National 12 - find out more...
 

Starfish experts

Started by Interested Party, 05 Jun 2013, 09:46

« previous - next »

Interested Party

I was reading my copy of Robin Steavenson's National 12 book, when I came across a couple of statements pertaining to the Noakes Starfish design.
1.  The designer (Mr Noakes) is recorded as recomending a 25/65 ratio for jib/main setup.  Is this still relevent after all these years?  What are peoples current thoughts especially with the advent of loose foot mains/spreaders/etc?  I am running a second hand mismatched set of sails and after a very recent thread I am going to have to have a look at the combination I have - just to see if; a.  It is likely to be legal.  b.  If it is a recomended configuration for the design.  The current main is the only loose foot main I am in possession of and the jib, is the best of a pile, but is certainly bigger that some of the older ones I have.  Looking down the line, having updated my mast, I hope to be looking at sourcing a new set - once I can come to terms with paying more than double the price I paid for the boat/trailer/etc for them. 
2.  Mr Steavenson describes a sliding jib fairlead arrangement on the trailing edge of the foredeck.  I saw something similar on Pendle Witch and have replicated it on Sparkle, Or at least I think I have.  On Sparkle, as you pull the jib in tighter, from the oposite side of the boat, which is where the crew is likely to be when close hauled, the fairlead and cleat will move inboard on the track.  When the tension is released the slider will return outboard - this is controlled by shock cord under the deck.  Mr Steavenson describes the action completely the opposite - i.e. when the tension is released, the cleat and fair lead returns inboard?  Seems a bit odd?
Cheers
Steve Hawkins
Steve Hawkins <br />N12 - Planet 672 -1948 (Holt modified 500 series)<br />N12 - Spider 2523 - 1971 (Spider) <br />N12 - Sparkle 2383 - 1967 (Starfish)

NTOACertification

Hi Steve
In the 60's the 25/65 Ratio was always the favoured rig for inland sailors and 27/63 or 30/60 for the sea sailors. In fact with the change in measurement on sails with metrication etc. the current Ratios are not that different with current jib area around 2.2-2.3 sq mtrs. A 25 sqft jib would measure around 2.28 sq mtrs.
In fact the most important thing to look at with either new or old sails is the jib sheeting arrangement. The track on the back of the Foredeck is the least favourable option and almost certainly any second hand sails would probably not fit this configuration.
Even in the 60's this was not most popular method of sheeting the jib. Where the jib clew eye is very close to its fairlead the actual geometry of the sail become critical and consequently mast rake changes have great effect on the jib.

It is far more important to be able to move the sheeting position fore and aft than inboard to outboard. Always remember that the starting point for sheeting the jib is to have line of the jib sheet running from the fairlead throught clew eye of the jib up to a point on the luff 45-50% up the luff of the sail.

If you are checking the sails you have it would be good to do the reverse of this. Lay any jib you have, find the 45 and 50% point on the luff of the jib measured from the tack and then extend two line to the clew eye and mark the lines on the sail for the last 300mm or so at the clew. Incidently this  usefull for any jib on any boat.
When you then set the sail on the boat ( with it rigged properly you can then see where the jib fairleads need to be in the boat.
I would advise you mark these lines on any sail you have as this is a visual guide as to what whether you are sheeting the jib correctly.
Some sailmakers will mark this or similar reference lines on a new sail anyway.
 
Hope this is helpful
 
Kevan Bloor

paul turner

Greetings Interested Party - I have the original Mike Nokes' Starfish N2020 with the original sliding fairlead arrangement which goes across the foredeck, not along the trailing edge. There is no shock cord pulling the fairlead in or out, just a line to pull the fairlead outwards for reaching - it automatically pulls inboard when close hauled. This may not be the best set up, but it's original and I'm going to stick with it!

As regards sails, if you want to retain the deck fairleads then the size and cut of the jib will be a limiting factor; I suggest that you talk firstly to Kevan Bloor (formerly of Alverbank Sails) about the sizes and then to Jim Hunt at HD Sails as they have our sail patterns.

I hope that you are coming to the Vintage Champs later this month at Foremark?

Paul N2020 8) (+ N1650, N2359, N2403 etc....)

Interested Party

#3
Thanks chaps,
Better go an get the tape measure out.
Looks like it was wrong on Pendle Witch (Starfish) and I have copied the mistake across to Sparkle....Doh!
Cheers
Steve Hawkins.
Steve Hawkins <br />N12 - Planet 672 -1948 (Holt modified 500 series)<br />N12 - Spider 2523 - 1971 (Spider) <br />N12 - Sparkle 2383 - 1967 (Starfish)

Interested Party

The old Bat Jib I have was last measured in 1987 and seems to be close to the numbers mentioned above.
I did do the 45% / 50% measurements and marked the sail appropriately.  And it would seem that I am petty close to be spot on.
This does not suprise me too much as the previous setup used fairleads mounted on the seats, either side.  The jib sheet passed very close to the aft edge of the fore deck, so when I mounted the rail, it effectively intercepted that line but a bit further up.  So I will leave it as it is for the time being - I will give it some more consideration when I redeck her...eventually.
I probably get away with it on Sparkle, as the fordeck might well extend slightly further aft than later designs?
Thanks for the info though.
Cheers
Steve H
Steve Hawkins <br />N12 - Planet 672 -1948 (Holt modified 500 series)<br />N12 - Spider 2523 - 1971 (Spider) <br />N12 - Sparkle 2383 - 1967 (Starfish)

paul turner

Hi Steve.
Hadn't realised that Kevan had replied when I posted; sorry if I caused any confusion.
Just checking the boat at the weekend I see that, despite wanting to leave the boat as original as possible, I have actually modified "Starfish" in two aspects:
1. I have left the deck mounted fairleads in the original positions, but fitted temporary ratchets to the side thwarts using string - no screw holes - to possibly re-gig the sail plan later.
2. All the old bouyancy straps have been removed and two larger bags have been fitted at the stern using covers made of old sail material.
P N2020 8)

Interested Party

I have a similar set of pulleys mounted on Planet but used to help pull the steel centre pate up. 
Sparkle also only has bouyancy bags at the back.  Unfortunately I popped one recently when I blew it up on a cold day......Next day was hot and it went pop.   Lesson learned...Doh!
Should of taken a pictue though
Cheers
Steve Hawkins
Steve Hawkins <br />N12 - Planet 672 -1948 (Holt modified 500 series)<br />N12 - Spider 2523 - 1971 (Spider) <br />N12 - Sparkle 2383 - 1967 (Starfish)

n12 Bottom Banner