Mistral Competition Fin

quintmatthew1 · Joined: 03 Apr 2015 Posts: 3 Location: Florida

I was having a blast on a old Mistral Competition board and hit something. When I started to spin I realized that I had lost my back fin. Is there a place that sells the specific Mistral fins or a good aftermarket fin that will fit the board.

DelCarpenter · Joined: 06 Nov 2008 Posts: 499 Location: Cedar Falls, IA

The fin box in the picture looks like an "A-box." Most A-box fins will fit, but A-box slots can be too narrow or too short for a particular fin. I think more boards had A-box fins than any other variety. I think most fins in the US up to about 35 cm today are A-box fins and there are larger older ones. They should be easy for you to find from either dealers or individuals.

In the US the A-box is also referred to sometimes as a "standard" box.

swchandler · Joined: 08 Nov 1993 Posts: 10588

In older European boards, it should be noted that they were often using the A Box concept, but the depth of the box was deeper overall. They were what is now considered an E Box. One can use A Box fins in an E Box, but it's best to fill the open space below the base of the fin with something. A piece of appropriately sized wood or plastic can be used, but one can also use a segment of rope or line too.

cgoudie1 · Posted: Sat Apr 04, 2015 5:22 pm Post subject:

Yeh, what Steve says about E boxes. Sometimes a pencil is a perfect
stabilizer for an A tab in a Euro box.

-Craig

joethewindsufa · Joined: 10 Oct 2010 Posts: 1190 Location: Montréal

having just purchased a Mistral COMP SST I would VERY interested on your feedback !!!

how much you weigh, winds & conditions board is used in with sail sizes ...

I am a HEAVYweight of 105+ kilos and hope to use this board in 20 kph in longboard mode, but also in 20-40 kph with an 8-oh planing

http://joewindsurfer.blogspot.com/2015/03/mistral-competition-sst.html

thanks in advance

quintmatthew1 · Joined: 03 Apr 2015 Posts: 3 Location: Florida

I am relatively lightweight only weighing 150 pounds (68 kg). Generally I am using it in winds from 20-40 kph and a 5.7m sail. I am in the gulf so I have some chop when it is windy. I am more focused on straight line speed instead on maneuverability. I am still new at this so I will probably be wrong but I think I would be best with a straight fin that is about 30?? cm. Please correct me if I am wrong. Thanks on the information on the fin box. I thought that was what it was but I wanted to be sure before I bought the wrong thing.

Matt

joethewindsufa · Joined: 10 Oct 2010 Posts: 1190 Location: Montréal

A and E box seem to max out at about 30 cm
since you are in Florida , is there a shop where you can bring your board and have them fit your board with a fin ??

wide and thick chord Smile

(some say slim for speed, but i like my tinho dornellas fin on my equipe i)

DanWeiss · Joined: 24 Jun 2008 Posts: 2296 Location: Connecticut, USA

Don't assume you can simply fill the E-box with a spacer and you are good to go. The reason E-boxes were used in the first place has to do with the materials and construction of the boards, not to make life difficult in the 1980s.

Most E-boxes were multi-piece assemblies installed into a female cavity itself molded into the bottom side of polyethylene hulls. Those boards that rarely reinforced around the box cavity itself given the blow-molding method used to make the boards. Mistral Competitions are different in construction, but similar in the way the molded box cavity accepts the box that itself is screwed into the cavity using very small screws.

Since the A-box fin fills only 2/3 of the E-box depth, the box fails to transfer the fin torque to the cavity with enough dispersion. The box then begins to twist and may ultimately fail by snapping the box, cracking old epoxy or glue that held box pieces together or ripping the mounting screws right out of the board.

That plastic box is about 30 years old and getting more brittle by the day. I strongly advise not using anything but an actual E-box fin. They actually are very common in freeride boards that don't use Tuttle.

swchandler · Joined: 08 Nov 1993 Posts: 10588

You have to admit Dan, old fin designs for old Mistrals Competitions were actually quite short in depth in contrast with today's view of things. But, you're right if you're interested in using longer fins to coincide with bigger sails. Yet, using relatively small A Box fins, the risk isn't too bad if the condition of the board is generally pretty good.

A8A8 · Joined: 10 Nov 2011 Posts: 9

If you are anywhere near Tallahassee, I can scare up several old mistral fins, one from an IMCO, the other from another old mistral board