# Thread: 19th c sail design

1. ## 19th c sail design

I'm doing some research on the sails we use on the ship's boats at the museum and I've run into a problem understanding what some nubers mean.
An example from around 1870
20211018_125504.jpg
The first line reads "Undergex (to do with the foot) 3-1=+1-2-3-4-3/8 2-"
And the second "Spritgex (to do with the head) 14=16=17=19=5/8 11"
I had a theory that "=" was and old way of writing Inches and "-" for Feet, but it doesn't really make sense... More importantly I don't get what kind of information the numbers represents.

Sometimes the numbers are written on the sail plan, here's an example from a slightly more modern sail
20211018_125528.jpg
At the foot it says "6 5 1 -1 -5 -6" (sorry for bad photo), one number per panel.
It sometimes says for example "+15 +2 +1 -2 -6 -16" and sometimes "+6 -1 -7 -9 -16 -11" (the odd last number seems to do with that panel isn't a whole panel)

Any guesses?

/Mats

2. ## Re: 19th c sail design

Originally Posted by mohsart
I'm doing some research on the sails we use on the ship's boats at the museum and I've run into a problem understanding what some nubers mean.
An example from around 1870
20211018_125504.jpg
The first line reads "Undergex (to do with the foot) 3-1=+1-2-3-4-3/8 2-"
And the second "Spritgex (to do with the head) 14=16=17=19=5/8 11"
I had a theory that "=" was and old way of writing Inches and "-" for Feet, but it doesn't really make sense... More importantly I don't get what kind of information the numbers represents.

Any guesses?

/Mats
Could they be the amount of gore cut on each cloth?
On these old lugsails there are no gores on the heads, they are cut on the luffs and feet of the sails.
Nimble sails.jpg
Nimble sail plan.jpg

3. ## Re: 19th c sail design

Maybe a formula for stretch of the cloth?

4. ## Re: 19th c sail design

Originally Posted by Peerie Maa
Could they be the amount of gore cut on each cloth?
What does "gore" mean in this context?

/Mats

5. ## Re: 19th c sail design

20211018_154814.jpg
All designs have these two measurements ("Tvärs"), one from the Tack and one from the Throat to the leech at a 90 degree angle.
So the sails are devided into three parts, called "gex" or just "g". The luff "gex" is the distance between those "tvärs" lines.

/Mats

7. ## Re: 19th c sail design

Originally Posted by mohsart
What does "gore" mean in this context?

/Mats
I knew that would not translate.
The angle at which the cloth is cut, measured up the long edge of the panel from a point square to the short edge.

8. ## Re: 19th c sail design

Originally Posted by mohsart
20211018_154814.jpg
All designs have these two measurements ("Tvärs"), one from the Tack and one from the Throat to the leech at a 90 degree angle.
So the sails are devided into three parts, called "gex" or just "g". The luff "gex" is the distance between those "tvärs" lines.

/Mats
Back in the day they did not lay out the entire sail. They cut the cloths to shape using the gore measurement. Then rotated the cloth so that they could mark off the next panel, and so on.

9. ## Re: 19th c sail design

Originally Posted by mohsart
I'm doing some research on the sails we use on the ship's boats at the museum and I've run into a problem understanding what some nubers mean.
An example from around 1870
20211018_125504.jpg
The first line reads "Undergex (to do with the foot) 3-1=+1-2-3-4-3/8 2-"
And the second "Spritgex (to do with the head) 14=16=17=19=5/8 11"
I had a theory that "=" was and old way of writing Inches and "-" for Feet, but it doesn't really make sense... More importantly I don't get what kind of information the numbers represents.

/Mats
What do the other lines of text translate to?

10. ## Re: 19th c sail design

Originally Posted by Peerie Maa
What do the other lines of text translate to?
The top part is a summary of how much cloth is needed, I don't quite understand all of it but the two numbers 6 5/8 and 7 3/8 seems to state the widths of the first and last panel and 21 and 10 the length of them and then a total at the end.
The line under the two marked says Förgex (Luff "gex") 3/8 again for the width of the last panel, "d" for "duk" (panel), 4.8 for the length of the panel. I don't get 39.6, here they usually sum up the height of the sail but it's something else in that example.
In this example the last panel doesn't go all the way to the throat, so it's a bit different from how I explained it earlier.
Last are the lenghts of every other panel.

/Mats

11. ## Re: 19th c sail design

Thanks, I'll try to work it out on paper.
Using the head dimensions to cut the cloth with a gore (angle) and the cloth lengths I get this, assuming 24 inch wide cloths.
Mats sail.jpg
I have not included the tapered panels, their seams will be 21 foot and about 10 foot at cloth 7, so there nay not be an 8th cloth. The dimensions quoted for the foot make little sense to me.
Last edited by Peerie Maa; 10-18-2021 at 02:59 PM.

12. ## Re: 19th c sail design

I realize my description doesn't add up completely, I described it as I've interpreted it in other cases.
If you want I could give more examples tomorrow when I have access to the drawings/descriptions again (they're at my work).
It's a fun detective job, but can be frustrating when I don't make any progress. I really appreciate you're taking the time to help me out!

/Mats

13. ## Re: 19th c sail design

Originally Posted by mohsart
I realize my description doesn't add up completely, I described it as I've interpreted it in other cases.
If you want I could give more examples tomorrow when I have access to the drawings/descriptions again (they're at my work).
It's a fun detective job, but can be frustrating when I don't make any progress. I really appreciate you're taking the time to help me out!

/Mats
If you know what the cloth widths will have been, you could draw it out following my thoughts, adding seam allowance and the luff and leech tapered cloths. (Adding a tapered cloth at the leach is really odd though)
You could then see if any of the other dimensions also correspond.

14. ## Re: 19th c sail design

It is a bit hard to know for sure, but it seems the widths were 1 aln which equals 2 foot, a foot was 10 inches at the time and an inch was 29.69 mm. I've seen it stated that the seams were 2 inches wide.
I cannot say that I understand your reasoning yet, but I'll definitely give it a try!

/Mats

15. ## Re: 19th c sail design

Originally Posted by mohsart
It is a bit hard to know for sure, but it seems the widths were 1 aln which equals 2 foot, a foot was 10 inches at the time and an inch was 29.69 mm. I've seen it stated that the seams were 2 inches wide.
I cannot say that I understand your reasoning yet, but I'll definitely give it a try!

/Mats
No wukkas.
By tabulating dimensions - gores and panel lengths - they could cut a sail without needing a loft floor.
The gore is the height of the right-angle triangle, whose base is the width of the cloth. So cut the gore of the foot, measure up the length of the cloth and mark and cut the head gore. The gore cut on the end of the bolt becomes the head, so turn the bolt over so that the two gores line up, and measure the cloth length against the first cloth. You now have cloths 1 & 2. Cut the foot gore off the end of cloth two, and measure the length of the seam. Then repeat with the head gore for cloth three and four, and so on until you have the length of the head.
You can then add the tapered panels that run up the luff.

Have a look at this, you will have to scroll up to the start of the chapter. https://books.google.co.uk/books?id=...0gores&f=false

16. ## Re: 19th c sail design

Originally Posted by mohsart
I may have cracked at least this more modern version.
For the foot, if I start with the distance from the lower cross line to the clew, and then add/deduct the numbers given and plot them as distance from the cross line, I get something that looks like an OK round.
For the head, if I start from the throat and do basically the same thing, only addition though, and measure from the upper cross line, I get a (though a bit flatish) round for the head.
I'll do a couple of them in larger format to make sure...
But dechifering the old notation, ie "1+1=3=5-3/4 d 4" etc is another matter.

/Mats

17. ## Re: 19th c sail design

Yep, that older one is a tad weird for the foot dimensions, and that there are two tapered panels.

18. ## Re: 19th c sail design

Did I say somewhere that the leech panel was tapered, or did you deduct that from the pictures?
(I don't think it is.)

/Mats

19. ## Re: 19th c sail design

Originally Posted by mohsart
Did I say somewhere that the leech panel was tapered, or did you deduct that from the pictures?
(I don't think it is.)

/Mats
Ah, OK.
I had assumed that they were tapered. I would not have expected such a narrow panel at the luff, as they are normally full width, whilst tapering the leech panel makes the foot wider than the head. So we have a sail with parallel leech and luff?
Is it a standing lug?

Could the second row of numbers be the reef points, starting 3 foot up the luff?

20. ## Re: 19th c sail design

I cannot get my head around the panel widths, when I draw the sail to my best understanding, they are all different.
I was thinking that the leech panel was narrower because they'd cut off a strip of it to sew onto the edge as reinforcement (whatever the name for that is again). No the leech and luff are not parallel, but the leech panel has parallel edges.
It is this kind of sail we talked about before, kind of a mix between a standing lug and a setee.
The reef points are mentioned separately, "2 reefs, at 25 ---- 50" or something to that matter.
Buut the foot round is also mentioned separately "Under rund 5 tum".

/Mats

21. ## Re: 19th c sail design

Originally Posted by mohsart
This is the basic shape, some are very high peaked with a short luff and some are not.
Most but not all have the tack running on a horse, and when you tack you kick the shackle over to the windward side.

ETA: Some pictures https://cbebarkarna.se/barkarna_bilder.html

/Mats
Last edited by mohsart; 10-19-2021 at 12:39 PM.

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