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Navigation skills for kayak fishing & touring
- Category: Safety & navigation
- Published on Monday, 04 January 2010 20:31
- Written by Holger
A kayak is the smallest ocean-going craft. To be able to venture safely out onto the open ocean, it is essential to familiarise yourself with, at least, the basic navigation skills. Of course, nowadays most of us have GPS and chart plotters at hand, which make navigation an easy task. But what if that masterpiece of technology malfunctions, or your battery goes flat? Then you will be forced to fall back onto your navigation skills, your senses & knowledge. Navigation is an ongoing process in your head. It is not only about finding the way, but it is also about taking mental notes, and being constantly aware of position, progress, speed and drift. So let's discuss how to master some navigational tasks the 'old school' way.
Bearings & Range
Most of our kayak fishing and kayak touring is done within sight of the coastline. That allows us to use the simplest form of navigation: Bearings and ranges. Choose a couple of stationary objects that you can see and identify them on your chart. Then watch them to line up while you are paddling by. A line drawn through the objects on your chart will match the range line through the objects, and your position is somewhere along this line ( which makes it a LOP/ line of position ). If you can gauge the distance to the object, you can gauge your position. If you have got a depth sounder on your kayak, and the depth is shown on your chart, there is another way to estimate your position. You already know that you are somewhere along the LOP in your chart. Find the right depth, and you have found your position.
A second range will enable you to plot your rough position on the chart. I often use this technique to find my fishing spots: 'If the cape and the big house are in a 90° angle to each other, I am in the reefy area.' And more precisely: 'If the rock is in line with the cape behind, and the big house aligns with the peak behind, I am exactly over my favourite spot'. An attentive kayak fishermen travelling along the coast will draw many ranges during the day while he paddles by. This enables him to judge his progress, drift, and the impact of wind upon him. After a while it will become second nature, and helps to understand the 'bigger picture'.
Compass bearings:
The use of a compass will enable you to take these techniques to the next level and find your precise position. You can use either a hand-held or a built-in compass to take your readings, but in both cases make sure they are well clear of any ferrous metal. To take a compass bearing with a built-in compass, simply point your bow at the object and take your reading. With a hand-held one, just point it towards the object and take your reading then. To get your position fairly precise, you'll need at least two objects you can see, and identify on your chart. Take a compass bearing of each of them, draw a corresponding line through them on your chart, and where the two lines intersect each other is your position.
'Rock straight north at 0° and the house at 270°. Ah, that's where I am'.
Crossings
Now that you know how to find out where you are, let's have a look at how to tackle a crossing out to an island or how to come to a specific point ( e.g. a reef ). Let's say you start on the beach, and you want to reach an island 3 NM east. Unfortunately, this is often not as simple as just hopping in the Kayak and following the compass at 90° east. Why? Because on the ocean you are under the influence of tides and wind. Have a look at the next picture. The tide is running north with 1.5 knots.
The green line is the desired course to paddle, straight east. The red cross shows where you would end up, paddling with 3 knots for an hour, sticking to a 90° compass course. Far off your destination. The current would push you 1.5 NM north. The blue line shows you the way you would paddle if you'd constantly correct your course and point the bow towards the destination. You will end up paddling a big curve. It works, but means a lot longer distance, longer paddle time, and a waste of energy.
So how can you avoid that curve? The easy way is good timing. Time it around the tide change. For our one hour crossing, start half an hour before the turn of the tide, and stick to the uncorrected 90° course. It will take you up north for the first half an hour, but then the tide will turn, and take you back down south straight to your destination.
Unfortunately, on some days, waiting for the tide does not work, or the crossing might be too long. So what to do?
Pre-correct your course. How to do that? I will show you in the next picture. Because of changing currents and tides, these calculations are normally done for a short(ish) time frame, ranging from 20 minutes to a couple of hours at most. In our case, to make it easy, we will use 1 hour. You will need a marine chart, a ruler, a pencil & protractor.
To start off, draw the desired course into your chart ( 90°, red dots ). Then you'll need a reasonable estimate of your paddle speed, and the speed and direction of the current. This can sometimes be difficult to guess, but good marine charts can tell you the average speed and direction of the current, and experience teaches you your average paddle speed in different conditions (yes, a GPS would tell you all that at the push of a button ). In this case we will assume you are trolling a couple of big lures and average a speed of 3 knots. The current runs with 1.5 knots north.
Now that you have the parameters, draw a vector in your chart, that represents to scale, the speed & direction in which the current travels within the given time frame ( blue, current N,1.5 NM long). To make that a bit clearer, if the time frame is one hour, and the current runs with 1.5knots, the vector is 1.5 NM long , for a 30 minute time frame it would be 0.75NM, for 20minutes 0.5NM, and so on. The more precisely and to scale that you work, the better the results. On every chart there is a scale which resembles the different distances on your chart.
Then take your compass or ruler, and measure on the scale the distance you would paddle within the given time frame ( 3NM ). Take that measurement, start at the end of your 'current vector' and see where the distance matches on the direct course . Make a mark. Draw a line (vector) from the end of your 'current vector' to the mark on your direct course. The mark on the direct course shows you where you will end up after paddling the given time frame, and the direction of the vector resembles the corrected course (heading) you will paddle to cross over in a straight line on the direct course ( ferry glide ), in our case 120°. It also shows you, that under the influence of the current you won't quite make it in an hour. It will take something around an hour fifteen for the crossing.
There is also a ferry angle formula which is an approximation of the proper vector solution, but it is quick & easier to do in a kayak:
Ferry angle = Current speed x 60 degrees
paddling speed
1.5knots x 60° = 90, divided by 3 equals 30°. Add the 30° upstream to your desired course and you get the 120° corrected course ( heading ).
When the current you cross is not on the beam, but closer 'on the bow or stern' ( 45° forward or after the beam ) the same ferry glide formula works with the factor of 40° instead of 60.
A long crossing would be divided into several parts, and a new course would be calculated for every part, always using the new parameters ( tide speed & direction ), starting from the last mark. On big crossings you would end up with a whole list: 9.30am-10am 130°, 10am-11am 145° and so on.
Following a compass course doesn't require you to stare constantly at your compass. Most of the time you will bring the kayak onto the desired course, then look straight ahead, in search of a landmark or cloud formation to aim for. This will keep your focus on the horizon, which helps your balance, and you are less likely to suffer from sea sickness. Check every couple of minutes, and change your landmark if necessary.
On a wind still paddling day, all this is fairly accurate. But there is one more important factor; the wind. Unfortunately, there is no easy method to calculate the impact of the wind. Here it comes down to experience and observation (or a GPS ), and you will be forced to adjust your course accordingly while you are out there, to make up for the wind drift. When in doubt, head higher into the wind. It is easier to fall back with the wind, than it is to make headway into the wind.
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