I don’t understand sail cloth weight.

[BenBowSirocco]

Originally Posted by GILow

I’m running out of sailmakers right now. I won’t name the loft because I don’t want to be seen to be bagging them and they’ve been by far the best to work with so far.

But I’m going insane trying to get these guys to understand the concept of a high clewed sail. It’s clear they are working to some kind of modern boat formula because each of them comes back to me with deck sweeping jibs no matter what I do. I’ve sent them photos of what I want, I’ve told them I want the clew 2 meters above the deck. But they come back with deck sweepers every time.

And yes, the weights have been the same between all the sailmakers, right up to this point when I finally gave them a full set of dimensions rather than using their proscribed measurement systems which don’t allow you to specify leech length. At this point the sail area shrank a lot and the cloth weight went up.

When we needed new sails on a one-off classical cutter with a high cut genoa- I used some inexpensive double braid tracer (1/8", 3mm) and physically mocked up the sail on the boat by tying a triangle. I then took photos of it rigged with its sheet, and in exact position I wanted it on the furler, measured the overlap, etc.. Lastly, I pegged the triangle down in a grassy field and measured each leg and the P.

The sail designer loved it, he of course took my dimensions and undercut the edges and made the shape correct to the boat in his fancy computer program in order to get the plotter to cut out all our panels in the correct center of effort location for our shape.. And whatever else his job entailed.



It was time consuming for us to do it this way, as it had to go up and down the furler a 100+ times, but we got a sail that was EXACTLY what we wanted.



I did also did choose to spend $500+ on the sail designer to design me a pair of custom sails instead of trusting my sail maker. Overall I felt the time and money was a great investment.

I was also able to include all of the sail design files on a jump drive with the sale of the boat.

[s/v Jedi]

The force on the sails is a combination of wind speed and the boat’s righting moment. If you reduce sail area, that smaller area will have to overcome the same righting moment so it needs to be stronger.

Except for multihulls, they will rip it apart so they must reef early until they can’t have any sail up anymore.

[Glassdog]

Since you are expecting sails for a Kelly Peterson 44, which is a heavy, cruising boat, I believe that your Yankee and staysail Should be moderately high, cut for both visibility forward, and correct operating on your roller furlers, if you have them. Sailcloth weights are usually indicated by the weight of the cloth for a square yard. no sale maker in his right mind which speck deck sweepers for anything other than racing boat.

[GILow]

Originally Posted by s/v Jedi

The force on the sails is a combination of wind speed and the boat’s righting moment. If you reduce sail area, that smaller area will have to overcome the same righting moment so it needs to be stronger.
….

Ok, I can see that logic. Subtle, but makes some sense.

[GILow]

Originally Posted by BenBowSirocco

When we needed new sails on a one-off classical cutter with a high cut genoa- I used some inexpensive double braid tracer (1/8", 3mm) and physically mocked up the sail on the boat by tying a triangle. I then took photos of it rigged with its sheet, and in exact position I wanted it on the furler, measured the overlap, etc.. Lastly, I pegged the triangle down in a grassy field and measured each leg and the P.

The sail designer loved it, he of course took my dimensions and undercut the edges and made the shape correct to the boat in his fancy computer program in order to get the plotter to cut out all our panels in the correct center of effort location for our shape.. And whatever else his job entailed.



It was time consuming for us to do it this way, as it had to go up and down the furler a 100+ times, but we got a sail that was EXACTLY what we wanted.



I did also did choose to spend $500+ on the sail designer to design me a pair of custom sails instead of trusting my sail maker. Overall I felt the time and money was a great investment.

I was also able to include all of the sail design files on a jump drive with the sale of the boat.

I just ended up giving them the luff, leech and foot measurements I wanted.

None of the sailmakers I dealt with asked for this info. They wanted just luff and J and left it to their software to make the decisions. Which is how I ended up with clews at knee level.

[Baronkrak]

Originally Posted by GILow

I just ended up giving them the luff, leech and foot measurements I wanted.

None of the sailmakers I dealt with asked for this info. They wanted just luff and J and left it to their software to make the decisions. Which is how I ended up with clews at knee level.

How does your sail plan compare with the following?

https://sailboatlab.com/data_sheet/4048/0/

[GILow]

Originally Posted by Baronkrak

How does your sail plan compare with the following?

https://sailboatlab.com/data_sheet/4048/0/

Nothing like it. That diagram is rubbish and is a good demonstration of why you cannot trust the internet for this sort of stuff. It has led to people cutting up to three or four feet off the boom to correct weather helm.

The original sales brochure from the 1970s gives a clue to what Doug Peterson was thinking. See attached…

[Jimbo2010]

people R trying to help......no need for that attitude

[Baronkrak]

Originally Posted by GILow

Nothing like it.

For a start this is good, tacking into consideration the comment that

(The Kelly peterson 44 is a moderate weight sailboat which is under powered).

Originally Posted by GILow

Most of the way through the process and suddenly the recommended weight of sailcloth for the jib and staysail have been increased from 9.88 to 10.88 Oz.

Sailmakers like us learn something new every day, from practical experience and from experienced customers. So nothing special about recommending a stronger cloth.

[Baronkrak]

By the way the boat on your attachment picture is the same boat, on a different angle, that the boat pictured on the link https://sailboatlab.com/data_sheet/4048/0/

[hpeer]

I believe he was referring to the profile sketch on the very bottom of the page, not the photo.

The profile shows a largish overlapping genoa.

Sailboatdata has the same profile.

I have often wondered how they were generated.

[Baronkrak]

Originally Posted by hpeer

The profile shows a largish overlapping genoa.

Genoa or spy?

[hpeer]

Well if you look it shows
Main sail
Try sail
Spinnker
Genoa
Stay sail
Storm stay sail

I do not see a non overlapping forestay sail.

As I said I wonder who generates these images.

I had a similar problem with my custom English cutter. The PO bought new sails from an established firm. Both were VERY heavy. The mail was workable but the genoa was not. Once I finally ran down the designers specified sail consist I saw the main was a good bit heavier than specified. The genoa was almost twice the specified weight. The genoa was so heavy it would not draw until nearly 7 knots.

Once I restored the designed headsails the boat sails, a smaller and lighter forestay sail working jib, it now far better and faster with far less weather helm. The sail maker who provided the heavy overlapping genoa said he “provided what I always do for this region.” He was very defensive despite my introduction saying I just wanted to understand how he came to his decision.

It is pretty clear the PO was a newbe and just went with the sailmakers suggestion, as I would have also done.

The point is that while many generalities may be accurate for newer boats the do not necessarily hold for older designs. And since these older designs are not common they may not be treated appropriately.

FWIW I had been to a number of sailmakers who claimed this sail was a great sail for this boat. Performance proves otherwise, by a large margin.

[rslifkin]

I've seen a few people end up with a poor performing, too-heavy genoa (often with massive foam blocks in the luff) because someone had it made with the idea of having a 150 as a "do-everything" sail.

In reality, it meant that it was too heavy to work well in light air, the foam blocks compromised airflow and upwind performance, and by the time you had enough wind to need the heavier sail, you had it rolled up a good bit because it was too big. The most recent example I'm thinking of ended up being much better off with a combo of a lighter 150-ish genoa and a 110. It turned out he already had a 110, original to the boat and had hardly ever been used in almost 40 years. Once you've got enough wind for it, the boat sails far better (and faster) with the 110 than it ever did with the heavy 150, so that lives on the furler most of the time and he only puts up a bigger headsail when light air is expected. Off the wind, it's easier / better to just fly the asym than to swap headsails.

[Baronkrak]

Originally Posted by hpeer

I have often wondered how they were generated.

This one is using CAD.