I am no expert but in my opinion is just a matter of scaling up the volume of the board and sail size.

Volume is easy to scale (1Kg about 1L), but I am not so sure how to precisely scale sail size since it is probably non-linear. There is a web-site that does  that http://videojibe.com/featured/windsurfi … alculator/ and you can put in two sailors and play around.

Anyway, point is that as long as you are using equivalent weight-adjusted equipment (board/sail) I think that it is then a matter of preference, e.g. "grunt" vs "soft".

and what is that !!!?!!!

I don,t agree completely with that.
Some sails are that soft and undertensioned that they don,t support a heavier weight. For example: the DD. When i pump it, i almost tear it apart ( my girlfriend ,62kg, bought one i was just curious how it felt).
Besides that, there is a limit of what you can upscale. When a light person sails a 6.0 you can grab a ???
I know that Dolf will throw in his 9.0, but not many people like to wavesail on a 70+wide "waveboard".
So in my opinion a heavyweight have a lot of bennefit with power wavesails from 5.5+.
With smaller sizes upsizing works great for my 88kg

Complex question in disguise as a simple one.

Big people need more power than little ones, and yes you can get it with draft and high lift sails, or with more surface area lower lift sails (defining lift = power/surface area).

Bigger person, bigger board, more drag to overcome, needs more lift. Simple so far.

But sails have a range of power (underpowered, in/near the designed power zone, overpowered, WAY overpowered). They don't all handle it the same, and don't all transition from one sub-range to the next smoothly.

I was out last week, without my usual kit but a brand new board (JP FSW 101), and an ancient NP XS Wave 4.7 in 25-35 kt winds. This is a deep draft, 1992-ish vintage sail but in good condition, fabulous sail in it's "zone", but that's 18-25 not 25-35. It's also hard on/off. I was really wishing for my Freaks (I've even used my 5.5 UL in such winds and had a great go of it) because I was getting stomped. Over-finned, over-boarded, over-sailed, getting punished. Same conditions on day 2 and I passed.

But I am fundamentally a long-distance runner type, slow-twitch fibers, sail all day long, and thrive with the smoothness of the Freak. Other sailors more endowed with fast-twitch, quicker reaction times, etc., might well be more naturally suited to the power development curve of deeper draft sails.

So it's not only match the sail to the conditions, it's match the sail to the physiology of the rider. If you've got gear that is powerful and instant-on, but you're more accustomed to gentleness, my advice would be to sail it for what it was built for as best you can. Some gear rewards aggressiveness, and on that stuff you're not gonna fare that well unless you ride it that way.

The Freak, however, is a 100% finesse sail designed for smoothness and impeccable technique. In the long run, I don't think you're gonna sail into your 70s and 80s and 90s unless you switch to such gear. In general, Time favors the softness of the Freak; Youth favors the lightness and colorful gaiety of the Freak; Femininity favors the light gentleness of the Freak. Some of it is mass, some of it is the rate at which it develops power, some is how easily it luffs, some is lightness, some of it is power/surface area; a LOT of it is the aptitudes, passion for specific conditions, and muscle contraction characteristics of the sailor.

It is NOT the sail for everyone; it's not for most nu-skool freestylists, not for lots of wave sailors, not for speed sailors, not for slalom/racers, not for those who's physiology matches up with rapid on-off power. But IMO it is the most versatile, best bang for the buck, most durable, all-around best sail on the market. No contest. If you only have ONE, I'd pick a 4.7 or 5.3 - good for teaching, good for pretty windy days, good for longboard / SUP riding.

I think you've spotted my situation here, I turn 50 in a few weeks and much as I may wish to deny it my reaction times really aren't quite as they were. I pretty much only wave sail and in intense stormy Atlantic beach break conditions at that. Having recently returned from a couple of weeks in the relative effortless ease of Baja I've become motivated to explore a change in approach at home.

There is a definite appeal to instant grunt for sure at times but is it really the best approach for the ageing heavy weight? I don't plan on retiring to flat water any time soon...

I especially like the 'impeccable technique' you supposedly need to have to appreciate the superfreak...
Now i know why i love them so much

Heila' Cammar,  I must be the exception!   I actually think that the GPS and the SuperFreak make the perfect combo: buttery smooth in very different ways (how's that for a strange take on sails? )

Thanks for mentioning that, but overall I think I still own him that cappuccino...

Stay tuned on my blog, 'cause I have a paddle test post coming up. Don't go any bigger than 8.5 inches width blade...
No, wait a moment: 90kg? Mmm... how would I throw that in the equation...?

Ha ha....

Meanwhile on the topic of rider weight, hard on's and flaccidity...

So heavy guy hangs off boom, sail twists, mast bends, de-power occurs and as Jeroen said on a DD this can be a problem. Is there any cut off weight or point when a soft Freaky type sail will always be twisting off excessively in response to the gorilla hanging on the boom and thus not really work that efficiently at all?

I'm just curious because I'd like to understand my sails better, is there a stage where setting the sail fuller with less downhaul simply won't cut it? Do you and indeed can you design sails to work equally well for a 50 to 100+kg rider or is the testing all done with the average 70-80 kg type and the rest left mostly to chance?

True.
I can,t judge a lightpersons sail, and i think thats the very same for lioghtpersons and heavy guys sails.
A pal of my 65-70kg used to sail a Search 5.4, liked it a lot till he tried a Combat..better handeling, power he could manage, control and all of these even on a Pryde just because he found a sail suiting his weight.

You know Jeff one of the things that has drawn me to your sails and this forum is your honest open approach, I can't imagine it's bad for business at all.

I do have three boards and a 5.3 probably covers 70% of my days which is why I chose that size for starters. I'll still want a bunch of other sizes regardless to how often I use them ~ just to be prepared.

Next time out I may try a grey 430 top on my NoLimitz sumo 400 bottom and see the difference.