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Re: 7:1 to 8:1 conversion [Re: ] #244152
02/16/12 04:15 PM
02/16/12 04:15 PM
Joined: Mar 2009
Posts: 932
Solomon's Island, MD
S
samc99us Offline
old hand
samc99us  Offline
old hand
S

Joined: Mar 2009
Posts: 932
Solomon's Island, MD
N20, but I suspect the leech loads are pretty similar these days on the F18 high aspect ratio mains.


Scorpion F18
-- Have You Seen This? --
Re: 7:1 to 8:1 conversion [Re: Andinista] #244303
02/18/12 11:11 AM
02/18/12 11:11 AM
Joined: Aug 2011
Posts: 14
W
Walls619 Offline
stranger
Walls619  Offline
stranger
W

Joined: Aug 2011
Posts: 14
Any diagram, for harken quad stack main block?

Re: 7:1 to 8:1 conversion [Re: Andinista] #244305
02/18/12 02:23 PM
02/18/12 02:23 PM
Joined: Dec 2007
Posts: 1,430
california
F-18 5150 Offline
veteran
F-18 5150  Offline
veteran

Joined: Dec 2007
Posts: 1,430
california
I have the 5 block on top with a triple and a double on a becket on bottom . Using a tapered main it works great for me.


Richard Vilvens
Brand Ambassador
PSA Capricorn USA
R.Vilvens@yahoo.com
Fairfield, Ca
F-18 5150

http://www.capricornsailing.com/
Re: 7:1 to 8:1 conversion [Re: Andinista] #244327
02/20/12 12:23 AM
02/20/12 12:23 AM
Joined: Aug 2011
Posts: 14
W
Walls619 Offline
stranger
Walls619  Offline
stranger
W

Joined: Aug 2011
Posts: 14
line route for 8-1 main block

Re: 7:1 to 8:1 conversion [Re: Walls619] #244339
02/20/12 09:16 AM
02/20/12 09:16 AM

M
MN3
Unregistered
MN3
Unregistered
M



Originally Posted by Walls619
line route for 8-1 main block


[Linked Image]

Last edited by MN3; 02/20/12 09:18 AM.
Re: 7:1 to 8:1 conversion [Re: Andinista] #244345
02/20/12 09:58 AM
02/20/12 09:58 AM
Joined: Jan 2005
Posts: 6,049
Sebring, Florida.
Timbo Offline
Carpal Tunnel
Timbo  Offline
Carpal Tunnel

Joined: Jan 2005
Posts: 6,049
Sebring, Florida.
Nice! Thanks for that picture, worth a thousand words. Now I've got to pull mine apart and re-do it right!


Blade F16
#777
Re: 7:1 to 8:1 conversion [Re: Andinista] #244351
02/20/12 10:32 AM
02/20/12 10:32 AM

M
MN3
Unregistered
MN3
Unregistered
M



Y/w

Re: 7:1 to 8:1 conversion [Re: Andinista] #244383
02/20/12 08:39 PM
02/20/12 08:39 PM
Joined: Aug 2011
Posts: 14
W
Walls619 Offline
stranger
Walls619  Offline
stranger
W

Joined: Aug 2011
Posts: 14
thanks ,now on to nacra rudder system non pivmatic..pull down line to cam cleat on rear beam continuous line,,schock cord up through rudder control arm?Sound right any decent picture will help possable upgrade;;

Re: 7:1 to 8:1 conversion [Re: Andinista] #244412
02/21/12 11:56 AM
02/21/12 11:56 AM
Joined: Apr 2006
Posts: 699
SE Pa. or Chesapeak Bay
HMurphey Offline
addict
HMurphey  Offline
addict

Joined: Apr 2006
Posts: 699
SE Pa. or Chesapeak Bay
Not so fast ....

Study that diagram closely on how to weave/thread the mainsheet line .... now, if you rotate the single block attached to the camcleat 90*, so that it is orientated ACROSS the axis of the triple and quad blocks, there is a way to weave/thread the mainsheat line w/ no crosses .... so it will operate cleanly ...

Can you fiqure it out??? (Hint: At one point, you will need to thread the mainsheat from the extreme outboard sheave on the Quad Block, down and through the Single Block, and then back up to the other outboard sheave on the Quad Block ...)

Try it ... it works really well, but you need to actually see it/play with-it ... to apprieciate how it works

Note: It works best if the Single Block is the same size sheave as the Triple and Quad Block's sheaves ....

Harry
H18Mag/P19MX

Re: 7:1 to 8:1 conversion [Re: samc99us] #244417
02/21/12 12:33 PM
02/21/12 12:33 PM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
enthusiast
Andinista  Offline OP
enthusiast

Joined: Aug 2003
Posts: 351
Santiago, Chile
Originally Posted by samc99us
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

Re: 7:1 to 8:1 conversion [Re: Andinista] #244420
02/21/12 12:49 PM
02/21/12 12:49 PM

M
MN3
Unregistered
MN3
Unregistered
M



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

Originally Posted by Andinista
Originally Posted by samc99us
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

Re: 7:1 to 8:1 conversion [Re: Andinista] #244427
02/21/12 01:35 PM
02/21/12 01:35 PM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
enthusiast
Andinista  Offline OP
enthusiast

Joined: Aug 2003
Posts: 351
Santiago, Chile
Did you notice the difference?
(I'm feeling guilty about spending that money in blocks rather than with my wife.. I need some reassurance..)

Re: 7:1 to 8:1 conversion [Re: Andinista] #244428
02/21/12 01:39 PM
02/21/12 01:39 PM
Joined: Jan 2009
Posts: 5,525
pgp Offline
Carpal Tunnel
pgp  Offline
Carpal Tunnel

Joined: Jan 2009
Posts: 5,525
I haven't actually tried mine but went to the 8:1 in the belief that I'm undersheeting while sailing alone.

I've little doubt the money is well spent.

Last edited by pgp; 02/21/12 01:39 PM.

Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: 7:1 to 8:1 conversion [Re: Andinista] #244429
02/21/12 01:44 PM
02/21/12 01:44 PM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
enthusiast
Andinista  Offline OP
enthusiast

Joined: Aug 2003
Posts: 351
Santiago, Chile
I ordered the quad blocks by the way. The single block idea was probably good but was about half the price, not cheap enough for a probably compromised solution. (That's how I convinced myself anyway..)


Last edited by Andinista; 02/21/12 01:56 PM.
Re: 7:1 to 8:1 conversion [Re: Andinista] #244430
02/21/12 01:47 PM
02/21/12 01:47 PM
Joined: Jan 2009
Posts: 5,525
pgp Offline
Carpal Tunnel
pgp  Offline
Carpal Tunnel

Joined: Jan 2009
Posts: 5,525
I did the same, for much the same reason. A lot of F16s are using the system and I wanted to keep the boat as current as reasonably possible.


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: 7:1 to 8:1 conversion [Re: pgp] #244434
02/21/12 02:00 PM
02/21/12 02:00 PM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
enthusiast
Andinista  Offline OP
enthusiast

Joined: Aug 2003
Posts: 351
Santiago, Chile
Here is how I intend to route the line, it seems to be the option with less crossings and with a more even distribution of the line segments speeds:
[Linked Image]

What do you think?

Attached Files
2.JPG (169 downloads)
Last edited by Andinista; 02/21/12 02:03 PM.
Re: 7:1 to 8:1 conversion [Re: Andinista] #244435
02/21/12 02:10 PM
02/21/12 02:10 PM
Joined: Jan 2009
Posts: 5,525
pgp Offline
Carpal Tunnel
pgp  Offline
Carpal Tunnel

Joined: Jan 2009
Posts: 5,525
http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=244434&page=3

I ran mine like the other example, though I came up with it through trial and error.

I could not make fine adjustments with 7:1, to sheet hard I'd actually lift my butt off the hull, that resulted in steering all over the place.


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: 7:1 to 8:1 conversion [Re: Andinista] #244440
02/21/12 02:20 PM
02/21/12 02:20 PM
Joined: Nov 2005
Posts: 1,203
uk
TEAMVMG Offline
veteran
TEAMVMG  Offline
veteran

Joined: Nov 2005
Posts: 1,203
uk
Originally Posted by Andinista
Here is how I intend to route the line, it seems to be the option with less crossings and with a more even distribution of the line segments speeds:
[Linked Image]

What do you think?




Whoa! cats cradle! The top block needs to be at 90 degrees to the triple


Paul

teamvmg.weebly.com
Re: 7:1 to 8:1 conversion [Re: Andinista] #244441
02/21/12 02:21 PM
02/21/12 02:21 PM

M
MN3
Unregistered
MN3
Unregistered
M



Originally Posted by Andinista
Did you notice the difference?
(I'm feeling guilty about spending that money in blocks rather than with my wife.. I need some reassurance..)


i can't say i felt much difference but my shoulders are less sore than usual.

Re: 7:1 to 8:1 conversion [Re: Andinista] #244449
02/21/12 05:00 PM
02/21/12 05:00 PM
Joined: Mar 2002
Posts: 66
ccat Offline
journeyman
ccat  Offline
journeyman

Joined: Mar 2002
Posts: 66
HM is right.

There is a much better way to reeve than the Harken diagram.

PM for a pic

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