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Thread: Sail design.

  1. #1
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    Default Sail design.

    Beuhler liked a sail he called a modified Dhow and used it as a steadying sail on his Diesel Ducks as an emergency sail. I'm interested in using a similar design on my boat. I've researched all I can using his books and website. I am in the planning stage to build my boat this fall. I would like to incorporate his sail ideas. I know I will need to add support structure to my hull and cabin to take a mast behind the cabin. In his book, he talks about using minimum rigging to reduce windage and a tabernacle to drop the stick to get under structures. My boat is a good bit smaller and lighter than his Diesel Ducks at 28 foot with a displacement of 16,200. Can anyone give me guidance on mast sizing, sail sizing, and rigging?

    http://dieselducks.com/index.html

    Running on what Beuhler called a modified Dhow to steady the boat.





    The design I am working with.



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  2. #2
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    Default Re: Sail design.

    Nice boat. I could not tell from the other thread but does she perhaps have a dory (narrow lengthwise plank) bottom?

    Do you really want a steadying sail or do you imagine something that will extend your range, maybe get you home if a breakdown. I don't really think this hull can be made suitable for the latter. A steadying sail helps hold the bow into the wind and slows roll under way but does not really give much power.

    I would not rig this boat anything like the Beuhler, which has radically different weight proportions. Also, loose footed sails like that rarely stabilize the boat when you're off the wind: rather the vortexes over luff and leech induce wobble.

    I'd be inclined to look to a rig that's more like a steadying sail, mast rising from the cockpit sole and braced against the aft end of the house. This makes for a mast that can hoist things as well as hold up a proper flat cut steadying sail.

    Given you Loop ambitions, hinging the mast step on the cockpit deck will make for easy striking and the mast should be light enough that you can then get it atop the house.

    Three stays: The shrouds with a bit of follow (athwartships line between chainplates abaft the mast) and a low slope head stay to the stem. It might or might not be worth the cost to hang an ultra low aspect sail from that headstay. Hard to cut and will only really work going to weather.

    You'll need to consult an NA to be sure you don't make the thing too big for the boat's stability and you engineer the mast as light as is safe.

    G'luck

  3. #3
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    Default Re: Sail design.

    Quote Originally Posted by ben2go View Post
    Beuhler liked a sail he called a modified Dhow and used it as a steadying sail on his Diesel Ducks as an emergency sail.
    [...]
    Can anyone give me guidance on mast sizing, sail sizing, and rigging?
    For steadying/emergency you don't need a very large sail, 3 square meters will do I think.
    Mast and rigging depends on sail size.

    /Mats

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    Default Re: Sail design.

    Quote Originally Posted by Ian McColgin View Post
    Nice boat. I could not tell from the other thread but does she perhaps have a dory (narrow lengthwise plank) bottom?

    She has a V bottom with a good bit of rocker but is planked flat either side of the centerline.

    Do you really want a steadying sail or do you imagine something that will extend your range, maybe get you home if a breakdown. I don't really think this hull can be made suitable for the latter. A steadying sail helps hold the bow into the wind and slows roll under way but does not really give much power.

    Yes, steadying with the ability to extend range and be able to get home if the engine dies. I am planning for a new Beta driveline. Being a former pilot, I like redundancy.

    I would not rig this boat anything like the Beuhler, which has radically different weight proportions. Also, loose footed sails like that rarely stabilize the boat when you're off the wind: rather the vortexes over luff and leech induce wobble.

    I understand that and wondered how a lose luff and foot would work.

    I'd be inclined to look to a rig that's more like a steadying sail, mast rising from the cockpit sole and braced against the aft end of the house. This makes for a mast that can hoist things as well as hold up a proper flat cut steadying sail.

    That's my origianl plan. At first the mast was going to be just big enough to lift the dink on to the cabin roof cradle for long passages, rough weather, and storage. I have plans for a light weight pram that can take a small 2.5-5hp outboard. Going based on stated weights plus a little extra added for insurance, 250lbs max.

    Given you Loop ambitions, hinging the mast step on the cockpit deck will make for easy striking and the mast should be light enough that you can then get it atop the house.

    My plan has been to use a hand operated winch to lower the mast forward into a cradle lashed on deck or prehaps a removable one that has a quick release deck mount.

    Three stays: The shrouds with a bit of follow (athwartships line between chainplates abaft the mast) and a low slope head stay to the stem. It might or might not be worth the cost to hang an ultra low aspect sail from that headstay. Hard to cut and will only really work going to weather.
    We think alike on the stays. I knew any head sail would be very small and only useable in a favorable wind direction.

    You'll need to consult an NA to be sure you don't make the thing too big for the boat's stability and you engineer the mast as light as is safe.

    Good advice. I'm currently looking at options in aluminum. Possibly a used sailboat mast and pole cut down and polished up.

    G'luck
    Thanks Ian. You're always a great help.
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    Default Re: Sail design.

    Quote Originally Posted by mohsart View Post
    For steadying/emergency you don't need a very large sail, 3 square meters will do I think.
    Mast and rigging depends on sail size.

    /Mats
    From the research I have done thus far, you're right on. 3 sq. meters would be roughly 11 square feet if I'm remembering my conversions right. Steadying sail is a breeze. I was hoping to utilize the mast for a little extra umph and to get to shore in an emergency. lol
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    Default Re: Sail design.

    Quote Originally Posted by ben2go View Post
    [...]I was hoping to utilize the mast for a little extra umph and to get to shore in an emergency. lol
    Sure. But I doubt you'll be able to go higher than 90 degrees against the wind with that hull and that kind of sail. For off-wind a tiny sail will work, it will only take a little more time.

    /Mats

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    Default Re: Sail design.

    Quote Originally Posted by mohsart View Post
    Sure. But I doubt you'll be able to go higher than 90 degrees against the wind with that hull and that kind of sail. For off-wind a tiny sail will work, it will only take a little more time.

    /Mats

    I'll have to catch the wind on a broad reach.
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  8. #8
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    Default Re: Sail design.

    3 square meters is about 32.3 square feet.

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    Default Re: Sail design.

    Quote Originally Posted by Ian McColgin View Post
    3 square meters is about 32.3 square feet.
    Quite right. I didn't multiply properly.
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    Default Re: Sail design.

    The thing is, you may need a sail area of perhaps one square meter to stabilize the boat.
    But a bit more sail will let you steer away from some rocks more easily.
    You still won't be able to sail against the wind, if that's your wish install side swords.

    /Mats

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  11. #11
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    Default Re: Sail design.

    Quote Originally Posted by mohsart View Post
    The thing is, you may need a sail area of perhaps one square meter to stabilize the boat.
    But a bit more sail will let you steer away from some rocks more easily.
    You still won't be able to sail against the wind, if that's your wish install side swords.

    /Mats
    Yes, it would be nice to have sails to help in the event of an engine out event to get to a safe anchorage or limp home. I never expected to sail to windward.
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    Default Re: Sail design.

    I was edutaining myself about loop cruising last month, so my first thought here is... "Even sail boats barely do any sailing cruising the loop" As I hear it, even coming down the coast in the intracoastal waterway you're pretty well sheltered and don't get much wind, well only as much as the small, light and slippy craft can make use of. Anyway, your time and money to waste, but I wouldn't commit a huge amount of either to something that's not going to benefit you much for the bigger dream. You may be giving yourself air-draft headaches also. Sure, with future use of the vessel more offshore in mind, you might make sure to arrange things such that you're not preventing this modification in future, but if you're wanting to loop cruise as first objective then from all I've read, it's just going to be a pain in the ass.
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  13. #13
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    Default Re: Sail design.

    Quote Originally Posted by ben2go View Post
    From the research I have done thus far, you're right on. 3 sq. meters would be roughly 11 square feet if I'm remembering my conversions right. Steadying sail is a breeze. I was hoping to utilize the mast for a little extra umph and to get to shore in an emergency. lol
    One square meter is about 11 square feet. 3 square meters is about the size of an El Toro sail, which will not extend your range much.

  14. #14
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    Default Re: Sail design.

    Quote Originally Posted by johnw View Post
    One square meter is about 11 square feet. 3 square meters is about the size of an El Toro sail, which will not extend your range much.
    Well. I never said that so and so many sqm would do this or that

    /Mats

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    Default Re: Sail design.

    Quote Originally Posted by Plyboy View Post
    I was edutaining myself about loop cruising last month, so my first thought here is... "Even sail boats barely do any sailing cruising the loop" As I hear it, even coming down the coast in the intracoastal waterway you're pretty well sheltered and don't get much wind, well only as much as the small, light and slippy craft can make use of. Anyway, your time and money to waste, but I wouldn't commit a huge amount of either to something that's not going to benefit you much for the bigger dream. You may be giving yourself air-draft headaches also. Sure, with future use of the vessel more offshore in mind, you might make sure to arrange things such that you're not preventing this modification in future, but if you're wanting to loop cruise as first objective then from all I've read, it's just going to be a pain in the ass.
    The Loop wouldn't be where I would use sail. It would be when I do the inside passage between Washington state and Alaska. The Loop would be where I would do testing when running outside in the open ocean.

    Again, I'm not looking to sail. Only to assist and in the event I have engine or diveline problems. I would turn and let the wind push me to an anchorage or hopefully a dock to tie up.
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    Default Re: Sail design.

    Quote Originally Posted by johnw View Post
    One square meter is about 11 square feet. 3 square meters is about the size of an El Toro sail, which will not extend your range much.
    For a main steadying sail, I would need about 150 square feet and for any kind of sailing I would need about three times as much. Readying around It seems a displacement vessel of about 20,000 pounds needs 150 sq.-ft. That's where I am getting my guestimation from.
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    Default Re: Sail design.

    Hard to tell from just a deck view and profile, but that hull looks like it will have extremely limited sail carrying ability. If I wanted the clutter, the salty look, and had legitimate use for a steadying sail, I might. More practical would be a nice droppable gin pole on one forward corner of the cockpit. For engine reliability, put in fuel filters in parallel and carry plenty of spares.

  18. #18
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    Default Re: Sail design.

    The points I was trying to make was there is very little sail area needed to prevent a boat from rolling.
    A bit more may be needed to be able to "sail" it, meaning stear away from some grounds downwind.
    More sail than that will not help.
    If it's 1 sqm, 3 sqm, 10 sqm or whatever is irrelevant.
    Or for a specific boat, if you want maximum "performance" it matters, but it really makes so little difference.
    Unless you put up too much cloth, then you could be in serious trouble.

    /Mats

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    Default Re: Sail design.

    My 2centx worth. Mast way aft would be a pain, in the front of the cockpit with stays down each side
    On the upper main cabin roof you would have lots of structural issues to deal with and stays in the way when you want to go forward.
    That's not a light boat at 16000 lb and 28'.
    I would look to mount the mast at the aft edge of the forward cabin. Fit a good quality roller furler headsail 150-200sq foot and that will give you 5-6knts from guessing her 70 -160 deg apparent wind angle.
    As others have noted if you want a steadying sail it needs a boom as it needs to be sheeted down hard. You could still fit one aft of the mast on the lower cabin top.
    No idea on area but it is up quite high so you would want to keep it small. The mizzen on our 8ton yawl is 100' and dose a similar job except it mounted much lower.

    What ever you do it must be easy to use. That's why I like a good furling headsail. Just pull the furling line in or out and sheet on.
    No sail cover, no ropes to untie. Having a boomed sail up high is a problem to handle. Sail covers, tie downs etc.
    It needs to be small enough to stay up In most weathers.
    Z

  20. #20
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    Default Re: Sail design.

    Quote Originally Posted by ben2go View Post
    For a main steadying sail, I would need about 150 square feet and for any kind of sailing I would need about three times as much. Readying around It seems a displacement vessel of about 20,000 pounds needs 150 sq.-ft. That's where I am getting my guestimation from.
    I don't think that hull will have the stability to carry 450 sq. ft. of sail. 150 is closer to the limit without a deep ballast keel, and even that could extend your range a bit.

  21. #21
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    Default Re: Sail design.

    Quote Originally Posted by johnw View Post
    I don't think that hull will have the stability to carry 450 sq. ft. of sail. 150 is closer to the limit without a deep ballast keel, and even that could extend your range a bit.
    I agree with you.
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