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Old 28th January 2009, 04:40 AM   #1
Crash
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Default What a difference a Mast Makes

Amazing difference changing a mast can make. I normally use a Gaastra Ignition 520 100% carbon mast on my Point 7 AC-2 9.7 meter sail with 15cm extension. This gives quite a flat profile with very little tolerance to extra downhaul and outhaul. The sail will also take a 490 mast with a 45cm extension. I rigged my Amex 75% carbon 490 and the sail was completely different much lower down power and a huge amount of adjustment on the outhaul.
This means the 520 mast is great in high wind conditions it really locks the sail down.
The 490 mast is proving a treat in light winds.

I use a Starboard 160 and find changing the fin as it blows really helps with high wind handling looks like there is another variable to take into account?

Yes I know the IMACs are differnt on these mast but is it best always to use the manufacturer’s mast and are there always big differences between brands?

Crash
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Old 28th January 2009, 05:31 AM   #2
wiindz
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Quote:
Originally Posted by Crash View Post
Amazing difference changing a mast can make. I normally use a Gaastra Ignition 520 100% carbon mast on my Point 7 AC-2 9.7 meter sail with 15cm extension. This gives quite a flat profile with very little tolerance to extra downhaul and outhaul. The sail will also take a 490 mast with a 45cm extension. I rigged my Amex 75% carbon 490 and the sail was completely different much lower down power and a huge amount of adjustment on the outhaul.
This means the 520 mast is great in high wind conditions it really locks the sail down.
The 490 mast is proving a treat in light winds.

I use a Starboard 160 and find changing the fin as it blows really helps with high wind handling looks like there is another variable to take into account?

Yes I know the IMACs are differnt on these mast but is it best always to use the manufacturer’s mast and are there always big differences between brands?

Crash
id imagine that it is merely the fact that the 490 is softer so it provides a sail tension that is a bit softer and so the sail can bend the mast more giving it more shape on those light wind days. but it sounds like you have it figured out, 490 for light wind, 520 for higher wind. fins however have always been a factor, the smaller the fin the more control in high winds. obviosly you dont want to go too small, otherwise you spin out, but you get my general idea.

small fin = good manuverability in high winds (if it has a good shape) but spins out in lighter conditions

big fin = better drive and points higher upwind in light winds (asuming that it also has a good shape) but overpowers you when the wind starts to crank and you are well powered up

by the way, a good fin can realy make a shity boad into allot of fun, while a shity fin can make the best board in the world a hassel to sail in any conditions
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Old 28th January 2009, 09:14 PM   #3
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doubt that its better because it is softer.
Sounds like it is better because the mast bend is different.
It sounds like the 490 mast is stiiffer in the bottom- more towards a constant Cirve/flex top type bend which means more low down fullness and adjustability of the outhaul .
It sounds like the gaastra mast is a stiff top/ soft bottom mast that makes the sail set too flat low down when downhauled sufficiently to release the upper sail area.
I would guess that the sail is cut for a more constant curve/flex top mast and that the gaastra mast is innapropriate for it.
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Old 29th January 2009, 01:35 AM   #4
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With the 490 and 45cm extension, you might watchful and cautious, as there's a good chance that you boom attachment point might be a bit outside the normally re-enforced area. Also, I think that it would be a good idea to use a shim to provide some mast protection.
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Old 29th January 2009, 04:37 AM   #5
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stevC has a pretty valid point, 45 cm is one hell of an extention, the flex point of the mast might be thrown off just from that, also, it will most likely be (as steveC said) out of the "boom zone" which is most likely re-enforced so a shim , in total agreement , would be a good idea
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Old 30th January 2009, 02:20 AM   #6
Crash
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Thanks for the information, I presumed that in order to get a mast with a reasonable bend characheristic the wall thickness would be the same with no reinforcement. With a good boom head with articulation I thought the stresses generated would have been well within the limits of the mast?

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Old 30th January 2009, 05:06 AM   #7
wiindz
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unless you are quite heavy and take a 9.7 out in 20knts+ you should be fine i think what is the recomended mast for this sail? because usualy a sail is designed around a specif mast and therefore will work the absolute best with that mast or an identical mast from a different make that still has the same characteristics as the one that your sail was designed around...
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Old 30th January 2009, 08:54 AM   #8
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Crash,

The downhaul requirements for a 9.7 are considerable, particularly with a race sail design. Given the boom lengths in that size range, especially in powerful gusts pushing the sail's limits, it puts a lot of stress on the boom/mast connection. In light wind at the lower end of the spectrum might be well within reason, but caution is always your best guide. On the safe side, no harm in adding some reasonable insurance (a shim) to buffer things a bit.
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Old 1st February 2009, 09:00 PM   #9
Crash
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As written on the sail "Ideal mast 520 Imacs 32 compatable mast 490 Imacs 29. The Gaastra Ignition mast is fantastically light 1.75 kilo but with a Imacs 34 is a bit to hard for the sail I think in normal conditions.
The lesson here I think is stick to the manufacturers masts that’s what the sails are developed around?
Thanks for the comments
Crash
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Old 2nd February 2009, 01:02 AM   #10
wiindz
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Quote:
Originally Posted by Crash View Post
As written on the sail "Ideal mast 520 Imacs 32 compatable mast 490 Imacs 29. The Gaastra Ignition mast is fantastically light 1.75 kilo but with a Imacs 34 is a bit to hard for the sail I think in normal conditions.
The lesson here I think is stick to the manufacturers masts that’s what the sails are developed around?
Thanks for the comments
Crash
well, yes and no... in ideal wind conditions absolutely yes, the recomended mast will work the best (or a mast with the same flex characteristics), but in less then ideal conditions a softer or stiffer mast may coax a little more range out of your sail, just be carefull not to go too soft or too stiff because a mast that is too soft may simply snap under the tension of a race sail and a mast that is too stiff may produce exesive tension on the sail body therefore shortening its life span and possibly ripping itin a "big" gust.. however a 490 is a second best mast so that should be fine and the 520 is only 2 Imacs stiffer and so shouldnt cause problems... would be interesting to have the ideal mast, and compare it to the two you already have though...
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