Proper forestay tension and mast angle

Moderator: GreenLake

Re: Proper forestay tension and mast angle

Postby GreenLake » Thu Dec 24, 2020 2:17 am

The tack would attach to the deck, but the first hank does not have to be at tack level, or does it?
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Thu Dec 24, 2020 2:54 am

I think not as the shackle is what holds the sail to the stemhead, 1st hank is about 14 in above that.

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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Wed May 05, 2021 1:41 am

Got my 1/8th in stays yesterday, trying to put them on and adjust them. following North Sails tuning guide. it looks like the mast has too much aft rake. I have a Tabernacle on the mast. the question is. do i just crank on the forestay until the measurement (25.1) is obtained or move the mast foot in the cuddy back to assist in getting the correct number.? the foot plate is screwed to the keelson (?) can anyone tell me how they set up their rigging? how far back from the bulkhead in the cuddy should the mast foot be. thanks

Garry
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Re: Proper forestay tension and mast angle

Postby tomodda » Wed May 05, 2021 10:00 am

Garry, hi!

I'm going to start my response by writing my usual - relax, go sailing! Don't overthink this.

I'm feeling a bit guilty... I suggested that you look at the North Sails guide as a rough idea of what to think about, not a "Bible" on exact setup. For everything you tune in your rig, you need to understand WHY you are doing it, and that comes with a bit of reading and a lot of experience (go sailing!). For rake specifically, that affects your helm balance, so your ability to point and your speed. Forestay tension affects your prebend, so your ability to respond to gusts. Yes, you can rake the mast via forestay tension, but that will affect bend. Better to move the foot of the mast or somehow shim it (I use washers). And it changes with wind strength, you need more rake in lighter airs. The DS rules don't let you change the rig as you sail (you can do it in other classes, adds a ton of expensive complication) so you do your setup before you launch. This is really more of a consideration if you race... For us shlubs, who cares if you are a tenth of a knot faster or slower? If you're racing in a true one-design (Daysailer only) regatta, then an extra 1/2 degree of rake can win or lose for you! Anyway, read this:

https://www.quantumsails.com/en/resources-and-expertise/articles/what-you-need-to-know-about-rig-tune-performance

Ignore what they say about raking via the forestay, it's different with our fractional rigs. In my life, with an old-fashioned hinge-and-pin tabernacle hinge (the pin is vertical, in front), I put an ordinary washer over the pin to rake the mast, does the trick. I did it after one year of sailing and noticing that I wanted a bit more weather helm. That's for LIGHT air days. On days with more than 10kts wind, I don't need it, the balance is fine. So, go sailing, get a good feel for your helm, take notes, then decide if a bit of rake works for you. Nobody but you can tell. Also, you'll have to figure out how to put the rake in on your own, it's very dependent on the exact structure of your keelson, how easy it is to adjust your forestay, etc. Anyway, take it slowly. And whatever you do, you absolutely don't want the mast to rake forward or bend forward. Take baby steps and you will get what works for you.
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Wed May 05, 2021 1:17 pm

Tom,

you ought to feel guilty, all of you experts. putting ideas in my head. :) I think I have the side stays to tight, thus not allowing the mast to move forward. when the rain stops I'll go out and loosen them put things back to original configuration. my tabernacle is the one with the two pins horizontally I guess i could leave the front one out as it really serves no purpose once the mast is stepped. also could modify it to have a vertical pin .

I do appreciate all the advice and guidance given as i try to become a novice sailor.

G.
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Wed May 05, 2021 8:03 pm

Ok, update on the install of the new rigging,
what I did was go back to the original foot location (actually 3/4 in more aft. It looks good, I have about 90lbs on the forestay, 150 lbs on the side stays, I took one of my welding vicegrips and modified it so i could take the pressure off the adjusting screw so I could add or remove tension, this was done with a Loos gauge on the stay. worked out great, not bad for 30 min of construction time.
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this is the spacing obtained
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Last edited by Fly4rfun on Thu May 06, 2021 5:28 pm, edited 6 times in total.
"Sail Aweigh" 1966 DS1 #2675
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Re: Proper forestay tension and mast angle

Postby GreenLake » Wed May 05, 2021 11:28 pm

Just when I think I've seen it all on this forum! Interesting.
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Wed May 05, 2021 11:56 pm

GL,

I've mentioned that I like to putter and make things :P . To adjust the tension on the stays i would have to disconnect the fore stay so it would release the pressure on the turn buckles, this way i dont have to, this releases the pressure just enough to be able to turn the knurled screw that adjust the tension.
it worked better than i thought it would. stays are 1/8 from D&R with standard turnbuckles.

G.
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Sat May 08, 2021 2:09 am

Tom, advice taken, I will admit I do get a little(maybe a lot) intense. not going to do any changes until i sail it, hopefully can get a idea if i need to make any. but the plan is to sail and enjoy it while trying to learn how it really sails.

thanks,
Garry
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Re: Proper forestay tension and mast angle

Postby GreenLake » Tue May 11, 2021 1:14 pm

Garry, there's a misunderstanding here somewhere. The first hank is not at the clew. So it (the first hank) can be a few inches above the deck w/o the foot of the jib having to also be that high.
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Re: Proper forestay tension and mast angle

Postby Fly4rfun » Tue May 11, 2021 2:12 pm

GL
thanks for the clarification, I think I knew that, just didn't say it correctly.
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Re: Proper forestay tension and mast angle

Postby GreenLake » Wed May 12, 2021 1:48 am

There's a benefit to a "decksweeper" jib: it cuts down on or eliminates pressure equalization across the foot of the sail, making the bottom portion of the sail more efficient.
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