It is usually caused by magnetic materials on the boat (or indeed the boat itself). Deviation is the deflection of the compass from its proper orientation. The degree of Variation and its annual rate of change is indicated on nautical charts within the Compass Rose. You will need to apply Compass error (Variation), but no Deviation if using a hand held compass (Deviation is only applied if you are using the ship’s compass and you know the Deviation).Ĭompass errors (Variation and Deviation): The difference between True North and Magnetic North is called Variation. You must be 100% sure that you visually identify the correct landmarks and, ideally, the landmarks should be around sixty degrees apart. Take a bearing with your hand compass of the landmark closest to your stern first, then closest to your bow, and finally, the one that is abeam (090° from your bow). On your chart select three conspicuous landmarks to use, to avoid large errors when underway. Three bearing fix: This is a great way to double check your position. (At the very end of this post, see the list of additional information included within the complete Navigation Section of Cruisers’ AA). So, for the price of a cup-or-two- of coffee, you could be better equipped to sail and more importantly be safe. You can now buy the complete book for $3.99 on Kindle. Below are FREE Navigation notes from Cruisers’ AA.

There are pictures, diagrams, short stories & articles.In the Navigation Section alone there are 53 A4 pages of great advice to help keep you safe.There are 235 A4 pages crammed full of tips, tricks, ideas and advice on living on board & cruising.Also, HERE, you will find more great navigation diagrams and pictures. There is lots more free information included, (below) – copy & paste if you wish.

GPS is only as accurate as the chart it relates to.

There are GPS errors (both human and in the unit!).

Electronic chart errors are not the only equipment that comes with errors.

So here is a good chunk of Navigation information from our book Cruisers’ AA And that is just what they are – tools – nothing comes with any guarantees!.It is a great reminder that we shouldn’t rely on ONE navigation tool.This, of course, goes for paper charts too.More critically, some hazards were not shown on a small scale. I read a great FB post this morning on how a cruiser found that different range scales on their electronic charts meant different information being shown. *pages of FREE navigation tips, tricks ideas & advice*īe safe & have a wonderful Christmas & New Year – fair winds.

Relative bearing and true bearing