I have been looking at getting a maui 7.6m tr4 or tr5. I had a look on www.peterman.dk/masts-all-imcs01.htm
I am looking at using a gaastra 100 460 as a substitute for a maui srs 100 460. There are slight differences in the numbers. I was just interested, is there a significant difference in such a small jump in numbers, is it a linear scale or exponential?
Gaastra SDM 100 (bend curve error? 10,3 stated) 460.0 23.9 10.7 63.2 73.9
maui Sails SRS 100% 460 (20601046, X0012/10) 459.9 24.9 25,5 9.4 66.8 76.2
I am a lightweight sailor approx, 70-72 kg and in all honesty don't think it can make the massive difference everyone is going on about. ps the gaastra mast would save me $$$ from buying maui new.
I can't make out what all those numbers are.
You need two numbers for the comparison: IMCS stiffness (should be about 25) and bend curve % difference (Maui sail would like around 12%)
Because individual masts from different models and years can vary a lot, I would not trust the figures on the Peterman list to be anything like your mast. Best thing is to test it yourself.
The formula for the stiffness is a bit complicated (and not all that relevant as most masts go close to spec) but the bend curve is simple: Support mast 50mm in from each end - pull string real tight along top of mast- hang exactly 30 kg weight on center of mast - measure deflection in mm at half point and points exactly between half and support points. Calculate top and bottom deflection as % of center deflection. The difference between top and bottom deflection as % is what you want. (ie 12% more deflection at the top is considered a standard constant curve mast.)
see: www.peterman.dk/mast-imcs-formulas.htm
I would rig it and see, the differences here seem very slight to me! more important on a race sail might be that the diameter around the batterns is similar so you get good rotation and the cam do not create a nasty wrinkle in the pocket.
Andrew, the figures are Length,IMCS Stiffness, IMCS bend curve, Base bend %,Tip Bend %
The Gaastra looks a bit softer overall, and a touch closer to true Constant curve which is 64%-76%. The Maui mast is overall slightly more "stiff top" than the Gaastra but the base/tip bend % indicates that it's bend "character" is a bit stiffer at the midpoint and bending a bit more base and tip relative to what the Gaastra mast is.
Steller, The differences don't appear dramatic, I would have thought it was in the ball park, but trying it is always best.
If you are unsure post on the "ask barry" section of the Maui website he is definitely the man to answer this question..
Hi Steller,
here are the dims for some of my 460 masts.
May 07 Gaastra Ign 460/10.8/16.9/12.6/63.9/74.5/10.65/26.6
May 07 Maui SRS 460/12.2/18.7/14.4/65.2/77.0/11.76/24.07
Jan 08 Maui SRS 460/12.2/18.5/14.0/65.9/75.6/9.72 /24.17 (459 long)
Numbers are; length/cm deflection at 25%/50%/75%/bottom flex %/top flex%/IMCS Bend characteristic/IMCS Rating
IMCS Bend Character 7-9 is hard top/constant curve, 10-12 is constant curve
13-15 constant/flex top,
These three feel pretty much the same and rig similar in my 7.0s (TR1 and 3) even though there's quite a difference with the Gaastra.
I've measured a lot of masts and it's surprising what you can make out of bits and pieces!
