Changing the flex of a NP mast?

A few years ago as a total newbie I wanted a big rig to get out in the lighter stuff.
So I saved my pennies together, bought a 8.4m KA Kontrol (no cam), a new boom and NP X9 490 mast. I shopped around to get the best deal on these new items.

Well as a newbie I thought that if the IMCS matched on the sail and mast - these 2 components would be well suited. sweet?

After a while of never being able to rig this setup right a guy at green point (who has heaps of NP gear) said that these mast's were "flex top".

When I downhaul to the recommended sail setting the top 3rd of the sail is super floppy while down low the battens are very difficult to rotate.

Has anyone ever "modified" a Mast to change its stiffness/flex properties??

Im thinking of wrapping the top section of the mast with carbon uni's (in line with the length) then followed by another layer of plain weave carbon. All using epoxy.

Has anyone tried this and how did it go?

This is not meant to be a NP bashing session (i like most of their other gear) however I think that the IMCS system needs some work.

any ideas?

This might shed some light on the subject

www.peterman.dk/windsurf-NP-X6-mast-study-780gb.htm

I'm currently using a NP X6 mast in a KA Koyote 5.3 which appear to rig and perform really well together so it's not necessarily true that 'NP masts only work with NP sails' which some would think is gospel!

Not sure how old the KA Kontrol is but I've been informed that newer KA masts are more flex-top than earlier ones which may indicate that earlier KA sails would suit a less flex-top mast better (i.e. lower bend curve rating).

I think Mr Love from KA would be the best person to comment on compatibility of Kontrol with X9 mast (over to you Martin!).



IMCS stiffness rating is different to the bend curve rating (i.e. flex-top, stiff-top, etc) which I don't think has ever been quoted by the major sailmakers (KA advise of the ideal mast bend curve for their sails) and both will have an effect on how the sail rigs and performs on a particular mast. Also, NP masts do appear to vary a lot in their bend curve, refer to following example from Boards mag 460 mast test specs (if you can trust these figures):

Thanks for the info Bender and Gazman, the German mast site is pretty informative.
The variation between brands is eye opening - my biggest lesson is to definitely try to rig the mast/sail combo before giving away any $$cash. Buyer beware!

Mr Love - It would be great if you could get the recommended mast for the 2006-7(Kontrol), to have help from a local rep is awesome.

If manufacturers published their curve stats there would be no mystery about it at all.

Yeah, thanks heaps Bender, have seen other Peterman mast info before which I could really relate to but your link (which I had not seen before) really opened my eyes to the possibilities and issues (considering I have been cross-fitting the wrong halves of X6 400/430 masts for some time now!).

Hey latedropeddy,

May be reasonably easy fix according to Peterman.dk X6 cross-fit study courtesy of Bender.

If it's an 06 8.4 KA Kontrol with luff of 503cm (rec mast 490/29) and you found an X6 460 base to use with X6 490 top, according to Peterman specs you would end up with a luff of almost 474cm (would need 29cm extension to fit sail) and the mast bend curve would drop from 15.2 (spec for X6 490) to around 12.5 (approx spec for X6 460/490 combo with 30cm ext). This may make the combo mast much more suitable for the Kontrol depending on Mr Love's (and AMAC's) response. Also, IMCS stiffness of X6 460/490 combo with 29cm extension would only be approx 1 IMCS point less (stiffness of approx IMCS 28 according to Peterman specs when using 30cm extension with either 460 or 490 mast).

This all assumes that all X6 masts in their respective sizes have the same bend curve and stiffness (what's the chance of that?).

Definately worth a try though I reckon if you can find a good X6 460 mast.

latedropeddy, It sounds like you are in Melb? if you would like to send me a PM we could organise a time to rig the sail up and take a look? and try a couple of different masts.
Regards Martin