How is your paper chartwork these days? When was the last time you plotted a three-point x, clearing bearings, or course to steer longhand? No, I can’t remember either. Theo Stocker introduces the January 2021 issue of Yachting Monthly

I’m pretty confident I can still do those things, and I have the paper charts and tidal atlases to do so.

But the reality of coastal pottering with a modern chartplotter on board is that it does all this for me (and they are becoming ever more capable), leaving me free to worry about sailing with a baby on board and all the challenges that brings.

More often than not, shaping a course to steer is now a case of heading into the tide a few degrees until the ‘course over ground’ line on the plotter matches my planned route.

On long passages heading across a tidal stream, however, that’s just not going to cut it and will lead to woefully inefficient passage making.

It was reassuring, therefore, to read Mark Browse’s lucid description of how to estimate course to steer in your head in two easy sums in the latest issue, with a method that works even for long Channel crossings.

Continues below…

It reminds me of a Navy captain I once sailed with who boasted that he had ‘a computer in his brain’ and who would challenge us to use the radar to calculate another ship’s closest point of approach.

Nine times out of 10 his estimate by eye of CPA and time to CPA was more accurate than our radar-assisted conclusions.

His secret lay in the same one-in-60 rule used for course to steer, and the mathematical magic of converting angles into distances and time.

Having a few tricks of this ilk up your sleeve will not only impress your crew, but also provide a critical sense check when it is all too easy to swallow what the chartplotter tells us as gospel.