National 12 Mast lengths

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Stephen Hawkins
Posts: 533
Joined: Wed Nov 04, 2009 11:41 am
Location: The much maligned Swindon Town

National 12 Mast lengths

Post by Stephen Hawkins » Thu May 02, 2013 9:22 am

I recently acquired a more modern mast for my 1967 Starfish National 12, Sparkle (2383).

The newer alloy mast came from a later National 12 design (Crusader), from the 1980's and has spreaders instead of the single diamond fitted to the mast currently in use. The Crusader is a cold molded design which is wider than my clinker Starfish

I was under the impression that the mast I have been using, was stiff/heavy and was looking to improve my lot before stumping up for a set of sails. The older mast is gold anodized, but of unknown origin - and, I suspect not original, as there was the odd deck fitting that did not really talley up with what was on the mast. It used to have a wheeled kicker but has been modified for a more modern set up. It is however, of the period - shall we call it a first generation alloy mast?

However the new mast is aproximately 13" shorter. Which would put the boom too low.

Assuming this new mast is indeed a National 12 mast, I can only a deduce that the more modern national 12 hull designs are not as deep as the older ones. Since all measurements are taken from the sheer line (an imaginary line drawn across the boat from gunnel to gunnel), I can only deduce that the amount of mast below that line is very variable – depending on the design.

So the masts are getting shorter as the designs are getting younger.

Perhaps I should have tried to look for a more modern Firefly mast.....Doh!

Cheers
Steve Hawkins

1967 National 12 2383 "Sparkle"

chris
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Joined: Sat Sep 18, 2004 7:43 pm
Location: somerset

Re: National 12 Mast lengths

Post by chris » Thu May 02, 2013 7:57 pm

The vital statistics:
HEIGHT OF SAIL PLAN
10.1 MAINSAIL
The height of the mainsail shall not exceed 6100mm measured from the sheerline in
way of the mast. The actual point of measurement shall be marked by the lower edge
of a band of contrasting colour on the mast. Where such band is not of paint, the point
of measurement shall be additionally marked by inscribing or similar into the mast
surface.
10.2 FORE TRIANGLE
The height of the fore triangle shall not exceed 4575mm measured from the sheerline
in way of the mast. The top of the fore triangle is the point at which the luff of the
foresail being extended, would cut the foreside of the mast when held at a downward
slope of 2:7 (angle 16 degrees) to the mast.

Stephen Hawkins
Posts: 533
Joined: Wed Nov 04, 2009 11:41 am
Location: The much maligned Swindon Town

Re: National 12 Mast lengths

Post by Stephen Hawkins » Thu May 02, 2013 8:38 pm

The new mast is a C section proctor.

I have to look into adding a new section to the bottom of the mast.

But first I really need to measure the sheer line on my current mast to make sure it measures.

It will give me a better idea where I stand with the new one. I.e. how much I have to add.

Anyone got an old busted C section mast that I can cut a bit off of?

Steve H
Steve Hawkins

1967 National 12 2383 "Sparkle"

angus
Posts: 128
Joined: Wed May 03, 2006 7:03 pm
Location: Aberuthven (just south of Perth)

Re: National 12 Mast lengths

Post by angus » Fri May 03, 2013 3:26 pm

Steve it sounds like your new mast has come off a double bottomed boat for there to be so much difference in mast length. A mast from a later single bottomed boat might be a few inches shorter but not so much to make it un useable with out extending.
N2153, N2969, Merlin Rocket 3484, Mini Sprint

Stephen Hawkins
Posts: 533
Joined: Wed Nov 04, 2009 11:41 am
Location: The much maligned Swindon Town

Re: National 12 Mast lengths

Post by Stephen Hawkins » Fri May 03, 2013 6:34 pm

I am afraid it was a bit of buyer beware. It was a spare second mast that came with a crusader, which is a single bottomed N12 - or at least it looked like it.

But is was new to the owner, who had just bought the boat and thought the spare mast was surplus to requirements.

So it went up for sale.

I have been looking out for one of these for some time, so jumped at the chance, only to regret my haste.

Rupert might come to the rescue this weekend. If not Tony. And I can always offer it back up for sale if I cannot get this sorted.
Steve Hawkins

1967 National 12 2383 "Sparkle"

Spiderman
Posts: 221
Joined: Mon Feb 28, 2011 8:25 pm

Re: National 12 Mast lengths

Post by Spiderman » Fri May 03, 2013 8:28 pm

Hi Stephen,
I may have a section of Proctor C about 7 ft long that was originally the bottom of a mast that was broken further up. I was planning to make a boom out of it, but that plan has been superceded so it is effectively surplus. Let me know if you are interested and if so I am to the West of Oxford if you want to collect it sometime.
Regards
Ian M

Stephen Hawkins
Posts: 533
Joined: Wed Nov 04, 2009 11:41 am
Location: The much maligned Swindon Town

Re: National 12 Mast lengths

Post by Stephen Hawkins » Sun May 05, 2013 7:30 am

Thanks for the offer Ian, I might take you up on it if other avenues prove to be dead ends.

Cheers

Steve H
Steve Hawkins

1967 National 12 2383 "Sparkle"

Stephen Hawkins
Posts: 533
Joined: Wed Nov 04, 2009 11:41 am
Location: The much maligned Swindon Town

Re: National 12 Mast lengths

Post by Stephen Hawkins » Sat Jun 01, 2013 9:50 pm

Well,

Rupert did come to the rescue with an abandoned Lark. The mast was a much later C section with spreaders.

I had to mount the shrouds using the chain plates off the Lark as the Lark shrouds were of a peculiar fit and miles too short.

The goose neck had to be moved up by 7cm as well.

The spreaders are mounted lower than is normal for an N12 (20cm), right on the c of g of the mast, but unless told otherwise, that is where they will stay.

Sailed her today, with Chris, at SCSC. All seems well.

So what are the rules when setting up spreaders? From first principles.......

Cheers

Steve H
Steve Hawkins

1967 National 12 2383 "Sparkle"

Sticky Fingers
Posts: 26
Joined: Tue Oct 12, 2010 9:57 am

Re: National 12 Mast lengths

Post by Sticky Fingers » Sun Jun 02, 2013 9:10 am

National 12 website tuning guide has a wealth of information. They are having their vintage champs end of June why not go along chat to the other helmsman about their boats. Howard chadwick has a starfish design and is very quick.,Martin

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