[MHml] Friction in lines and blocks

[Rob Denney]

G'day,
If Roy's cruising cat with a stayed mast is the dark side, then this is a
comment from way beyond the dark side ;-)

On the unstayed masts on harryproas which do not have ballestron rigs, such
as my 15m solo boat, the wing mast is round where it goes through the deck.
This round is continued up 300mm/12" from the deck.  The boom fits on this
part of the mast, in plastic bearings.  The boom can rotate independantly of
the mast but cannot move vertically.  ie, it is self vanging.  Leech control
is done with a multi purchase block along the top of the boom.  Angle of
incidence of the rig is controlled by a 3:1 line from the cockpit to the end
of the boom.  This line sees less load than a traveller line as there is no
traveller friction to overcome.

Much cheaper than the systems mentioned above as most of it can be built,
rather than bought.  Probably lighter as well as there is no traveller,
winches or huge blocks required.  Whether the deep boom is a plus or a minus
I am not sure, but suspect it does not make much difference.

Won't work on most boats, but is great on unstayed masts.

regards,

Rob

regards,

rob

On Dec 7, 2007 5:56 AM, Roy Mills <rsirfj at shaw.ca> wrote:

>
> ----- Original Message -----
> From: "Claas van der Linde" <Claas.vanderLinde at gmx.ch>
> To: "Informed discussion of multihull issues" <multihulls at steamradio.com>
> Sent: Thursday, December 06, 2007 9:56 AM
> Subject: Re: [MHml] Friction in lines and blocks
>
>
> > Ross writes:
> > >In carbon the boom will save more than that - so overall a positive
> > >saving of weight.
> >
> > That's the right attitude. On our boat modifications, replacements or
> > repairs are only allowed if they result in an overall weight saving.
>
>
>        A comment from the "Dark side", having seen little which has not
> been from the racing types.  My main sheet is an 8 to one set up as per
> Tennant's diagram. lead through a clutch and passing by a Lewmar 24 2
> speed
> none selftailer. The Traveller is a 12 foot length of Harken track and
> positioned by a 3 to one tackle, also passing through a clutch located
> alongside the main sheet clutch,and passing close by the same winch. All
> blocks are the 3 inch Harken Big boat ball bearing jobs. TYpically I do
> not
> need the winch to tighten the mainsheet as much as I want for the 490
> square
> foot main provided I can get both hands on the sheet, if I can't, then the
> winch comes in handy. I sometimes do need the winch for the traveller, but
> a
> lesson learned a few years ago helps a lot to minimise that too. I had
> turned a mark from a broad reach to a beat, the traveller was well down,
> the
> main sheet tight. I tried to wind in the traveller without easing the main
> and ended up breaking one of the traveller blocks, which at the time was
> not
> a 3inch Harken. So I learned to dump the main sheet, haul in the traveller
> hand over hand, then haul in the mainsheet similarly. May not be up to
> racing speed but it always seems to work fine.  One thing I have in common
> with earlier posters is that when the main sheet is tight the traveller
> will
> not ease, despite the ball bearing car, until I have eased the main, and
> as
> they have found it does not require much of an easing to let the traveller
> move down, then the main can be hardened again. The traveller will move
> over
> the full length of the track because the two double blocks on the boom are
> spaced about 18inches apart, something you might think about Ross.
>
>        I don't hand hold the sheets, relying upon the fact that the main
> and traveller clutches are close by the tiller in each cockpit and the
> sheet
> tails are stuffed, not coiled, into tail bags so should run freely.  Like
> Martin I launder the sheets each winter, though I had not thought to use
> fabric softener. Unlike Claas I do not restrict modifications to weight
> savers only, the 550 pounds it cost me to fit the sitting headroom 8
> seater
> cabin is worth every ounce, and more.
>
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