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Alternate mainsheet solution

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Ryan L
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230 Posts

Response Posted - 01/22/2012 : 14:12:10

Maybe I don't understand what you're saying... How is the lateral force on the eyebolt any different than the lateral force on the bolt used for the tang? The force will be in the same direction and focused in the same area of the bolt. the main difference is that I'm suggesting using easily replaceable, more pliable, and arguably stronger dyneema rather than a metal tang. Inspecting the tang won't help, this kind of fatigue can't be seen with the naked eye. But I'm interested in hearing more about your concern. Especially if there is something I'm missing here... It certainly wouldn't be the first time! Thanks

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DaveR
 <blockquote id="quote">quote:<hr height="1" noshade id="quote"> Here are some other threads regarding the mainsheet tang failing <hr height="1" noshade id="quote"></blockquote id="quote">

And I'm sure there's more than those two. Just like a stay, a rudder or numerous other parts in time they wear and can break. Periodical inspection. The thing that bothers me about the eye bolt is the lateral forces being put on it,but who knows, it may work as well or better than the tang over a long period of time, and only time will tell.
<hr height="1" noshade id="quote"></blockquote id="quote">

Edited by - Ryan L on 01/22/2012 14:56:05

islander
Master Marine Consultant

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4018 Posts

Response Posted - 01/23/2012 : 06:45:23

Ryan, I agree with your above statement, Tang or bolt the angle and force is the same. My only thought about your set up was that you said that you left the eye bolt slightly loose so it could rotate. This movement will slowly allow the eye bolt to grind away at the hole in the softer casting slowly enlarging it and getting looser. I would set it at the angle of your choice and tighten it down. Then again if you like it to rotate get a bushing from a hardware store and put it in the casing then put the eye bolt through it.

Edited by - islander on 01/23/2012 06:54:53

DaveR
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2015 Posts

Response Posted - 01/23/2012 : 08:15:56

The further away from the securing base of your bolt/extrusion that the object of your downward pressure is attached the more force is put on that securing area (or seat?) of the bolt. Even with just the eye of the bolt out there the force might be doubled. So you have much more force on your end cap and it's attachment to the boom. That's why Catalina went with the tang that keeps that force to a bare minimum.

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redeye
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Response Posted - 01/23/2012 : 10:44:55

I think I'll buy another tang... after 28 years mine might be stressed...

Thanks.

Edited by - on

Ryan L
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230 Posts

Response Posted - 01/23/2012 : 11:52:32

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 Ryan, I agree with your above statement, Tang or bolt the angle and force is the same. My only thought about your set up was that you said that you left the eye bolt slightly loose so it could rotate. This movement will slowly allow the eye bolt to grind away at the hole in the softer casting slowly enlarging it and getting looser. I would set it at the angle of your choice and tighten it down. Then again if you like it to rotate get a bushing from a hardware store and put it in the casing then put the eye bolt through it.
<hr height="1" noshade id="quote"></blockquote id="quote">

I agree. I originally left it loose because that's how Catalina left the bolt for the tang (so the tang could rotate). The dyneema serves the same purpose.

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Ryan L
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230 Posts

Response Posted - 01/23/2012 : 11:58:08

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DaveR
 The further away from the securing base of your bolt/extrusion that the object of your downward pressure is attached the more force is put on that securing area (or seat?) of the bolt. Even with just the eye of the bolt out there the force might be doubled. So you have much more force on your end cap and it's attachment to the boom. That's why Catalina went with the tang that keeps that force to a bare minimum.
<hr height="1" noshade id="quote"></blockquote id="quote">

Ok, now I understand what you're saying. I considered that when I was first thinking about this system and discussed it with the engineer at seadog. He told me that as long as the flange (he might have called it a collar) at the base of the eyebolt made contact with the end cap then the forces are dissipated. Like a backing plate for deck hardware. I'm probably not using the correct engineering terms here but bottom line was he said he's confident it's no problem. When you consider the difference in distance between the tang/endcap and eyebolt/endcap we're talking about millimeters. It's possible the eyebolt with flange may ultimately be stronger than the tang setup despite the slight increase in distance?

This seems to me to reinforce the other post regarding keeping the eyebolt tight rather than allowing it to rotate.

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dmpilc
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4593 Posts

Response Posted - 01/23/2012 : 14:38:19

I would keep it tight also.

Thinking out loud: The Catalina 25 std rig carries a mainsail that is only about 16 sq. ft. larger than a C-22 main sail, and the C-22 main sheet is attached to the boom by means of an eye strap and single swivel block. Wouldn't a slightly more substantial eye strap instead of a bail on the C-25 boom be satisfactory in lieu of the tang (edit: at least for boats on inland lakes)? Or does the extra weight of the boat enter into the stress equation also?
C-25 main: Luff 24.60, leech 26.00, foot 9.50
C-22 main: Luff 21.00, leech 23.00, foot 9.66

C-25 TR main: Luff 27.66, leech 29.25, foot 9.58
C250 main: Luff 24.50, leech 26.50, foot 11.00

Interesting that the C-22 main's foot is just a tad longer than either C-25. The C250 main's foot is longer because the mast is stepped more forward than on the C-25. Consequently, it also has a shorter J dimension for the headsails (9.0 ft. vs 10.5 ft.)

Edited by - dmpilc on 01/23/2012 20:25:22

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.