Mast/sail. Worst idea ever?

[Kirk]

I've got a bunch of harbor freight tarps & some clearish shower curtain material.

I'm making a 7 foot by 10 foot or 7 foot by 12 foot pontoon boat.

Need an inexpensive mast & sail solution.

I've got a bunch of harbor freight 5 ft 6 in by 7 ft 6 in tarps. Gluing & sewing this together make something usable?

I've got an old sewing machine & a couple ladies probably willing to give me a few lessons.

I could probably hunt down something like a used 14 foot hobie but probably kind of pricey. One guy wanted $500 irr. Altho boating season starts in about a month here so deals maybe be gone soon.

 

[gonzo]

The shower curtain is useless. What shape and size sail are you making? I would think the pontoon will largely go downwind.

 

[DCockey]

Lots of sails have been made using plastic tarps. Tyvek and similar material has also been used. Performance will not equal a sail made from proper sailcloth though the design can be a bigger factor in determining performance.

Duckworks forum may be a source of information though it's been a long time since I visited there.

 

[Kirk]

The shower curtain is useless. What shape and size sail are you making? I would think the pontoon will largely go downwind.

Was hoping to use the shower curtain more as a window vs anything structural but maybe it's just instant fail/rip. Cutting out some smaller squares in tarp to see through. Using a tarp on each side sandwiching the clear curtain. Altho probably could track down old car convertible top that someone is replacing & take some of that for the window.

Shape & size open to suggestion. Guessing if i looked at hobie 14 size to start. & then downgrade. Maybe 50% of sail area give me some margin of safety. & not wanting a 22 foot mast to deal with.

different shape be better probably necessary Especially as deck gets crowded with bikes.

 

[Kirk]

Lots of sails have been made using plastic tarps. Tyvek and similar material has also been used. Performance will not equal a sail made from proper sailcloth though the design can be a bigger factor in determining performance.

Duckworks forum may be a source of information though it's been a long time since I visited there.

Thanks.

Am i looking at right web site? Typed in duckworks & sail.

Sails - Really Simple Sails - Duckworks Boat Builders Supply https://duckworks.com/really-simple-sails/

Least I'm seeing is like $250. & still have to get a mast.

 

[Will Gilmore]

I would suggest a lateen rig as the simplest and best performing option for a home made sail. You should be able to get away with a flat cut that way.

The problem with the shower curtain is it won't keep its shape. Too stretchy. It would work fine for a window, but for a small homemade boat, it's just a fun exercise, not that much value for the work.

I think you should go for it, though. Don't get caught up in all that value and efficiency $#!+.

Have fun.

-Will

 

[Kirk]

I would suggest a lateen rig as the simplest and best performing option for a home made sail. You should be able to get away with a flat cut that way.
View attachment 176722

The problem with the shower curtain is it won't keep its shape. Too stretchy. It would work fine for a window, but for a small homemade boat, it's just a fun exercise, not that much value for the work.

I think you should go for it, though. Don't get caught up in all that value and efficiency $#!+.

Have fun.

-Will

Lol

I like that sail!

 

[Kirk]

I've strung quite a few tennis rackets.

I've got a reel of polyester 17 laying around. be nice if it was polyester 15 maybe.

What about laying out a sail using a weave from tennis string. Then sandwiching the tarps & a clear window on each side. If it ripped Guessing be easy repair. & polyester pretty indestructible.

 

[gonzo]

A lug rig would not need to cut the tarp, only to reinforce the corners and edges.

 

[upchurchmr]

Pretty much the worst idea ever.

Better to save your pennys for a real sail and mast.

But you could have fun until it stretches/ tears and you have to paddle back.

Plan on it.

 

[Rumars]

Go online, buy a whatever complete dinghy rig you find. Sunfish/Sailfish, Optimist, etc. even a windsurf rig will work for you.
Otherwise google "polytarp sail".

 

[Tiny Turnip]

There are plenty of folk making sails out of polytarp, tyvek, and painters cloths. You'll find plenty of tutorials on YouTube. Some of them use 'no sew' solutions, using adhesive or tape. They will still reward care in the making, particularly if the sail has shape, and I'd think of it as learning and experimenting - your project sounds like its an experimental project anyway. Here's an article from Duckworks:

 

[Rumars]

Don't forget, even if you make a polytarp sail, you need spars and lines for it to work.
Example sunfish rig:
Material: 6061-T6 Aluminum Alloy
Mast -round tube
Length: 10' (3.05m)
OD: 2-1/4" (57.15mm)
Wall thickness: .083" (2.11mm)
Spars -round tube
Length: 13' 8" (4.17m)
OD 1-1/2" (38.1mm)
Wall thickness: .065" (1.65mm)
The actual sail costs 120$+17$shipping NP Sunfish and Lateen Sails https://www.neilprydesails.com/shop/sun

 

[sharpii2]

Just about anything can be made to work as a sail (and I mean one capable of upwind work).

Just look past the yacht clubs and racers, and look at 3rd world working sail boats instead.

Most of them have low aspect ratio sails. And most are probably cut flat.

You need relatively strong sail cloth to hold an airfoil shape. But non-airfoil shape sails have worked for centuries.

Your tarps can be used as sails just as they are. Just put a yard at the top and a boom at the bottom. And have the yard, at least, cross the mast by about 1/5 its length. You can do the same with the boom, or you can have the boom start at the mast. If you go that route, you'll need some way of holding it there. The first sail I ever made used an eyescrew and a hook for that purpose.

You'll probably need an 11 ft mast, a halyard line to raise and lower the sail, a cleat to secure it to, a sheet line, and a pulley for the sheet line.

Then you're good to go.

You'll need stays to hold the mast up.

You could make a 7 x 12 catamaran, and set up two of these sails in tandem.

The hulls of this catamaran need to be pointed at both ends. And the deck needs to be shorter than the hulls.

This is the basic design. It will have to be engineered, of course. And you're probably going to have to spend more than $500 dollars to build it. And it's going to weigh a few pounds (maybe 200).

But, with one or two rudders, and maybe a lee board, it can be made to work reasonably well.

The sails are going to billow, forming a curved cross section. This will create lift, but not as well as an airfoil cross section will.

A crude airfoil cross section is a curve with a flattened aft portion.

A polytarp can probably be persuaded to billow with such a cross section by having battens, that are a little less than half the length of the sail, installed on the aft portion, parallel to the yard or boom. You'll probably need two or three of them, maybe more.

They can be made of maybe 3/4 inch PVC pipe, and sewn or taped to the sails.

 

[Skyak]

I've got a bunch of harbor freight tarps & some clearish shower curtain material.

I'm making a 7 foot by 10 foot or 7 foot by 12 foot pontoon boat.

Need an inexpensive mast & sail solution.

I've got a bunch of harbor freight 5 ft 6 in by 7 ft 6 in tarps. Gluing & sewing this together make something usable?

I've got an old sewing machine & a couple ladies probably willing to give me a few lessons.

I could probably hunt down something like a used 14 foot hobie but probably kind of pricey. One guy wanted $500 irr. Altho boating season starts in about a month here so deals maybe be gone soon.

Polytarp and most plastic films are very poor sail materials because they stretch too much, don't fold well without damage, are difficult to attach to, and have poor UV protection. You will see them used by beginners for low performance sails because they figure "I don't know how to make a sail right, so there is no sense spending time or money on quality material sources." If you do study what it takes to make a good sail you will realize that using poor material makes the task much harder and the result doomed to poor performance.
Your description of making a 7X10 "pontoon" boat instead of a "catamaran" leads me to believe polytarp may be appropriate to the craft. If you do use polytarp, definitely make a Sunfish style boomed lateen sail on an unstayed mast like others are recommending. It has the lowest stress on the sail material and the easiest management of righting in gusts.

The cheapest source of decent quality sails is to just buy used. That goes for entire rigs too.