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maf
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| Joined: | Sun Jul 27th, 2008 |
| Location: | |
| Posts: | 2 |
| Mana: |  |
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Posted: Mon Jul 28th, 2008 03:49 am |
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Hi, I'm considering ordering the plans and building a Nutmeg. I've got access to a Sunfish rig and this seems like a great way to get a good hull for it.
I have a concern about the leeboard, mostly since I've never sailed with one. I don't have any problems building a daggerboard case and modifying the boat but I'm not sure if it would disrupt all the other physics of the design. I'm guessing the placement of the board is a big factor in how everything else works.
Any thoughts on this? I figured the leeboard was done for ease of construction but I've built cases for centerboards & daggerboards before. Thanks!
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Pathfinder
Member
| Joined: | Fri Jul 25th, 2008 |
| Location: | Texas USA |
| Posts: | 9 |
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Posted: Tue Jul 29th, 2008 05:43 am |
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Hey maf, while my Nutmeg plans haven't arrived yet, I have built boats with daggerboards before, and I'm always tinkering with designs. I'm sure Dave or Thom will be along shortly to correct me if I'm wrong about anything.
I figured the leeboard was done for ease of construction but I've built cases for centerboards & daggerboards before.
Yes, a leeboard is easier to construct, but many people(Bolger,Michalak etc.) like them because they also free up interior space in the boat.
I don't have any problems building a daggerboard case and modifying the boat but I'm not sure if it would disrupt all the other physics of the design. I'm guessing the placement of the board is a big factor in how everything else works.
Yes, the leeboard (or any other type of foil) does need to be balanced under the sails center of effort. Too far to the front or rear and you will wind up with "lee helm" or "weather helm". Essentially this means that you will have to apply correction with the rudder to keep the boat on course. In the case of lee helm the boat may sail off without you if you fall overboard. Some designs use a slight bit of weather helm as a safety feature. With a small degree of weather helm, if you fall over, the boat will hopefully point into the wind and stall. (if you're familiar with the nautical term "in irons" imagine a boat that wants to do that on it's own.)
If all of that sounds complicated or makes your head swim, here's the good news: You should be able to place the daggerboard the same distance from the stern as the leeboard. This is due to a unique requirement of leeboards. They always need to be at or very near the boats widest beam. What this means is that most designers place the leeboard at the boats widest point and then adjust the sail position to balance over it. My guess is that this is what Dave did when placing the mast step for a Sunfish sail. So if you stick with the Sunfish sail as you've indicated, you should be fine placing the mast step per the plans, and then placing the daggerboard the same distance from it as indicated in the plans. (Yes we could get really technical about the performance differences between different foils, and adjusting foil size, but my gut tells me that on a boat this size with the Sunfish style rigging you'll be fine.)
I have a concern about the leeboard, mostly since I've never sailed with one.
Why not build the boat with the leeboard and see how you like it? It's easy and if you decide that you want a centerboard or daggerboard later, the space in the hull will still be there to add them. I think you'll find there is no real learning curve to sailing with one, as opposed to those pesky elephant ears (loose bilgeboards mounted on both sides) that have to be adjusted each time you tack. Really you'll probably find that the boat sails much the same and you soon forget that you don't have a centered foil.
Hope that helps
~Clint
Edited to add: If you really want to learn about balancing sails Jim Michalak has an excellent essay here: http://www.jimsboats.com/2007/1aug07.htm#Sail%20Area%20MathLast edited on Tue Jul 29th, 2008 05:53 am by Pathfinder |
maf
Member
| Joined: | Sun Jul 27th, 2008 |
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Posted: Wed Jul 30th, 2008 04:29 pm |
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Thanks Clint, I appreciate the detailed reply. I'll give the leeboard a shot. Once I started looking around for leeboards, it seems like there's a lot of them.
Like you say, I can always go back & fit a daggerboard case if it seems necessary.
Thanks again!
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