good. Coated the test foils with it too. I had a gallon of grey marine paint on hand.
    The trip pics on the Hudson in Albany NY. Winds from the south at 15 and incoming tide. I basically sailed from east to west, crossing the river a few times. Felt like I was gliding along and the healing felt solid and at times I stood up and moved around the cockpit a bit. Felt stable enough to paddle standing.
    It's a fun little boat and suits my sailing fix just fine. I only chose 3ft vs 4ft wide because of transport issues in that I just wasn't feeling comfortable strapping a normal PDR on my roof rack. This one fits inside nicely with about a foot of hanging out the back end. I've even strapped it to the roof rack a couple times.
     
  5. Gabe
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    Gabe Junior Member

    image.jpg
    It almost ended up up a paddle boat kayak thing. But I had some oak from a salvaged futon frame and plus I really wanted to sail this summer. Voila. I can remove the mast eallsily enough and it transforms nicely.
     
  6. Gabe
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    Gabe Junior Member

    image.jpg 110lb paddler. I'm 190lb. and both transoms are a couple inches above the water line. It draws 4" of the 6"PDR rocker with almost 200 lbs. at 3 ft wide. The boat weighs 75lbs.
     
    Last edited: May 12, 2015
  7. Gabe
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    Gabe Junior Member

    image.jpg fits in car nicely
     
  8. messabout
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    messabout Senior Member

    I see a dagger board in one of the pix, but I do not see a case for the board. Where do you insert the board?

    I think the ugly mortar box looking PDR has been made into a cute little boat. It appears that you have done a nice building job.
     
  9. sharpii2
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    sharpii2 Senior Member

    Congrats on your successful build.

    Looks like you came up with a very useful and convenient little boat.

    I'm thinking of something similar.

    mine will be 10 ft long, but with the same 3ft Beam.

    Do you ever sit on the side decks?
     
  10. Gabe
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    Gabe Junior Member

    Thanks, I love the little boat. I know shorty pen built a 12' by 3' and seems to like it a lot. A 10'er would be the perfect boat- long enough to lay in comfortably and accommodate a couple sealed air compartments. I have two air tight compartments but no room to lay down. I thought I might make something to span the opening and lay on top. It would be just long enough to lay on top and put an a frame tent over the boom. The side decks are almost useless except for when I capsize (haven't yet except to test self rescue) practically no water will need to be bailed. I sit to one side or the other on deck just aft of the cockpit with room to slide side to side and not bump the tiller. Seems to be the sweet spot for balance when under sail. I've considered cutting the side decks out and the sweet spot so that I can sit in the boat and slide from one side to the other. It's funny you said 10' cause I've been thinking the same thing. What's a couple extra feet - more room for camping. I'm really surprised more people aren't making these 3' wide boats. They're suprisingly stable. I stand and fish from the cockpit sometimes and don't feel tippy at all. I even like to push it to the tipping point just for fun. It's not like it will sink or anything. Do it, build the ten footer. I think you'll like it. Now I might build a ten foot version next so I can accommodate a passenger or comfortably solo camp.
     
  11. Gabe
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    Gabe Junior Member

    I have a leeboard slot cut into the rail on either side. Just need to remember to switch it from windward to leeward when tacking. It stays nicely pressed against the freeboard once in the slot. I sometimes think I don't need it because I have about 4% of the sail in freeboard alone running under water. I have smaller daggers I'm considering using in tandem. But think it will be overkill
    image.jpg
     
  12. messabout
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    messabout Senior Member

    Gabe; what you have are lee boards not daggers. It appears that you may be using them upside down. The pointy parts, as underwater plates,are not very efficient for countering leeway. Make the lee board parts rectangular and you won't need them on both sides of the boat unless you are sailing at precarious heel angles. That would presume the placement of cleats or brackets at or near the chine, to hold the bottom of the board in place when the board is on the windward side. Less busy work that way.
     
  13. Gabe
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    Gabe Junior Member

    I haven't used the pointy ones yet, just the one rectangle one that you saw in my first post. I'll stick to the rectangle cause it seems to be working fine
     
  14. sharpii2
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    sharpii2 Senior Member

    Hi Gabe.

    Attached are some sketches of my proposed 10 footer.

    As you can see, it has a much deeper rocker. It has one inch of rocker per foot of Boat, approximately.

    The sides are 15” tall and the side decks are about 8” wide.

    The idea of the deeper rocker is to allow the boat to heel over more before the transoms dig in.

    This effects three things:

    1.) it presents more of a “V” bottom to the water,
    2.) it decreases the whetted surface, and
    3.) it presents a large flat underwater area to leeward, which may preclude having to use a board.

    The board shown is a simple, true lee board. It is always set on the lee side of the hull. It is only secured at the top, with two lanyards, so is free to pivot and/or bounce up if it hit’s a stump. The only trick is that it has to swap leading and trailing edges every time it switches sides. But it’s simple, cheap, and easy to repair on site.

    The rudder hangs on a hinged false transom, so it can kick up if it hit’s a stump. It is held down with a single shock cord, attached to the bottom of the boat. It is controlled by a yoke and a continuous line, which leads through eyes on the bow transom.

    The idea is to have everything easily at hand. The mast is nearby too, so raising, lowering, and even reefing the sail can be easily done while on the water, without me having to move too much.

    The seat sits on a set of rails, so it can be moved fore and aft, to adjust the boat‘s sailing trim. Another seat can be added for a small passenger.

    Flotation will come from insulating foam, which will be installed under the side decks.

    These narrow box boats get much of their stability from low placement of the crew weight, which tends to act as ballast. The initial stability may not be that great, but there is a wider range of stability, with less likelihood of the boat turtling, should she capsize.
     

    Attached Files:


  15. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    Boardless sailing

    Gabe.

    I've been thinking about your boat and the possibility of sailing it without a board.

    It may be possible, if you immerse the lee side all the way up to the transoms.

    This would give you what is, in effect, a long shallow keel with considerable area (approx. 2.50 sf). This may seem quite generous, but is really not, because long keels work differently than short deep ones.

    Short deep keels (or boards) act as aircraft wings, as the water flow on the windward side is at least as important than that on the lee side.

    Long, shallow keels work more like snow plows, where the flow on the lee side of the keel (in relation to the wind) is most important. For this reason, long shallow keels are not as efficient as short deep ones, as almost all the lift comes from the lee side .

    From my calculations you should still have enough keel area. But this isn't the end of the story. Having more area only somewhat compensates for the inefficiencies of a long shallow keel.

    Because it works more like a snow plow and less like a wing, it needs a greater angle of attack to get sufficient lift.

    My guess is that you will be able to get at least 140 degree tacks, or maybe even 120 degree ones (made good).

    This will never win any races, but may well win a few water front bets:D

    The trick will be getting the balance just right.

    It appears that your mast is set about 18 inches from the bow. This puts your Center of Area (CA) of your sail at about half the boat length back. Te Center of Lateral Area (CLA) is a bit further back.

    You may have to rake the mast aft a bit to make up for this. Or you can sit far enough aft to move the CA of the sail aft by the trim of the boat.

    It may be tricky to get this just right (bring your board in case it doesn't work out).

    But if you do, it may be great fun.

    Part of the trick will be to get the boat moving at a good clip before turning into the wind. Then watch your wake. It should be trailing just slightly upwind of the boat.

    I hope you try this.

    When I build my ten footer, I'm sure going to.
     
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