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9th January 2008 12:02 AM
rethanaish
Thank you !!

Expander, very good analysis !!
7th January 2008 05:32 PM
Expander --

Some times ago in Neil Pryde Windsurfing Forum I made a brief analysis about a severe design fault in a 2005 NP UXT aluminium extension.

At that time I used this kind of extension for my racing sails (from 10 to 12); as everybody knows, down-haul tension is formidable in these sails (maybe over 600 kgs) and this factor should force any serious racer to buy aluminium extensions rather than carbon ones.

Anyway, NP UXT extensions was, at that time, a good choice, at least till 2005 series; in fact, as you can see from following photos, I was able to broke an UXT red (purple) series extension bought in 2005.




At a first sight, extension plastic base was broken inside aluminium tube, certainly due to extreme down-haul tension... at a more accurate sight, plastic base was broken at level of front inox rivet: or better, there was an evidence of an original old fissure that has been extended till structural collapse.

For this extension (2005 model), NP has placed two rivets, one in front side, the other on back; previous NP aluminium extension instead, always UXT series but bought in 2004 (yellow series), had a different rivets location: in 2004 series they were placed sideways when in 2005 series they were placed one frontally, the other in the back.




At a deeper analysis, what I've highlighted was how these rivets worked:




In 2004 (yellow) extension, rivets that were placed on side of aluminium tube, worked like they has been on a rotation axes, allowing main bending force to be distribuited on base plastic top collar; in 2005 (red) extension instead, rivets that were on front and back of aluminium tube, were directly subjected by bending force and shearing stress that caused their breakage or a direct damage of plastic base (with following break-down of base structure as shown above).

What I've highlighted was that in this extension, under high loads, both rivets worked under a not calculated shearing stress: how to explain all this ? Evidently, like a design fault.

Now I want to make some consideration: NP makes a lot of very good products like, for example, X9 booms and, of course, their beautiful sails... however other products are less good like, for example, X9 masts (the damnation of all RS5-RS6 sailors), X6 booms (a boom with a ridiculous stiffness), old carbon and alu extensions, etc...

But now I have to admit the truth: new MXT alu extension is a very good product, heavy duty, with a formidable pulleys system and a long life Dynema rope, really designed taking care of lesson from previous errors in extensions production (see above)... I've bought this extension in 48 and 34 cm sizes using them from large Formula sails till small Slalom ones (from 11 to 7 m) and till now I had no problems.

So, I have to render unto Caesar that which is Caesar's: sometimes NP cocks things up but, with MXT extension, they have made a good product.


- Expander.
6th January 2008 08:40 PM
rethanaish I have the same problem with my X6 boom(2005), i hope its only the plastic tube....
18th June 2007 07:16 PM
Guest
RE: Neil Pryde MXT power base & mxt mast extn??

It's on the home page of Neil Pryde
18th June 2007 06:09 PM
Guest
RE: Neil Pryde MXT power base & mxt mast extn??

Hi there
Can you please explain to me what's the problem with the MXT??? I have one , Ihavent't use it yet, I cannot find any feed back about the problem!!!!

Thanks

Gab
18th June 2007 01:28 PM
Guest
RE: Neil Pryde MXT power base & mxt mast extn??

I have an X3 boom(2005, the monocoque construction) where the hard plastic tube under the clamp on front end, holding it in place, have developed many cracks to the extent where it looks as if it is going to disintegrate!!! Anyone who knows more about this or other problems with the X3-X6 booms from 2005 onwards?
John
8th May 2007 05:34 PM
kingo
RE: Neil Pryde MXT power base & mxt mast extn??

Just spoken with my local shop.There has been a re-call on all the ones that
have been re-called before.So if you have already had a replacement better
return trhat one too
Also there has been a re-call on all X-tenders with x9 masts.eerrr they don't fit!!!:@Classic Neil Pryde.
8th May 2007 11:21 AM
Guest
RE: Neil Pryde MXT power base & mxt mast extn??

Try North. Way better.
8th May 2007 10:20 AM
Guest
RE: Neil Pryde MXT power base & mxt mast extn??

YEp, both my:@:@:@:@ friend and I have MXT and the base plate screws loose. It is a bit unnerving and I to are fed up with with crap NP matrix parts. The sails are good but the booms and masts and now extentions are nothing short of second rate. I own all NP kit but will now slowly dump it in favour of chinook or something better.
6th May 2007 02:48 PM
nifty
RE: Neil Pryde MXT power base & mxt mast extn??

Just great! I was thinking about getting one of those.:@
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