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Thread: Put a Sail on a Skiff

  1. #1
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    Default Put a Sail on a Skiff

    I built a rowing skiff about 3 years ago and am getting tired of rowing. Whenever there is a breeze I wish I was sailing.

    My boat is 15ft long with a 3.5ft beam, a flat bottom and must weigh 90-100lbs. I want to put a sail on it from a CLC Jimmy Skiff which is 60sqft. As far as I can tell after comparing different boats, 60sqft sounds about right......feel free to disagree. I'd rather the sail be too big than too small.

    I've gotten farther along than the two drawings below. I did some amateur math and I'm working on the mast and sprit boom now. I may also make a clamp on leeboard for now instead of the centerboard to save time and figure out the balance. I've never made anything like this before so the centerboard is somewhat intimidating.

    I'll follow up with another post later with my progress so far......and challenges....I'm finding it much easier to read about building a round mast than actually making one!

    skiff2.jpg14.jpg1.jpg

    Sail Plan.jpgHull Plan.jpg

  2. #2
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    Default Re: Put a Sail on a Skiff

    Looks to me like you are on the right path.
    I might make the rudder blade a simple kick up. Beyond the protection from grounding, angle of dangle of the rudder blade changes performance of tacking/gybing/pointing etc.
    The one drawn looks like it might drag the boat down..act as a brake turning. Force the boat to turn in a wider circle.
    A kick up allows you to play with the blade at different angles, same thinking as having a temp leeboard to check balance.

  3. #3
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    Default Re: Put a Sail on a Skiff

    That's a canoe shaped boat, too big a sail can spell trouble.

    Todd Bradshaw has written the definitive book.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  4. #4
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    Default Re: Put a Sail on a Skiff

    Starting out with a leeboard would get you sailing much faster. It doesn't have to clamp on, but can hook over the gunwale as in some Phil Bolger designs.

    Starting out with a leeboard would allow you to adjust the location to get optimal helm balance. Then if you want to add a centerboard you would know the proper location.

    A daggerboard would be much less work to build than a centerboard and would take up much less interior space. For very small boats daggerboards are more common than centerboards.

    In the photo your lovely companion wears a pfd, but you do not. When sailing a small boat a pfd is a must. A swim can happen when you least expect it!
    I will beg you for advice, your reply will be concise, and I will listen very nicely and then go out and do exactly what I want! (Apologies to Lerner and Lowe.)

  5. #5
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    Default Re: Put a Sail on a Skiff

    I drew the rudder as one piece and shallow draft for simplicity, but maybe performance-wise it's not worth it. The kick-up rudder also wouldn't stick down below the boat for beaching which is a plus.

    I have Todd's book! For 55-65sqft on a 16-18ft canoe he says (paraphrasing) you'll do some hiking but in steady wind balancing from inside the boat should be sufficient. I should mention I am not new to dinghy sailing and don't mind sitting on the rail with my foot under the thwart and leaning out when the wind picks up. Also my boat looks like a canoe but is a little more stable being at least 6in wider and with a flat bottom. I keep my PFD in the boat under the seat, but I promise to wear it if i'm sailing!!

    I've never seen the Bolger hook-on leeboard, but it sounds like the simplicity I'm looking for....I'll have to look into that. I would like to make a centerboard trunk just to learn how, but I only have 6 months before it gets warm again and i'm SLOW. I've also been wondering, if balancing the helm with a leeboard....would that change when you switch over to a centerboard, moving the board from leeward to centerline? Center of lateral plane is the same but the drag changes. I assume more weather helm with the centerboard....but maybe negligible?

  6. #6
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    Default Re: Put a Sail on a Skiff

    ? Center of lateral plane is the same but the drag changes. I assume more weather helm with the centerboard....but maybe negligible?
    Bolger--and other authorities--have termed offset foils as having negligible performance deficiencies, if any. In fact, they say the only problem with an offset board is that it adversely affects our sense of proportion.

    I built a 12-foot Summer Breeze and use a single fixed leeboard. The boat sails equally well on either tack. (Granted it is not a high-performance design by any means)

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  7. #7
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    Default Re: Put a Sail on a Skiff

    Looks an awful lot like my duck punt. I imagine itíd sail just as well even without a foil or rudder...

  8. #8
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    Default Re: Put a Sail on a Skiff

    So I bought myself a 16ft douglas fir 4x4 at the lumber yard to shape a small solid mast from and a 12ft 2x4 for the boom. It will be a 16ft mast 3” in diameter, no splicing, no gluing.

    4.jpg

    I determined the diameter from an equation for freestanding masts found in both Skene’s Elements of Yacht Design and Chapelles Designing and Planning Books (I have more books than experience). Then I drew a curve like the one below on it with a diameter of 2.5in at the step, 3in at the thwart and 1.25in at the head. I found similar sized masts in "The Sharpie Book" for the head and foot diameters.

    15.jpg

    The first problem I had when cutting the mast was my circular saw could not cut all the way through so I had to draw the curve on both sides of the mast and cut half way through on opposite sides. When I did this the two cuts were not perfectly aligned which created a little step in some places which caused a problem keeping the saw flat when cutting the next two sides.

    2.jpg 6.jpg 5.jpg

  9. #9
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    Default Re: Put a Sail on a Skiff

    It could maybe sail like a duck punt....but there's something about that fixed rudder that comforts me!

    I don't mean to say a leeboard is a deficiency, just that the fore/aft location of a leeboard for balance may be different than a centerboard due to the leeboard and centerboard each having drag at a different location athwartship.

    Catching up to the present....I then drew lines on my square mast to cut the corners off at 45 degrees. This was also a bit challenging for me because the saw would all of a sudden get stuck and i'd try to back it out and it would gouge.

    9.jpg

    I then used a power plane to cut the 8 sided mast into a 16 sided mast....which was no problem at all! I also cleaned up most of the gouges at this point.

    7.jpg

    I also cut the sprit boom shape, which was a little tougher with the power plane because the board was a bit bent.

    Capture2.jpg

    And that's how far I have gotten so far.

    Capture.jpg

  10. #10
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    Default Re: Put a Sail on a Skiff

    Cute boat!

    With 3.5ft beam and a sail that's the same size as that of a Laser Radial, won't you be running out of righting moment fairly quickly? I respect Todd's knowledge so maybe I'm just approaching it from the viewpoint of someone who sails in an area where strong winds are common.

    The rudder looks very low aspect; any particular reason? Why not a "cassette" rudder, which drops vertically in a box? They offer excellent balance and shoal draft when needed.

  11. #11
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    Default Re: Put a Sail on a Skiff

    I had the same thoughts as TerryLL about the form of the hull.

    I wonder if you might be better off with a four sided spritsail (i.e. like an Opti) with or without boom to keep the center of effort low, rather than the taller leg o mutton sprit.

  12. #12
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    Default Re: Put a Sail on a Skiff

    Ok so it sounds like the consensus is 60sqft of sail on a boat with a 3.5ft beam is too much...or say too much for an open boat with kids

    So what is more reasonable? 50sqft?

    Here are the boats I was comparing to:

    Viola Sailing canoe 14ft LOA, 3.3ft beam, Optional sail sizes 50sqft, 64sqft (for advanced sailors) and 68sqft (expedition with 3 reef points)
    Capture.JPG

    Jimmy Skiff - 13ft LOA, 4ft 2in beam, 60sqft sail
    Super Sailfish - 13.5ft LOA, 3ft beam, 75sqft sail (too much)
    Crabbing Skiff (Chapelle) - 18.5ft LOA, 3.5ft beam, 60sqft sail
    Capture2.jpg

  13. #13
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    Default Re: Put a Sail on a Skiff

    Looks like a fun project. I put a sail rig on my Steve Redmond "Whisp" years ago, and more recently made numerous modifications to address the shortcomings of the original sail plan.

    The Whisp is just shy of 16' long, with 42" beam but lots of flare out from a narrow bottom. I think it's lower sided than your boat. Nonetheless, I have 90 square feet of sail on it -- 75 in the main and 15 in the mizzen. In the light wind we get most of the summer in Pennsylvania, this is not too much. If it's breezy, I just tie in a reef or two. I agree with your thinking that having a generous sail plan isn't a problem if it can be managed effectively.

    When I made the last round of changes, I reported on them here in this thread The cassette rudder works very well, and as has been said, a daggerboard in an offset trunk works just as well as one on center.

    My two cents:

    A 3" DF mast is way overkill. When a boat is tender, it rolls with the punches. A much thinner, lighter spar will work. Mine is 2" diameter at the partner, and has survived a fair bit of abuse. (I'm not arguing with the textbook numbers as they do apply to most boats -- but these light skinny craft are different. If you look at Bolger's spars on comparable boats, you'll find dimensions similar to what I used.)

    While the boat is in the shop, I would advise building in watertight compartments in the ends. The bigger the better. With big inspection ports, you can keep stuff in there. And putting foam or something for flotation under the thwarts would be wise, too. (Note my capsize experiments at the end of the linked thread.)

    Good luck with it. I'll be following.
    -Dave

  14. #14
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    Default Re: Put a Sail on a Skiff

    I agree with a generous sailplan. Most small boats are sailed more in light and gentle breezes. I sailed a 17' Folbot Super (kayak) this summer with 36 or 55 sqft sails. Neither was too much, though the Super is very stable and I am not light.

  15. #15
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    Default Re: Put a Sail on a Skiff

    What a practical little boat. Good lucks with the refitting.

  16. #16
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    Default Re: Put a Sail on a Skiff

    ...and a 60 foot regular cruising sail will not be as powerful as a turbo Laser sail.

  17. #17
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    Default Re: Put a Sail on a Skiff

    Reminds me of a project some years ago when I added a sailing rig to a 14 ft. dory. Turned out to b a bit tippy, due to the narrow bottom. I ended up using a plate steel centerboard, which helped a lot with the stability issue.

  18. #18
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    Default Re: Put a Sail on a Skiff

    Ok, so I think I'll stick with the 60sqft sail and add a row of reef points to bring the sail down to maybe 75% which is 45sqft. I'd think that would be reasonable at around 15+ knots and if it's near 20 I don't want to be out in this boat anyway. Also yes I believe you when you say the mast is way overkill at 3in diameter. Looking at the crab skiff with 60sqft of sail, it's hard to read but it looks like the mast diameter is 2-3/8in. I'd love to make a hollow birsdmouth spar, but I don't have a table saw or the much free time.

    238.jpg

    Watertight compartments would also be wise, thanks for the link, there is a lot to look into there!

  19. #19
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    Default Re: Put a Sail on a Skiff

    Out rigger?

    twood deal with that heavy mast.
    It's all fun and games until Darth Vader comes.

  20. #20
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    Default Re: Put a Sail on a Skiff

    It's been a while and I wish more has gotten done but.....

    So I planed down my 3" diameter mast to 2-3/8" at the thwart a 1/16th of an inch at a time and reduced the weight from 27lbs to 17lbs with a CG 6' off the bottom.

    3.5.jpg

    I also measured out where my thwart will go, cut it out and fit it in. Now I need to go buy some plywood.

    2.jpg

    I've also drawn in some fwd and aft tanks with hatches and a kickup rudder trying to maximize underwater area when up.

    4.jpg
    5.jpg
    Attached Images Attached Images
    • File Type: jpg 3.jpg (65.3 KB, 0 views)

  21. #21
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    Default Re: Put a Sail on a Skiff

    Looks good!

  22. #22
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    Default Re: Put a Sail on a Skiff

    Very nice. Once you get out sailing, you may find the conventional tiller awkward, depending on how you sit. When building the rudder, I suggest leaving allowance to add a yoke for a push-pull tiller or even a perimeter line. It's not hard to make both and have them interchangable.
    -Dave

  23. #23
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    Default Re: Put a Sail on a Skiff

    Your centerboard as drawn looks too far forward.
    Otherwise your work looks good.
    Have fun.

  24. #24
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    Default Re: Put a Sail on a Skiff

    I would like to avoid any outriggers due to the added complexity building and launching.

    Throwing over the helm on this boat takes on a new meaning! The tiller drawn is about 5’ long and only has about 15 degrees to each side before it’s over the rail. I think the rudder could be adapted to take a yoke if this turns out to be a problem.

    Including half of the original rudder I believe I tried to draw the boat with a lead of about 7-8% (I’d have to check the computer). The low-aspect rudder and large skeg pulls the CLR back quite a bit although I was wondering how effective the shallow skeg would actually be on a healing flat bottom boat. But you’re probably right, I don’t have any experience in sailboat design, which is why I am just going to start off with an adjustable hook-on leeboard.

  25. #25
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    Default Re: Put a Sail on a Skiff

    Then again you might not need a board at all....
    Do some research on sailing a duck punt and I believe you'll find most don't use a board.
    Once the boat is heeled the chine acts as the leeway prevention.
    Your boat looks very much the same.

  26. #26
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    Default Re: Put a Sail on a Skiff

    It's been a while and I've been sidetracked by other projects, but I have made some progress.....

    I made this mast belt sander out of a threaded rod and a couple wheels.....most exciting sanding I've ever done!
    B5.jpg

    I'm questioning how to cut the heel of the mast.....I started some cuts like this with a hack saw then stopped. I was thinking cutting an octagon or more then sanding round, then I thought there may be a better way?

    B3.jpg

    Front bulkhead, deck and thwart dry fit (held by friction).

    B1.jpg

    Front "deck" beams being epoxied on.

    7.jpg

    And as of tonight all sanded and ready for install.

    Capture.jpg
    Last edited by Stōs; 04-30-2021 at 11:15 PM.

  27. #27
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    Default Re: Put a Sail on a Skiff

    Have fun. I did something similar about 60 years ago and because I was uninformed, but eager, she sailed to be hell in every direction but upwind.

  28. #28
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    Default Re: Put a Sail on a Skiff

    I had a fairly productive weekend installing all my forward 'deck', bulkhead and thwart parts. My fillets around the bulkhead turned out a little small due to poor planning and not enough putty mixed up. I should have just finished one side of the bulkhead, then could have mixed up some more putty for the other side after I realized I was running low. I would have just made more but the epoxy was already starting to kick and didn't want to mess with it anymore.....so I've sanded the fillets for now and will add more putty and glass them over.

    Next I'll add some finger-sized fillets along the top of the deck, make some small corner supports for the back of the thwart, a short hatch frame and the hatch itself.

    C1.jpg

    C3.jpg

    C2.jpg

  29. #29
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    Default Re: Put a Sail on a Skiff

    I didn't get around to finishing everything this summer but I did get the forward area buttoned up and painted for August so I could use the boat again.

    I also found a cheap place to order a Bolger Surf sail so I'll be using that sail instead of one for the Jimmy Skiff. The two sails have dimensional differences of only a few inches. Also I'm surprised I didn't find the Bolger Surf design earlier when I was comparing boats and sail areas because the Surf is a flat bottom double ender which is 6" longer and 1" wider than my boat with a 59sqft sail!

    To do list:
    cut slots and holes in spars, varnish
    make rudder
    make leeboards
    make rear water-tight compartment
    buy all rigging lines, hardware, etc.

    skiff3.jpg

    skiff5.jpg

    Structural integrity testing:
    skiff7.5.jpg

    Forward deck drain:
    skiff7.7.jpg

    Bolger Surf sail I ordered, 59sqft:
    surf.jpg

  30. #30
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    Default Re: Put a Sail on a Skiff

    Nice!
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  31. #31
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    Default Re: Put a Sail on a Skiff

    I got the sail in and strung it up to the mast with some garden twine (for now) to take a look at it and confirm the holes I needed to cut in my spars.

    I cut the holes in the spars, stained them and have 2 coats of varnish on them so far.

    skiff13.jpg

    skiff10a.jpg

    skiff12.jpg

    skiff9.jpg
    Attached Images Attached Images

  32. #32
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    Default Re: Put a Sail on a Skiff

    That sail looks nice. Itís almost time, now, eh?

  33. #33
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    Default Re: Put a Sail on a Skiff

    Looks great.
    -Dave

  34. #34
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    Default Re: Put a Sail on a Skiff

    That's gonna fly if you can keep it on its feet

  35. #35
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    Default Re: Put a Sail on a Skiff

    Quote Originally Posted by Hugh MacD View Post
    That's gonna fly if you can keep it on its feet
    Could always retrofit wings.
    It really is quite difficult to build an ugly wooden boat.

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