Lateral marks-know your shapes and colours!

Maybird recently sailed down Lough Foyle to Derry or Londonderry as it is called on the Admiralty chart.The passage is some 18 miles from Magilligan Point at the seaward end.
Lough Foyle covers a vast expanse but is very shallow and has an average depth of just 3 mtrs!The narrow channel down to Derry  is marked with port and starboard posts although in many areas there are just either port or starboard posts on their own so you have to use some commonsense plus monitor your depth continually to assess the width of the channel.Motoring down to Derry-the channel is so narrow and the wind direction was such that we could not sail and remain in the channel.The pilotage was straightforward and the mate ticked off each and every lateral mark against the handwritten pilotage plan so we knew exactly where we were in the channel without having to refer to  the elecronic plotter.It was bright sunshine and the green and red posts were easy to identify.

Contrast this with our passage out of Derry.We delayed our departure time by 3 hours to let the radiation fog disperse but the visibility was still “POOR’ when we cast off.What really helped us identify the channel was the shape of the top marks on the port and starboard posts.The visibility was such that you could not easily identify the colour of the posts but the silhouette of the topmarks was as clear as day.

In addition to the shape of the buoy or the shape of the topmarkona post the colour can be useful if you can see it.Sailing around the Solent one gets used to very big cardinal marks that are visible from a few miles away.This is not the case off Ireland’s west coast.In Sligo Bay there are two cardinal marks that define a “dog leg” that sets you up to sail down a transit of the Metal Man and Oyster Island Lighthouse.Approaching Sligo Bay even in “GOOD” visibility it was very difficult to identify the top marks on the two cardinal buoys.However it was easy to identify the colour scheme of the south cardinal mark-Yellow over Black and then the north cardinal mark-Black over Yellow even though we could not make out the distinctive arrows down  and arrows up topmarks. 

I guess the moral of all this is that there will be occasions when you have to use whatever scrap of information you can glean from the buoy or post or withy by its shape,its colour and its topmark.The cormorants in Lough Foyle had their own distictive outline so their was no mistaking their profile as they sat on the topmarks drying their wings in the early morning sunshine.

You can learn more about all shapes, sizes and colours of these marks on one of our Day Skipper Theory Courses  or to experience it in a hands on environment you could do a Day Skipper Practical Course

Posted by: firstclass