Anyway, been playing with the idea of adding a kamal to my paddle after reading an old edition of David Burch's "Fundamentals of Kayak Navigation".
It mentions you can make a standard one out of a 15cm metril ruler and simply 57cm of string knowing that at a distance of 57cm, each CM in the ruler represents 1deg of target angle. It can be used to guestimate distance off from known objects using their widths and angles off.
For those that have done this, what have you used to calibrate it given say your arm length and paddle. Have you tried some kind of marking that wont come off or perhaps a piece of tape and then on the tape, marked off in some permanent fashion..
Calibrating I meassured out a course on a football field. Two sticks placed 10m apart. Then meassuring a point perpendicular to this line and 10m away. That gave me the relative 1:1 angel mark. Meassuring points 5m , 15m, 20m, 30m gave me the angels for 1:2, 3:2, 2, 3 relative distances.
In practice as for finding the marks on the paddle, I just keep my normal grip, close one eye and hold out the paddle. I used different colored tape on my paddle for denoting the various degrees.
I hope it make sense. I found the kamal to be very practical. It is very nice to be able to say ‘now we’re half way’ during a crossing.
All of the above probably doesn’t make sense, if one hasn’t read the Burch text.
Oh and sorry that I never got the finish the webpage.
Here is a quick way to judge distance offshore with just your finger and your two eyes!
1. Stretch our your arm with your index finger pointed straight up in the air.
2. Line up your finger with an object on shore, looking with ONE EYE.
3. Without moving your arm, now look with the other eye. Your finger will APPEAR to have shifted to the right or left, depending on which eye you started with.
4. Your distance from the object is approximately TEN TIMES the distance your finger appears to have shifted!
For example: you sight a tree on shore. You judge that your finger has shifted about 200 feet from eye to eye. So, you are approximately 2000 feet from that tree on shore.
You can fine hone this by taking measurements over known distances, such as in a parking lot or the football field you mention. Depending on the length of your arm and the distance your eyes are apart, you may need to use a different conversion factor ... 9, 11, whatever. It works pretty well!
finger method… I think the estimated degree’s offset via the finger and the one eye method is supposedly about 6 degrees. with that knowledge and the width, you can use the formula 60 x target width (miles)/target angle(degrees) to get distance(miles).
I gather your ratio is simply a “rule of thumb” and easier than doing math at sea.
One warning about the finger method Make sure nobody, especially a power boater, is in your line of sight. They might not realize that it’s your index finger that’s pointed at them!
