The Global Positioning System (GPS) is a set of satellites sending signals to your receiver. When you have contact with two or more satellites you will get a position. GPS works very well today. When comparing the given positions to the charts, we have always been right on. Furthermore, we have not once had the GPS failing on us.
Quality usually pays, but our handheld, cheap back-up GPS has proved just as accurate as our main unit.
Besides giving the position in terms of latitude and longitude, the GPS will often also have features like speed over ground, waypoints and anchorage alarm.
We don’t use all the features but setting the waypoints has been very useful. You can pull up a display that looks almost three-dimensional, showing the boat, the course and your deviation from the course. If you go outside the limits, the GPS give a warning sign. Columbus surely would have liked that!
The speed displayed from the log mounted under the boat shows only speed through water. We don’t use it much anymore. Instead, the GPS take in account the drift and the current and give the true speed SOG (speed over ground).
There are plenty of good brands around. We use a Raytheon NAV398 as our basic unit, and a Garmin 12 as back up. They both work great.
While this is great in archipelagos, harbours, and the Caribbeans, it is not really useful when it’s just your little boat and 15000 feet of water beneath (unless you are checking for whales).
What you want to know is what is in front of you – and as close to the surface as possible. Containers floating around for instance - hitting one of those under full sail will sink your boat in no time.
Forward-looking sonar will theoretically give you a chance to detect containers and other big things close and beneath the surface. If it works? It didn’t for us. Waves constantly triggered false alarms; large fish under the boat scared us silly – so we ended up simply turning it of. But we still thinks it’s great at shallow waters and to check for fish. The forward looking sonar is also great when approaching shallow waters in order to estimate approaching ground as opposite to the grounds already excisting under the boat.
We use a Probe from Interphase Technologies and are happy with it.
On the Ocean we use the Radar mainly for detecting squalls that could bring heavy wind, and thus give us a warning for adjusting the sails.
The downside is that a Radar need a lot of power. And we mean plenty. Your best bet is probably to switch the Radar on for a short while every hour or so, to scan the area when out at sea. If you have plenty of power on the other hand, the Radar is a great companion at long night watches, warning in time for approaching objects.
The Radar we used was a Pathfinder SL70 from Raytheon. When approaching St. Lucia in the middle of the night at landfall, the Radar failed (the cursor stopped moving) and we have to navigate through the reefs and squalls by GPS and Sonar only. While batteling one extra heavy squall, we almost run into a cliff, and were just seconds from ending our passage in the same fate as the original Santa Maria.
We sent the radar for repair, got it fixed, it still didn’t work, we returned it again and eventually got it back in order. We are however not happy with it yet. The power consumption is huge and it sometimes fails to notice even large and close ships, no matter how we adjust the gain (the sensitivity).
The Radar has a feature that gives a warning sound when a ship or a squall moves into a certain range. When you are out on the Atlantic in 12 feet of waves however, the Radar gives alarms either constantly or not at all.
We had our radar antenna mounted aft, on a 7’ radar mast. Most other boaters mount their Radar mid-high on the mast and we will probably change to that position on our next boat.
Our log gave in after two weeks. We sent it for repair but haven’t been able to get it to work since. Have to admit though that we haven’t spent too much energy on it.
We check it for deviation once in a while, but it is always accurate. Only fault is the compass-light not working, so we simply use our head torches when steering at night. We also bring a simple handheld $ 3 compass for emergency.
The wind vane worked great in up wind but lousy on down wind. The autopilot was the opposite. So we found a system working them both together and didn´t need to hand steer at all during most of the passage. Several days before land fall however, the autopilot died.
The loss of the autopilot gave us four days of hand steering at the end of the passage. It was hard since we were only two, but also awarding since it forced us to look more intensely at the sky and the sea.
We had brought a brand new autopilot unit with us as a back up. This one we mounted on St. Lucia and have used it since. It hasn’t been tested in storm yet but seems to work fine.
It’s a Raytheon ST4000 and is said to be a little too weak for a 37 feet boat. The next step up required some additional 5000 dollars however, so we decided on it anyway. The electronic display is very simple and useful. It is silent and doesn’t use a lot of power. Actually, we haven’t even had to use the wind vane since we installed this AP.
The wind vane is useless in light wind and work better the more wind you have. In high wind the autopilot may burn and/or stop working. When the wind direction changes back and forth, the wind vane will give you a smooth and sail-effective ride, compared to the autopilot.
There are different kinds of wind vanes.
The one used at Santa Maria is an auxiliary rudder fitted to the stern of the boat. Attached to the rudder is a wind vane made of sailcloth. You operate it by steering the boat to the desired angel of the wind, climb to the aft and tighten the wind vane in the position it has at that wind angel. Often you´ll have to do this a couple of times before you get it right.
When the wind force changes, you´ll have to adjust the vane again. Our wind vane is not as smooth as we would like it to be. Attaching a small trim tab at the back of the auxiliary rudder would probably fix that.
Most blue water cruisers use a servo pendulum unit. It is a masterpiece of mechanics and will surely bring out the kid in every captain. While at the Canary Islands, we had a French family preparing for the crossing next to us at the dock. During the entire week, the husband never stopped adjusting and making improvements to his very dear servo pendulum unit.
Instead of a sail, this vane uses a lightly balanced piece of thin plywood for catching the wind. The boat is set on course and the vane is aligned with the wind and then fastened. When the wind push the vane from either side, it will bend down. A servo-rudder will then change the course to the desired. We don’t have any hands-on experience with these units, but have been told that they work very well – probably even better than ours.