| |  Re: 7:1 to 8:1 conversion
[Re: ]
#244464
02/21/12 09:13 PM 02/21/12 09:13 PM |
Joined: Jun 2001
Posts: 12,310
South Carolina Jake 
Carpal Tunnel
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Carpal Tunnel
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South Carolina | I agree with Andinista and have recently added another block to my 8:1(even after reading this thread). Sure i can now probably apply more force, but i don't want to. my goal was to need less strength to sheet to the same amount (i have shoulder issues). Also i have a hard time believing the sheeting forces are the same on an f18 and n20... but i am not an engineer I don't suggest modifying an existing block system. "Upgraded" an 8:1 system to a 9:1, but the existing block hardware was not beefy enough to handle the loads, found out the hard way 3 days into Tybee. This statement suggests that an increase in purchase means necessarily an increase in max load applied. Is that really true? Don't we want to actually lower the pull to acheive similar results? Therefore more pulleys should mean lower load and not higher, except at the connections in both ends, where the total load is applied. That's assuming that the goal is to distribute the load rather than apply more total tension. Maybe I'm wrong there.. Still, we are talking about a 10 to 15% increase in purchase, which comes with a decrease in overall efficiency because of the higher friction, therefore, the total tension is increeased in less than that. Would that be enough of an increment to break the blocks? If not rearranging blocks too differently (like the single block suggested in the first post) I think it shoudn't Nacra 20 has a softer, bendier, mast so you have to be careful not to oversheet more so than the F18...but, we sheet them similarly.
Jake Kohl
| | | Re: 7:1 to 8:1 conversion
[Re: samc99us]
#244467
02/21/12 11:21 PM 02/21/12 11:21 PM |
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C. Team_Cat_Fever
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Carpal Tunnel
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Roanoke Island ,N.C. | I don't suggest modifying an existing block system. "Upgraded" an 8:1 system to a 9:1, but the existing block hardware was not beefy enough to handle the loads, found out the hard way 3 days into Tybee. If you added a point of purchase you decreased the load on the hardware (blocks)itself. I think you were just using some old busted-butt, brokedown, shite. i've used an 8:1 modded to 9:1 since it was allowed by class rules ,at least 4 Tybees worth.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
| | | Re: 7:1 to 8:1 conversion
[Re: Jake]
#244583
02/23/12 10:26 AM 02/23/12 10:26 AM |
Joined: Dec 2001
Posts: 5,590
Naples, FL waterbug_wpb
Carpal Tunnel
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Carpal Tunnel
Joined: Dec 2001
Posts: 5,590
Naples, FL |
Nacra 20 has a softer, bendier, mast so you have to be careful not to oversheet more so than the F18...but, we sheet them similarly.
? I thought it was easier to oversheet Rob's wildcat than Forrest's N20 - both in 18+ conditions... maybe I was just seeing things? Or are you referring to the N20 with aluminum mast? I never considered that carbon mast particularly "bendy"???
Jay
| | | Re: 7:1 to 8:1 conversion
[Re: Andinista]
#244586
02/23/12 10:38 AM 02/23/12 10:38 AM |
Joined: Jan 2007
Posts: 139
Hernando, Florida Mlcreek
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Hernando, Florida | Jake,
Can you oversheet the N20 to the point of breaking the mast? Using the OEM 8:1.
Forrest
Last edited by Mlcreek; 02/23/12 10:38 AM.
Forrest
I-20
USA 645
" There ain't enough rum in the drum!"
| | | Re: 7:1 to 8:1 conversion
[Re: Mlcreek]
#244591
02/23/12 11:00 AM 02/23/12 11:00 AM |
Joined: Oct 2005
Posts: 1,152
tampa, fl ksurfer2
old hand
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old hand
Joined: Oct 2005
Posts: 1,152
tampa, fl | Jake,
Can you oversheet the N20 to the point of breaking the mast? Using the OEM 8:1.
Forrest Not with a wuss like Stank pulling strings you can't! 
If your havin girl problems i feel bad for you son
I got 99 problems but my beautiful wife ain't one
| | | Re: 7:1 to 8:1 conversion
[Re: ksurfer2]
#244593
02/23/12 11:10 AM 02/23/12 11:10 AM |
Joined: Dec 2001
Posts: 5,590
Naples, FL waterbug_wpb
Carpal Tunnel
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Carpal Tunnel
Joined: Dec 2001
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Naples, FL | +1 on that Karl!
I don't recall anyone ever breaking a mast from oversheeting a main (on any boat except maybe an H16 before they started raking the masts back). Even with the 10:1 setups?
Only N20 masts I've heard that broke were stuffing into a wave with spinnaker up (Mike H), letting the mainsheet go with the spin up, and getting tossed around at Jensen Beach during the T500. Maybe there are more out there?
Jay
| | | Re: 7:1 to 8:1 conversion
[Re: Andinista]
#244603
02/23/12 12:24 PM 02/23/12 12:24 PM |
Joined: Jan 2007
Posts: 139
Hernando, Florida Mlcreek
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Posts: 139
Hernando, Florida | Karl,
Don't let him fool you....when others ain't looking, he begs me to pull them. Plus, I'm expected to keep the waves off of him.....was that skipper or slave driver?
Forrest
I-20
USA 645
" There ain't enough rum in the drum!"
| | | Re: 7:1 to 8:1 conversion
[Re: Mlcreek]
#244614
02/23/12 12:53 PM 02/23/12 12:53 PM |
Joined: Jun 2001
Posts: 12,310
South Carolina Jake
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 12,310
South Carolina | Jake,
Can you oversheet the N20 to the point of breaking the mast? Using the OEM 8:1.
Forrest I doubt it. In big air upuwind and sheeted properly, the I20 mast looks like a wind surfer rig to me. After sailing F18 for a while and coming back to the 20, I had to get used to seeing that much bend in the rig. I'm not sure you could do any damage even with 10:1 though.
Jake Kohl
| | | Re: 7:1 to 8:1 conversion
[Re: Mlcreek]
#244669
02/23/12 04:29 PM 02/23/12 04:29 PM |
Joined: Jun 2001
Posts: 3,906
Clermont, FL, USA David Ingram
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 3,906
Clermont, FL, USA | So with a 10:1, you crank your stick and don't break it? Typical 20 drivers, always inappropriately cranking their stick. Speed tip, less cranking more sailing.
David Ingram F18 USA 242 http://www.solarwind.solar"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
| | | Re: 7:1 to 8:1 conversion
[Re: ccat]
#244886
02/28/12 09:27 AM 02/28/12 09:27 AM |
MN3
Unregistered
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| HM is right.
There is a much better way to reeve than the Harken diagram.
PM for a pic Hi CCAT, i have PM'ed you 2x trying to see that diagram. Can you please send or post it? Thanks | | |
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