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  1. #1
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    Default sailing canoe vs light dory

    Michael seems to be one of the best people to offer this question to considering his designs, but I thought it might be better to post it publicly vs. emailing him.

    with regards to the bolger light dory, the general consensus seems to be that a sail will not work on it. At the same time, there are designs like "Beth" and other sailing canoes & kayaks that do well enough with sails, despite the fact that a dory may have better overall stability (yes they are initially tippy, but wouldn't it just sail along on it's ear?)

    I guess my question is "why do sails work on canoes, but not light dories?"

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  3. #2
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    Here comes MIK's opinion about dories: Q&A Are Lightweight Dories Good Boats? - Michael Storer Wooden Boat Plans

    From the page:

    "And DON'T get me started on Sailing Dories ) Any of them that work are sailing dinghy uppers with a dory bottom panel only but highly rounded topsides above that - either that or heaps of ballast.

    A small rowing dory is hard to design well - a sailing dory is much more difficult as it sails on its stability."

  4. #3
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    Thanks, I have read that article a few times before, but it basically rehashes the point that dories don't sail unless they are more of a swampscott or skerry type.

    My thought is that while Michael's design "Beth" has a beamier bottom than a light dory (32" vs 24"), it would seem that:
    1) the dory is less likely to go over than the canoe
    2) there are other canoes and kayaks with sails that have less beam

    while the dory may perform poorly or not at all pointing higher towards the wind, I don't see why it wouldn't perform well enough through as much as 180* off the wind with some sort of low aspect rig.

  5. #4
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    Bolger's light dory design is so popular, someone before you has tried it.

    I would suggest the forum at Woodenboat.com and ask there under "Plans/Designs". Huge wealth of information will fall into your lap. There are lots of row boats with downwind rigs, though the only thing downwind rig I've seen on the Light Dory is an umbrella.

    The BETH and the Light Dory are two different animals for two very different purposes.

    Anyway, ask here. I'll be watching.

    The WoodenBoat Forum

  6. #5
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    The problem with a dory is many fold and the biggest problem is most things called a dory, actually aren't real dories, but skinny bottom sort of looks like a dory kind of thing. The sharpie suffers this same problem. There are about a dozen distinctly different dory types, some are better at some things than others. Some can sail, but sailing and sailing well are two different things.

    The sailing issues with a dory are that most have a quite "slack" bilge turns and no other stability advantages (ballast on the end of a fin for example). In the 19th century, a dory could sail quite well, but only when it had a belly filled with a ton or two of fish, which sank them down enough to offer some "bearing area" and ballast. In this condition they could bash through things, carrying momentum in light air or rise over seas in heavy (one reason for the dramatic topside flare on most).

    I'm not much of a dory fan, mostly because I've sailed real dories and found them wanting to say the least. Now, as to the "modified dories" of which most designs actually are, well this is a mixed bag. Some will modify the bottom beam, making a fatter boat, which offers some initial stability to the hull form, but also increased volume. The increase in volume, means the designer has to drag out the ends finer or consider other options, such as decreasing the topside flare, to whittle down the increases. Most of the time these changes just make them worse, though they may still have styling clues of the dory to which they're supposedly related.

    If you take the Bolger approach to the dory, you accept it for what it is and live with it. What Bolger did was make as the name suggests, a light dory. It doesn't have any real immersed volume, so takes little to propel it. It's narrow bottom makes her maneuverable (as does it's rocker) and she'll pick up displacement uniformly as she's loaded. Under sail she lacks "power" but this is what you'd expect from a slack bilge, narrow bottom craft without a bulb keel. It would be possible to use a canoe style of sail plan on her, but you'd be hiked out and hanging on most of the time, which isn't well suited to the dory hull shape.

    What the dory does best is, get on an off a beach with a big load of fish in it's belly. As a surf boat, the shapes are well suited and you just live with whatever else she offers. If you are willing to weigh down a dory, to get some immersed sailing lines, then you can do okay, but you've now picked up a good bit of displacement in the process, which needs to be propelled. If using human power, the two aren't especially cohabitable.

  7. #6
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    Thanks PAR, that sounds like one of the most logical explanations I've gotten so far.


    callsign222, I posed the question over there as well in the "dory design" thread under the design subthread, but got a lot of the typical " you can't sail a dory! build an oughtred design instead!". I guess part of the reason I ended up being an engineer is always having to ask "why?"

  8. #7
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    Thanks PAR for jumping into the breach.

    Another aspect is the style of sailing.

    The Canoe will feel unstable with weight moved even a little off centre. Which gives a modern sailor immediate feedback. But the modest beam keeps those forces relatively small - the waterline beam (which gives you stability) and the deck beam (which you can use to increase stability but becomes a source of instability when the wind drops) are not much different.

    The Dory on the other hand has a narrow waterline but a wide deck beam. So if you have your bottom perched on the gunwale and a powered up sail to balance then the tipping forces become rather large if the sails start producing less power. You have to move well into the boat to get your weight over the wetted portion of the hull.



    With the canoe (at least one without a hiking plank or leaning board) you can move your weight in by just bending forward. Right to the point where the person's centre of gravity is over the side of the boat there is some degree of stablity. So there is only a small movement between leaning out and being inboard.



    It also depends on your sailing background. If you used to twitch modern dinghies where you use the sails to balance your weight in a dynamic way ... then you can have a much bigger difference in waterline beam and effective width the crew can extend out to.



    I'd say that big sails are a benefit in this type of boat because the boat is always trying to capsize to leeward. So if there is a lull or a windshift you can steer and adjust sheets to keep the crew out on the wing or give time for one member to make it back in. Having him/her run to the other side is like having two come in.

    MIK

  9. #8
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    makes sense, thanks for your reply.

    I think my conclusion is that it is possible to sail a light dory, but the fact that it would just be so much of a PITA to do, it's just not worth the effort. (although it would be a sight to see one overcanvassed with skipper on trapeze ripping along like one those skiffs you guys like down that way, granted he probably wouldn't stay upright very long )

  10. #9
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    Quote Originally Posted by smithb9 View Post
    makes sense, thanks for your reply.

    I think my conclusion is that it is possible to sail a light dory, but the fact that it would just be so much of a PITA to do, it's just not worth the effort. (although it would be a sight to see one overcanvassed with skipper on trapeze ripping along like one those skiffs you guys like down that way, granted he probably wouldn't stay upright very long )
    Boston water is much colder than Australian water too!

    That is more of an influence on boat design than people think!

    MIK

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