Updates to 2004 tuning guide for 2003 hull ?

Sail trim, rig tuning, and related topics.

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tkoetje
Posts: 20
Joined: Wed May 13, 2015 6:02 pm

Updates to 2004 tuning guide for 2003 hull ?

Post by tkoetje »

I have hull 34, a 2003 North American build and have finally set the mast base up as per the north 2004 tuning guide, i.e. 480 mm behind the bulkhead. I cannot shift it forward any more without pulling it and re drilling / tapping bolt holes in the mast step. Otherwise, my mast rake (headstay length) and etc. are within a 1/4 inch of correct. Has anyone with an older hull gone with a mast base at 460mm ? is it worth the effort ? Are the bulkheads in the same relative positions in the boats, or did things change over the course of the builds ?

I've not raced with the new set up yet so its not clear what impact it will have. real soon now though.
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Vento Solare
Posts: 382
Joined: Wed Dec 31, 1969 8:00 pm
Location: Newport, RI

Re: Updates to 2004 tuning guide for 2003 hull ?

Post by Vento Solare »

Your mast position and inability to reach the desired end point is a common J/109 condition. See this procedure I posted a few years back in Tipe & Tuning section.

I'm using North Sails and was told it was close enough without redrilling.
tkoetje
Posts: 20
Joined: Wed May 13, 2015 6:02 pm

Re: Updates to 2004 tuning guide for 2003 hull ?

Post by tkoetje »

I saw that, thanks, mostly just wondered if there was any difference for the older hulls.
Bengt J
Posts: 54
Joined: Tue Oct 25, 2016 2:36 pm

Re: Updates to 2004 tuning guide for 2003 hull ?

Post by Bengt J »

On Zig Zag, hull #37, the mast butt is all the way forward at 464 mm, rake at 2252 mm(swing arc), J at 4072 mm. This setting works very well with our Quantum sails.
TPI the builder of US boats was never known for accuracy, variations of up to plus/minus 0.5" to be expected. Still boats of different age are very evenly matched for speed and point, crew work and tactics makes the biggest difference.
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