Sheeve sizing, mainsheet

simonfraser said:
I have 60mm triple ratchet lewmar.

Need to go up to 8:1 there is no spare becket on the lewmar.

Harken do 8:1, can i drop down to 40mm sheeves ?

Will that make a difference re friction ?
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I'd be chary of going to 40mm sheaves - I'm using Harken 60mm Carbolite Harkens on my main, obtained direct from Harken US as I couldn't get much sense out of their UK branch (which probably had more to do with Boatshow confusion than lack of service). these are now obsolescent, their replacements can be found:-

http://www.harken.com/blocks/blocks.php

http://www.harkenstore.com/uniface....?CATALOG=409Z56LC7FV66&CATEGORY=409Z56LC4WKD6
 
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simonfraser said:
Tnx Charles, why is the .uk part soooo bad, why bother ??!
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I wouldn't say they're "bad", just a smaller operation, less stock and no techies.
The 57mm sheaves aren't cheap (in the UK) but mine have been going trouble-free for 11 years, I just have to check the lashing annually, and I've come down to 10mm Dyneema on the main to get it to run easily.
Not only did they advise and support me on mainsheet blocks but designed from scratch single line reefing which has since appeared on their US site. The 60mm carbo cheek blocks weren't even available in UK.
Certainly their kit is 1st rate - winches, blocks, recirculating mainsheet horse, roller reefing even if expensive.
Ironically I couldn't find the "correct" section for the mainsheet horse track (theirs was either too small an x-section or too big) and am using Lewmar for that.
 
The friction is a function of the rope size and construction as well as the sheave size.
Is a fine tune on the 6:1 possible?
8:1 can be a lot of string in the cockpit.
 
I have just fitted an easylock 8:1 twin geared system (basically continuous line with two cams pull both ends for 4:1, one or the other for 8:1) haven't used it yet. They are a bit of a marmite issue in my experience but very solid and excellent value for money. I find that 'tweakers' are a bit of a PITA on cruising boats.
 
simonfraser said:
wklein, that a harken product ? Do u have a link ?
My boat just right for tweaking, not keen on marmite though ;)
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Harken do make one with their usual price tag. The one i mean is made by easy marine (sorry not much on internet) and distributed by meridian zero.


I got mine nearly new from ebay for 110 quid.
 
This? http://www.force4.co.uk/8691/Easy-matic-2-Two-Speed-Mainsheet-System.html

and

http://www.mailspeedmarine.com/sail...lutions-centre-mainsheet-3-1-6-11051593.bhtml

ah. here's the 8:1 http://www.mailspeedmarine.com/sail...lutions-centre-mainsheet-4-1-8-11051695.bhtml but you probably need the heavier Easymatic 2 that I can only find here http://www.svb24.com/index.php?sid=x&shp=1&cl=details&cnid=11411&anid=1644



I have a 6:1 ball bearing mainsheet system at the moment. I certainly couldn't cope with 1/3 more rope in the cockpit and with frictional losses I doubt if there would be much reduction in load.
I wanted the Easy Matic but ran out of readies.

Is this http://www.ebay.co.uk/itm/HOLT-ALLE...essories_SM&hash=item3f1664f746#ht_665wt_1110 any interest?
 
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Main sheet system

An 8 to 1 pulley system for the main I think would have a bit to much friction especially for releasing in a hurry. No matter how good the blocks. 4 to 1 seems to be the ideal size for purchase gained versus friction.
The options then are for a tweaking 4 to 1 purchase on the tail normally attached to a becket or you can try the doubled up system. (as already described) To use and release as a 4 to 1 system you grasp and release both ropes from the twin cam cleats. To pull in as an 8 to one you pull one rope and leave the other cleated. Both systems work well but both need to be readjusted occasionally to balance the length of the 2 tackles.
Or you might consider the system where the main sheet goes to the gooseneck then back to a winch to get the real power you want. good luck olewill
 
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