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Thread: Help estimate some weight

  1. #21
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    Quote Originally Posted by Fisher View Post
    Wade/Dave I will send you okes a scale, now that's leke babers, now judging photos can be very misleading, 20lbs to Wade, it is not easy to etamate Dave's fish but say about 25lb would be my guess. the last baber I cought and weighed was about 12 years ago, so don't shoot me if I'am wrong.
    Thansk Squire.

    You must join us. I hope to get a permission slip for this coming weekend.

    Chat later
    The best day to go fishing is any day that ends in a "y"

  2. #22
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    Quote Originally Posted by Wade View Post
    Thansk Squire.

    You must join us. I hope to get a permission slip for this coming weekend.

    Chat later
    Jis man, I would love to go, but Ernst booked nebo and I don't eavan think I will make that either 1) because of the risk of meeting a floater in the vaal head on (the sewerige spill on the 5th), and 2) I need to work on the bloody website, those okes that should desighn it is testing my patiants and it now it seems if I am the client as well as the prodution manager ! and 3) eavan worse, I need to swaai quite a lot more rods and reels to make up some fishing credits before I can go fish again
    There is not a single bad person on earth, only persons that have been badly influenced.

    If you would like to be better person, remove the things that have a negative influence on you TODAY.

  3. #23
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    Quote Originally Posted by Fisher View Post
    Jis man, I would love to go, but Ernst booked nebo and I don't eavan think I will make that either 1) because of the risk of meeting a floater in the vaal head on (the sewerige spill on the 5th), and 2) I need to work on the bloody website, those okes that should desighn it is testing my patiants and it now it seems if I am the client as well as the prodution manager ! and 3) eavan worse, I need to swaai quite a lot more rods and reels to make up some fishing credits before I can go fish again
    I know how you feel.

    I do not think Stacey will let me get away as it is our anniversary this coming weekend. Oh well. Hope you get to some water soon. I know i want to...
    The best day to go fishing is any day that ends in a "y"

  4. #24
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    Quote Originally Posted by Wade View Post
    I know how you feel.

    I do not think Stacey will let me get away as it is our anniversary this coming weekend. Oh well. Hope you get to some water soon. I know i want to...
    Happy Anniversary Wade.

    TIME TO BUILD UP THE brownie Points Boet,
    It's not in the catching, it's in the learning something new.
    view albums at. http://www.flytalk.co.za/forum/album.php?u=659

  5. #25
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    Knew I had something around, had to dig through my FF folder on my PC to find it though...


    Is there a way I can estimate the weight of a fish from length measurements?
    ------------------------------------------------------------------------

    The use of formulas to make estimates is common in biology, medicine and many other fields of science and technology. These applications generally use scattered data points and yield approximate results. In determining the weight of fish, the value of the constant (K) is adjusted dependent on the species of fish and how fat or skinny it is.

    THE FORMULA FOR FISH WEIGHT IS:

    The (Girth) squared in inches times the (Length) in inches, divided by a (Constant = K) is equal to (=) the weight of the fish in either pounds or grams.

    USING THE IMPERIAL SYSTEM of INCHES & POUNDS:

    For slender fish similar to trout: K = 900
    For fat bodied fish such as a permit or a fat black bass; K = 800

    Fat Black Bass Example: Girth = 18 in and the Length = 17 in.

    18 x 18 = 324
    324x 17 = 5,508
    5,508/800 = 6.9 pounds, the weight of the fish

    Trout Example: Girth = 13 in. and Length = 16 inches

    13 x 13 = 169
    169 x 16 = 2704
    2704/900 = 3 pounds, the weight of the fish

    USING THE METRIC SYSTEM of CENTIMETERS & GRAMS:

    Girth and the Length are in centimeters (1 in = 2.54 cm) and the weight is in grams (1 pound = 453.6 grams). The formula is the same except:

    For a slender fish similar to a trout, K = 31.1
    For a fat fish such as a largemouth bass or a permit, K = 27.8

    Fat Black Bass Example: Girth = 45 cm, Length = 43 cm

    45 x 45 = 2025
    2025 x 43 = 87,075
    87,075/27.8 = 3132 gms = 3.13 kg = 6.9 pounds

    Trout Example: Girth = 32 cm, Length = 41.5 cm:

    32 x 32 = 1024
    1024 x 41.5 = 42,496
    42,496/31.1 = 1366 gms = 1.37 kg = 3 pounds.

    Well known angler and author Dan Blanton advises that the Constant K= 800/27.8 should be used for bonefish, tarpon, redfish, striped bass, and similar species. Barracuda, pike and trout that are not excessively fat or girthy are more accurately described, as are Pacific bonefish that have less girth by using K = 900/31.1


    But then again, did you measure the length and girth....???

  6. #26
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    Thanks for that Jan.

    I will make a note of it.
    The best day to go fishing is any day that ends in a "y"

  7. #27
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    Wade, according to those calcs, you've put on 6.42kg since you started the thread..

    Don't worry mate, I've put on 8.43kg..
    The more you know, the less you need (Aboriginal Australian proverb)

    Only dead fish swim with the stream (Malcolm Muggeridge)

  8. #28
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    Excellent!! Thanx a lot JanK!!

    quickly made an excel spreadsheet and punched in the values of recent fish, works like charm!! no more guessing now!!

  9. #29
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    Well from that formula (using the 31.1 for slender fish) the barbel I caught today weighed 15.67 kg's and it was slightly smaller than the two in the pics. Nice one, but I think I'd better take fisher up on his scale offer chop chop
    Check your knots!

  10. #30
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    Quote Originally Posted by chris williams View Post
    Wade, according to those calcs, you've put on 6.42kg since you started the thread..

    Don't worry mate, I've put on 8.43kg..
    Since joining Flytalk I have gained 10 kg. ( All the Vaal Outings are seriously to blame )
    It's not in the catching, it's in the learning something new.
    view albums at. http://www.flytalk.co.za/forum/album.php?u=659

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