I had a run on a slalom board for the first time in about 20 years a couple of weeks ago, having only sailed on wave gear for years. I'd forgotten how much quicker slalom gear is, and how much fun it is to just go stupid fast and do long floaty jumps! Anyhoo, it got me digging around in the back of the shed. Founds some mid 90s vintage North Prisma cambered race sails and Spectro freerides that haven't seen daylight for decades, are still in pretty good nick, and might put a smile on the dial. Thing is I broke the masts I had for them and never got around to replacing as I've been sailing wave gear since.
They took what North called a constant flex base and constant flex->flex top top, IMCS 27-29, from memory they could all rig on a 460. I've tried putting an IMCS 19 CC top from a 400 on the base from an IMCS 25 CC 460 but that's pretty average - too much extension and too soft up top. Straight up 460 CC IMCS 25 also looks pretty grim, need something more toward a flex top. They're old sails, I don't want to spend a heap just to give them a go - anyone in Vic got something lying around that'd do the job?
Hi Pete I had the '1995-6 Prisma 6.3 and 7.0 Spectro ,loved those sails
i did have a north mast 460,25 ,75% ,I broke that then ,moved to a 75 % flying objects that was more of a
flex top ,both worked well .crank the prisma right down and don't drop it in the water ,the luff pocket was so heavy when full of water .enjoy the slalom buzz ,
Thanks Tardy. Yeah, I remember trying to waterstart the Prismas once the luff tube filled up being a bit of hard work! Legs going round like a bloody eggbeater to lift the tip and drain it 
They weren't bad for their day though. I remember broad reaching on a 6.5 in WA for what seemed like a lifetime, and the sail wasn't the limiting factor, it was the bollocks required to hold the thing down in 30+ knots on a square railed slalom board that was doing it's best to kill me.
Looking at how it flops around on a CC it certainly needs something flex top, not sure how that maps on to say Unifiber FL/FH curves. Not inclined to spend hard earned on a new mast just for old sails though - not much around these days seems to use flex top - so they may just go back in dark recesses of the shed until an archeological dig unearths something suitable somewhere.
Neil pryde use flex top. might give that a try. simmer and hot sails are constant curve flex top.
I had prismas around that era too. Not sure if I used the right masts. 
really well built sails. Didn't fall apart like pryde. 
You could try mis-matching sizes. It won't be perfect but a 460 base and a 430 top of the same brand will give you a 445 flex-top of sorts.
Select to expand quoteAwalkspoiled said..
You could try mis-matching sizes. It won't be perfect but a 460 base and a 430 top of the same brand will give you a 445 flex-top of sorts.
Yes, did this for a NP sail and it worked well. Leech fell off properly at last. I wouldn't call it mis-matching as much as mixing. Ezzy recommends this as the primary mast for a number of their sails and sells individual mast sections to accommodate this.
Select to expand quoteAwalkspoiled said..
You could try mis-matching sizes. It won't be perfect but a 460 base and a 430 top of the same brand will give you a 445 flex-top of sorts.
Yeah, I've been hunting around for a 430 same as my 400 and 460 - the 400 top is too soft and short - but they're all hiding under people's houses these days.
