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adywind
Joined: 08 Jan 2012 Posts: 665
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Posted: Tue Apr 16, 2013 6:55 pm Post subject: Fin sanding |
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How smooth /grit #/ would you wet sand an old fin and in which direction? |
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DanWeiss
Joined: 24 Jun 2008 Posts: 2296 Location: Connecticut, USA
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Posted: Tue Apr 16, 2013 7:49 pm Post subject: |
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600 grit in the direction of flow after any repair or paint removal. Or, use a "normal" 3M pad for more common cleaning which is so very important to performance.
Others will chime in that they never bother to clean their fins and it goes fine, but from testing I can tell you that a fin with salt crystals and/or oil from one's hand will not perform nearly as well as one simply prepped with a 3M scrubby.
It's the same as keeping the bottom of boards very smooth and clean. It's a serious difference. _________________ Support Your Sport. Join US Windsurfing!
www.USWindsurfing.org |
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U2U2U2
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Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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Posted: Tue Apr 16, 2013 9:02 pm Post subject: |
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depending on the action being taken, if you are removing nicks or more, I use a sander, and progressively go down with wet sandpaper to mirror fine, like 1000 grit.
not so certain which direction matters when you use above, but water flow direction on the last few series cant be wrong
try to maintain the original shape , even if you make it smaller _________________ K4 fins
4Boards....May the fours be with you
http://www.k4fins.com/fins.html
http://4boards.co.uk/ |
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keycocker
Joined: 10 Jul 2005 Posts: 3598
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Posted: Tue Apr 16, 2013 10:36 pm Post subject: |
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600 is likely better. Notice there are not many shiny fins on the market?
It goes against instinct but a lot of winning watermen swear by 600 in the direction of flow creating less drag than mirror finish of any kind.
Same on your bottom and your Hobie, and raceboat. |
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adywind
Joined: 08 Jan 2012 Posts: 665
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Posted: Tue Apr 16, 2013 11:39 pm Post subject: |
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Yeah, that's the dilemma I'm having: mirror finish or 600 like the bottom of the board? Does the finish play a role in how much grip a fin has ? |
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tramontana00
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Joined: 15 Feb 2010 Posts: 204
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Posted: Wed Apr 17, 2013 2:11 am Post subject: |
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Yes it does. Mirror finish will make it easier for water to detach from the fin and it will be more prone to spinouts.
Sand with 600 or 400 grit and keep your fin clean. Direction of sanding is not important.
Water flows around fin in layers (millions of layers). Goal is to create a surface that will keep water layers attached to the fin and friction between water layers rather than between water and the fin itself. There is most optimal sanding grit for every speed.
Don't believe it. Ask sharks. They have gritty skin and swim faster with less effort compared to other fish. |
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norcom
Joined: 16 Jun 2008 Posts: 137
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Posted: Wed Apr 17, 2013 8:01 am Post subject: |
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I keep damaging my fins on the beach/oysters. I repair them but they look pretty bad afterwards; though they still seem to work ok. I'll try the boardladys advice next time with the glass instead of epoxy but I have a feeling that'll be even worse. Maybe the edge will look better though. |
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adywind
Joined: 08 Jan 2012 Posts: 665
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Posted: Wed Apr 17, 2013 9:47 am Post subject: |
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norcom wrote: | I keep damaging my fins on the beach/oysters. I repair them but they look pretty bad afterwards; though they still seem to work ok. I'll try the boardladys advice next time with the glass instead of epoxy but I have a feeling that'll be even worse. Maybe the edge will look better though. |
Im using JB Weld for fin repairs.Its easy to work with, takes like 12 hrs to dry and then just wet sand it 400 grit and you are ready to go. Its strong enough to not having to use glass or anything, cheap-what not to love about it?! Just make sure to leave the fin hanging upright when drying, because although its very thick and holds its shape it still may deform some. |
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U2U2U2
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Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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Posted: Wed Apr 17, 2013 10:33 am Post subject: |
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I use Gorilla epoxy for ding repairs on FINs. If it has a large area I would probably add fiberglass or carbon.
the 600 grit or smoother debate.....
whatever floats yer boat
How smooth are the Americans Cup boats _________________ K4 fins
4Boards....May the fours be with you
http://www.k4fins.com/fins.html
http://4boards.co.uk/ |
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dllee
Joined: 03 Jul 2009 Posts: 5329 Location: East Bay
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Posted: Wed Apr 17, 2013 11:33 am Post subject: |
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I talked to America's cup crew and National level Aussie18 crewman.
Most say finer than 600, cross hatch about 30 degrees from direction of water flow.
If you're using a freestyle, wave, or freewave board, it makes no difference to you.
If you spend the 200 bucks on Tetonic's blades, then make sure it's done. |
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