Map & Compass

This is a short video we shot the other day. It’s a quick, to the point, lesson on navigation. I’m sure most of you already know how to do this but some may not.

In many areas, ignoring grid variation would introduce a significant error. Perhaps this isn’t the case where Mr. Jacobson is paddling, but I think it bears noting, at least for those of us up here in Maine, where you’d miss your destination by nearly a half mile if you ignored variation, and made a 1 mile crossing.

Variation is incredibly important
so there needs to be map and compass 201. BWCA users can ignore…we in the East and West cannot.

this is more complete to understand declination

Quite a silly thing to say in general, but for some locales it is 0 degrees, or quite close to it.

Here is link to map of declinations -

Here is website with more of a point and click interface

How serious are those errors?

1deg error on 1 nm ( nautical mile) will be ~100 feet.

For example in Maine, Acadia, it is ~17deg West. 17deg error in navigation over 1 nm distance will get you off course ~1700 feet ( actually 1770 or so) which is asking for trouble when trying to navigate between islands

Declination changes over the years
The magnetism is in constant flux :slight_smile:

Old maps may be off , as the earth evolves forward.

ever changing magnetic field.

a nice animation of the earth’s field over the last 400 years

Yes, declination is an issue in some parts of the continent. In the video Cliff makes mention that on the map he has in front of him the grid lines are so close to true north that it isn’t a problem. Maybe we will do a 201 to please you Out Easters.

If we were in an area that it mattered, the type of compass that Cliff is using has a manual adjustment to the degree wheel that you set the declination offset once and forget it, (for that area). This way you can line right up to the grid lines. You should look into getting one.

adjustable compasses
for hiking I loved using a compass with such an adjustable declination. But not so much for kayaking. The reason is my deck compass. Since my deck compass is only magnetic north I end up using magnetic and never true north. To make this easy I draw lines on my map parallel to magnetic north then whenever I need to measure direction on a map I do so against those magnetic north lines. I use my lines similar to how folks use the compass rose but my lines are in handy locations on the map so that I can measure with just my hand compass. This way I never once need to convert.

Or you can use a nav aid
and throw out marking those lines on the map,

but the OP situation referred to canoe tripping where deck compasses are not used.

Out Easters & Out Westers


set and drift ??

– Last Updated: May-15-13 11:46 AM EST –

...... dose anyone have to deal with current and or wind drift when making open crossings ??

Paddling is slow and low powered , seems drift would be more accented than other faster modes (ie., ... airplane , power vessel) .

Even in an airpane if relying solely on pilotage and dead reconing , I couldn't get from A to B w/o accounting for wind drift (WCA) .

So suppose one wanted to make a 5 mi. due west crossing with a 12kt N. crosswind and a 3kt. N.W. current ... in the dark . How will you account for the drift so you can find a 200' wide entrance on the landing shore ??

Maybe it's just me but I figure if you can't do it in the blind , in the fog , in the dark ... you just plain can't do it at all (daylight or not) .

currents wind and compass error
The keys to dealing with current and wind are knowing how they affect your speed and knowing what speed your GROUP paddles over a long period.

And as we discovered on one trip it’s a good idea to line up boats on the beach and check everyone’s deck mounted compass. A metal cooking pot in the front hatch is enough to send one of your mates paddling off in the wrong direction.

One of my favorite local trips is to cross over to the San Juan islands on a big current day. This amounts to a 5-7 nm crossing with 3kts of cross current and wind opposing current. We do it using a compass and paddling a constant course with no gps cheating. Our direction of travel is 45degs from our heading at times.


– Last Updated: May-16-13 1:40 AM EST –

I think the term set is applied to current, and drift to wind. Either way, it adds another variable to account for.

There's a formula to calculate ferry angle to compensate for set. IIRC, it is as follows, for two easy-to-visualize situations:

Current speed / paddler speed x 60 = ferry angle when there's current perpendicular to the intended crossing path.

Current speed/ paddler speed x 40 = ferry angle when there's current that's at 45 degrees to the intended path.

As for wind drift, I don't know...maybe just keep an eye on what it's doing to you as you cross, using both a compass heading AND a series of ranges. I haven't yet had to deal with situations with both strong current and strong wind on a crossing to a landing with little room for error. There's always been enough leeway to make corrections en route.

The scary part is
that neophytes will see this, follow it to a T, and get themselves into a real pickle.

Keeping it in context
Yes, calculating sideways drift due to current and/or wind wasn’t accounted for here, but not an oversight in this case. Does a cross-country hiker maintain course by watching that compass dial as he walks? NO, and neither does someone traveling by canoe. There was one step in that video which was too darned obvious to even mention, and that’s that one uses the compass to pick a landmark on the opposite shore. Once your landing site on the opposite shore has been visually identified, you just paddler to that spot, and you WILL get there regardless of wind or current because you can SEE it. There’s just no need to extrapolate this particular topic to include such things as sea kayaking to island destinations that are beyond one’s range of vision.

By the way, anyone who’s heard any of this basic stuff by Cliff Jacobson knows that a hand-sighted target still can’t be hit with pinpoint precision, so it’s a good idea to aim well off to one side of where you expect the portage to be located. That way, you know which direction along the shore to go while searching for the path. If you aim as close as you can to the portage location and it’s “right there” when you reach shore, no problem, but if it’s not "right there, you can’t know whether you missed it to the right or left. So, for example, if you intentionally aim a little to the left of your target, you KNOW that it’s to your right once you hit shore.

It would have been much more helpful
if this video stated what it was. A beginners guide and not all inclusive.

Declination is important… And I beg to differ that understanding drift is not important. Much paddling here is done in the fog… You just cannot aim off at a target and follow it visually. While it need not be covered in a basic video it is worth mentioning the limitations of the material presented.

Example. We used our chart and compass to plot a course from Isle Au Haut to Stonington. At the outset we could see a landmark…heck we could have recognized it without the compass. But ten minutes into the ten mile crossing the fog whammed us. Now we had nothing visual to go on… and drift with tidal current needed to be accounted for. Did we? uh uh We noted that there was a nun 2 on our course…we were so glad to find it in the fog. But along the way the nagging feeling occurred that we were being pushed too far west. Sure enough a close look at the chart reveled another nun number 2… farther west. A quick recalculation of heading needed put us back square in Stonington just as the fog lifted.

This is where your safety bearing comes into play…the one heading that no matter where you find yourself lost you can follow and hit land.

highjacked thread
Guideboatguy is right, this thread unfortunately got highjacked right from the start.

What started out to be showing a simple two minute video on using a compass to cross a lake, it quickly got rerouted to sea kayaking in the fog off the coast of Maine where set, drift, currents, and deck compasses do come into play. The video CLEARLY stated that in this particular instance declination was not a factor, and the map CLEARLY showed we were crossing a lake, not a sea, not an ocean, a lake, a small lake at that.

vector plotting
Hey Pilotwingz,

When dead reckoning in an area with current, sea kayakers use vector plotting to determine the corrected heading, and expected speed over ground, so that they will reach their destination across a KNOWN current. In reality, you’re probably nuts to attempt a crossing like this in fog, but in good visability it is useful to determine the correct ferry angle in longer crossings where a visual range isn’t an option.

You can find how to do this in a kayak navigation text, or by taking a kayak navigation course. Not rocket science, but too complicated to describe on a keyboard.

Yeah, well…
Then maybe they take the tidal predictions as gospel, too.