Hi guys, I have a newbie question. I have a NeilPryde 430 75% carbon, probably 4/5 years old. I got two of them for a silly price (less than 100 bucks).
I have an Ezzy Freeride 5 2011 5.5 mt which requires an RDM 430 with a downhaul of 440 at max. If I try to downhaul my SDM to 440, the Ezzy doesn't get the right shape yet. I notice that I should go down to 446 or 448. Unfortunately with one of these old SDM, I downhauled to 442 and it broken! 
The second one went down to 446 but I believe it is not enough yet, the battens are still behind the mast and the curve of the sail is not tight to the mast yet.
Now I am scared with the second one so I am wondering to know, what should be the maxim luff for a 430 SDM 75%? The model is a C75, which is not available anymore in NeilPryde catalog.
Just wondering, as anyway, I ordered already an RDM Ezzy 430, but in the meantime, here is blowing between 20-25 in these days and I wanna get out in the water! 
Be glad that mast broke when it did -- not when you're a long way offshore!
There's no way you should be able to break a mast by downhauling it (by hand anyway). The stresses when sailing are far greater than the stresses when downhauling...
So downhaul the living daylights out of your other mast, and if it breaks then be glad you didn't sail with it
That said, the way you know how much downhaul to put on is by looking at the leech, not the luff.
Most out your problem is an Ezzy on Neil Pryde mast which probably has completely wrong bend curve.
But clarify what you mean by "battens are still behind the mast"?
Ezzys are very rotational - that is, the battens sit next to the mast (like they overlap the mast) whereas many sails have the battens sitting behind the mast (on the trailing edge of the mast)
If by "behind the mast" you mean when you are rigging you can't see the batten ends as they are under the mast, then that is correct for an Ezzy
Ooops got my RAFs the wrong way around 
right u are Nebbs (have my tail between my legs and heading for the corner 
)
But I think you were lucky if a NP mast worked in an Ezzy though as only some NP's are constant curve in the 12-14 range, most are not.
Can't find it now but when I saw a table (not on the Peterman.dk site, elsewhere) the older CK75 masts were pretty damn flextop (18-19 range)
Thank you Mark for the explanation.
Yes, I do have a CK75 so I believe, for now, until I get a 430 Ezzy RDM I will have to 'adapt' to this wrong setup, which is better than nothing.
It's important to me to understand that by down hauling 10 cm more a mast it shouldn't break. I believe that one was pretty in bad conditions.
No downhauling a mast will not break it. It was just old and unfortunately that happens. Or put another way, it is not the sail/mast combination that broke it.
Thank you Mark, this is exactly what I was looking for.
So now I have an additional question:
Why the hell I can't downhaul more than 442 my 430? If I try it is so hard that I barely downhaul it an additional centimeter.
Is there any trick?
