Communications at sea

Tidal heights and the rule of twelfths

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

In our previous article we looked at tidal curves and how we can use them to find the time of a specific height of tide. Following on from this we now take a look at how we calculate a height of tide for a specific time. This is not a complex calculation but it helps...

Understanding tide tables and tidal curves

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

No two coastal places have exactly the same tidal pattern. There are many factors that influence this, from the shape of the coastline, the funnelling effect of channels and estuaries, the depth of the sea and the proximity of oceans. The times and heights of tides...

Tidal terms and definitions

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

In a previous post, we looked at some of the basic principles involved with understanding tides, including what causes their rise and fall, the resulting tidal streams and the tidal range that varies according to coastal topography. For those who are learning or...

Fixing position at sea using traditional methods

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

Following on from previous posts concerning traditional navigation methods, this post looks at some traditional methods used for fixing a vessel’s position at sea, within sight of land. Electronic fixes using chart plotters are very straightforward to record,...

Estimating and plotting your position at sea

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

In a recent post we discussed the importance of being able to estimate your position at sea if the vessel’s GPS fails. In this post we go a little further with a reminder of how we go about estimating and plotting our position using traditional methods, when out...

Estimating your position at sea

by Simon Jollands | Communications, Crewing skills, Navigation, Preparation

Navigators use a combination of techniques to estimate their position at sea. The primary method used today is GPS (Global Positioning System), a network of 24 satellites that became fully operational in the 1990s and was originally restricted for use by the United...