Avoiding "The hard bits at the edges"

Ah yes ... the hard bits at the edges

You don't want to bump into those by mistake. Mostly it will just be embarrassing, but it could be costly. If you're very unlucky (or silly) it could be very costly ... and we don't want that, do we?

First the sanity check:

In the UK, at least, you are at greater risk of drowning in your car than in a boating accident.

OK, that's a statistic and perhaps a bit silly. Very few people go sailing in their cars ... they drown by driving into rivers, lakes, canals or the sea, but it does give a perspective.

What we are talking about is the hard bits that you don't want to hit and ways to avoid hitting them. Most of that isn't too hard, especially with modern GPS, but it remains as important as it ever was. This i

page covers some basics of navigation and pilotage. The two terms are nearly but not quite interchangeable. Generally Pilotage refers to finding your way about when you are close in to land, for example getting into a bay, river or harbour, whilst Navigation is about covering larger areas of water where you may not be able to see you destination.

What exactly are these bits we're trying to miss?

At first glance that's a really dumb question, isn't it. We're trying not to hit the land.

The reason I ask it is to put "the land" into perspective ... what, and more importantly where, is it?

People have set off sailing with a road atlas for navigation. They figure that if they stay on the blue bits and follow the landmarks, they'll be OK. That stands to reason, doesn't it? Well, no ... very definitely No. NO! NO!

Road atlases have no need to document what goes on in the sea, and they don't. What's blue on an atlas may not be quite so blue if you're sailing in it, and it has tides and streams and some rules. Like on land, the bottom of the sea bed can be lumpy or hilly. And if it's under the water, you often can't see how hilly. It can be shocking, embarrassing, and dangerous to bump into an underwater 'hill' when you're ten miles away from 'land'.

Fortunately, sailors have Charts, which our word for "maps of the sea", which tell us, usually very accurately, where the hills, rocks, piers, wrecks and whatever else actually are. We need to understand those charts, how to see the hard bits and how to avoid them.

I do not plan here to go into great detail. There are books and sea schools that do that, far better than I can and I strongly advise that you sign up on a course or two. There's lots to learn, but most of it is fairly easy. A few bits are rather harder, involving some sums, but worth learning if you can. Some of those harder things have "rules of thumb" that mean you can do a quick approximation rather than do the sums. But ... it's always good to know that there's a certain depth of water under the keel, or a certain air-space between your mast and that bridge. Much of the time, if you're not sure, you can 'heave to' or drop the anchor or pick up a mooring buoy and sit down to work it out in your own time. Usually there need be no rush. We're here to relax.

Understanding where the hard bits are

There are several different styles of Chart around, but they all have similar information. They help to show how much water there is in a particular place, they show where there are rocks or wrecks to avoid and of course they show the obvious edges of the sea. They also show other things we'd like to know about, for example how fast the tidal stream flows, where the buoys are (or should be!), other marks useful for navigation (the church on the hill, maybe). They show us where there are good places to anchor and where anchoring is not allowed. The show us the fish and shellfish farms. They show us the deep channels where the larger ships go in in some places the "dual carriageways" and similar that those same ships are expected to use. Most of us in smaller boats are expected to stay out of those, except when we must cross them.

All (or virtually all) charts have colour coding for the sea that gives a rough guide to depth of water. These colours are different for different depths of water, and usually(!) indicate the minimum depth of water that should be at that point. I say usually, because under some unusual circumstances there might be less. Take one of those courses ... they'll explain.

If your boat draws 1.5 metres (about 5 feet) and all the blue on the chart indicates 2 metres (about 7 feet) or more, you can probably sail anywhere on the blue you like in good conditions. Consider though what happens if there are 1/2 metre high waves, or 1 metre high waves, of 2 metre high waves. Not only do those waves reduce the depth of water in their troughs, but after a certain point, they interact with the depth and begin to rear up and break. You've seen it on the beach ... little waves 100 metres off shore rise up into 'breaking rollers' and crash onto the sand. Always add plenty of margin for waves in shallow water.

There are usually marker buoys for the bad places and the good places, which can help a lot. Those buoys are colour coded and shaped to help identify what they are and what they mean. They are standardised around the world, which also helps rather a lot but ... there are two slightly different standard system areas, known as IALA region A and IALA region B. Generally the Americas are region B and the rest of the world is region A, but there are a few exception, notably Japan, Korea and the Philippines, which are also region B. The reason for the difference is the huge cost and complication needed to standardise to one system, and anyway, most of us only sail in one of the regions anyway. The differences are in the "lateral marks" Wikipedia: Lateral Mark and [[ IALA Buoyage System. Broken link ]]. The cardinal, isolated danger, safe water and 'special' marks are common.

Some places use leading marks, which are a very efficient way to indicate a route or channel, particularly in places with many dangers and a cross-flowing stream. Keep the two marks in line and you are on the safe route. Leading marks are specially placed cases of a transit, which is probably the most useful and reliable method there is for being sure of where you are. Working the Sails: Marine Pilotage Planning - Clearing Line, Transits and Safe Track.