Main Sheet Line Length

Moderator: GreenLake

Main Sheet Line Length

Postby jdubes » Tue May 11, 2010 2:58 pm

I just installed a 3:1 mid-boom block setup on my DSI. Any thoughts on the main sheet line length now? I was thinking that it's now about 62 feet with the 3:1 block setup. Any thoughts?
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Postby GreenLake » Tue May 11, 2010 3:56 pm

62' seems high.

Here's how I would estimate this:

Boom is about 10'. So mid boom is about 5' from the mast. For 90° you get about 7.5' distance, plus the contribution from the height of the boom, say a little over 5' total height. Together this would add to 9'. Because the tackle is rigged to disadvantage, you need to cover that distance 4 times to get a 3:1 purchase. And you need a few feet to hang on to when the boom is all the way out.

Under my assumptions that doesn't come out to more than about 45'. However, if the distance from the mast is larger by a fraction, just multiply the estimate by that fraction, to get a better estimate.
~ green ~ lake ~ ~
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Postby jeadstx » Tue May 11, 2010 4:40 pm

Are you adding the mid-boom sheet arrangment like a DS2 or do you still have the end boom part of your original DS1 setup?

John
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
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Postby GreenLake » Tue May 11, 2010 5:35 pm

In my estimate for your setup I assumed only a 3:1 tackle from the mainsheet block on the CB to mid-boom.

My own setup is more like the original setup, with the end boom part etc. (all four blocks are single sheave).

From the CB trunk(block) to mid boom (block) to end boom (block) to rope traveler (block) back to end boom (becket on end-boom block).

With that configuration I estimate 45' of sheet. However, I just have 37' and that's always been sufficient.

One reason my estimat is high is that the boom never goes out to 90°, because of the swept-back spreaders on the DS. Another is that the boom probably doesn't rise as high as I assume in my rough estimate. Finally, the block on the rope traveler is elevated and doesn't stay centered, bothreducing the length of sheet needed to reach the actual end of the boom.

The rigging measurements on the site say 44', without indication of how that is to be configured.

Anyway, 62' for your setup seems too high, unless you have a much higher purchase (5:1).
~ green ~ lake ~ ~
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Postby jeadstx » Tue May 11, 2010 5:46 pm

I just replaced my mainsheet on my DS2. I bought the 44' length shown in the rigging measurements (on this site) before I pulled the old mainsheet off the boat. After I removed the old mainsheet I measured it and it was 30' long. So I am going to cut down the new mainsheet to match the 30' length. The way I look at it, it's easier to cut the line shorter, than to try to get it to grow longer.

Any other DS2 folks that can verify the correct length of the mainsheet for a DS2?

John
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
jeadstx
 
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Joined: Tue Jul 08, 2008 11:10 am
Location: Dripping Springs, Tx

Postby jdubes » Tue May 11, 2010 8:17 pm

My thought was that if the base spec called for 45, clearly a 3:1 block setup would add say 2 wraps around the block at 6 feet each. Hence 60ish. I run the standard triangle at the end of thr boom.

I've never taken the time to measure it all myself, I figured someone must have done it already :)

Any thoughts? Now that I think about it, 45 for thr base spec might be to large.

Jason
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Postby GreenLake » Tue May 11, 2010 9:30 pm

I would estimate 7-8' not 6' but otherwise, yes. And you won't need 44' unless you need a very long tail to operate your sheet while hiking when you go downwind :shock: 8)
~ green ~ lake ~ ~
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mainsheet length from the original source

Postby Roger » Tue May 11, 2010 11:13 pm

Main Halyard rope ¼” x 50’
Jib Halyard rope ¼” x 35’ 9”
Mainsheet 5/16” x 25’
Jibsheet 5/16” x 26’
Mainsail outhaul 3/16” x 8’
Boom Downhaul 3/16” x 3’
Spinnaker Halyard 3/16” x 34’
Spinnaker Pole Lift 3/16” x 17’
Spinnaker Sheets ¼” x 30’ (2)

(source: sailboat owners forum original document from Bangor Punta Marine rev 5/4/79 Fall River MA)
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Postby jdubes » Wed May 12, 2010 2:37 am

Thanks for the responses, i'm going to go with 45' of line.
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