sail plans

Discussion in 'Sailboats' started by bilgepump, Dec 30, 2008.

  1. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    Again Thank you Alan you have been very helpful.
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    My apologies Bilgepump, I read 15' x 58' instead of what you actually wrote.

    Small cat ketches and yawls are reasonably plentiful. You'd be wise to look many over and study the "centers" relationships and general trends in these size and configurations. Staying close to existing designs will insure you don't make huge errors as you develop knowledge about design. Frankly, it's what all budding designers do.

    The nice thing about small boats is, trim issues can usually be easily corrected on the water.

    I have a number of designs of that size and several different rig configurations. If your sailing area tends to be on the light wind side, then error for a higher SA/D ratio, say 20, which I'm assuming for Akron. Also the CE/CLP lead will differ considerably depending on several factors. The hull type plays a role as does the rig type/arrangement and appendages. The last cat ketch I did was 18' and carried about an 11% lead with a small amount of balance in the rudder (10%). This was an unballasted, day boat, no cabin, just a covered foredeck. A cat ketch will be more forgiving in lead placement then a regular cat boat or sloop. A yawl is fairly forgiving, but not as much as the ketch. In short, the more sails you divide the area up into, the less the lead will move around in use, making a more forgiving design.

    As far as sail area you can carry, much depends on the "power" of the hull's ability to resist being flipped onto it's side. Some shapes are easily tipped, others very stiff and difficult to roll. More information about the general shape and displacement would be helpful (as has been mentioned previously).

    Again, my other half has swatted me in the back of the head for you . . .
     
  3. alan white
    Joined: Mar 2007
    Posts: 3,730
    Likes: 123, Points: 0, Legacy Rep: 1404
    Location: maine

    alan white Senior Member

    You had asked about the relative size of the yawl mizzen sail. Generally, a yawl with a jib should balance the boat well if the mains'l is furled, and even if there isn't a jib, the mizzen might be a quarter the size of the main, but in any case, it is just big enough to be of value in balancing the helm by being eased or hardened up, in other words, acting a lot like the rudder of an airplane. Yawls are handy in this regard. As said, if they have jibs, they sail well with mains'l alone or with jib and mizzen with the main stowed.
    I'm switching to a yawl (from the current sloop rig) for that reason and also because the yawl is very manueverable in tight spots, even able to back up, which is often an advantage when mooring or anchoring. They're also great for reefing the mains'l, holding the boat's head to the wind, or as a riding sail.
    Besides, I like a lot of strings to pull and I also don't like to leave well enough alone.
    When and where were you in Maine, Bilgepump?
     
  4. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    Roughly 10 years ago I was around 18 or 19 at the time. I was on Mt. Dessert Isl. doing a roofing job and I fell in love with the entire landscape and the people. I grew up on the Raritan Bay in NJ and if I wasent swinging a hammer I was swinging a gaff on tuna and swordboats. Maine seemed like paradise to me people still live the "right way" hands on and "Downeast tough" I struck my first and unfortunately last bluefin in the gulf. But what you have said is exactly the reason behind my inquiry I want a boat that is not so geared to local winds as I plan to realy sail it from Cleveland out to Gulf of St. Lawrence. So I want to have self steering capabilities as well as light air and varying winds, and like you mentioned manuverability.
     
  5. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    To Par: No worries but if I were to build from the skerry plans provided by CLC Boats there plans call for a 56sqf spirit or a sloop rig of 58sqf main and 18sqf jib what I'm trying to figure out is how to get the numbers on a mizzen. I'm sure its not as complicated as I think but more of a matter of reducing the mainsail area. The plans call for no ballast aside from the human type. As Alan had said it (the mizzen) should be roughly a quarter of the mains area but with all the replys talking about all these equations I'm more confused then when I started. I'm not building her to stay in Akron if you've ever been here you would understand,(LOL) but I'm trying to find the happy medium with the sails. I had planned on adding lead to the daggerboard as you mentioned in your 18 footer. In my simple way of thinking there must be an easier way to figure this all out given that I have the suggested sail ares from the plans.
     
  6. TeddyDiver
    Joined: Dec 2007
    Posts: 2,614
    Likes: 136, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

    PAR pretty much said it in the post #17.. There's no simple answer nor any right sail area.. instead there's multiple choices each having pros and cons.
    BUT to give a starter you can have the CLC original mains 56sqf and ad a 18sqf mizzen and, if you like, jib same size... lot to play with :D
     
  7. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    Thanks man that was an easy answer to follow, I suppose its going to be a matter of a little experimentation on a local lake before beating acroos Lake Erie
     
  8. alan white
    Joined: Mar 2007
    Posts: 3,730
    Likes: 123, Points: 0, Legacy Rep: 1404
    Location: maine

    alan white Senior Member

    Bilgepump: You'll find that there are many boat plans showing both sloop and yawl versions. A study of those similar to your proposal would be worthwhile to examine. In looking at several of those designs, see how things are shifted around. Note how the main was cut down to compensate for the additional sail area in changing to a yawl. If you can, get a book that shows how to find the CE of any sail plan. You should see, even on simple drawings others have made of boats with both sloop and yawl versions, where the centers of each sail are, what the areas are, and what relative areas were chosen to maintain the same overall CE.
    I'm 45 minutes from Mt Desert Isle. Beautiful area, though too crowded during the Summer. I love this area too, though it's no place to get rich! I have sailed the coast a lot over the years, but I have discovered that a boat on a salt water mooring doesn't work for me these days.
    I have a pond across the street that's perfect for my needs----- I'm ten minutes from my front door to actual sailing even without rushing things.
    I can still occaionally trailer the boat to the coast for a day's sail.
    Are you planning on doing the Erie canal?
     
  9. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    Yeah I'm going to give it a shot although I've been told its a pain in the you know what! I know exactly what you mean about the mooring my last boat was a 67 Whaler Montauk that I had moored about 200yrds (high tide) from shore and no dinghy! Needless to say I'm a hell of a swimmer!!! Yeah the island seemed like a touristy place but still the scenery is like no other on the east coast a lot like Oregon or Wash. As far as the trip goes though I have nothing else to do being that there is no work here so what the hell right!
     
  10. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A reasonable rule of thumb is to take a sloop rig, cut 10 to 15% off the length on the end of the boom and find a place to fit the mizzen. It was common practice to convert CCA style yachts to yawl rig (favorable rating under the racing rules) by this very method.

    On your little boat, it might be much simpler to use scale drawings of the sail plan and see how much the CE moves as you shorten the boom. The CE can be pulled back, to balance the yacht with a mizzen. You'll find the CE isn't especially hard to figure out with some drafting tricks or you can use simple geometry.

    You can also change balance a fair amount with appendage alterations. I've installed more then one skeg (or enlarged the existing one) to relieve helm pressure, rather then install a bow sprit and new headsails. I've also hacked off the end of centerboards to change balance.

    Settle on a hull from. Calculate the CLP with the centerboard fully deployed and the rudder all the way down (a pin and the cardboard cut out trick works fine). If the rudder has a balanced blade then only use 50% of it's area for CLP calculations. For a Bermudian yawl rig of normal proportions 12% lead will be a good starting point.

    To get you started on looking at other designs, this is one of mine.

    http://www.boatdesign.net/forums/boat-design/ricellis-aluminum-gift-10388.html

    It's actually a sloop, but carries a mizzen because of rapidly changing weather patterns in the area which it's sailed. On any given day you can start out in the morning with fluky 2 knot zephyrs, then build to a nice easy 8 knot mid morning, then a thunderstorm rolls through with wind strengths over 25 knots, leaving you with zephyrs to ghost back to the loading ramp. Under these conditions you'll want multiple hoist options, so in the zephyrs you'll fly jib, main, mizzen and mule. As the winds come up the mule and eventually the mizzen come down, then your first earnest reefing begins.

    As far a proportions, it's a ketch, but the CE is well aft. The skeg is now an 1.5" deeper and the full length of the bottom, so the mizzen can stay up longer (weather helm). The CE is low and far enough forward, with the mizzen doused, that she can carry on as a sloop for a long time, before needing a serious reefing. This was the point, a design that could move in very light air, tolerate heavy air and have a broad range of usefulness in the "average" wind strengths they'd encounter. As a ketch, she carries about 6% lead, which is "soft" but intentional, because of wind strength. As a sloop about 14% and under jib and jigger around 17%. Notice how the lead move progressively forward as the sail plan is reduced down? This accommodates building helm pressure with increased wind strengths.
     
  11. bilgepump
    Joined: Dec 2008
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: akron

    bilgepump Junior Member

    THANK YOU that is exactly what I needed to know, so a little math and I think I'll have it you guys have been more then helpful Happy New Year by the way!!! the Gift is beautiful!
     

  12. bistros

    bistros Previous Member

    Having done the Erie Canal (in a power boat) and also out the St. Lawrence, I'd opt for the trip up the river. In the Canal you will be under power 98% of the time, and waiting 70% (for various reasons) of the time traveled. The Canal is slow, narrow, shallow in places and can be crowded. Needless to say the lower reaches of the Hudson are busy at best and dangerous at times.

    Going up the St. Lawrence can be a trip back into time, and almost to another world. The Gaspe Peninsula in Quebec is spectacular, remote and beautiful. Some of the Canadian National Parks (Farillon, Fundy etc.) are places most never see in a lifetime. Plus, you can sail all the way. It's kind of cool to be in a "foriegn" land (province of Quebec) where French is spoken as a first language (although almost everyone speaks English as well).

    Just my opinion.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.