Jean-Marc I agree, the Agrelon, Ken and Mark H. deserve a Medal, and I hope SB appreciates the time & effort they put into advicing and sharing their great experiences with your products for newbies of low-wind windsurfing like myself. I'm impressed by details of Ken's and MarkH's responses - Ken's experience in sub-10 knts sailing, and Mark's excellent comparison of the iS144 and iS150.
No doubt that sub-6 knts windsurfing is a major challenge, yet for a guy like me that started windsurfing in 1979, and continued for 25Y as a short-board, sinker dude, coming up to a SUP has been quite a deja-vu from my haydays of Mistral Competition Epoxy (18 kgs masterpiece in '79), and my Division 2 racing in 81-82. Then everything about low wind dissappeared for these 3 decades until after a 5Y break I thought I should return into the Windsurfing ratrace. Yet, to get into shape I bought an SUP (11'9, 230L) from Naish, which actually got me into this whole exciting puzzles of Slalom and Low-wind gear.
The Naish SUP with a 8.5 Simmer 3XC can sail from app 2 -10 knts without a problem, yet its length and weight (have you remarked that no SUP manufacturer state "weight"?) make it a snail when it comes to planning. Love Ken's points on "pumping", cause coming on a SUP you really learn what the word means, as the surface is not easy to "unstick". As I sometimes sail a spot with swells, in no wind it's important to have some speed, so to get onboard and waveride (which is a LOT of fun). So SUPsailing in low-winds is fun in waves, while on flatwater not exactly exhilarating; not the way Ken described it as coming up 'n down. Maybe a better fin (=longer weed fin), would make the SUP come up to plane faster?
Above 12 knts the SUP even with its loooong, small pintail becomes a chop-smacking, "slamming door" type of experience with massive volume in the front-end to mid sections (like the Cobra boards of the mid 80's). I've sailed a Formula board once and it gave me a different feeling, yet the door effect was still there!
The difference btw the SUP and Windsurfing boards became very apparent as I switched from the SUP to sailing the RRD X-Fire 120L right after. It was such a transition of sensation of acceleration and sound - going from the bang-bang of a snail to the shwwww of a fast-moving racer - both on a well trimmed 8.5 Cambered sail with a 48 MFC fin. It was a trip and then I catapulted in a damn weed island!
What is also evident in your own marketing, is that light-weight is important in low-winds acceleration! I tried a Technora & WC Futura 122 in 7.5m2 (15 knts) winds last year in Egypt, and there was definitely a difference in acceleration and keeping the board on plane - ít felt like the "lightness" took you faster through lulls.
That's why I kept asking the question to you/Team on "Width versus Weight" for 2 boards (iS144-150) that are extremely close when sailed in 10-11m2 and around on avg. 2,5 Beauf. or 10 knots.
a) If I put a 11m2 Overdrive on a WC iS144 with a 6x cm fin, it's still a floater for me (as I'm 15 kgs lighter than Mark, yet my bad technique will make me follow his recoms). It will blast then from 10 knts.
b) The "heavier" iS150 Wood will be able to reach planning faster given its width (Ken mentioned: "only slightly"!), thus I can just as well go for a monster sail (12> m2) for 8-16 knots range of sailing. Yet we are not abs clear here!
Have you done any such weight to width comparisons? If WIDTH is more important than WEIGHT, then why did you launch a WC line at all? JP has a GOLD line with Carbon+Honeycomb, often >1-2 Kg lighter than their normal Wood cousins (e.g. JP Super Sport 74 V127 with Length: 250 cm /8'2" , Width: 74 cm /29.1", rec sails: 6.0-9.0m2 and Volume: 127 liters, comes in 3 variants GOLD: 6.6 kg/14.6 lbs, PRO/Same as SB's WC(?): 7.0 kg/15.4 lbs, and FWS/FULL WOOD SANDWICH/similar to EB Wood(?): 8.0 kg/17.6 lbs - all with variances of ±6%). If WIDTH as in the Formula boards is such an issue, why does everyone makes boards on the 120+ cm ranges - my suspiction is that they are not FUN to sail in "normal" = Choppy seas. So, can you please chip in in this final round - if Width is IT, then I'll go for it, and drop all pretenses of buyng a cool lighter board for lighter winds...
Non-team folks, thanks for all the given advice so far! Let SB then enlighten us on the Weight vrs Width issue (unless all of you gurus have done that too) ;-D