Sailmaking isn’t exactly voodoo magic, but because it’s pretty tough to find much information on sailmaking & sail cloth, we wanted to share everything we’ve learned in our quest to make the right decisions about our new headsail.

This is a very technical video, so be sure to watch it after a good night’s sleep and a cup of coffee. Get ready to learn some stuff!

Our new sail is coming from Precision Sails. Interested in a new sail? Give them a shout and tell ‘em we sent you. The level of customer service this loft offers is unrivaled. You can get a quote for a new sail here:

Hope you enjoy!

Lauren & Kirk

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Episode Dialogue

All right, we have a rainy day today.

We wanted to take some time out on this rainy day to talk to you a bit about what did I say the title of this was gonna be?

I was only off a little bit.

‘Cause that’s what goes into making a sail.

So our boat came with two sails. One headsail. Oh, it came with a spinnaker. Our boat came with three sails, our headsail was 155% was great for the Great Lakes, because usually the winds were somewhere between eight and 15 knots, and if they were any higher, you didn’t want to be out in the lake anyways, because it was awful. The surface conditions were terrible, but as we have come further south now, and we’re gonna be sailing in higher wind conditions,

We needed something smaller so our

was primarily to be a sail that was much smaller than the headsail that we had. It was a very large sail, and the sail was no longer holding a very good shape. Design consideration number two was, we wanted a sail that was going to have a very good shape, and hold that shape for as long as possible, and that’s really kind of what we want to get into some of the nitty gritty and details of today is how we determined the type of sail cloth we were going to go with, and the type of sail design we were gonna go with to enable us to have a sail that was going to last for a very long time.

And also the size that we picked, but that was simple. Should we start with that?



Disclaimer: We don’t propose to be experts. These are the decisions that we made. If you choose to build a sail based on these design criteria that we set out, we do not take responsibility for any amazing sails that you may or may not create.

We had 155, and we ended up deciding that we wanted a 115, but ultimately ended up with a 110.

We had heard from other Tartan 37 owners that 110 was actually a really good size, but we were like, oh man, that’s so small. We had 155. Let’s go just a tiny bit bigger, just to make sure that we have sail area.


[Jeremy] Hey, how’s it goin’? This is Jeremy calling from Precision Sails.

Going through the design process with Precision Sails, they were able to actually take the measurements from the rig of our boat, put it into a 3D model, and then build the sail to fit our boat, and when they did that, what they discovered is that actually at a 115%, the luff of the sail could potentially rub against our shrouds and the spreader

Our spreader.

when sheeted, weigh in for upwind sailing.

So they’re like guys, 115% probably isn’t gonna be great for your boat.


So it was do we want to go with 110%, which is what we had heard most Tartan 37 owners had done, or do we go bigger to like 130, 135%? And what that does is pull the luff of the sail behind the spreader, so that it would be billowing out around the spreader? And in the end, what we determined is the main design criteria for the sail was to be a small enough headsail that we could sail comfortably in 20-25 knots of wind, and as soon as you start to furl a sail, no matter what you do, it kind of starts to change that sail shape negatively, so the more that we can sail with a sail that is completely unfurled in more conditions, the better the sail shape we have, the more efficient that sail will be, and the less wear and tear we’ll actually be put on that sail, and have a better sail for sailing upwind. Downwind, our sail performed fine, and any boat can sail downwind with really any sail, ’cause when you sail downwind, the wind is just whooo, pushing you forward, so you can put up any shape, any sail, a towel, a sheet, whatever, and you could sail downwind.

And you could sail a bathtub

Like you don’t need to have anything super special.


But the beauty of sailing, the magic of it comes when you start to turn your vessel around into the wind and you can still keep moving into the wind, so you’re no longer being pushed by the wind, you’re being pulled.

You’re actually being pulled


And so the way that that works is if I have a sail here, this is our headsail, the boat is heading this way.

We’re gonna be looking down on the boat.

You’re looking down on the boat.


So the wind is blowing this way.

So here’s the boat.

Yes, okay.

Okay, let’s sail.

When you’re going upwind, the shape matters. You’re going downwind, it doesn’t, right? You’re going downwind, and the wind’s coming this way.

Let me go under here. Whooo!

So you’re going upwind. You sail shape matters. When wind blows over the sail, you’re creating basically an airplane wing by having this shape, so what happens is the wind flows over the top of the wing. It flows through the underside of the wing, or the inside of the sail, but it takes longer to go around this portion of the sail for the wing. What that does is that generates a low pressure, a pocket of low pressure in front of the sail or on top of the wing, and it actually pulls your boat into that low pressure. When you don’t have a very good sail shape, when that pocket gets over here, that’s no longer pulling your boat forward. That’s actually pulling your boat sideways, and what that does is that heels the boat, and so that’s a much less efficient sail because it’s just translating all of that force into a heeling movement, rather than a sailing forward movement. So the sail shape is really important because that’s how your boat moves, and so that’s why we wanted to windward.

To windward, yeah.

So that’s why we really wanted to focus on getting a sail that would retain that optimum sail shape for as long as possible. Let’s talk about the sail that we ended up getting. We ended up getting a 110% tri-radial headsail made from Challenge Warp-Drive Sail Cloth.

Now that’s a frickin’ mouthful, and we’re gonna break down what each one of those things means.

We’re referring to three different things. The size of the sail, the design of the sail, and the material that the sail is made from.

110%, so that means it is–

10% larger than the area which comprises of the forestay, the top of the cabin roof, and the mast.

That. So tri-radial, that refers to the actual cut of the sail, because you know how sails are ginormous, and there’s no way that there’s a loom that could make one big giant piece of sail.

Not to mention, they’re three-dimensional.

Yeah, that’s true.

And canvas is one-dimensional.

Yes, so tri-radial refers to the way that all of the pieces of the sail are cut, laid out, and sewn together.

There’s a number of different ways that a sail can be designed. The most common and most cost-effective method being a crosscut sail. Strips of canvas that are laid

On top of one another. They’re stacked.

On top of one another.


With a bevel cut in the front and the back of them. When sewn together, it creates that shape that you want to see when viewed vertically. The slightly more complex and advanced version of that is what’s called a miter cut sail, and your strips are run diagonally. The next iteration is what is called a bi-radial sail that has pizza wedges that radiate from both the tack and the head of the sail, and then what we ended up with, which is sort of the most complex, most costly.


But also the most beautiful looking version

‘Cause that’s what we’re about.

Is a tri-radial. It has pizza wedges radiating out from all three points. To understand why the tri-radial, and to understand why we went with a Warp-Drive sail cloth, we have to dig into the sail cloth a little bit to understand how it’s made and some of its properties and key differences.

Key differentiators.

So the two main different types of sail material is woven fabrics and laminate.

There’s other materials that are more exotic than just polyester, but when it comes down to it, polyester is the most economical, affordable, popular,


and UV–


resistant material that you can use.

A woven material has threads running 90 degrees to each other. One of the threads, let’s just say it’s the one that runs up and down is gonna be perfectly straight. The other thread that runs 90 degrees to it is crimped, sort of like that. This thread is gonna be the stronger thread. When there’s loads pulling on it from either end, this one is only gonna stretch the amount in which the material itself will stretch. This one on the other hand, when loads are applied on either end can do a lot of stretching. When any stretch occurs, that’s when you’re gonna have a blown out sail.

In a crosscut sail, the fill fibers or the straight fibers are typically run vertically. The warp fibers are run horizontally, and so as a crosscut sail ages, your pocket moves aft and your sail is less efficient. So the way to combat that is to start to look at miter cut sails, bi-radial sails, and tri-radial sails.

Or get a laminate.

Or get a laminate.

No, don’t get a laminate.

Will you be a sail for me? Make a big sail.

Like this?

No, make it with your hands as big as possible.

Okay, like that?

Yeah. The highest points of load on most sails radiate out from the corners of the sail. A tri-radial does the best job of all the sail designs in managing these loads because of the way its panels are cut and laid out, but this is only possible with a warp-oriented fabric.

So why is the Challenge Warp-Drive Cloth so special? Traditional sail cloth is fill oriented, meaning the straight fibers AKA the strong fibers, those least susceptible to stretch, run across the loom. This means your panels of cloth with the stronger fibers could only be as long as the loom, not very long. Warp-Drive sail cloth is warp oriented, meaning the straight fibers AKA the strong fibers actually run down the loom, so you can have stronger fibers run as long as needed.

And by using a warp-oriented cloth, we actually put that stronger thread, that thread that’s gonna stretch the least, almost exactly in line with the highest loading points of the sail.

Which means that a tri-radial sail is gonna stretch the least.

When using a warp-oriented cloth, such as Warp-Drive. In the past, before a warp-oriented cloth was available, they couldn’t make a panel large enough to make the sail cloth orient this way, and if you oriented the cloth this way, you’d probably end up with more stretch than you would with a crosscut sail made from traditional sail cloth, because you’d be aligning the stretchiest fibers along the paths with the most load.

Which is actually why you don’t make a tri-radial sail with regular woven Dakron.


What have we learned here today? We chose a tri-radial because using the Challenge Warp-Drive Sail Cloth, it would give us the best sail shape over the longest period of time. Dakron has fantastic UV-resistance, and we also got Precision Sails Elite and Offshore Packages to produce a very bulletproof sail.

Not literally.

No, I don’t think I’d take refuge behind the sail. But we are extremely excited to get the sail onboard. When working with Precision Sails, they felt more like a technology company than a marine industry company. They’re based out of Vancouver, British Columbia, but they do all of their work remotely.

And they do all of their design in-house.


[Jeremy] You kind of just walk through the design.

When you’re talking to someone about the design of your sail, you’re actually talking to the guy who’s designing the sail. In the two bottom panels, that center line doesn’t match up.

Yeah, these?

Yeah, what’s the reason for that little difference? Is that just what you were saying about having all the stitching in different spots?

Exactly, exactly.

Okay. You’re not talking to a salesman.


You’re not talking to someone who’s translating your requests to someone in a foreign country somewhere.

[Jeremy] The big panels, right? And they’re under a lot of strain, so we just don’t want everything to match up. We want load to press here and press there.

[Kirk] Got it.

[Jeremy] These kind of have to. If you have these too far off from each other, they start to work against each other. You’re talking to the person that’s actually tweaking the parameters of your sail, and is going to be responsible for the design of your sail.

That was really cool to watch the sail like turn around.


That makes sense though with the stitching. I mean the two that are offset, because they’re 180 degrees.


But the other ones are actually at a 45-degree angle, so they’re not actually pulling diametrically,


so they can be lined up.


If that makes sense.

And now we sit here. What is this called?

Eager anticipation.

Now we sit here in eager anticipation, waiting for our sail to be shipped to us.

We used to have two batteries right here.

This is gonna help us finish our electrical installation. This also…

[Lauren] A murder weapon?