Carbon is a lot stiffer than G10, so yeah once you get past a certain length making a G10 fin is not worth it really.

Now I'd call that not even damaged really. The cracks are only in the outer resin gelcoat it appears. You get that just from flex in normal use.

Fill with a metal filled epoxy like JB Weld or Devcon plastic steel (use the 24hr cure versions not 5min) which you should be able to find at auto stores.
Then next day sand back with a 100 grade and then 240 and 400 wet n dry (wet sanding) and all done.

Phew that fin looks fine ...you should see some of mine ...light sand is all thats needed.
I use to do a bit of long boarding ...mistral equipe and mistral escape 11.3 foot by memory ...used a 38 , 40 ,42 ,
yes I think the fin is a good size if you use your centre board correctly .
to big a fin is hard to drive down wind .remember long boards have a lot of rail in the water .
hard to say 100 % unless I sail it ....but I think it's a good one .to start .

i always say if a fin is not scratched or scuffed, it has NOT been used....
some wear n tear is quite acceptable and yours is pretty close
as Mark suggests - epoxy does the job
i don't get quite as fancy as he does though - MarineTex or Marine Epoxy
also sand and often put some primer on for looks and to see where it needs more
here is a sample: more could be done on the one spot, but it is good to go


my Mistral Equipe One is a Euro/US type box and I would not put more than 12"/30 cm fin
the TWO version comes with a power box and the fin is a G10 for the CHS board and carbon for the XR model
the length of those fins is 38 cm and they are slalom fins - here is the G10



short wider boards use giant fins - over 50 cm to 70 cm - with giant sails > 8 m²
large freerides use fins in the 40s with large sails 7 - 8+
longboards ironically do NOT use long fins with big sails > 7 m²
perhaps it is as tardy says - with the centreboard and rails more is NOT needed

this summer I plan to do some fin tests on the Mistral Equipe II/two
have other power box fins and will even try a Makani weed fin ...

Hi Melih,

One of the reasons I asked about what fins people use is, from the 2010 Worlds in Latvia. There were 9 out of 42 starters on the Mistral Panam. With the fin size ranging from first fin at 54cm down to 40cm with a 9.5m sail. Then 42cm down to 35cm with a 7.5m sail. With most sailors registering a larger and a smaller fin.

Interesting, has thinking and behaviours moved on in the last six years? Do people only use one fin?

www.internationalwindsurfing.com/userfiles/documents/RB_Worlds_2010_Latvia_Equipment_List.pdf

Dear Parked,
I am not experienced person in long board races. But many of Turkish surfers are using different size of fins in races. I am talking about fun boards. Two things are important for the fin size. 1. boards volume 2. power of the wind. You are completely right about this paradox. I am not a racer but I have got three different size of fins. (36-38-42 cm). Eventually nobody use one fin. Bye Melih...

Parked said..
Thanks to everyone for the suggestions on the DIY repairs. Because the Centreboard and Fin have damage, I've decided to go for a local repairer as the Centreboard alone is no longer in production and have no interest in messing it up. Will post pics soon, hopefully.

Hi Parked,
have a look in the buy & sell accessories, choose Mistral in Make/Brands on the left. A few centre boards there that may or may not be of help
Dave