It's a classic scene from World War II movies. The captain and his executive officer are hunched over the radar operator, the three of them staring intently at a glowing screen. A radar beam circles the blank screen once, twice, a third time. Then, suddenly, the screen lights up. "There he is," the captain exclaims. The captain turns and, with fire in his eyes, shouts, "we've got him this time! Battle stations!"

It's an exciting scene that pumps the adrenaline every time. It is also completely wrong.

Anyone who has spent any time staring into with a radar screen quickly discovers that there is a lot of information being presented – some of it useful, most of it not. According to the Rules of the Road, a mariner has to consider the limitations of his radar unit when making decisions, but most radar units don't include a list of these limitations in the owner's manual. A radar class will cover these limits, but there is no requirement for recreational boat owners to take such a class.

The limitations are sea and air clutter, minimum and maximum range resolutions, beam width and beam height. Although these may sound technical, the basic concepts are fairly simple – even intuitive.

The old square-riggers of the golden age of sail were all about the knots: they had miles of rope and used scores of knots to control their canvas power plants. Boats today use far fewer lines and knots, but a knowledgeable mariner can still look at a boat and quickly tell the owner's level of seamanship by observing the lines. Are they neatly coiled and properly knotted, or tangled in a landlubber’s snarl?

Your lines tell a lot about you, and knowing how to correctly handle rope and tie knots is far from a dead art. The Ashley Book of Knots, the bible of the knot-tier, contains more than 3,500 knots, and more have been developed since it was published in 1944. Luckily, most mariners can get by with far fewer: we count six-and-a-half as essential. With these knots you can do just about anything you need to do on a boat that involves rope.

We'll explain each in detail, but first a few basics.

TIE AND UNTIE

Most marinerÂ’s knots have three characteristics: they are easy to tie, do a specific job well and are easy to untie. This last is very important: you do not want to break fingernails or have to resort to a knife.

In any marine store, you will find two kinds of rope: three-strand twisted, called laid line, and various types of braided rope. Braided rope is the kind you see most often today. The knots below were originally developed in laid line, but will work just fine in any type.

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