How many spline weights do I need?

Discussion in 'Boat Design' started by Smoothride, Oct 18, 2006.

  1. Smoothride
    Joined: Sep 2006
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    Smoothride Dog Owner

    Howdy Y'all;

    Yup, I just started out with westlawn, and I haven't found a definative answer on how many ducks/whales I need. As I'm moving to south korea in 3 months, I'd rather order them now and save on shipping!

    I almost think about 6 will do it, but I've heard of people ordering as many as 10. Do you really need that many for this course?

    In real life, although I saw no ducks actively being used in a design office I worked in, do any of you out there use them? (In the design office I worked in, the boss had some that were very attractive paper weights, or sometimes, just to look at [maybe he even handled them late at night ;) ]).

    Are plastic splines generally used, or do people use wood?

    Thanks for answering "another damn spline weight question!" :D

    SR
     
  2. Earl Boebert
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    Earl Boebert Senior Member

    Dunno about the course, but one old timer I read (L. Francis? Can't remember) said that if you use more than five for a given curve it's guaranteed not to be fair. FWIW.

    Cheers,

    Earl
     
  3. Smoothride
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    Smoothride Dog Owner

    Huh, that might very well be true! L. Francis Herreshoff is probably the highest authority in design!

    thanks!

    SR
     
  4. CDBarry
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    CDBarry Senior Member

    Plastic splines are fine, as are steel ones (made out of strips of the stainless steel stock for machinist's rules - buy it from machine shop suppliers). Plastic splines can be made by ripping scrap acrylic sheet, and I used cat food cans (or coffee cans on the loft floor) filled with lead shot and resin for weights - they have the advantage that they can be stacked to concentrate weight.

    That said, I once worked for an older gent who had a dozen beautiful bronze ones that the shipyard he had worked at made him from pieces of a scrap propeller.
     
  5. westlawn5554X
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    westlawn5554X STUDENT

  6. Smoothride
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    Smoothride Dog Owner

    Gentlemen;

    Thanks for the responses:

    CD: Now everyone is going to want ducks made out of old scrapped ship's propellers! That's the coolest thing I've heard so far.

    westlawn: I'll end up getting the edson ones, they'll last forever. I've been using calculators, fingers, and anything else that will work as spline weights, and those flexible metal splines with the plastic coating suck, I'm finding...
     
  7. SailDesign
    Joined: Jan 2003
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    SailDesign Old Phart! Stay upwind..

    6 may be all you need, but 10 will allow you to double-up for harder curves.
     
  8. Eric Sponberg
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    Eric Sponberg Senior Member

    I found that even at 10, I did not have enough--it depends on how large your drawings are--I usually draw up to D-size (24" x 36"). I ended up with 16, although never used all of them all at once--maybe up to 12.

    I disagree with the statement that you should not use more than 5--again, it depends on the line and the batten. Plastic battens (which L. Francis never had) are particularly flexible, and you need more ducks just to hold them steady so that they don't deflect from the pressure of your pencil. I use both plastic and spruce battens. I also have a 4' long stainless steel straight edge which is great for drawing the grid pattern for the lines plan.

    Of course, these things get used less and less since most work these days demand the use of the computer. But I still have them and use them from time to time. I still have and occasionally use my slide rule!!!

    Eric
     
  9. westlawn5554X
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    westlawn5554X STUDENT

    he... slide ruler is useful if you... still love the love for old stuff... feel real good... better than a calculator...

    You can milled your Duck and Whale from Stainless steel... I have ordered different spline weight for the right parameter bf milling........................

    Good luck
     
  10. Smoothride
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    Smoothride Dog Owner

    Thanks again everyone, I will probably go for 6 or 8, not quite sure just now, but 10 will just be too expensive right now... $35 apiece is nasty!

    I didn't know the plastic splines were so flexible, it's good to be forewarned.

    SR
     
  11. yokebutt
    Joined: Aug 2004
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    yokebutt Boatbuilder

    Sounds like a "How many clamps do I need?" or "How many vice-grips do I need?" question.

    Yoke.
     
  12. Smoothride
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    Smoothride Dog Owner

    Yoke;

    Yup, you're right, I'm learning... slowly.
     

  13. longliner45
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    longliner45 Senior Member

    well Im no n/a,, but by trade ( in the old days) was a journeyman millwrite and journeyman utility machinist ,, I was tought the old way ,,even tho,many tools and computers and programs are availible,,,,,I believe if you can do it the hard way ,,,because someday youll have to,,the easy way is that much easyer.iv been told that when you can use a machinist scale and be within 10,000 your good , and if you can do that ,,the other tools were easy,,like mics, my point is it is good to see that somewhere they still have old school methods,,,just makes me feel that much better about the future of boat design,,,,,,,,,,longliner
     
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