How does this work?

[chalky]

Can anyone explain how the stem fitting (removed from N760) should work? Looks like it should tension the jib Luff? There is a pulley on the central fulcrum...

[Tim Gatti]

Hi John - Just a guess....
Presuming left of photo is to point of bow - my suggestion would be that the forestay fastens to the screw shackle on the front of the fitting. The foot of the jib is fastened to the piston-clip shackle on the right which pivots upwards under tension. You'll probably find a short wire strop with a block on it fastened to the mast near the point of the shroud attachment. External jib halyard shackled to head of jib, through block on strop , down and through pulley on fulcrum (front to rear) tensioning will lift rear of fitting clear of base plate and halyard can be run aft to a cleat  near base of mast, giving you a 2:1 purchase on the jib halyard. Tim

[kevan bloor (Guest)]

John
Tim is correct regarding this type of stem fitting.  Any jib used on this needs to have jib hanks to keep the jib aligned to the forestay.  It was very common for the early boats to have jib halyards coming back down the forestay and across the foredeck.  Some of the foredeck arrangements had racks mounted sideways to apply extra tension to the jib halyard.  If you don't use jib hanks the jib luff will sag off to leeward and very badly effect the upwind performance of the boat.  Make sure that the pivot pin is sound since if it breaks you lose both the anchorage for the jib and the forestay at the same time! (as I know when the stem fitting on my March Hare (1964) gave way)
On looking at your photo the snap shackle is a later addition and with this orientation the jib would have to be attached to the snap shackle with another shackle, otherwise the wire eye at the tack of the jib would be orentated across the boat rather than in line with the centreline.
Kevan

[Male ....OSOH (Guest)]

Hmmm, I can't say I'm very well qualified to be definative as this item would appear to date from a period before my time.......
However, it does have the outward appearance suggestive to me of a "Sony Ericsson" ?  It may be one of the models with MP3 functionality and also badged "Walkman".
I'd love to be more helpful and specific about the model number but I'm afraid these were items which were under constant development for commercial gain and released in numerous guizes. No sooner were flash new models offered for sale than their replacements were being brought to market.

[MikeDay]

In addition to Tim's and Kevan's wise guidance, I think that the fitting attaching to the stem fitting was called a 'rocker'. The idea was to have the forestay and the jib halyard tension in balance - hard to achieve in practice.  Kevan's guidance about breakage is to be noted - these rocker fittings were very inclined to break because of the weakness where the hole is.  If you see the other current thread about jib halyards, you'll understand why Twelves left this kind of arrangement behind.  In the mid 60s, most people dispensed with this arrangement, drilled out the hole on the stem head fitting a bit, and used a big bronze shackle to attach the jib tack directly to the stem, with a range of devices used to get enough tension in the luff.  As the Class rules required a forestay then, we had them loosely attached with a piece of string to the same shackle, flopping around so they didn't affect the luff tension.  Your choice now is between antique authenticity and functionality ...
Mike D
N3496 

[Tim Gatti]

Not sure what the mast gate arrangement is on your Landamore John, but I have kept my forestays in place on my vintage boats with wooden spars on a just in case basis. Also as Kevan says - it gives you something to hank the jib to.  The older boats just can't sustain the sort of jib luff/rig tension that you might otherwise apply to a more modern 12 with an aluminium mast, so the more support you can give to the jib luff - the better

[chalky]

all makes sense now, will test/ check pivot as mast is deck stepped! pictures of boat on www.n760.blogspot.com 

[GarryR]

<div class="postbody">Many bits of advice concerning the old style jib tensioners where the jib is hauled up its own halyard and and hanked to the forestay say that this is done so that the forestay provides support to the jib luff and prevents sideways movement when beating to windward. On my old deck stepped merlin from 1947 even if the forestay is relatively tight when "at rest" ie no rigging, once you pull up the jib and tension it, the forestay slackens to the point where it would flop about if the jib was not hanked to it. So I guess I am asking what is the point of hanking in the first place if there is all this untensioned forestay providing no support. In fact it seems to me that the jib luff stops the forestay flopping around than vice versa!!  I have put this on this posting topic as well as it possibly pertinent to both!!

[JonathanReubin]

Howdy, Chalky.  I have one of these fittings on 1719, well its similar as the rocker is a flattened V.  With the tack on the rear part, the tension pulls up on the rocker and theoretically tensions the forestay in unison thereby splitting the tension between luff wire and forestay.  I think mine is a brass fitting so will fail sooner rather than later so I am watching it carefully.  When it goes then it will be a standard stainess replacement and a highfield tensioner on the halliard and a system to tension the forestay to stop flopping.
On a Merlin i have I do not have a forestay at all so have to remember not to drop the jib before using the spinny halliard as a beach forestay.  Only did that once and the fancy footwork to catch the mast before the club window bust was equalled Renaldo! On another old boat the hankless jib is tensioned on a highfield and the flopping forestay is really not too much trouble except when the crew fouls it on the spinny pole.
 
It should be ok on your boat as I doubt you are going for huge tensions unless you want to reduce the beam and increase freeboard!