[Public-List] Mainsheet diameter

[Jonathan Bresler]

Gord,

How about roller bearings?   Believe winches have roller bearings.
Guessing each ball bearing is pointed loaded, plain bearings are “surface”
loaded, and roller bearings are loaded along a line on each roller.

Jonathan

On Tue, Oct 31, 2017 at 1:29 PM Gordon Laco via Public-List <
public-list at lists.alberg30.org> wrote:

> We’ve got SURPRISE’s mainsheet rigged 3:1, so the load in the hand is
> somewhat higher.  That led me to use 5/8”, not for strength, but for
> comfort.  I fitted blocks large enough to handle this comfortably, so
> there’s no issue with friction when it’s running out.
>
> I used to have 3:1 with the option of pulling down the dead end to make it
> 4:1 as originally rigged, but found years went by without the need for
> this, so 3:1 it is.
>
> I like 3:1 because when rounding the leeward pin there’s so much less
> sheet to haul in when starting back up the course... and of course the lack
> of the extra turn in the tackle relieves friction.
>
> Funny thing about friction and blocks... Harken has us all trained to feel
> we need ball bearings but the fact is that ball bearings are only superior
> in narrow circumstances, and always in low load situations, such as light
> air sheeting and easing. (that goes for things like outhauls etc too).
> Plain bearings (stainless steel on bronze) are best in high loads with
> regard to both strength and low friction when hauling in.  And, (here comes
> the real heretical observation) this is true for winches too...
>
> But I’m sure most won’t believe it...
>
> Gord
>  #426 Surprise
>
> On 2017-10-31, 1:08 PM, "Public-List on behalf of Stephen gwyn via
> Public-List" <public-list-bounces at lists.alberg30.org on behalf of
> public-list at lists.alberg30.org> wrote:
>
>     The mainsheet, with it's 4-to-1 purchase, is never under very heavy
> load.
>     The diameter is more about what's comfortable in the hand. I use 10mm
>     which works out to somewhere between 1/2" and 7/16", but closer to
> 1/2".
>     It's fine. The jib sheets are single lines, and listening to the sound
>     as they are tightened and doing some undergraduate physics, the tension
>     is sometime 700lbs, still much less then the breaking strain of 10mm
>     polyester line.
>
>     SG
>
>
>
>     On 10/31/2017 07:28 AM, public-list-request at lists.alberg30.org wrote:
>     >   Great resource, thanks George.
>     > Is everyone using 7/16" for the mainsheet? I planned on 1/2", bad
> idea?
>     > Thanks
>     > Chris
>
>     --
>
> -------------------------------------------------------------------------
>     Stephen Gwyn                        | Tel: 1-250-363-3136
>     Canadian Astronomy Data Centre      | Fax: 1-250-363-0045
>     Herzberg Astronomy and Astrophysics | Cell: 1-250-885-6969
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>     Victoria, BC, V9E 2E7, Canada       |
> http://astrowww.phys.uvic.ca/~gwyn/
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-- 
Jonathan M Bresler
S/V Constance Alberg 30 #262
Annapolis/Eastport MD