Slightly different sail for Dinghy Vee

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ekollector
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Slightly different sail for Dinghy Vee

Post by ekollector »

Hej Morten
Although I'm still busy cutting the hull pieces, I started to wonder about the sail. Would it be possible to have a sprit sail design where the boom is higher above the boat (to pass easier overhead), as well as potentially an even greater sail area? I was thinking of something where the sail is more extended horizontally - longer boom, without having a taller mast or sprit, allowing for the boom to be higher, and the sail to potentially have more area.
Thanks, Laszlo
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Post by Boatplans.dk »

Hej Laszlo,

One thing that is important when changing the sail layout is to make sure the sails centre of effort is at the same longitudinal position before and after the changes. Therefore you should evaluate the changes carefully before deciding which changes to make.

So if we take the first thing, having the boom higher. That is easiest achieved by simply making the mast higher. If you want to have 1 foot more headroom below the boom you simply make the mast 1 foot higher. This will move the centre of effort upwards but it will not make any changes longitudinal, so it will not affect the balance of the boat. Moving the centre of effort upwards will however produce a larger healing moment, which will need to be balanced with the hull and the position of the crew.

Having a larger sail area by making the boom longer will move the centre of effort aft. Now first I must say that I haven't made any calculations about this and the changes might be so small that the centre of effort will still be at an acceptable longitudinal position after the changes. But general speaking it will be necessary to take some steps to get the boat back in balance. It can be done two ways, by changing the hull (moving the centreboard aft, moving the mast forward) or by changing the sail layout.

Since moving the centreboard is not a good solution for this boat you will have to move the mast or change the sail layout. Moving the mast forward can be done, but you will need to make some modifications to the hull to make sure the mast is still well supported. Changing the sail layout can be done different ways. If you add a jib it will compensate the centre of effort and move it forward again. If you change the sail to a standing or balanced lug you will also be able to move the centre of effort forward.

That was a terrible lot of words for saying nothing specific :) but drop me an email when you are ready to make the rig and I will of course help you determine and calculate some more specific on the changes you have in mind.
Morten Olesen - Boatplans.dk
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ekollector
Posts: 7
Joined: Sun Oct 08, 2006 10:39 pm
Type of boat I like: <-- Please read instructions to the left and delete this text. Then, tell us what type boat you like! :-)
Location: West Chester, PA

Post by ekollector »

OK Thanks for the info, I also managed to read some articles about this, so I'm slowly coming up to speed. I've actually never sailed before. :roll: I'll send you a design when I come up with one. I'm thinking of moving the mast forward, just a bit, so that it's on the other side of the front frame member. I'll attempt to design a 50 to 55 square feet sail, which will also be 1 feet higher. I wasn thinking of lengthening the daggerboard by about 6 inches to accomodate this. I'm also thinking of making the mast tiltable, so that I could play with the centre of effort, to exerience actually what it does.

By the way, I think I found an error in the plan: the daggerboard box's dimensions are smaller than the actual centerboard. I haven't cut these pieces out yet - but noticed it.
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Post by Boatplans.dk »

You are right about the centreboard, it should not be wider than the box :oops: I wonder where that dimension came from. I will make a correction to the plans and sent it to you. Thanks for letting me know.
Morten Olesen - Boatplans.dk
Website: http://www.boatplans.dk/
Blog: http://BoatBuildingArticles.com/

Check out my author page at Amazon and browse for boat building books: http://www.boatplans.dk/news.asp?news=amazon
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