I understand you can go faster by keeping your board flat i.e. not digging in the windward rail or even slightly to leeward. Can manage this most of the time on a narrow board by forcing my feet to hold it this way but on a 75cm wide isonic?

Any help here

Point your toes, this helps take the weight of your heals and helps the leverage lifting against footstraps.


alternatively commit more weight to the harness and lighten up your feet

Wider boards like the iS have the back foot straps out wider as well to give leverage against the fin. It is not hard to keep the board flat because of this. Many boards and fin combinations actually benefit from being rolled slightly to le'ward. My theory is that it does a few things:
1. the bottom area in contact with the water is slightly reduced on the angle.
2. The rig can be raked back further which allows the front of the board to rise and reduce wetted area.
3. The fin produces a slight vertical lift component which also reduces wetted area.

Well....them's my theories anyhow..

what size fin,sail how much wind and how heavy are you lil jon?
r.hood

Select to expand quote

sailquik said...

Wider boards like the iS have the back foot straps out wider as well to give leverage against the fin. It is not hard to keep the board flat because of this. Many boards and fin combinations actually benefit from being rolled slightly to le'ward. My theory is that it does a few things:
1. the bottom area in contact with the water is slightly reduced on the angle.
2. The rig can be raked back further which allows the front of the board to rise and reduce wetted area.
3. The fin produces a slight vertical lift component which also reduces wetted area.

Well....them's my theories anyhow..

Sailquik's No.3 is the theory I also favour. And a bendy fin or one that's loose in the box enhances the effect.

Was talking to Tim from MI about this as I'd noticed the fins on MI are adjustable in lateral angle. He said this was indeed a trimable feature designed to take weight off the hull. They don't actually use much of the available adjustment - they don't want to risk the hulls getting too light.

Apart from the control issue, it's a smaller relative gain for MI to shift lift from the hull to the fins. MI has such a great righting moment that the required hull lift - ( and hence drag from this source) is a smaller fraction relative to fin lift than it is on a windsurfer. But they've thought about it - or to quote Tim "We've thought about everything"

Select to expand quote

snides8 said...

what size fin,sail how much wind and how heavy are you lil jon?
r.hood

It's a 122 litre isonic, 75cm wide with a 6.6m sail (I'm getting something bigger when I have the cash) and most of the time I use a 39 select weedie and sometimes a 44cm pointer. And I'm 71kg.

Select to expand quote

Little Jon said...

It's a 122 litre isonic, 75cm wide with a 6.6m sail (I'm getting something bigger when I have the cash) and most of the time I use a 39 select weedie and sometimes a 44cm pointer. And I'm 71kg.

I have a 105 Hypersonic which is 75 wide and I found my Lessacher 36 way too big when I tried it the other day. The 30cm Select weed still felt a little too big and I was using a 6.5 sail and I weigh about 73kg. I am sure the fin is restricting the top end speed a little.

Select to expand quote

Little Jon said...

snides8 said...

what size fin,sail how much wind and how heavy are you lil jon?
r.hood

It's a 122 litre isonic, 75cm wide with a 6.6m sail (I'm getting something bigger when I have the cash) and most of the time I use a 39 select weedie and sometimes a 44cm pointer. And I'm 71kg.

Lil John i think your problem may be that your sail is a bit small for the board along with you being on the light side.
A bigger sail would help in pining the board down and giving you some control back. Thats my 2cents

Cheers Bender

Select to expand quote

Little Jon said...

snides8 said...

what size fin,sail how much wind and how heavy are you lil jon?
r.hood

It's a 122 litre isonic, 75cm wide with a 6.6m sail (I'm getting something bigger when I have the cash) and most of the time I use a 39 select weedie and sometimes a 44cm pointer. And I'm 71kg.

Do you find it easier to trim lee side down with the 44cm fin Little Jon? I usually sail my 72 wide Fanatic falcon with a 38 but went out with a 42 yesterday it certainly trimmed a bit better. Maybe not as fast as a smaller fin but because it goes upwind so much better there's more chance of you being on a downwinder when the one big gust comes along and getting a better GPS max.

A longer fin has its lift centred lower down so should be more effective at holding up the windward rail.

The 6.6 is to small for the IS122, 7.5 and up would be the go to get the best performace out of the board.Also having a bigger fin is going to help triming the board.
Other than that just Practice

Thanks for the help