[MHml] Main Halyard

[Ross Hobson]

Charleston is an inshore boat (sister to Ted's Rosebud) and is IMHO a different beast to Mollymawk (my ex-offshore tri)
we have 10mm spectra (marlow) 1:1 halyard, masthead ZS jammer with a 12:1 cascade downhaul.  it all works very well. we loose no slip due to the jamming and once the downhaul is off you can unload the ZS by hand
and so far i have not manged to induce creep (even in its previous guise as a 1:1 with a mast base clutch)
 
many offshore boats now use masthead locks with no problems and certainly i would use one in that situation in future
 
whne i flipped Mollymawk- the main was on the deck already.....
 
Ross

________________________________

From: multihulls-bounces at steamradio.com on behalf of Paul Nudd
Sent: Wed 16/05/2007 01:05
To: Informed discussion of multihull issues
Subject: Re: [MHml] Main Halyard



I had a ZS jammer on the mast in 1995 and I took it off, mainly because
I feel that it is important to be able to quickly release the halyard.
The ZS cannot be released under load, I needed to reload the halyard
onto the winch then winch the halyard up a little to unload the ZS in
order to release the ZS and then release the halyard.
Now I leave the halyard on the s/t winch so that I can drop the sail
quickly when necessary. It also means I achieve full hoist. When using
the ZS I lost a few inches to allow the ZS to jamm.

Presumably, using a ZS at the masthead would entail losing a few inches
of hoist for it to jamm, then to release the ZS the halyard would have
to be winched up those few inches to release (remotely). Also the ZS
would fail to the locked (not fail-safe) position. All this is of course
no big deal on Charleston where a capsize is 'not the end of the world'.
On many other boats a capsize would be 'the end of the world' - "well
hardly ever" - "we hardly ever capsize at sea".


I once tried a 12mm spectra halyard with a splice but the splice tail
(14mm?) wouldn't go through the sheave.

I still agonise over to splice or knot to splice as Creighton has sewn
the seeds of concern over the splice tail working through the 2 sheaves
(2:1 halyard) and the knot is replaceable and a professional splice
costs $60
The 1:1 11mm 1998 vectran halyard failed at the knot after 9 years.
I will be using 2:1 (half the load) 10mm 2007 vectran which may be
better than the older stuff, so can I expect a few years out of it with
a knot at the top. I imagine I was perhaps using 20% of the load
capacity of the old stuff, thus the failure after 9 years.
I guess I will be using about 10% of the load capacity on the new
halyard so if I use a knot it should last 'forever'.
Alternatively I could perhaps use 2:1 6mm 2007 vectran and use maybe 50%
of the load capacity and need a splice. If I had a lightweight carbon
mast perhaps I would be looking for the last bit of weight aloft saving
and use the 6mm but I have a rather heavy, very strong aluminum alloy
mast and there are easier ways to save a bit of weight aloft.
I will leave that to the next owner and just try to turn over a good
strong reliable package.
I will continue to maintain the boat to the highest standard but will
undertake no further development.
PN
Ross Hobson wrote:
> Paul
> On Charleston we have reduced any stretch to zero by installing spinlock
> ZS jammer on a remote release at the mast head - even is we manage to
> strech 10mm dia (8m core) spectra the actual working length is only
> 300mm
>
> We use a 12:1 downhaul
>
> It's an easy way of getting around all that rope plus it reduces mast
> compression
>
> I would splice every time - as I said in a prveious email having
> undetaken the load cell (instron) tests - a knot reduces rope strength
> at at least 60% and a proper tapered splice only 10-20% reduction in
> rope strength
>
> But you may be using the knowt as a'fuse' so you don't overload
> things....
> :-)
_______________________________________________
Alter your subscription details or unsubscribe at the bottom of this page:
http://www.steamradio.com/mailman/listinfo/multihulls

Multihulls mailing list      (Multihulls at steamradio.com)