Powerboating - Part Twelve

The other day I was lucky enough to be sipping a cold beer on the flybridge of a brand new $1.2 million cruiser, watching a good friend of mine demonstrate the latest in electronic aids for the modern boatie.

To say the layout was impressive would be to understate the situation: terms like Star Wars and Mission Control sprung to mind as system after system was put through its paces.

While the boat was cruising through sunny Queensland waters, it was receiving information from overhead satellites to determine its exact position, and using this data to automatically steer the ship.

At the same time, microwave energy was being pulsed in every direction as electronic eyes searched for looming obstacles. Transducers fired ultrasonic waves at the seabed to determine the depth of the water and how fast we were travelling through it, then comparing this to our computed speed over the ground.

Samples of the wind's speed and direction were being fed to the system's computer. This and other information was being collated, digested, digitised and made available to the skipper through an array of screens and instruments that could be selected at the touch of a button.

Possibly, it could also make a decent cup of coffee and have the decks swabbed. But I don't joke about those things anymore, because when it comes to the marine electronics available to the average boating person today, anything is possible.

BLACK BOXES
When I decided to write this series of articles on marine electronics, I knew I was going to need some assistance.

I can't help it. I'm basically a pulleys-and-levers type of person. I like to see pistons, cams, cogs, cranks, cables and sheaves in the machines that I fiddle with. All these little black boxes silently communicating with each other confuse me and make me feel old.

As always, if you need assistance, seek the best, and one of the leaders in marine electronics in this country would have to be Cain Marine. This company is headed by Errol Cain and supplies and fits electronic packages to, among others, the Riviera range of boats manufactured on the Gold Coast.

Since these craft are exported to all corners of the globe, Cain Marine can, and does, configure systems from the very basic to the most complex for some of the most demanding customers in the international market.

When you consider that they give a worldwide warranty on their workmanship and equipment, you have to assume they know what they are doing.

Errol Cain was kind enough to give me a large slice of his time and was extremely patient with me as he explained and demonstrated what is available for the boatie in the year 2002.

Because most of us don't have the money to order a full package in one hit, our electronic equipment tends to grow a little haphazardly. The result is generally a bunch of instruments that aren't compatible.

It doesn't have to be this way. Take the example of the impressive equipment manufactured by Raymarine, formerly Raytheon. The underlying principle to all their gear is that it must be able to operate alone, but if another item is purchased, then connectivity and the ability to share data will automatically follow.

To allow this to happen, Raymarine has developed a system called Seatalk, which is unique to its instruments.

Simply put, data from various collectors, such as transducers and antennae, is put onto a wire that is connected to every display unit.

The advantage of this is that if you are looking at the radar screen and want to know the depth, by pushing the correct buttons, the depth can be shown on the radar screen. This is certainly good engineering.

TOOLS NOT TOYS
So, lets talk about a person who has a medium-sized powerboat, say, 10m or so, with incredibly ancient electronics on board (me). This owner decides to do a complete upgrade, but wants to spend the money over a period of time, as he does not have a lot of cash (definitely me!).

Firstly, what's important and what constitutes toys? I guess that depends on the individual, but in my opinion, knowing water depth has been a necessity since man first began boating. Errol Cain had already urged me to put a good deal of thought into all of these decisions. I decided that my first new piece of electronic equipment would be a depth sounder combined with a fishfinder.

Most depth sounders use sound waves to detect depth, because sound travels seven times better in water than air. A transducer, similar to a small microphone, is mounted to the underside of the ship's hull. This generates a pulse of sound that travels to the bottom of the ocean and is reflected back up to the transducer, which detects its return. Obviously, the deeper the sea the longer it will take for the sound to travel to the bottom and return. By measuring this time, the depth sounder can convert it into a depth measurement.

If the instrument is only a depth sounder, then this is all it will do. However, if the transducer sends out a continuous stream of pulses, and plots the time return on graph paper, then the instrument is, in effect, drawing a picture of the seabed as the ship travels over it. Nowadays the plot is done on an electronic screen, but the results are the same.

When these instruments were developed many years ago, it was noticed that if fish were present under the hull, the sound wave would bounce off them and return early, indicating a much shallower depth than was really the case. This apparent error was a useful guide to the presence of fish - information of abiding interest to most anglers. This data is now incorporated on the screen, so that fish are displayed as blips between the seabed and the surface.

Only two decisions remain. One is whether to go for a colour or grey scale screen. For my money, it's colour every time and hang the expense. The second decision, and it is here that advice from experts such as Cain Marine can save you a lot of money, is the type of fishfinder. Raymarine make a combined fishfinder/chartplotter for not a lot more money, and the decision to go with this piece of equipment saves a lot of vital room in front of the helmsman. It is this kind of advice and expertise that makes purchasing through a reputable dealer just plain commonsense.

PLOTTING YOUR POSITION
Having fitted the fishfinder and replenished the bank account, the next toy - sorry, vital piece of equipment - on my list is a plotter. This is a much more recent invention than the depth sounder. A small radio receiver mounted high on the boat listens for radio beams emitted from satellites orbiting the earth, providing a global positioning system (GPS). When the boat's receiver obtains three or more of these signals, it obtains a fix by a process known as triangulation.

This process is identical to obtaining a position off three points on the coast when using a chart for coastal navigation, although the accuracy is truly astonishing.

This fix can be displayed as simply latitude and longitude and transferred to a chart, but a plotter will do all this and more. The plotter screen will display a map (chart) of your location.

These electronic maps are small cartridges loaded into the machine. Each map covers a different area of the globe, and it goes without saying that you must have the correct one for this system to work. It's not much point having western Tasmania loaded if you're off the Whitsundays!

The plotter will determine exactly what chart has been loaded when it is first turned on. The information from the receiver is analysed and shown as the ship's position on the chart. This information is continually upgraded as the boat travels along its course, thus the skipper always knows where he is. I can quite confidently state that until GPS came along this often was not the case.

Because we selected the Raymarine fishfinder/plotter in the first instance, it is not necessary to buy another screen to display plotter information. At the press of a button, the unit will toggle between the fishfinder and the plotter or, if you wish, show both on a split screen. This is very useful if you wish to return to exactly the same location on a regular basis.

To simplify matters even more, the plotter can have waypoints inserted on the chart and alert the skipper with a small alarm when they have been reached.

NEEDLE IN A HAYSTACK
To explain further, assume there is no chartplotter onboard. Imagine that when you leave your regular mooring you head off into the bay until the headland is abeam. At this point you turn and line up the leads for the channel and, once through the channel, steer 023o Magnetic for roughly an hour, depending on the tide. At this point your favourite fishing ground is around someplace. You hope. So do your mates.

Well, with the miracle of electronics, let's replay that scene.

The last time you were fishing on those grounds and had a good day, you noted the latitude and longitude. The next time on the boat, you turn on the plotter and move the cursor so that it is abeam of the headland where you turn and line up the leads. By pushing the right button you mark this as 'Waypoint one'. The turn at the end of the channel is marked as 'Waypoint two' and the fishing ground as 'Arrival'.

This course, (called 'Tracks') is saved in the memory under any name you want to invent and can be retrieved at any time. So the next time you go fishing, you turn on the plotter, bring up the course and head out. When the first waypoint is arrived at, the plotter will beep, as it will at the second and, more importantly, when you arrive exactly over the fishing spot. What could be easier?

Well, don't be surprised, it can get a lot easier still, and a whole lot more accurate. Next month we will be looking at the integration of an autopilot into the system, as well as lots of other goodies.