H18 Diamond wire tension? :: Catamaran Sailboats at TheBeachcats.com

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H18 Diamond wire tension?

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Dogboy

Rank: Mate

Registered: Mar 19, 2004

Last visit: Apr 12, 2024

Posts: 960
Posted: Aug 20, 2018 - 10:29 AM

CatFan57I take it from that that there is still some point at which the diamond wires on an H18 (or any other boat) could be so loose as to de-power the sail owing to leeward bowing of the mast

As I said before, it depends on what school of thought you are using to tune your mast. Modern boats that use pre-bend depower by increasing spreader rake and diamond wire tension and reducing mast rotation. Old-school boats (like the Hobie 18) do the exact opposite - depower by slacking the diamond wires (they may actually be flopping around) and increasing mast rotation.

I don't think you would ever see an F18 depower by loosening the diamond wires.

For the OP, I agree, start with the diamond wires snug and loosen from there if you end up over powered. The honest fact is that the H18 just isn't as sensitive to tuning as the modern boats. You may notice some slight power differences going from the extreme ends of the tuning spectrum, but this is not going to be a night & day change.

Having a functional and powerful downhaul setup is more significant IMO.

sm
indiana18

Rank: Lubber

Registered: Jul 26, 2018

Last visit: May 03, 2019

Posts: 25
Posted: Aug 20, 2018 - 12:24 PM

makes sense to me, and thanks for the downhaul suggestion.
JohnES

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Registered: Sep 01, 2002

Last visit: Apr 08, 2024

Posts: 786
Posted: Aug 22, 2018 - 05:10 PM

I have never owned a Hobie 18, but there was one real sweet one at our yard once that was owned by a guy I use to sail with on my NACRA 20... The two of us would have the NACRA singing when the winds were being cooperative, and we both came to the conclusion that it was; as he put it in his southern draw..., "what y'all have dar is ayy NAYSCARR wid saaaiiiiils."

Anyway, as I said, he had a pretty sweet 18 and he kept the diamond wires pretty lose... I had asked about that one day as I have always gone in the opposite direction... Told me he leaned about that at a regatta, that is he went up to the winning boat after the first day and checked it out... said that was the first thing he noticed... and the next day they were the same... lose Said he loosened his up and noticed a vast improvement...and had left that way.

Oh, his boat had a composite mast, my be different for the all aluminum mast..

FWIW...

Edited by JohnES on Aug 22, 2018 - 05:17 PM.

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John Schwartz
Ventura, CA
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JohnES

Rank: Mate

Registered: Sep 01, 2002

Last visit: Apr 08, 2024

Posts: 786
Posted: Aug 22, 2018 - 05:36 PM

CatFan57I'm not an H18 owner (am the fairly new owner of a P18.2),

Now that I am an 18-2 owner again, I have pulled out all my old notes... glad I didn't trash those old 3.5 Floppys... A good general setting for your diamond wires should be at about 16" above the tang, that is with the mast standing you should be able to squeeze the wires to the mast they should touch at 16"... not as accurate as a Lose gauge.. 14" is about a tight as you want to go, and 20" is as lose as you want to adjust them.

For the spreader rake, about 1 1/4" aft...

Edited by JohnES on Aug 22, 2018 - 05:39 PM.

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John Schwartz
Ventura, CA
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indiana18

Rank: Lubber

Registered: Jul 26, 2018

Last visit: May 03, 2019

Posts: 25
Posted: Aug 23, 2018 - 11:38 AM

JohnESI have never owned a Hobie 18, but there was one real sweet one at our yard once that was owned by a guy I use to sail with on my NACRA 20... The two of us would have the NACRA singing when the winds were being cooperative, and we both came to the conclusion that it was; as he put it in his southern draw..., "what y'all have dar is ayy NAYSCARR wid saaaiiiiils."

Anyway, as I said, he had a pretty sweet 18 and he kept the diamond wires pretty lose... I had asked about that one day as I have always gone in the opposite direction... Told me he leaned about that at a regatta, that is he went up to the winning boat after the first day and checked it out... said that was the first thing he noticed... and the next day they were the same... lose Said he loosened his up and noticed a vast improvement...and had left that way.

Oh, his boat had a composite mast, my be different for the all aluminum mast..

FWIW...Edited by JohnES on Aug 22, 2018 - 05:17 PM.

So I tested both tight and loose settings yesterday with a good amount of downhaul. I too have a composite mast. Looser definitely seemed faster. Winds were 10-15. With the wires tight, the boat almost seemed kind of bound up; like it wanted to move faster with the given wind, but just wasn't. With the wires loose, mostly on a beam reach, the windward wire didn't even fully tension under near hull flying speeds. This makes me think the mast doesn't bend a whole lot, but the looser setting definitely felt better. The wind at my lake is hardly ever consistent, but I would like to test w a GPS someday.
Dogboy

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Posted: Aug 23, 2018 - 12:10 PM

Like I said in my original response, you are at the low end of the weight spectrum, so loose diamonds will likely be preferred. If you had 75-100 Lbs more crew weight, you would probably find yourself under-powered with the loose setting.

Also, the windward diamond wire will always have a tendency to go slack under load because the mast is bending in that direction. On any given tack, the leeward diamond wire is what limits the amount of mast bend.

sm
CatFan57

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Registered: Mar 16, 2018

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Posted: Aug 23, 2018 - 04:08 PM

JohnESNow that I am an 18-2 owner again, I have pulled out all my old notes... glad I didn't trash those old 3.5 Floppys... A good general setting for your diamond wires should be at about 16" above the tang, that is with the mast standing you should be able to squeeze the wires to the mast they should touch at 16"... not as accurate as a Lose gauge.. 14" is about a tight as you want to go, and 20" is as lose as you want to adjust them.

Okay, glad you saved your notes, and thanks for the tip. I have not messed w/ diamond wire tension as yet, but now I will check it.

I also checked my P18.2 owers manual (there's a novel idea, right?), and it says to set tension so the wires touch the mast anywhere from 12" to 20" from the lower attachment point. So your 16" suggestion will give me a more precise point to shoot for as a starting point.

I notice the manual also says: "WARNING: If the diamond wires are too loose the mast could break under high pressure loads."

Edited by CatFan57 on Aug 23, 2018 - 05:11 PM.

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1998 P18.2
Sailing out of SHBCC, NJ
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JohnES

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Posted: Aug 24, 2018 - 09:50 AM

CatFan57 I notice the manual also says: "WARNING: If the diamond wires are too loose the mast could break under high pressure loads."Edited by CatFan57 on Aug 23, 2018 - 05:11 PM.

I have never seen a Prindle 18 or an 18-2 mast break.... and I have seen them take some abuse.... but there is always a first time... 20" is pretty loose for the diamond wires.... I have found that setting and forgetting has always been the best policy... where are yours set now....

If you're going to start playing with your diamond wires I was going to recommend getting a Loos Gage, but I see they are are $100 plus bucks these days.

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John Schwartz
Ventura, CA
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indiana18

Rank: Lubber

Registered: Jul 26, 2018

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Posted: Aug 24, 2018 - 11:39 AM

DogboyLike I said in my original response, you are at the low end of the weight spectrum, so loose diamonds will likely be preferred. If you had 75-100 Lbs more crew weight, you would probably find yourself under-powered with the loose setting.

Also, the windward diamond wire will always have a tendency to go slack under load because the mast is bending in that direction. On any given tack, the leeward diamond wire is what limits the amount of mast bend.

sm

Right and right!
CatFan57

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Registered: Mar 16, 2018

Last visit: May 10, 2023

Posts: 126
Posted: Aug 24, 2018 - 03:32 PM

JohnESI have found that setting and forgetting has always been the best policy... where are yours set now....

If you're going to start playing with your diamond wires I was going to recommend getting a Loos Gage, but I see they are are $100 plus bucks these days.

I won't be at the boat til this weekend, so I don't know where mine are currently set. I bought the boat used and never thought to check the existing tension, so this thread is prompting me to check it. I don't have any plans to start playing around with different tensions, so don't think I'll get a gauge. I just want to check it to make sure it's in the appropriate range and equal on both sides, and hopefully set it to a tension that gives lots of power.

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1998 P18.2
Sailing out of SHBCC, NJ
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