Things I have learned from building and designing boats

Discussion in 'Boat Design' started by David L. Dodd II, Mar 29, 2021.

  1. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    As a small homestead farmer, I watched the supply stores change over from high wattage incandescent grow lights, to lower wattage florescent, then to "greener" low energy bulbs and now I'm hearing, though I haven't seen them in my store yet, about LED grow lights.

    The paradox is, the newer bulbs contain chemicals that the people at the transfer station have to handle with extra care and the low energy bulbs don't put out the heat so now, to get your seedlings started right, you have to also use heating pads under the plants. In the end, the shift to greener and more energy sustainable plant lighting equals more equipment, more toxic chemicals, more electricity and a lot more expense.

    I appreciate the effort and the sentiment, but incandescent bulbs are the way to go for some applications.


    I do like LEDs though. Except the blue ones mounted on cars because they keep making me think I'm being pulled over by the police.
     
  2. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    I have learned that a boat's actual use should dictate its design. And great care must be used to find out what that actual use is. Be honest.

    There is as much such a thing as too much boat as there is not enough.

    So far, I have designed 6 scows for the only client foolish enough to have me as a designer: me.

    Two were 12 ft JB312s*, two were pdracers**, and one was a 10 ft JB310. 4 of them could get me on the water with substantial gear. One could get me on the water with only minimal gear.

    Where it was to be stored pretty much dictated my final decision. It will have to be stored in my mobile home, in the winter months, and on my car during the summer ones.

    It needed to be relatively easy to get on and off the car roof, but not necessarily super light. That kind of ruled out the two pdracers. The beamy, short hull would be harder to get up there than the longer, narrower design. Also, the longer, narrower design could stow all the sailing gear in the hull, so it would be out of the sun.

    Pdracers are best with huge sail areas, starting with 65 sf and going up from there. The two I designed had 65 and 70 sf, which I think is a good balance between performance and usability. If I were to race with an eye toward winning, I'd start with 80 sf and go up from there (the class has no SA limit).

    The narrower JB310 I chose will carry only 42 sft (per its class rules). In light breezes, it will probably just sit there, where the pdracers would probably scoot along, even with their more moderate rigs. But all the spars of the pdracers are longer than the boat, and would have to be independently strapped down on the car roof, in one rather large wind catching bundle.

    *a class of 4 by 8 ft straight sided scows. pdracer.com

    ** a class of 3 ft beam, straight sided scows, which I am inventing. (I'll start a thread about it, once I complete and sail my boat, which will be the first of its kind.) (and maybe the last.)
     
    Last edited: May 4, 2021 at 4:27 AM
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  3. clmanges
    Joined: Jul 2008
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    Location: Ohio

    clmanges Senior Member

    You've got your footnote markers reversed. Also, one of the more popular sails for the PDR is the Bolger 59, a leg-o-mutton rig he spec'd for several of his small boats.

    Aside from that, I'd like to know more about the 3xx-class boats. I got an offer of a complete free PDR, but it won't fit in the bed of my pickup, which measures 39 1/2" between the wheelwells, and I will not consider trailering. This is causing me to consider just such a design myself, and I'd be comfortable with the extra length as well. If I do this I would plan to use a junk rig on it because it reefs instantly and can use a shorter mast. See here:

    The Junk Rig Association - Cash prize of 250 GBP - Dinghy Design Competition https://junkrigassociation.org/technical_forum/10211344

    Are you going to use a stretched version of the PDR's hull curve, or something different?

    Finally, of all these boats you've designed, how many have you built and sailed, and what did you like or dislike about them?
     
  4. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    If you don't have a cap on your pickup, you can probably fit 2 pdracers in there. Just put them in on their sides.
    Yeah, the Bolger 59 rig is the most popular, followed by various forms of the balanced lug rig. But if you want to win a race, you need a bigger rig. The beamy hull can easily handle it. When Mike Storer came to the US with his version of a pdracer, which was completely class legal at the time. He blew everyone else away. His boat was well engineered, light (around 55 lbs IIRC. A typical boat weighed closer to 100 lbs ), had a 79 sf rig, and its rocker cut was about 1 inch shallower than the intended design, but within the class tolerance of the time. I think his superior performance was more due to the weight of the boat and crew and the large sail area than it was to the rocker cut. But still. this caused a huge dust up which crippled the class. Shorty cranked down on the rules hard. The tolerance got reduced to 1/2 inch. So now, all the boats built to the Storer design became illegal. This broke my heart, even though I didn't have a pdracer myself. If I had stuck around in the group, I may have been able to help prevent this.

    As it is. I have had this idea of a 3 ft wide class for some time (more time than I'm willing to admit), and I have decided to start it as a developmental class, with a mind toward internal handicaps, if some boats turn out wildly superior to others in the class. So there is no defined bottom (rocker) shape. There is a requirement that hull profile fit in a proportionate polygon (see attachment), without any portion of the hull crossing any of its lines.

    The sail area will be in proportion to the weight of the boat and crew, rather than a specific sail area. The formula for this does not require a scientific calculator. I'm doing this to avoid creating incentives to make the boats as light as possible. There are plenty of other classes that do this. I think it's time to try something different. I also want to avoid ever towering rigs that complicate set up and use of the boat, so I added a requirement that all the spars, including the mast, must fit within the hull when taken down. multi-piece masts are forbidden.

    There is a high likelihood that some boat and crews will weigh as little as 200 lbs and as much as 600 lbs. People come in all shapes and sizes. The heavier boats are also going to be the longer boats, but are going to have proportionately less initial stability, due to having deeper sections. But this higher initial stability, in the shorter, lighter boats may not make up for the greater theoretical hull-speed of the longer, heavier boats. So I'm working on a length handicap. So, this is all I'm willing to say about the rules I'm developing at this time.

    I share with you an interest in easy reefing. My boat has just one reef point, but should be able to reef while underway. Its rig does somewhat resemble a Chinese lug, but has only two boomlets (sometimes called battens). The top one is lowered onto the bottom one, a snugging line is pulled and cleeted, and the job is done. The sail area is shortened by almost 50%. I have already built this contraption. I hope it ends up working.

    And no, I haven't built any of these boats I have designed. The one I'm building now is the first boat I will have built in almost 50 years.


    Joeboatgage2.png Joeboatgage2.png
     

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  5. clmanges
    Joined: Jul 2008
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    Location: Ohio

    clmanges Senior Member

    Maybe thirty or so years ago I could have ... certainly not now. And if I didn't have the pickup, I wouldn't even be using a plastic kayak any more because it would hurt too much to get it on and off the roof of a car. The boat has to go in the truck bed right side up, and if it's too heavy, I'd make some sort of ramp and a rope tackle to drag it on with. No trailering for me, either.
    Interesting; that explains why there's no length specified on your template.

    Doesn't this mean that, in a competition, an official would have to measure sails and weigh boats and crews, as well as measuring the hull? I'm sure you'd have to allow entries within a range of acceptable limits, otherwise check-in would be a nightmare.

    I do like the requirement of having all the sticks fit in the boat, but I like the idea of a folding mast even better as it saves a little more fuss and handling. You could even leave all the lines attached.
     
  6. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Funny, because I do custom art and woodwork. I specialize in pyrography. When I first started estimating the pricing for a piece, I used my plumber as a standard, $100/hr. When I totaled the final value for a given project I couldn't help but look at the result and think, no one is going to pay that for art, so I cut it in half. I also don't charge for the preliminary work, thinking of all the sketches and adjustment going back and forth as part of the bidding or sales process. In the end, I think I only make a quarter of what I originally set out to make.
    20180403_122100.jpg
    WBurnd, Trout W&L-Big.jpg
    My latest one is a mermaid weather station made with a piece of cherry the customer had h held onto for thirty years and wanted something special made from it.
    I won't show it here because my customer and friends wanted something that showed the seductive nature of the siren, and I'm not sure what is acceptible here. Beautiful work! https://forums.sailboatowners.com/threads/beautiful-work.1249929159/#post-1695046 , but I'm quite proud of how it came out.

    -Will
     

  7. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    I hear you. I'm headed down the same road myself. In the trailer park I live in, I'm not allowed to keep the boat outside. And I would have to rent space to keep any trailer. I also won't be able to sail until I retire. I work 6 to 7 days a week and have other responsibilities on top of that. This is why I haven't built anything yet.

    There will be a maximum length limit of 13 ft. But, because of the peculiarities of the hull profile, combined with the hard SA limits, some may want to build shorter boats. A bigger, lighter one may not be competitive. I'm working on a 'length handicap' to mostly make up for shorter hull lengths. I don't want to end up with people diliberately building slow boats to take advantage of this handicap.

    No. There would be an 'honor' system. But the winning boat and crew would be weighed and measured immediately after the race.

    I don't see how a shorter, non-folding mast can't do the same. I want to get away from tall rigs. The truth is that tall rigs are superior to shorter in all points of sail except down wind. They are also a capsize hazard. Not so much while under sail, but when accidentally caught aback. This is when the longer capsize arm is not made up for by greater aerodynamic efficiency. There are other things about tall rigs I don't like, but this is my main objection.

    If tall rigs are allowed, all we will see is tall rigs, at least in the racing part of the fleet. Shorter masts are easier to set up and have far more material and construction options than tall ones, as tall ones must be light.

    I have seen some creative multi-part tall masts. My favorite is the Tim Cleary mast for a 59 sf leg'o'mutton sail. It had 3 pieces. One was a 2x4. One was a 2x2. And the top was a 1x2. The mast was twice as long as the boat. The 3 pieces were held together with 4 bolts w/wing nuts, then the sail had to be lashed on (leg'o'mutton sails usually have no halyards).

    I would also like to see a bit more creativity in this new class than trying to copy what the high-end racing fleets are doing. But I might reconsider.

    My boat will not be a competitive racer, as it intended primarily for fishing. It's 10 inch wide side decks will preclude moving my bulk to windward very much.
     
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