# Thread: A Seil in California

1. ## Re: A Seil in California

Photos:

The manager and supervisor inspect the new spruce.

2. Senior Member
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## Re: A Seil in California

You can do the calculation. The stiffness in some direction is proportional to the moment of inertia in that direction. The formulas on https://www.engineeringtoolbox.com/a...ia-d_1328.html show that for a rectangular cross-section, if you orient the thin direction across the direction of max force (not sure which that is for you) then the stiffness only goes down by 18%. Beware the stiffness in the thinner direction though which goes down to (0.82)^3 = 55% of its designed value.

3. ## Re: A Seil in California

Thanks Neil! I did not know that I could calculate stiffness this way. If anyone's interested, I found the formulas for an oval here:

https://en.wikipedia.org/wiki/List_o...oments_of_area

The calculations for a oval cross section work out the same as for a rectangle. Start with a circular cross section 60 mm in diameter. Diminish one axis by 10 mm. Stiffness in your thick axis is 83% of the original circle's. Stiffness in the thin axis is only 58% of original! I had a suspicion that things would get floppier but would not have guessed so much.

Which is too bad, because the yard is already shaping up in the shop.

My plan is to orient it so that it is thickest vertically to resist the loads of the downhaul and the mainsheet. I don't think it should experience too much loading fore-and-aft or athwartships because it's free to pivot about the mast. If it turns out to be too floppy, I'll cut it down to make a pole for running downwind and make a new yard.
Last edited by pez_leon; 01-10-2022 at 04:58 PM.

4. ## Re: A Seil in California

Originally Posted by pez_leon
Great to hear from all of you. Frank, your comments on the possible sail plans are interesting. Vivier includes both the boomless sail plan and the sail plan for the balanced main with boom. I haven't quite made up my mind but am leaning toward the boomless misainier. What I read about the misainier falls into two camps: people who haven't used it, who express trepidation about handling the large sail and moving the mainsheet in a jibe; and people who have used it, who laud its simplicity and performance. Anyway, thanks for sharing, and thanks for the link to your website. Your video is beautiful.
Rick and Thorne, thanks for the local welcome. I'll look into the local TSCA for sure.

James
I have an Ilur with a misainer rig. You have it basically correct. However, I underestimated the performance penalty for the loose footed main, and now I keep imagining converting to a balanced lug.

Downwind of course there is a penalty, but it is not just a matter of sail area. There is also the problem that you can't let the sheet out very much, or the peak of the yard will go forward of the beam, and then you will set up a rhythmic rolling motion that feels like its trying to capsize you. A balanced lug does not have this problem.

There is also a penalty upwind, which feels unfair. One of the advantages of the misainer is supposed to be an optimum sail shape when close hauled. And that's true—on the good tack. As long as the yard is clear of the mast, the sail is perfect. On the bad tack, I believe the misainer suffers more than the balanced lug. I used to sail a Caledonia Yawl with a balanced lug, and I don't remember there being such a difference in the two tacks. On the Ilur, because the lower part or the sail wraps around the mast, it presents a poor shape, with high drag. A boom on the bottom of the sail would hold the luff forward, and present a better leading edge.

The best justification for the misainer is if you like fishing. This was the original reason for the misainer. For setting gear, or working lines, its nice to have the boat as clear as possible. The lack of a boom is very nice while fishing because it keeps the boat clear.

5. ## Re: A Seil in California

Originally Posted by photocurio
I have an Ilur with a misainer rig. You have it basically correct. However, I underestimated the performance penalty for the loose footed main, and now I keep imagining converting to a balanced lug.
Interesting! Thanks for sharing this. Having already sewn the sail and built the yard, I'm in no position to change now- but I'll watch closely and report back, whenever the boat gets launched. I do wonder if the lack of a boom will be a nice feature with small kids aboard. We'll find out.

6. ## Re: A Seil in California

We finished shaping the yard. Not quite as straight as a ruled line, it sort of peaks up in the last meter or so, but I'm telling myself that this is a secret asset as it will deflect back to straight with the slightest load from the sail. Here is my boy taking it from 16 sided to round:

His interest in following my instructions started low and decreased. At some point I hit on the strategy of giving him 600 grit sandpaper (it being obviously six times better than 100 grit sandpaper) so that we no longer needed to argue about taking off too much wood. We got on great after that.
Last edited by pez_leon; 01-20-2022 at 04:53 PM.

7. ## Re: A Seil in California

On to the mast! I started hollowing each half in the middle of baby bedtime. That meant quiet, meaning no power tools, which was a nice excuse to pull out the plow plane.

Once the kid woke up I switched over to kerfing out the center with a circular saw:

I've got the hollows formed and am creating the mortise for the sheave now.

8. FF
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## Re: A Seil in California

It is such a good idea to start with building sails, rudder, spars etc. for when you start with the hull, like I do, and she is finished, the other parts seem to take ages and it is easy to hurry up far to much.
I like your canvaswork, btw. I do canvas- en sailmaking workshops sometimes in winter, and I think especially canvaswork, is very much worthwile. Frank

9. ## Re: A Seil in California

Great to hear from you, Frank! It's nice to have some affirmation on my backwards construction sequence. The few people who know I started building a boat keep asking me when I launched her. All this work and nothing resembling a hull to show for it!

Mast work continued. Both halves are hollowed. A mortise for the sheeve is cut oversized, then brought down to dimension with hardwood cheeks.

Glue up with thickened epoxy and every clamp that could suit. I ended up throwing a few temporary screws in for good measure. The resulting glue line looks good.

Taking it down to octogonal. If you look closely at the facet on the top right, you'll see where it moves from smooth to rough. This shows the limit of my draw-knifing prowess; the rough bit has yet to see the plane.

A neighbor stopped by for a chat and fell in love with the spruce shavings that came off this project. She ended up taking a bag for some as-of-yet undetermined art project! At least I'm not the only one who likes a neat curl.
Last edited by pez_leon; 01-31-2022 at 03:14 PM.

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## Re: A Seil in California

Looks great! I envy you the natural light!

11. ## Re: A Seil in California

Very cool! I like that way of making a hollow mast. Seems like it could be scaled up larger than birdsmouth?

Do you hope to splash this summer?

Mike

12. ## Re: A Seil in California

Thanks for writing, Mike! Your Ilur build is a great resource. I nearly chose to make a birdsmouth mast after reading your description. I suppose this method of gluing up halves could be scaled up- maybe that's why it's detailed in Bud McIntosh's book, which focuses on keelboats.
A summer splash would be wildly optimistic. I'd love for it to happen but think that summer 2023 is more likely.
Long time readers will recall that I chose this design in part out of concern for capsize recovery. Here's a new video capsize test in flat conditions:

It's hard to generalize from this gentle water to the behavior of a boat in a real mess, but I like what I see.

Google translate offers this for an English version of the video's comments:

Arwen Marine (RAM) 2021 gathering at Lac du Der. Saturday morning free program: "I capsize my boat to see"... On the Swiss Seil "Aurore", Anne and Fabien decided to do it in raincoat, boots and self-inflating vest. Everything went well, like clockwork (obviously), and Fabien tells us that the self-inflating vest is not the total handicap that some decry, and he only (partially) deflated it when bailing out to increase freedom of movement. The water temperature (22°C) and the almost total absence of wind and chop make this series of tests by about twenty boats of little significance, because capsizing generally occurs due to severe conditions, but it has allowed many volunteers to see serious or trivial problems. In particular, I picked up two rudders, a few shoes, sponges, water bottles, etc. My fortune is almost made. More seriously, these tests showed that some participants did not succeed in righting their boat without assistance, nor in getting back on board alone despite the optimal conditions... These exceptions confirm the usefulness of this test, despite its apparent ease. We will renew it as much as possible during future RAMs, and will follow the progress of the failing crews. Lesson No. 1 is that it is imperative to release the GV halyard of the capsized boat so that it remains in the water when the boat is righted because its weight with that of the yard and the boom is enough to make capsize the righted boat again when coming on board, regardless of the effect of the wind. To be continued !

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