SJB1 said...

I've got a 5.3 Severne Blade that has a 435 luff. Reccomended mast is a 400. To me 35cm of extension is too much....I think it may explain a recent carbon extension failure towards the base. Considering mixing my 430 and 400 PowerEx skinnies for a better fit. Should I use 400 base and 430 top or vs verse? Thanks

I mix my Ezzy 460 and 400 to make a 430, if you want more flex/loose leech in top of sail/mast, then use the longer top, or vice-versa

Not sure why, but using the shorter bottom section works better than using the shorter top section.

430 bottom , 400 top will give a flexier top , stiffer bottom combo . The sail will set fuller down low with a tight lower leech and looser in the head , more like a race sail.
The opposite will mean the mast bends more down low flattening the sail down low . The upper leech will not twist as much so you will find yourself downhauling more to get upper leech twist . As the Blade has a lot of preshape down low this may be the better combo for you .
It is also going to depend on how the Powerex bend curve compares to the Severne RDM bend curve which is what the sail is designed around . I think they are quite similar, but there will be some difference . This will have a bearing on which combo works best .
The only way to find out is try !!!
Regards Martin

G247,
I just looked on the wbe site myself...you're right...430 is recommended. That's interesting beacuse a very well known person that sails on Severnes reccommended 400.