Hey - any views around rider weight ignoring minor differences in the weight of boards and kit? The dude I sail with has almost exactly the same set up, right down to the same board. The biggest difference is that I'm 10kg to 15kg heavier which has a very large effect on the water. On the same size sail I get dusted on to the plane every time (obvious). However in light conditions I can spend the majority of the time slogging and he the majority of the time planing without too much skill difference (I'm probably not as good technically but doesn't explain massive difference). I reckon I'd need a sail 1.0m bigger to try and match up - I.e. his 7.5 would mean 8.5 for me to plane at the same time albeit I'd then be faster planing due to extra sail size and weight to apply as fin pressure. Can anyone else draw a comparison 
???
I know what ya mean ..sail with 2 guys 15- 20 kg lighter .75 &80 kg vs 95 kg when they are on a 7.0 ,I use a 8.0
ocean sailing ,them 6.5 me 7.0 .
them 115 &120 litre me 125 litre .
hope this helps .we use the same size fins ? 42
,I smoke em on my 125 tabou rocket .when I rig it right .you should be as fast ,you just need slightly bigger .
"size matters" 
simple example: look @ the KONA races
EVERYONE has the same board
sail size you are allowed to use depends on your weight
trying to make it an even playing field
analyse wind n water and choose YOUR sail size
(sometimes more kilos require more litres too)
in REALLY light wind there is often kite foiler with 20 meter kite and me on Mistral Equipe 2 XR carbon longboard with 8 or 10 meter sail - and NO ONE else
i am over 100 kilos
this one showing how weight affects sail size choice is from wikipedia:
Sail size and board size scale directly proportional to rider weight. Fin size goes up, too, but less so. In other words, if you an your lighter buddy are on the same gear, with only your sail size a meter larger, you're still at a disadvantage.
One example: I'm about 25-30% (20 kg) heavier than my wife. She's usually on 90 l, I am on 110. When she's on 4.0, I'll be on 5.0; if she's on 5.0, I'll be on a 6.5 and have a slight advantage in the lulls. Our skills are very similar, and we sail together more than 100 days a year in all kinds of conditions.
Select to expand quoteboardsurfr said..
..... Our skills are very similar, and we sail together more than 100 days a year in all kinds of conditions.
Anyone NOT envious? 
Select to expand quotejoe windsurf said..
"size matters"
simple example: look @ the KONA races
EVERYONE has the same board
sail size you are allowed to use depends on your weight
trying to make it an even playing field
analyse wind n water and choose YOUR sail size
(sometimes more kilos require more litres too)
in REALLY light wind there is often kite foiler with 20 meter kite and me on Mistral Equipe 2 XR carbon longboard with 8 or 10 meter sail - and NO ONE else
i am over 100 kilos
this one showing how weight affects sail size choice is from wikipedia:
Must be a nice consistent wind speed ..e.g - 13kts says I'll need a 7m. Bit optimistic and probably for very good sailors on slalom gear.
My friend Dave " frothie" Rogers is about 6ft 4....and about 150kg
He took up windsurfing about 3yrs ago.....
He is killing it.....treats a 10m sail like its a 7m and rides a massive 240l custom carbon art, it is fairly narrow at about 80cm....
His gone from beginner to immediate and is trimming well and drawing decent lines.....
He is flying......such mass needs to create massive lift....but then as he trims better with practice that massive force in lift he creates is great potential for speed
He is close to doing the same speeds as everyone else even though his on massive gear.....
We also got a mini frothie in big Gareth. ..his killing it too
He uses widish slalom boards with twin fin deltas...
