DIY sails, rigging, daggerboards for kayak - reasonable expectation for sailing to weather?

Discussion in 'Boat Design' started by Ryan Bailey, Jun 3, 2022.

  1. Ryan Bailey
    Joined: Jun 2022
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    Location: Tasmania

    Ryan Bailey Junior Member

    Hi all.

    For the past 8 months, I've been working on making sails for my sea kayak. After finding it didn't sail to weather at all, I added some daggerboards just behind the cockpit, Even with this however, I can't seem to get more than 80 degrees to weather (am I using that term correctly? 80 degrees means only barely going upwind at all, right?)

    I've gone out 'sailing' four times so far - three times at the local lake, where I was barely able to head upwind at all (see pic.) The last time was at the beach, on a day with 20 - 25 knots of on-shore wind, and a swell of 1.5 to 2 metres. I wasn't able to tack upwind at all in these conditions, but I was able to thoroughly test my ability to roll back upright and reset my rigging. Unfortunately my geotracker app decided it didn't want to play that day, so I wasn't able to get my downwind speed.

    I find myself very disappointed with the boat's ability to sail upwind. A little research shows most boats can go about 45 degrees to weather, and even square rigged boats could do 60 degrees.

    Does anyone have any advice?
    Would having the daggerboard further forward help? (Though that would interfere with paddling)
    Should I replace the daggerboard with a keel? (Though that would make entering and exiting the boat a nightmare)
    Should I replace the sail with a bermuda rig?

    In short, is there something really obvious I'm missing?
     

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  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Welcome to the forum Ryan.

    I am not surprised that you find you cannot sail to windward!
    Re your sail, it appears to be very 'baggy' - I think it would probably set better if the sheet (the rope for pulling it in and out) was just attached to the end of the boom, rather than going up to the end of the sprit and the masthead as well.

    And your leeboard (that would be a better name for it, rather than a daggerboard) is too far aft - with your set up the centre of area of the sail is forward of the centre of lateral resistance of the daggerboard, so the boat is going to keep on trying to 'fall off' when you try to point up - did you find this happening?
    Try moving the leeboard a bit further forward, and flattening the sail a bit, and see if this has any effect.
     
    Last edited: Jun 3, 2022
  3. clmanges
    Joined: Jul 2008
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    clmanges Senior Member

    Just by very rough eyeball guess, I think your leeboard pivot would need to go right across your lap.

    Obviously that won't work. About the only thing I can tentatively suggest is a second set of leeboards (one may do) mounted forward, probably forward of your front hatch. You'd have to experiment with how to separately control each of them to get the trim you need.

    Google 'lee helm' and 'weather helm' for more understanding of your boat's failing; as set up, it's giving you an extraordinary case of lee helm, being made even worse by your rudder. This is very bad, because in the (hopefully unlikely) event that you fell out of your boat, it would take off downwind at speed and leave you swimming.

    Where did you get that sail? I've never seen anything like it.
     
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  4. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Hi Ryan,
    You've come to the right guys for help. This is a bright, experienced, and very helpful group of mariners here. I don't have much in the way of design experience, myself. I read a book once. But I do have some experience as a sailor. There are actual architects here who can help more, but it is my understanding that the CLR (Center of Lateral Resistance) is typically located just aft of the CE (Center of Effort).

    The experts who taught me what little I know were very old school, well before computers, and the methods they used to find these values only gave rough approximations.

    Basically, for the CE, the center of the sail was used by treating the sail as a simple triangle, straight lines from tack to peak to clew, back to tack and finding the center of the triangle. That is your CE. It gets a little more complicated with more sails, but not much more.

    The CLR was found by making a cutout of the profile of the boat below the waterline. Include the keel or lee board or dagger board and the rudder. With this cutout, you find the balanced vertical centerline. That's your CLR.

    The next part depends on experience as a designer and a sailor. Design the boat so the CE is between 5% to 15% of the waterline length ahead of the CLR. This is what I learned was a good general rule for locating the sail and keel of a boat.

    Looking at your sail design, I would like to suggest, as a kayaker, you might also want to shorten the boom; narrow the aspect ratio of the sail. This may increase efficiency, even if it gives you less sail area and slower performance going down wind. The advantages will be: better sheeting angles to windward and less danger of entangling the paddler sitting in the cockpit. Try moving everything foreward. With the sail closer to the bow, you will have more room for working the rig and you can locate the lee boards more comfortably for paddling. They don't need to fold up to aft, they can be raised ahead of their pin center.

    Good luck and I can't wait to see what everyone else has to say or what you do in the end.

    -Will
     
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  5. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    Some good advice given above.If you can get hold of a book called "Canoe Rig" there may be some useful pointers that would help with your quest.
     
  6. skyl4rk
    Joined: Aug 2006
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    skyl4rk Junior Member

    +1

    Attach your sheet to the boom, about 2/3rds of the way back from the mast. The sheet should pull the boom down slightly to stretch the sail flat.
    Either move your leeboard just forward of the middle of the cockpit opening, or add a second leeboard just behind the mast.
     
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  7. Ryan Bailey
    Joined: Jun 2022
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    Location: Tasmania

    Ryan Bailey Junior Member

    Thanks everyone.

    It looks a bit like the sheet goes up the sprit to the mast-head, but it stops at the boom, as you suggest it should. The other line you see goes through a pulley on the mast, and down to the base of the mast, where I can pull on it to furl the entire contraption - the two booms being on primitive hinges.

    The baggy shape of the sails are likely from poor measuring out and sewing - it was my first time using a sewing machine in well over a decade. The sails themselves are made from old bedsheets.
    I've had a few people say this would make them heavy once they get wet - which it does, though it doesn't seem to affect the boat's stability or handling. Still, I'll make a new sail (out of a different material) and see if that helps.

    Pivots? As in rotating on the vertical axis? I hadn't even considered this possibility. At the moment, their frame is just bolted to rails set on the rear deck. I'll have to consider this, but it may be a tad complicated for a DIY project.

    Clmanges, you're completely right about not being able to move them up alongside the cockpit, and your idea of adding a forward set of leeboards is a good one - I should be able to incorporate the holes already existing on the forward rails, and just use longer bolts to hold it all on. Might switch to stainless steel boards though, as the drag is already considerable from the wooden ones I currently use.

    Regarding the boat getting away from me, this isn't really a problem. The only way I'm able to come out of the boat is if it's beached, or upside down, and the boat's unstable enough that the boom would catch in the water within a few meters anyway.

    Regarding the sailing rig, it's loosely based upon a flat earth sail, pretty much designed for kayaks. The ones that are commercially available are much smaller than mine though, and only let you sail downwind. Their advantage is the spars can fold up to the mast, and the mast itself can fold down onto the deck, and all this can be done from the cockpit of the kayak - all with a minimum of rigging. I included two pics - of them in action and folded up, I found on the net.

    Mine is oversized in comparison, and unfortunately the mast does not fold down like the commercial ones. The sheet for mine goes to the rear of the boat before coming up to the base of the mast, and if the mast folded, that would require an extra two meters of sheet - that would be hard to keep out of the way in normal operations, and could potentially get tangled around my arm or something if I have to bail out in a capsize. My workaround is to pull the mast base out completely, and lay the mast on the deck, base at the front of the boat and tip of the mast near my cockpit. It currently keeps sliding off, but that should be a easy fix. Not really worried about it till I can actually sail into the wind.

    You make some good arguments for it. I'm more interested in being able to go to wind than racing downwind. I had to google sheeting angle to find out what it means. This is the booms angle compared to the length of the boat? If I moved the mast forward, I can see this helping, but at the moment the biggest thing restricting this is my body, which is just behind the mast.

    Regarding safety, this is my number one concern. I've found I'm completely unable to roll back upright with the mast in it's slot, though if I wait till I'm completely upside down, I can pull the mast out, roll up as normal, then recover the mast. The sheets and lines are well out of the way of the kayaker, and I havn't yet had any problems with the sails - perhaps because I'm so close to the base of the mast, where there's so little sail. I eventually want to be doing solo day trips on the ocean, so how the sails, rigging, leeboards, etc affect rollovers and recoveries are top of my mind when making design modifications.

    Again, I hadn't really considered having lee boards with a trim feature. I assume the trim is so I don't constantly have to be using the rudder?
     

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  8. Ryan Bailey
    Joined: Jun 2022
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    Location: Tasmania

    Ryan Bailey Junior Member

    Thanks Sky, that's a brilliant suggestion. That may be what was causing the sails to be baggy, too.

    Thanks again to everyone for your friendly responses - a lot of forums can be somewhat elitist with people new to a hobby/profession, and I found myself pleasantly surprised.
    I'll start with adding a second leeboard forward of the cockpit, and moving the sheet to 2/3 of the mast, and coming through the rear lee board mechanism, rather than through the rear of the boat. If that doesn't work I'll try a different sailing rig and sail.

    I'll post some more pictures detailing my current rig later.
     
  9. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    I'll save you some grief, your sail won't go to windward regardless what you do with the boards. For windward work you need an airfoil shape, like the wing of a plane.
    Your quickest way to success is buying an Optimist sail, then you can play with the board(s).
     
  10. Ryan Bailey
    Joined: Jun 2022
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    Location: Tasmania

    Ryan Bailey Junior Member

    Here's the pics as promised. I would take some pics of the sails actually on the boat, but the weather's pretty miserable at the moment.

    A quick google of Optimist sails puts them well out of my current budget, at around $600 Aud. I'll start looking into how to make curved sails. Was hoping I wouldn't need to.
    Might keep an eye out for second hand ones.
     

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  11. Will Gilmore
    Joined: Aug 2017
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    Will Gilmore Senior Member

    Ryan, I'm not trying to be condescending, but this is twice you've written something that makes me wonder about your understanding of how a sailboat works. Do you know why sailboats use keels, dagger boards, center boards, lee boards, or any underwater feature that may be referred to as lateral resistance?

    None of these things replaces a rudder, but they can help make rudders more efficient. However, what these features primarily do is give the hull directionality against the lateral forces of the sail. Without a flat plane that resists lateral movement, but allows for forward movement, a sailboat will only sail in the direction with the wind. There would be no windward component to the sailing vectors. A boat sails as much under the water as it does above the water. With a well designed hull with lateral resistance, combined with efficient sails, a boat can actually sail faster than the wind.

    Imagine two forces at crossing angles to each other, sort of the way the blades of a pair of scissors cross each other, one blade below, one above. Next, put a boat pinched in the crossing angle of those two closing blades. The scissors can't cut the boat, but they keep closing. The boat must move along the two blades in a direction towards the open tips of both blades. There would come a point, with the closing angles just right, that the boat has to slip along those blade edges at a rate of speed that exceeds the closing speed of the two blades, just for it to get out of the way of the shearing edges. By the time those blades snap shut, the boat hull that was caught between those blades, could shoot out from the closing tips at a considerably faster velocity than the closing speed of those shearing blades. The top blade is the wind, the bottom blade is the water's lateral resistance on the boat.

    Ice runners on an ice boat, wheels on a land boat, and rails would all do the same basic job with varying degrees of frictional resistance to forward motion, but they all allow the sail to work because of the lateral resistance.

    Again, I don't mean to be condescending, I'm just concerned because some of your comments led me to wonder if you understood sailing theory. If you already do, just ignore my short lesson above.
     
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  12. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Funny, but the original specs for the Optimist Pram, given to Clark Mills, the designer, was for a bedsheet sail. Clark talked him out of that particular design feature.

    It's not because a cotton bedsheets gets heavy when wet, but because it can't keep a good shape or offer enough resistance to air flowing through it. Your bedsheet sail isn't going to perform well whether you sew a wing-like foil shape into it or not. Try using old tent fly material, if you're on a budget and want light weight.

    I wouldn't worry too much about the foil shape. You can improve the sails efficiency by shaping it better. Sail makers have sophisticated design software and get paid well to know how to build good sails. Just keep it clean and simple and gain a basic understanding of how these things are suppose to work. The flat cut sail will still develop some shape for sailing if you put the right trimming features into the design.

    You want to understand the downhaul and the outhaul. Learn what a vang does and a Cunningham. Study the parts of a sail, the luff, the roach, the leech, the foot and the battons, and how each of these things work to shape a sail.
    What Rumars is referring to is designing the sail with the camber (the airfoil shape) forward of center. This helps give a greater forward component to the lift generated by the sail. New sails are designed with this shape. Old "blown out" sails loose this shape and the camber moves aft, towards the center, causing more heeling than foreward force. This also can be why a boat doesn't point as high to windward as it should.

    Often, the trim controls can improve this deficiency, but they can't fix it. A better sail design for your purposes may be the pacific lateen rig, like a sunfish. You should be able to find some old used sunfish sailboats on Craig's list or something for less than $500. You can cut the whole rig down to better fit your kayak, but keep the basic design. They do pretty well with flat cut sails.

    -Will
     
  13. Ryan Bailey
    Joined: Jun 2022
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    Location: Tasmania

    Ryan Bailey Junior Member

    I understand the absolute basics of sail theory, but literally everything I know of sailing comes from what I've discovered on the net in the last 8 months. That is, I have no friends that sail, I've never been on a sailboat, and up to eight months ago, I hadn't lived anywhere sailboats could be used.

    My travels on the net have made me aware of the leeboards' role in preventing the boat slipping sideways, somewhat aware the role the airfoil shape has in pushing the boat to windward, and vaguely aware that it's important to have your keel/centerboard/leeboard roughly under the center of the sail area.

    I was somewhat mistaken in my assumptions about what a leeboard's trim would be, assuming it would be like an aircraft's trim for it's aileron, rudder or elevators. That is, rotating it by some degree either left and right or up and down. I couldn't really see the point in this, other than possibly acting as a second, fixed rudder. A quick google search, alongside your post above has revealed both the form and function of the leeboard trim however.
     
  14. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    You don't need an olympic sail,
    221$ buys you a training sail. Optimist Sails Store https://isails.com/optimist-store/?gclid=EAIaIQobChMIiK_fh8eX-AIVtY9oCR2J8QakEAMYASAAEgJNYPD_BwE
    Or 255$ Training http://www.optisail.com.au/category37_1.htm
    As for second hand, you can start here, there's one for 20$ Log into Facebook https://www.facebook.com/groups/vioda
    Here are your local clubs to ask for used gear: Clubs https://www.revolutionise.com.au/tioda/club/
     
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  15. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member

    In addition to the points mentioned already, particularly with reference to centre of effort and centre of lateral resistance, a decent foil section on a leeboard will help the boat point higher. Have a look at the Open Canoe Sailing Group website, and Solway Dory (also sailing canoes rather than kayaks but many of the principles apply, and just looing at the rigs, outriggers, pivoting leeboards and rudders will give a good idea of what helps.

    If you get into the sailmaking aspect, maybe consider a kit? Google kayak sail kit or similar. They will have precut shapes, and some at least should offer a decent sail design. Finally, telltales on the sail can be a huge help to telling you when you are sailing efficiently, and help when trying to point.
     
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