Select to expand quotesailquik said..N1GEL said..
This might be okay for waves sails, but certainly not for race sails. For example, I'm 85kg and there's no way I could get going in 22knts with a 5.2m sail. My slalom boards range from 87, 100, 115. I feel pretty comfortable using the following sails/boards in the indicated wind strength (and I'm a pretty average sailor):
18-24kts --> 8.0m --> 115ltr
22-27kts --> 7.3m --> 115ltr
25-30kts --> 6.6m --> 100ltr
27-33kts --> 6.0m --> 100ltr
30-35kts --> 5.5m --> 87ltr
35-45kts --> 5.0m --> 87ltr
This will change a bit, depending on whether the water is rough or flat, but generally this is pretty much what I use.
For me at 72 KG take off 1m and 15-20 Litres. 
Ok. I'm only intermediate but- these are for gusty winds)- 65kgs
5-15kts - 7.8m + 115ltre ( freemove)- won't plane till c 13kts consistent. The slalom gets going earlier as it weighs nothing but not much fun in chop.
12-18kts 7m + 89ltre
15-20kts 6.4m - 89( patchy) or 79 ( consistent)
20-25kt - 6m - 79ltre
25-30kts - 5m - 50ltre speedboard flatwater
Sail / board etc combo also depeneds on flat or choppy water. Big cammed sails can be a pain to uphaul and waterstart so I feel safer using them in shallow water.
Select to expand quoteN1GEL said..
This might be okay for waves sails, but certainly not for race sails. For example, I'm 85kg and there's no way I could get going in 22knts with a 5.2m sail. My slalom boards range from 87, 100, 115. I feel pretty comfortable using the following sails/boards in the indicated wind strength (and I'm a pretty average sailor):
18-24kts --> 8.0m --> 115ltr
22-27kts --> 7.3m --> 115ltr
25-30kts --> 6.6m --> 100ltr
27-33kts --> 6.0m --> 100ltr
30-35kts --> 5.5m --> 87ltr
35-45kts --> 5.0m --> 87ltr
This will change a bit, depending on whether the water is rough or flat, but generally this is pretty much what I use.
You either significantly overestimate the wind strength or you are one strong fella. For example, I'm 93kg, I use full slalom sails and I'm starting to get uncomfortable on my 7.9 and looking to rig my 7.1 in anything over 18kts.
^ +1
at over 100 kilos I use
20-40 kph (~10-20 knots) 8.0
30-50 kph (~15-25 knots) 7.0
which means @ about 20 knots it is a 7.0 m² sail
water gets a little choppy at this point and 80 cm wide boards have issues
use < 70 cm wide board(s)- Fanatic BEE 124 or even a Mistral Equipe I/one works well
find it incredible that Nigel uses 115 liter board with an 8-oh !!!
(sorry, forgot people don't like the OH )
guess it depends on width
this year i plan to use an 80 cm wide 120 liter board in 16 knots
with 8.4 cambered and 8.5 non-cambered sails
There is no real right or wrong re sail size. Use what works for you but keep an open mind. The op was after bigger sails to get going in lighter winds and these days most sails are fairly good. As you get more experience you can use bigger sails in strong winds and get going with smaller sails in light winds. But generally racers will use much bigger sails to make sure they keep going in the lulls. It also depends a lot on wind angle. Sure formula uses 12m sails in almost any wind and they go around a course so at first you would think you should be able to hang onto a 12m. But the formula guys only go upwind and downwind. They are impossible to reach, (in stronger winds anyway) way too much sail and way too much fin. Then you see the pwa guys hanging onto big sails on slalom races. They are mostly going lower than a reach and probably for about 4 minutes and absolutely have to be on the plane tthe whole time, not really the way us weekend sailors roll. Then a full cam sail is completely different to a wave sail. In 15knots on flat water i will be comfy with a reflex 9.7 whilst someone wave sailing in offshore conditions with a safe passage out and not wanting to jump but really nail the bottom turns on the way in might be on 5m or less, thats a sail half the size of the flat water guy for the same wind. Whatever you have got, rig it up and have fun.
Intresting topic 35 to 45 knots in Geraldton is basically close to unsailable in waves we be on 3.7 3.0 im 95kg would ride my heavier 85L round railed pin tail thruster with rocker but hey its mast high but still often reasonably smooth at the right locations its the apparent wind wipping up the faces and chops seas not swell sixe that turns everything into hard work holding a clean bottom turn rail wind strengh must differ from state to state ( and it can due to moisture content and topography etc etc Anyway flat water makes a big difference you can hold a bigger sails but 37 to 45 knots and a five hmmm want be super flat. At that stenght you want a 360 flexi mast 3.5 or smaller
Definitely depends where you are and what you are doing. Aa set the speed record in luderitz with a 5.4 and 50 plus knots of wind. And was putting it in a van to go upwind!
isnt 35knots a light breeze in geraldton 
Swell sailing 1 to 5m 0 to 12 knots 5.7 rotated around 2 thruster boards 110 L 100L 10 to17knts 5.5 rotated around boards mentioned 17 to 25 knts 5.0m roatated around 100L and 86 L pin tailed thruster 25 to 33 knts 4.7 86 L board 30 to 40 4.2 86L 35 42 knots seabrease ccasonally put up 3.7 but after a few hours at 30 to 40 gotta be able to keep the car on the road driving home hhhheee Anyway one thing i say to you brother is lighter the wind your board needs volume to carry the extra weight of your rig ,point being no matter how big your sail is if the boards is to small in volume you aint going anywhere / one last one is bigger sails become relient on the right masts and booms ie carbon
You sound as if your efficient enough to ride other crews equipment and see if to like it / keeping it simple a floaty 140 L and max 6.2 standard foil sail set spongy and full should get out on flat water / swell gernerates power redusing the need for big rigs just need a floaty floaty boatd to get out to them ,in any wind strenght to just turn around and ride in, slaye slash and gouge the beasts 
go da eye under over or make it bleeeed
