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Thread: Cosine Wherry sail rig, again

  1. #1
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    Default Cosine Wherry sail rig, again

    I looked at some old threads, and it sounds like people are in consensus that the cosine wherry isn't terribly well suited to sailing.

    So here's my situation: my friend is giving me an unused cosine wherry. I already have a dedicated rowboat, with which I'm very satisfied, and I have a daysailor. But now I have a real hankering for a sail and oar boat, so I'm going to rig the cosine wherry to sail, understanding the limitations of this boat as a sailboat. Hopefully this will get me through, at least until I get the time and funds to build a better sail/oar boat myself.

    How much sail area and centerboard area would you suggest for this boat? It's 14' long. I'm not sure what the WL beam is, but max beam is about 4' 2", I believe. I'd guesstimate the bare hull at about 100 lbs; of course that will go up when I add the extra fittings. I'm thinking of borrowing the sail, centerboard, and rudder design from Joel White's Shearwater. I think Shearwater's sail area is 69 square feet. Does this sound about right to you? I'm pretty set on a centerboard just off center of the keel. I don't want the depth limitations of a daggerboard, and I'd rather not deal with leeboards.

    Any advice from people have sailed similar boats, such as whitehalls?

    Thanks in advance.

  2. #2
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    Default Re: Cosine Wherry sail rig, again

    Try rowing the Cosine before you start any mods. You don't say what you're current pulling boat design is, but you may find the Cosine to be a much better, faster and more stable boat. Try it with 8.5-9' oars if you can. I can row my Cosine alongside sliding seat guys for a number of miles, and I'm not a strong rower.

    That said, the Shearwater setup looks like it might work well. I'd build and install the CB and rudder, then use a temp mast base and partner to get the position of the mast and sail tweaked for the boat and your weight. You'll have problems tacking with the long pulling-boat keel and hull shape, so don't expect fast tacks, and be prepared to take a long time to tack or paddle across.

    I've only seen one Cosine with a sailing rig and it was a floating trainwreck that did nothing right -- but yours I'm sure will work out better.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  3. #3
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    Default Re: Cosine Wherry sail rig, again

    I've rowed a Cosine Wherry.

    My advice is don't do it. It's a lovely rowboat It'll make a mediocre to terrible sailboat. The sections and the initial stability are all wrong for sailing. If what you really want is a sail & oar boat, sell this one and build or buy one of those instead. I think you'd be throwing away time and money towards getting what you really wanted if you spent any time at all on this kind of mod.

    You can't just put a saddle on a cow and go steeplechasing.

  4. #4
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    Default Re: Cosine Wherry sail rig, again

    I've seen both of you guys around here a lot, so I'm excited to have both of your opinions. Thorne, my other rowboat is a Challenge Wherry. One of my mentors from the Alexandria Seaport Foundation designed it a number of years ago as a kit boat, but for some reason it never took off like the Bevin's Skiff. At 17 feet, it's essentially a longer, leaner, lighter version of Bolger's Gloucester Gull. It's even less fit for a sail conversion.

    The Cosine Wherry hull is sound, structurally, but it was definitely built by an amateur. To put it nicely, it wasn't executed in the most elegant fashion. It was donated to the Alexandria Seaport, and they are giving it to me because they came to the conclusion that it would need some real finishing work before they could sell it for any reasonable profit. The boat would probably rot away otherwise, so I figured I wouldn't be wasting a whole lot if I could borrow a sail from a friend and build a CB from scraps I have from old projects. At worst, I'd be wasting my spare time.

    Thorne, could you elaborate on why that other cosine wherry is a "sailing train wreck"? Was it design related, or did the builder do a poor job with something, or was it a combination?

    James, will you explain to me what it is about this boat that makes it unsuitable for sailing, when there are other boats of similar beam and displacement that will sail? I understand that there are some sections that are more suited to sailing than others, but I must admit, I haven't taken a good look at this boat in a while (haven't picked it up yet). What is it about this boat that sets it apart from, say, Oughtred's Acorn series, or even some of Pete Culler's rowboats? If I remember correctly, these designers often offer sailing rigs for their rowboats. Not disputing your answer- just trying to further my knowledge of design.

  5. #5
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    Default Re: Cosine Wherry sail rig, again

    If you really want to tinker with a sail on a Cosine Wherry perhaps a downwind only rig, similar to what Paul Gartside uses on his Flashboats would be a good place to start.

    Nothing there other than the weight of the rig to spoil the rowing characteristics. Most boats of that type could be rowed to windward faster than they could be sailed in any case.

  6. #6
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    Default Re: Cosine Wherry sail rig, again

    I would try it. I sail a 15' double paddle canoe, it is light, narrow (28"), shallow, without frames or flotation, v-bottomed, in every way unsuited to sail. But it is fun and fast and easy to car-top. The canoe uses a thwart that clamps on the gunwales, acting as mast partners and carrying a leeboard. You don't have to cut the hull. Be careful, the leverage of the 14' mast has split a lap in a fresh breeze, now I luff when called for. I would try a cheap used sail or experiment with polytarp. Let us know what you do, and how well it works.

  7. #7
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    Default Re: Cosine Wherry sail rig, again

    The sailing Cosine that I saw was totally filled with stuff by the builder, and was too heavy to row well and too full of stuff to sail well. Fault of the builder / operator.

    GOSH I hope he isn't on the Forum!! No insult intended but he didn't make it very far on the row, which was easy and less than 3 miles each way.

    People sail Whitehall designs all the time, some of which are better for sailing with more rocker and less keel than the Cosine, others very similar. But as long as you're OK with paddling across the wind or taking very long tacks, it will be fine.









    For comparison here's mine at the destination dock. I was testing out some fiberglass 10.5' sweeps a friend gave me, and am using one here to keep the boat off the dock. They only worked well in dead flat water, but my spruce 9' spoon oars are much nicer to use.
    Last edited by Thorne; 08-01-2017 at 12:35 AM.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  8. #8
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    Default Re: Cosine Wherry sail rig, again

    Sounds to me like you've got almost all the materials on hand and an itch to try it, so why not go ahead? The boat will feel overpowered with that sail and one person on board when the wind starts to build, but if you can put in a reef or two, it will become perfectly manageable. I have to agree with James that it won't be the optimum sail and oar craft, but that's not to say you can't have fun with the experiments.
    -Dave

  9. #9
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    Default Re: Cosine Wherry sail rig, again

    I have a stretched Cosine wherry, she is 17ft 3" overall & is a lovely boat to row. She also has a 75 sq ft standing lugsail on alloy spars, all fit in the boat & there is no daggerboard or centreboard. She will sail with the wind just forward of the beam as her sharp bow tends to bite the water well. Try & point higher & you might as well get the oars out! Off the wind she goes like a train.
    I subscribe to Paul Gartsides view that rigs for boats like this are primarily for downwind use. I had a similar slightly larger boat that had a daggerboard & bigger rig, all the extra sailing gear & case meant she was heavier & didnt row so well.

  10. #10
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    Default Re: Cosine Wherry sail rig, again

    I have a Cosine, and added a "downwind only" rig. The boat rows so easily down wind, that I have just stopped using the sail rig. If you have a good, light, row boat under about 16 feet , keep it that way, and forget sail.

    Tony.

  11. #11
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    Default Re: Cosine Wherry sail rig, again

    If you're just dying to have wind power the boat along, how about using a kite? Put a tiller and rudder on the boat and get a water-launchable Hydra kite. They're $300, and you don't bung up the inside of that great cosine wherry with a mess of stuff.

    I see the photo of the cosine where with the electric outboard on it. I can't....why?....oh never mind. The cosine wherry is the best rowboat I've ever had the pleasure to push around, why mess with it? I'm all for experimentation, I really am, but... I don't know. There are limits.
    CLC Skerry = "Vingilothiel"

  12. #12
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    Default Re: Cosine Wherry sail rig, again

    Look...a CLC skerry kit...a nifty row/sail boat kit available at a steep discount in your neck of the woods.

    https://washingtondc.craigslist.org/...245522185.html

    Mind you, I have a skerry and I honestly don't like how it sails all that much, though perhaps I'll change my mind if I change the rudder-tiller configuration. It rows well, but not as nicely as the cosine wherry I got to play with for an afternoon, 6-7 years ago.

    I also spotted a Shellback dinghy...row and sail, but a MUCH better sailor than the cosine wherry is going to be.

    https://washingtondc.craigslist.org/...248024500.html
    CLC Skerry = "Vingilothiel"

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