[MHml] Friction in lines and blocks

[Bradford Johanson]

Seahorse mag presented a series of articles on this subject a year ago done
by the seacart trimaran people, they came to the same conclusion: big
sheaves, cascading systems with the smallest line possible. A good read.
they also measured the friction on the small tackle/ winch solution which
carries lots of friction as well coming in, but much less going out.

FWIW:
My mainsheet is a 5:1 with 3" Harken big Boat Blocks to a 55 Barlow winch
(it came with the boat) and 7/16 Spectra mainsheet (left overer from America
Cubed from 1992) What a wimp.
Traveler 6:1 with 3" Harken Dinghy blocks using 7/16 Dacron line.
Brad Johanson
F-40 Northern Rainbow

On Dec 5, 2007 5:05 PM, Dave Howorth <dave at howorth.org.uk> wrote:

> On Wed, 2007-12-05 at 22:09 +0100, Martin Schöön wrote:
> > What could happen in a high load case is of course that one
> > type of bearing starts to misbehave or even break down.
>
> That's the traditional argument for roller or plain bearings - apart
> from cost. Something like: 'Ball bearings are OK for temporary loads but
> not for standing loads'. No idea whether it's still true, or ever was.
> But I bought some very pretty Rutgerson roller-bearing blocks because of
> their high load rating.
>
> > Given the new insight my report provides us with it may be that I
> > should really convert my main sheet to winch + tackle. I don't like
> > the idea of winches and handles and all that for single handed
> > sailing though. I would be forced to use both hands for sheeting in
> anything
> > but the lightest breeze. Today I use both hands when the wind is up
> > but it is a very quick maneuver.
>
> You also have to move to where the winch is. You can't just choose the
> sunniest place to sit :)
>
> > Using a video camera for measuring speed would work but I don't
> > have one.
>
> Most digital cameras and even phones will now do video with reasonable
> time resolution. High space resolution is probably not an issue.
>
> Cheers, Dave
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