tarps for sails?

[cybulski]

I am interested in making some sails. I have been reading about several different techniques, and it just so happens that I have 5 cotton module tarps. They are like new, and are good size something like 24x16 , ill need to get a accurate measurement when I can let go of this coffee cup. Anyone try this before? I don't really expect them to last very long, i think that will depend on how much i use them, and how much i let them flap :eek:.
Just want to try, the experience might give me a little different understanding. And I will be able to say I made them.

http://www.woodenboat.com/forum/images/misc/progress.gif

[GBVT]

Lots of folks have done it with polytarp. A crap tarp lasts a summer or so of hard use, takes $10 and a couple of hours to build. Michalak's book has tarp sail building info. And the duckworks folks could probably help you out. Edges need to cut with curves to put draft in the sails or darts need to be sewn in. Great way to experiment with different rigs.

[cybulski]

these arent really polytarps.The cotton module cover is used to protect compressed cottons from moisture, dirt and other causes of contamination.
these covers are constructed with high tensile seamless fabric for extreme strength and durability. The cover is pretreated with UV inhibitor to prolong the life span and to prevent fading and deterioration caused by harmful sunrays.

[cybulski]

I unrolled one. The unseamed center, which is the section I want, is 24x12.Ifound a few tags, no info except for the manufacterers name.I just went to the manufacturers website, but didn't find any specifics on this particular type. It is heavier than the 7oz polytarps i have, almost double.still looking for info.

[StevenBauer]

no info except for the manufacterers name.

Which is?








Steven

[Cuyahoga Chuck]

Some of the answers have to do with how heavy this material is and how big a sail you intend to fly in relation to the boat size.
Building a sail that can stand up to normal use isn't a quicky passtime. If you are going to use this stuff you had better be certain the project isn't jinxed from the start by too heavy a material.
Also, it wouldn't hurt to see if whatever sewing machine you intend to use will handle multiple layers of this stuff without spitting it's guts out.
A sailmaker I met fingered the sail on my little pram and said, "looks like 3.2 ounce dacron". Whatever it's made of it has been "popped" by sudden gusts numerous times and has survived intact. A lot of the strength is due to the fact that a conciderable amont of hand work has been done to install the boltrope etc. The sail is an ordinary, off the shelf item.

[Brian Palmer]

Use the search function for other threads on sailmaking.

Your best best is probably a pre-cut kit from Sailrite for making your own sails. Seeing how they have cut each panel nd how they go together will be a great education.

Good, properly shaped sails are one of the best investments you can make for your sail boat.

Sailing with poorly shaped sails is like driving a badly tuned car that is prone to sluggish starts and stalling at stop lights.

Brian

[Thorne]

Get this book:

http://www.woodenboatstore.com/images/300306S.JPG
http://www.woodenboatstore.com/Sailmakers-Apprentice/productinfo/300-306/

As BHOFM and others above point out, making a sail with any material that is too heavy / thick will cause the sail to only work in really heavy winds -- usually the time to get off the water in small boats.

A sail for a small boat should be of relatively thin material for optimum performance in light winds -- plus it reduces the weight aloft.

If you just want to practice and make something out of material other than Dacron, consider some of the cotton-based alternatives. I think that our local sailmaker expert, Todd Bradshaw, has made some recommendations in the past as to Sunbrella and other canvas-like materials for alternate construction.

Sails can be made from the Home Despot lighter-weight canvas painter's tarps -- but they rapidly go baggy, mildew easily, and can be a waste of a lot of time and effort. Here's one on my friend's boat _Tortuga_, photo by John Kohnen -
http://farm3.static.flickr.com/2357/2540929040_03fe954b5e_o.jpg

[CarlZog]

Winter before last, on a voyage passing between the isle of Tortuga and the Haitian mainland, I saw a couple small boats using old American billboards -- huge, photoprinted plastic sheets of advertising. Seemed to work for them, and kinda cool looking.

Carl

[cybulski]

After further research I found that they were produced by KBH in Clarksdale Mississippi its called THE SHED module cover, it is 7oz. Not as heavy as i thought.My boat is 23ft sharpie with cat ketch rig. The main will be 22, mizen 18.

[Todd Bradshaw]

Seven ounce might be OK, but most cotton fabric doesn't have the stability needed or the minimal porousity needed to make a good cotton sail. I don't know anything about this particular cloth, so I can't offer an accurate opinion of it as sailcloth. Even if you knew how to make a sail, and even better, what changes need to be made to the process to make a cotton sail, it's difficult even for experienced sailmakers to design and build a properly-shaped, decently performing sail from a fabric that they aren't familiar with. The stretch and stability portions of the design work are estimates based upon experience working with a particular fabric or type of fabric. Start tossing unknowns into the equation and things get very unpredictable, very quickly.

If you're seriously interested in making sails for your boat, it might be better to learn something about real sailmaking in the process and a kit would give you a much better chance of building something that works and is worth being proud of. Free fabric is great if you can get it, but there is far more to building a decent sail than the cost of the cloth. In the long run, spending all that energy on a sail made from unknown, questionable fabric may not be as great of a deal as you think.

[James McMullen]

Good sails can save a mediocre design from being too boring.
Bad sails can wreck an otherwise perfect boat.

A Sailrite kit sail is much more likely to actually be a good sail--you save money by using your own labor, not by starting out with makeshift materials. A sail made from a tarp is unlikely to get the best from your boat.

[I, Rowboat]

A Sailrite kit sail is much more likely to actually be a good sail--you save money by using your own labor, not by starting out with makeshift materials. A sail made from a tarp is unlikely to get the best from your boat.

I second that sentiment. You can spend a bit more time and frustration and likely wind up with a poor sail (despite any claims otherwise), or you can spend a bit more money, a little less time, and wind up with a vastly superior sail if you go with a Sailrite kit.

[floatingkiwi]

If you get to California, by any chance, I have many sails, some of which I am anticipating using the material for redesigning for my use. You are welcome to a couple of them if you can find them useful.
In fact, is anyone in need of Ohlson 30 sails? I have a bunch.

[kenjamin]

I second that sentiment. You can spend a bit more time and frustration and likely wind up with a poor sail (despite any claims otherwise), or you can spend a bit more money, a little less time, and wind up with a vastly superior sail if you go with a Sailrite kit.

I third that sentiment. Sailrite kits rock!

http://ford.physics.fsu.edu/Xena078.jpg

[floatingkiwi]

I third that sentiment. Sailrite kits rock!

http://ford.physics.fsu.edu/Xena078.jpg

Cool little boat mate. What do you call that thing, not her name but what is she?

[kenjamin]

She is a Caledonia Yawl drawn by the artist himself, Iain Oughtred. I messed with the sheer a bit or she would have turned out prettier. The real beauty of this design is that she's so darn practical. She's a real load carrier and slick enough to actually do without the outboard. She sails on a breath of air and can be rowed in a pinch. My 2.7 liter Tacoma tows her easily. OK, I like my boat!

[cybulski]

Thanx for all the suggestions :). I think i am going to go with the sail kit. I think you guys are right I just wont be happy with a tarp sail,of my design.
And would probably kick myself in the @$$ every time i tried to use them.
Really appreciate the help :)

[WX]

You could use Odyssey III material and it comes in a good range of colours. I'm going to use it for my junk rig.

[cybulski]

You could use Odyssey III material and it comes in a good range of colours. I'm going to use it for my junk rig.
im not familiar with that material, ill see if i can find some stats on it.

[Todd Bradshaw]

Do not try to use Oddysey II to build regular fore and aft sails!

It is good fabric for covers, but makes lousy sailcloth. The only reason that you can get away with it on junk sails is because they are jam-packed full of structural stuff (like big, full battens)and are cut flat. It would be absolutely miserable for a "normal" sail where the shape is designed into the cut and the fabric is expected to hold that shape. The result, due to Odyssey's minimal stability, would be deep, drafty sails where you have little or no control over the sailshape (entry angle, entry curve, draft amount, draft location, leech or foot firmness. etc.). It would be like building a sail that's blown out from the very start and is the reason that some other fabrics (like nylon) were tried forty years ago and dumped like a hot potato.

[WX]

One small point Brad, modern Hasler/MacLeod Junk sails have about 8% camber built in to them. This has made a substantial difference to the windward ability. The R&D on this modification was carried out by Arne Kverneland in Norway. here's a pic of his yacht.

http://bambooman.gallery.netspace.net.au/albums/odd-sods/20050906_021_Johanna_1024_dots.jpg

[Todd Bradshaw]

That doesn't change the fact that although Odyssey is a great material from a handling and durability standpoint, it has lousy stability as sailcloth and will not hold its designed shape. He may be cutting what he thinks is draft into the sails, but it is very obvious in the photo above that what he is getting in use is sag and bag, not draft. The deepest "draft" in that sail is consistently falling along the widest sections between each set of battens, not in a pre-determined location where you would want the maximum draft to be. It's too far aft (as I mentioned above) and in addition, the run-out between that point and the leech should be a fairly flat curve and is actually a lot closer to being a hooked leech in every instance. It's just like building a sail that's already blown-out. I'd love to stick a bunch of white draft stripes on that sail, at which point it would be painfully obvious just how bad the shape really is. If you want to see a fully-battened sail that actually has draft and draft control, go look at a Hobie Cat main.

I have no clue who Arne Kverneland is or whether I'm supposed to be impressed, but in my opinion, you are being suckered-in by the fact that the sail has camber or depth between the battens (as opposed to being the normal flat cut) and assuming that it is draft. It's not, and it has no better shape or ability to hold that shape than you would get with spinnaker nylon.

We use the same basic shaping technique to shape the gores on balloons - only without battens and vertically, rather than horizontally. It that case, it's done to add shock absorbency to the structure - specifically because of its lack of stability and rigidity. It will yield and change shape under pressure. This is not something which is desirable on fore and aft sails.

http://webpages.charter.net/tbradshaw/e94fabe1.jpg