Holy Bernoulli Batman! :: Catamaran Sailboats at TheBeachcats.com

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Edchris177

Rank: Chief

Registered: Nov 26, 2009

Last visit: Aug 10, 2024

Posts: 2531
Posted: Dec 17, 2009 - 11:05 PM

I was up at the cottage yesterday, & decided to have a closer look at the sail. I mounted a small Harken block from just below the ceiling, & hoisted the main. Bloody H@$l, that's a big rag! That ceiling is 20' up, & I still had most of the sail on the floor.
With the exception of one small green tape patch, (you can just see it on the luff, below the yellow stripe)there are no holes, patches or repairs. In fact most of the original telltales are still attached. Should I remove that green tape, & have the sail sewn? The tape doesn't look that old, but the boat wasn't used for the last 2 years, the tape could have been there for years. My concern is potentially having the defect spread, ruining the sail. Or are those sail bandage tapes plenty strong for a small hole?
I noticed the telltales are the same color as the stripes they are on, making them rather hard to see. Do others change them out to more contrasting colors? I was even thinking of magic markering them black so they would show up better. Zoom in on the one on the orange stripe to see what I mean.
The sail on the bannister is from my old Invitation, it seemed like the best place to dry it out, though my wife has issues with my version of decorating.
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edited by: Edchris177, Dec 17, 2009 - 10:10 PM

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--
Wolfman

Rank: Chief

Registered: Jun 24, 2009

Last visit: Jun 15, 2023

Posts: 1555
Posted: Dec 17, 2009 - 11:37 PM

I don't think that holes in a dacron sail spread all that easily. At least I haven't found that, one of my old mains has a couple of small holes in it and they pretty much stayed when I sailed with it for half of last season. I think the repair tape is pretty good and you probably will do more damage trying to get it off. If the hole forms through the tape or moves beyond it then get it repaired.

I see what you mean about the tell tales! I would probably switch them out for black ones, they are very visible through the cloth. Magic Marker would work in the short term.

Yeah, I'm currently storing a jib and trampoline in our back room and I think I had better move them soon or the wife is going to do something bad to me. She also seems to be taking offense to the Harken blocks on the bedside table...

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Dec 18, 2009 - 09:31 AM

Quote She also seems to be taking offense to the Harken blocks on the bedside table...

I dont even wanna know what perverted things you can do with a block in bed..... ok i wanna know
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Dec 18, 2009 - 09:43 AM

QuoteWith the exception of one small green tape patch, (you can just see it on the luff, below the yellow stripe)there are no holes, patches or repairs. In fact most of the original telltales are still attached. Should I remove that green tape, & have the sail sewn?

I only see green below your Leach (not the luff).. but i think the tape is fine. you could/should be able to remove tape from dacron without much problem so when it looks old... you can easily repair that.

As for your tell-tails.. i doubt they are original.. and putting the same color tail on the same color panel is uber silly (trying not to offend anyone here) so YES change them.

I would NOT use a marker .. (unless you are willing to have marker on your sails)... inks do funny things when wet, and if rolled onto itself. I have a nice series of rust stains that went through 4 layers of dacron on my jib... its ugly and i bet its bad for the material.

Tell tales (and leach tales) are about the cheapest and easiest things to change on your sails.. and they are very important... so i would buy new ones and re-do it.

PS if you dont have leach tails... you are missing out on an important indicator. My friend said he never thought he needed them until he started to sail with a USA flag attached to his leach... Often the flag was flying forward (towards the mast) even while underway.. this showed him that he had negitive air flow at his leach.. and he quickly purchesed leach tails.. to learn the correct way to tune his sail.
Wolfman

Rank: Chief

Registered: Jun 24, 2009

Last visit: Jun 15, 2023

Posts: 1555
Posted: Dec 18, 2009 - 10:00 AM

Actually, I just put them there at the end of the season and never moved them. Didn't even realize how that could be interpreted until a few hours after I wrote it. :)

Hmm, never thought of the marker running. Good catch.

D.

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Edchris177

Rank: Chief

Registered: Nov 26, 2009

Last visit: Aug 10, 2024

Posts: 2531
Posted: Dec 19, 2009 - 05:00 PM

Thanks, never thought about permanent ink bleeding through, I won't do it.
You are correct, I mixed my luffs with my leech, that green is the only one.
I may not be an experienced sailor, but I know a bit about airfoils, did a few courses in aeronautical engineering early in my career. I don't know why all blow boats DON"T come with trailing edge tell tales. We had access to a supersonic wind tunnel,(very small working area) as well as a low speed tunnel. While experimenting with various angles of attack, & their effect on the lift/drag curve the yarn tufts were enlightening to say the least. We had them glued every 3 sq inches to a wing, & it was surprising how/when some of them would burble, showing breakdown of the laminar flow of the boundary layer. Wings also have washout, similar to twist in a sail, though not as pronounced.
Many people assume that you want smooth flow over the ENTIRE wing, but that may not generate the greatest lift. In fact some turbulence can help to re energize the boundary layer, & keep it attached longer. Other wings utilize vortex generators for the same purpose. A wing with leading edge slats, drooping ailerons, & slotted flaps might have many areas of boundary separation, but they pull like a mule. Once you get away from the ground, thing cam be cleaned up for better efficiency. The clean wing performs best at only a certain speed, I'm sure sails are much the same, & therein lies the art of trimming. It would be wonderful to put a sail in a wind tunnel & derive true scientific empirical data about what tweaks result in the most pull. I think many would be surprised that some tell tales will be luffing at this point

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--
Wolfman

Rank: Chief

Registered: Jun 24, 2009

Last visit: Jun 15, 2023

Posts: 1555
Posted: Dec 19, 2009 - 05:29 PM

I'm pretty sure that they do put sails in wind tunnels for testing. Especially at the high end professional level such as sail designs for the America`s cup.

My aeronautical engineering background isn`t very complete (mostly self study dealing with drag on piers) but one thing to keep in mind is that a sail will always be an imperfect wing. It is flexible so it will change shape in areas where there are vortices and where separation occurs. The windward side isn`t shaped like the bottom of a wing so it is more difficult to preserve even airflow. Also the flow varies along the big high aspect ratio sails we use due to twist. So everytime you trim you create more problems as you solve others. The best we can try for is non-turbulent flow over as much area as possible (at least on a reach).

Because of this I`m beginning to understand the importance of adjusting the mast rotation, although I still haven`t figured it out in practice. The REALLY good sailors probably have a better practical feel for everything we are talking about and can take advantage of some of the turbulent boundary layer physics you are talking about. At that level though I think it has more to do with feel and experience, or in my case Voodoo and sacrificing chickens. :)

D.

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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kgatesman

Rank: Mate

Registered: Feb 06, 2009

Last visit: Jun 25, 2017

Posts: 223
Posted: Dec 20, 2009 - 02:54 PM

Sailtape will hold for a long time. When you take it off, it will leave a gooey residue. I wouldn't take it off, unless it is falling off, or the sail is being repaired properly.

I have colored white sail tape with Sharpies to match the color of the panel with a hole, but not anywhere near a contrasting panel.
lawrencer2003

Rank: Mate

Registered: Sep 05, 2004

Last visit: Oct 19, 2015

Posts: 327
Posted: Dec 20, 2009 - 07:02 PM

I'd find an awning maker or sail maker and have that hole fixed. My experience is that Dacron can run. I HATE holes in my sails. Then again, if the tape is holding then no worries. Change the telltales. They are really valuable and you need to see em.