Thank you Lester. That may be what I am missing. I’ll work on that today.
Don
Marino
I’m wondering if the short chords are giving us a problem because the shorter the chord the thicker the sail material gets(relative to the chord length). This would make the material stiffer which would stretch the adhesive which would negate some of the wedge(just a guess). When I made my main it seemsed flat until I hung it(horizontally) and then it showed draft. I thought that all the draft was from gravity so I made a flat sail and it showed no draft hung the same way. What thickness/type of sail cloth did you use?
Don
Marino ,
it is worth looking at : http://www.onemetre.net/Technicl/Outhaul/Outhaul.htm
It is very interesting but how much can be applied to my tool is another question.
I have in my hands 3 drawings each one representing a ruler with a courved edge , one shows 0.288%, the other 0.42% and the last 0.57%. all are suggested for making sails. No reference is given about the draft that could be obtained.
Claudio
PS: download the sail making software called SAILCUT 4 and play with.
Claudio
I’ve noticed that when you are refering to wedge thickness(as above) you say 0.35% or 0.40%. Shouldn’t this be mm. or is this a language thing. Its not important(unless I’m wrong). Please don’t take this as a criticism. I don’t want you to get upset with all our questions and go away. I want to make this work for me as I beleive it is a good system. The sail that I made is smoother and evener than the ones I made with blocks. I think this is because the tape joint is flat as opposed to angled open with blocks. Unfortunately we haven’t had a chance to actually sail these sails and that will be the final test. We have to remember that this is a method of broadseaming and there is more to sailmaking than broadseaming. That said I seem to have a problem getting large draft on short seams at the top of a sail. Have you made such a sail or do you decrease the draft towards the top when you make sails. Maybe this is something that hasn’t been run across before.
Don
I’m using 60 micron mylar. Like I said before, I know it might be heavy/stiff, but that’s what I have in hand.
It also beats the 0.75 Oz spinnaker cloth I used to use, because it came from an very old spinnaker that blew appart, and the cloth is really stretched.
Maybe I did something wrong when I assembled the jib, I’'l do it again, more slowly this time…
Also, GOOD NEWS!!! I found (by accident) how to easily remove the first layer or DS Tape:
- Place the first DS tape as per the instructions
- Place the panel as per the instructions.
- Place the secon layer fo DS tape BUT starting at one edge of the panel (or less than 1 mm from the outside) and extend it over the other edge
- Place the other panel as per instructions
- Lift the assembled panels from the jig by lifting the DS tape from the side where the two layers extends.
- Remove the first layer of DS tape by lifting the tape from the side where only the first layer extends from the panels… It will lift cleanly!!!
Let me know if I didn’t explained well enough (english is a second language for me, and is not unusual for me to make no sense at all sometimes- or more)
Lester
Does this spreadsheet take into consideration the effect that one seam has on the next. Maybe that would account for the difference between your figures and Claudio’s findings.
Don
Claudio:
I would like to second Don in this; I we make too many questions is because we are REALLY interested in this, not to make any criticism…
Keep around supporting us!!!
I’m using .0035"(90 micron?) so you should have better results than me. It’s some old map material, way to stiff but cheap for experimenting. I have some Trispi for when I think I’m
competent.
Your English is as good as mine and it’s my first(and only) language.
I’m going out to the workshop to see if I can arrive at some conclusion.
Don
Hi Don
Nope! The spreadsheet assumes one seam in isolation…
Hi Marino
It is part of the percentage. 2% of 29 is 29 / 100 * 2…
Hi Claudio
Perhaps. I think the necessary approach is to take the measurements in the same way every time. For example, the sail should be rigged, the rig stepped, a defined amount of twist, outhaul, and mast bend set, the boat should be held horizontally, and the sail photographed from the mast head. Then at least you can get consistent results, but your results may be different from someone else’s.
[QUOTE=Don]Claudio
I’ve noticed that when you are refering to wedge thickness(as above) you say 0.35% or 0.40%. Shouldn’t this be mm. UNQUOTE
NO - 0.35% and 0.40% (Fm%) are the multipliers factors .
Go for a while to the Table : take a vertical line at 0.35% (Fm%) and you will cross the blue band around 11% Draft , instead starting from 0.40% you will fall on 12.5% Draft.
This is what I means for a big change indipendently of the wedge thickness that is function of the Cord lenght.
Hope will be clearer
Claudio
Oh Yeah, I’ve been dealing so much with a 100 mm seam where the MF and wedge thickness are the same I got confused.
Don
I understand Don not simple to put together
Draf in % that may varies fro 2 to 14 %
Draft position in %, that may varies from 30 to 50%
Fm % , that may varies from 0.2 to 0.5 %
Cord lenght in mm,
Wedge thickness in mm
When the values are some time very close
Ciao
Claudio
One of the things I’m learning is that the final sail shape(on the boat-in use) can vary quite a bit from the sail blank(seamed but no luff curve). This creates the problem that every sail must be finished before any comparison can be done. I’m wondering if I take a working sail (on a boat) and Accumeasure(accumeasure in now a verb) it, take it off the rig and set it up in such a way as to duplicate the readings, that I may come up with a method of measuring blanks. The luff curve will complicate things but I think by setting it up with the correct backstay tension I can ignore it from then on. The luff curve is more an interface between the sail and mast anyway.
Any pooh-poohs or ideas.
Don
Suspecting some misinterpretations on how to use the tool, I add this sketch and in next some very explicit photographs
Claudio
Effects of mis positionning the panels on the jig (tool)
Claudio
Claudio:
I sent you a PM on Sailcut.
All: I re-did the jib, but this time I applied the first layer of DS tape with the wedges still on. Whilst the topmost seam shows very little (if any) draft, the lowermost one shows a better draft curve. Will try tonight to make the mainsail (which have a lot longer chord)… Will let you know the results…
Claudio
LOL. I actually did that on my first seam. It took me a minute to figure out what I had done wrong. Haven’t made the same mistake since.
Don
Another way to set this up will be to change the wedge possition of the luff side and place it, for example, 10% closer to the screw (middle). Same results without having to unscrew anything…