Although I'm not familiar with your exact boards, 130ish and 7s are good sizes for this stage of your sailing. I weigh in around 92-94 kg so should be similar. I'm assuming this is for mainly flat water judging by your gear choice.

Your wind range of 10-25 knots is quite broad so I'll break that down into some bands -
18-25kts - use the 7.0
14-18kts - use the 7.7
under 13 knots you're going to need at least 8sqm and be prepared to work quite hard to get on the plane. It can be done with a 7.7 but you'll be slogging a lot.

Choosing a fin for the conditions rules of thumb:
Bigger fin means you can push harder on it before you start planing. Once you are moving and get close to planing, it will generate more lift and get you onto the plane faster. However, once you are planing it is still creating more lift and more lateral resistance which makes controlling the board harder.
- A bigger fin allows you to have a bigger sail
- When your fin is a bit undersized, you'll struggle to get on the plane but once on the plane the board should feel ok. Steering more downwind to get planing can help here.
- When your fin is really too small, you'll start to spin out once on the plane when a bigger gust comes though.
- When your fin is a bit too big, you'll get on the plane, but in the bigger gusts the board will start to get a bit bouncy and in extreme cases you'll start "tailwalking".
- When your fin is really too big for the board, the board will start to "rail up" or feel like it wants to roll over. You'll know because your ankles will start hurting trying to keep the board flat. If your straps are in the furthest out position and this is happening, you have too much fin.

I don't think you need a bigger fin with your current set of boards and sails, The 82/83cm board widths should allow you to sail with the 48cm straight fin most of the time, unless you feel like the board is getting bouncy or railing up in higher winds, then change onto the smaller one. Bigger fin is going to make the board harder to control once you are on the plane. You should work on bearing off and pumping the sail to get onto the plane. 48cm should be enough to take up to 8.5sqm sails easily before you need more fin.

Keeping on the plane - When you are already planing, and then dropping off the plane, it is usually down to not enough sail to keep pulling you forward for the amount of wind. You need more sail or more consistent wind to keep on the plane.

Buying gear is not going to solve gusty wind, you either rig for the gusts or the lulls.

gregob said..

Do you think it matters much what type of fin I am using or is it really just the size in general until I am sailing faster?

I'm no fin expert, but for what you're doing now, straight to a slightly swept back fin would probably be good. The more swept back the fin, you typically get a little more area to push against for the same vertical length and it also mean that the "centre" of your fin is further back.
I think the effect of that is you can push a little harder on the fin at low speeds, and you can take a shorter fin to get a "looser" feel with your board. That's good for going over swell/chop and making it easier to tilt/steer the board with your feet. I also think the swept fin clears cavitation a little quicker if you're doing chop hops or sailing in choppy water - but that could be my imagination

To give you an example - I have 2x 32cm fins, one is very straight and the other is very swept back. The swept fin feels more like a 34cm straight fin.

...and now all the fin gurus can start roasting me over a medium flame

The ideal sail range for the Naish is 7.0 - 8.8
The ideal sail range for the Exocet is listed as 7.8 - 10m
The two sails you have are not making the best of the wind range your boards offer. In fact the 7.0 is too small for the Exocet.

Both boards are 82cm wide.
The Select fin selector recommends a 44cm fin for a 7.2 sail (range 40 - 46) and a 46 fin for a 7.8 sail (range 42-48) for a board of that width.
The freeride (swept back) fin is easier to gybe and gives more control.
An upright fin gives more lift and speed.

Choose a longer fin if you have difficulty getting planing
The board tends to slide to leeward
It is hard to push against the fin without it spinning out
You feel the board is sticking to the water

Choose a shorter fin if the board keeps wanting to go to windward
The board lifts out of the water and tail walks
It is hard to keep the board level and you get sore shins
Hard to initiate and control the gybe

Windxtasy said..

The ideal sail range for the Naish is 7.0 - 8.8
The ideal sail range for the Exocet is listed as 7.8 - 10m
The two sails you have are not making the best of the wind range your boards offer. In fact the 7.0 is too small for the Exocet.

Both boards are 82cm wide.
The Select fin selector recommends a 44cm fin for a 7.2 sail (range 40 - 46) and a 46 fin for a 7.8 sail (range 42-48) for a board of that width.
The freeride (swept back) fin is easier to gybe and gives more control.
An upright fin gives more lift and speed.

Choose a longer fin if you have difficulty getting planing
The board tends to slide to leeward
It is hard to push against the fin without it spinning out
You feel the board is sticking to the water

Choose a shorter fin if the board keeps wanting to go to windward
The board lifts out of the water and tail walks
It is hard to keep the board level and you get sore shins
Hard to initiate and control the gybe

That makes sense. I had a day two weeks ago in 25kts on the Naish with the 48cm and a 5.7 sail, and it kept jagging to windward everytime i tried to hook into the harness. Ahh I see now, Too much fin! I have a 38 cm Drake so I should try that in 25kts + I take it ?

I'll have to keep my eye out for an 8.5 mt NP sail :)

well there you go greg,

7.7/48cm for light winds, 6.7/36cm for stronger winds and 5.7 for nuking.

i'm of similar setup to sav911

I run a 125lt fsw and 4.7,5.3,5.8 wave sails. i'm in the process of getting the boom fixed for my 6.4 to get that back in action. fins 24cm and 32cm and I've just ordered a 36cm for the really light stuff.

the 4.7-5.8 sails and 125lt board cover everything from 15 knots up to 35 knots. over that I keep the 4.7 and use an 84lt board. the 6.4 gets me going in 12 knots. under 12 knots I put the 5.8 on the sup.

I've got slalom gear. an 8.5m, 11.5m sails, 42, 48, 70cm fins, 120lt slalom board etc but I just don't use them anymore. the end of the day it's horses for course. go big go small it can all get you planning and having fun. oh yeah i'vre got a 95lt wave board a that sits in the rack.

horse for courses at the end of the day.

kinda starting to think about a new slalom setup for something different again. probably based around a 7.8m sail and a 125lt board.