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Old 9th July 2010, 10:21 PM   #1
Join Date: Sep 2006
Posts: 459
Question Us Fin boxes ???

Could somebody please clarify the situation with "US" fion boxes.

I know there are a few versions that resemble the US box but was under misguided assumption the "US" fin box has definitive measures.

Apparently not.

MFC fins (in US style) are supplied generally with a 3mm step on base (upper part when fitted) which corresponds with base of fin box. Custom versions dont need the step ??? (I think) so some MFC fins are supplied stepless. (???) If you remove the step to facilitate fitting in a custom box does this render fin unsuitable for a "standard" US fin box (as fitted to production boards)

Spoke to MFC and they said for past few years fins have been supplied with step unless they are destined for "custom" boxes.In which case they are flat ????

Isn`t it time we had some standardisation ?????

Have an MFC fin with no step; do I really have to start making "fillers" for fin to sit on ???
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Old 11th July 2010, 05:11 PM   #2
Join Date: Sep 2006
Posts: 97

Please give under the fin a 5-7cm long and 5 or 6mm thick roap in, than fix it.
Maybe that you have to try what work on best. Wolfgang
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Old 12th July 2010, 06:15 AM   #3
Join Date: Aug 2006
Posts: 40

Hello, Floyd,

Found this: http://windsurfingdirectaskevan.blog...er-i-have.html

Notice that the author interchanges the use of the US, A and E box, but I seem to recall that there were dimensional differences.

The “E” box MIGHT have been thinner, thus fins with “bumps” on them had to have the “bump” removed, otherwise it would not fit down into the box. I had to do this on a Bic Alto waveboard I once owned when I fitted a non-Bic fin. It is possible that the “E” box is used in “thin tail” boards where space is at a premium or custom boards, as you have mentioned.

“A” box and US boxes MIGHT have been the same (does the “A” stand for “American”?) and are deeper than “E” boxes.

Am very willing to be corrected on the above.

Just took some measurements on my 2009 JP RWR 82: depth of fin box, 26.5mm. Depth of JP fin head, 24.5 mm, so there is 2mm (approx 0.080") clearance between the top of the fin and the bottom of the fin box. There is no bump on the JP fin.

I have an MFC FreeWave 28 cm fin, with a bump at its front end which I just fitted into the JP RWW. It appears to me that the bump controls the depth when the front of the fin is fitted into the box and the screw is tightened. The bump appears to be superfluous, because the original JP fin does not have the bump, nor does it come anywhere near to contacting the box when the fin screw is tightened. NOTE: the MFC is sitting slightly above the fin box, so the bump has to be removed or slightly filed down.

It would be great if Bill Kline (gsport) or someone from Chinook, True Ames, Rainbow etc. could clarify/add to the above. You might care to post the query on the rec.windsurf forum (it would make a nice change from all of the clothing ads!).

Hope this helps.
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Old 15th July 2010, 04:16 PM   #4
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I had a Bic Tribal with US-E and I still have in Venice a Drops Slash 98 with US-A, the most common us-box.
In my experience US-E(UROPEAN) is WIDER than US-A(MERICAN). Original Bic fin (Select X-Wave) was perfect in the Tribal finbox, impossible to insert in the box of Slash; on the opposite all ather us box fins were perfect for the Slash, loose in the Tribal.
Don't ask me why but in my actual AHD Seal 88 the box seems to be an US-A with the hole in the middle of box (US-E of Tribal had the hole in the front end of box), but every fin seems to be loose until you screw down it, and at the end it is tightly screwed...
The mystery of us-boxes... powerboxes for everybody!!!
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Old 15th July 2010, 10:22 PM   #5
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Join Date: Aug 2006
Posts: 18

I'm pretty sure that the width of the two boxes are within 2 mm of each other, and that may be due to small manufacturing tolerances. The big (only) difference is the greater depth of the E-box.

Many fins are now spec'd for E-box, but use tabs or laminate that can more easily be reduced or eliminated than if the entire base was a smooth surface. This makes it less expensive for fin makers to offer a fin for both boxes.
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