Does water temperature affect fin performance?

Discussion in 'Surfboards and Surfboard Design' started by Roy Stuart, Oct 12, 2015.

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  1. Oct 14, 2015 #101
    Towelie

    Towelie Well-Known Member

    2,864
    Nov 27, 2014
    i hope they come in diff colors, so my dumbass doesn't confuse which ones to use...

    LB when are you planning on getting back into shaping for money? i'm trying to get a spot closer to the front of the line. seriously.
     
    Towelie, Oct 14, 2015
    Towelie, Oct 14, 2015
  3. Oct 15, 2015 #102
    Roy Stuart

    Roy Stuart Well-Known Member

    1,514
    Jan 27, 2013
    Lol I'm too busy for that caper, and need to do lots of testing and investigation before I even apply it to my own boards.
     
    Roy Stuart, Oct 15, 2015
    Roy Stuart, Oct 15, 2015

  5. Oct 15, 2015 #103
    brewengineer

    brewengineer Well-Known Member

    3,537
    Jun 22, 2011
    We are in agreement here.
     
    brewengineer, Oct 15, 2015
    brewengineer, Oct 15, 2015
  6. Oct 15, 2015 #104
    Roy Stuart

    Roy Stuart Well-Known Member

    1,514
    Jan 27, 2013
    Did either of you look at the changes in fin behaviour vs viscosity in the example given? They are big changes, whereas the difference in water density is so misiscule that it is insignificant. Take a look at the graphs shown in the the first example. You need to think this through more thoroughly.
     
    Roy Stuart, Oct 15, 2015
    Roy Stuart, Oct 15, 2015
  7. Oct 15, 2015 #105
    sisurfdogg

    sisurfdogg Well-Known Member

    5,399
    Jun 17, 2013
    Damn! More homework!
     
    sisurfdogg, Oct 15, 2015
    sisurfdogg, Oct 15, 2015
  8. Oct 15, 2015 #106
    Roy Stuart

    Roy Stuart Well-Known Member

    1,514
    Jan 27, 2013
    Roy Stuart, Oct 15, 2015
    Roy Stuart, Oct 15, 2015
  9. Oct 15, 2015 #107
    LBCrew

    LBCrew Well-Known Member

    6,024
    Aug 12, 2009
    Roy... I have taken a good look at your data, and don't dispute your claims. But in answering your original question, maybe I'm not being clear enough. I do not disagree that viscosity changes due to temperature affects the fin's interaction with the water in the ways you describe. I'm saying it has an imperceptible affect (at least for me), so I disagree with those that say it matters, all other factors taken into account.

    Are you only looking at double foiled, symmetrical fins?
     
    LBCrew, Oct 15, 2015
    LBCrew, Oct 15, 2015
  10. Oct 15, 2015 #108
    Roy Stuart

    Roy Stuart Well-Known Member

    1,514
    Jan 27, 2013
    Yeah basically one won't notice it in terms of drag I shouldn't think ( although the added drag on the surfboard hull and fins is significant).

    The most noticeable possible difference is likely to be fin stall and spinout. this will only happen on fins with a short chord which use foils which are sensitive to the Reynolds number.

    So, I think it's relevant if one is trying to reduce fin area and chord as much as possible for optimal efficiency. For most fins there's probably no real issue.

    I just research and think these things through when the ideas come up. With this one it's just parked as a possible factor in the relevant brain file. In practical terms it might drive me to make smaller fins to push my envelope a bit.

    Anyway if any of the good folk here find spinout issues with small, narrow flex fins in cold water it might be a viscosity issue.

    Just something to think about, or not as one chooses.
     
    Roy Stuart, Oct 15, 2015
    Roy Stuart, Oct 15, 2015
  11. Oct 15, 2015 #109
    DawnPatrol321

    DawnPatrol321 Well-Known Member

    17,845
    Mar 6, 2012
    Not
     
    DawnPatrol321, Oct 15, 2015
    DawnPatrol321, Oct 15, 2015
  12. Oct 15, 2015 #110
    Roy Stuart

    Roy Stuart Well-Known Member

    1,514
    Jan 27, 2013
    Roy Stuart, Oct 15, 2015
    Roy Stuart, Oct 15, 2015
  13. Oct 15, 2015 #111
    LBCrew

    LBCrew Well-Known Member

    6,024
    Aug 12, 2009
    Roy... What's your take on adding a little bump at the base of the leading edge? Seems reasonable to me, so I actually added a little contour on my last board that should have some affect. The jury's till out...
     
    LBCrew, Oct 15, 2015
    LBCrew, Oct 15, 2015
  14. Oct 15, 2015 #112
    Special Whale Glue

    Special Whale Glue Well-Known Member

    2,318
    Oct 8, 2011
    Re-Roy, make me a board with well placed a glory hole so the blowfish can do their thing while I paddle out. Thanks.
     
    Special Whale Glue, Oct 15, 2015
    Special Whale Glue, Oct 15, 2015
  15. Oct 16, 2015 #113
    brewengineer

    brewengineer Well-Known Member

    3,537
    Jun 22, 2011
    What separates you from a scientist, is that you are only playing in the theoretical, with no work given in the practical. You can play with Re calculations all day, but it means little without experimentation and data acquisition. However, you should be able to afford the necessary tools needed to experiment after that million dollar surfboard sale.
     
    brewengineer, Oct 16, 2015
    brewengineer, Oct 16, 2015
  16. Oct 16, 2015 #114
    waterbaby

    waterbaby Well-Known Member

    1,461
    Oct 1, 2012
    and don't forget the dimples...it's all dimples nowadays
     
    waterbaby, Oct 16, 2015
    waterbaby, Oct 16, 2015
  17. Oct 16, 2015 #115
    LBCrew

    LBCrew Well-Known Member

    6,024
    Aug 12, 2009
    Easy to shape... a bich to glass... maddening to sand.
     
    LBCrew, Oct 16, 2015
    LBCrew, Oct 16, 2015
  18. Oct 16, 2015 #116
    headhigh

    headhigh Well-Known Member

    2,985
    Jul 17, 2009
    So much repetition in this thread. Waves are better in winter. Stop doing math and enjoy surfing.
     
    headhigh, Oct 16, 2015
    headhigh, Oct 16, 2015
  19. Oct 16, 2015 #117
    Towelie

    Towelie Well-Known Member

    2,864
    Nov 27, 2014
    you just don't get good math down there, you'd be hooked on it too.
     
    Towelie, Oct 16, 2015
    Towelie, Oct 16, 2015
  20. Oct 18, 2015 #118
    brewengineer

    brewengineer Well-Known Member

    3,537
    Jun 22, 2011
    I remember the first time I tried math. Blew my friggin mind.
     
    brewengineer, Oct 18, 2015
    brewengineer, Oct 18, 2015
  21. Oct 18, 2015 #119
    Towelie

    Towelie Well-Known Member

    2,864
    Nov 27, 2014
    Yup, it's not to be trifled with. a few of my college friends became full blown math heads.
     
    Towelie, Oct 18, 2015
    Towelie, Oct 18, 2015
  22. Oct 18, 2015 #120
    kidrock

    kidrock Well-Known Member

    2,042
    Aug 1, 2010
    Yup, we gots a real big math problem over in my neck o' the woods. You can always recognize a math freak by all the missing teeth.
     
    kidrock, Oct 18, 2015
    kidrock, Oct 18, 2015
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