Compass Question No. 2 -- Best type of compass for a C Dory?

[Les Lampman]

Y'all know I've espoused on this in the past (sometimes at great length!)!

The problem I have with compasses on small boats is that they're not usually swung and they're often not very far from things that affect their accuracy.

From a boat provider's standpoint I'd rather deliver a boat with no (mounted) compass with a complete understanding of what you need to do in the case of an electrical failure than a boat with a compass that the operator thinks is accurate and isn't. It gives a sense of security that is false.

I can't tell you how many times I've sat in the helm seat of a boat, spun the wheel, and watched the compass spin with the movement of the steering cable. Not good.

In the last few years most of the nav systems we've installed have featured radar overlay. In order for that to work the nav system needs a fast heading update input. The GPS is too slow with its 1 second updates. What we've usually installed is the KVH Azimuth 1000 electronic compass. This sits up on the dash just like any other compass (so you have something to look at) and it also feeds heading information to the nav system (via NMEA 0183) at 10 times per second and this keeps the radar overlay (as well as MARPA) happy.

The KVH is also not as affected by the closeness in a CD22 (or similar) of the wiper motors, display, etc.

So, when someone asks me what compass to install on a boat the KVH is my "go to" recommendation. Why isn't it in the Marinaut 215? It wouldn't fit...and bitterly disappointed was I. So I installed a Ritchie Explorer compass on the dash and a remote KVH heading sensor.

If you don't have a nav system that can utilize fast heading update and/or if you don't want to spend the money for the KVH Azimuth 1000 then by all means install some compass if you like but then figure out how accurate it is before you follow it blindly.

Most folks can't steer a compass course worth a darn. Why? Because it's hard work. It takes concentration (usually just when other things are going on demanding your attention) and it takes lots of practice (knowing your compass, your boat, and anticipation), practice most of us don't get. It's a LOT different sort of following a heading on a nice day then it is when visibility is zero-zero, the water is rough, you're in shipping lanes, and there's debris in the water. For that reason most folks have a chartplotter, set a waypoint, then follow the course on screen (a steering screen is nice for that).

That's also why a preponderance of our boats have an autopilot (under $1,000 now if you have hydraulic steering). I'm not trying to give folks a way to set it and take a nap, I'm trying to give folks a tool that keeps them on course when the stuff hits the fan and when stress levels are high enough; when most folks have the hardest time staying on a compass course. I don't consider it a toy, I consider it a tool...and a safety item on top of that.

So what happens when the boat has an electrical failure or the KVH stops working? In the case of the KVH going up in smoke the nav system will still compute heading and course over ground. In the case of an electrical failure nothing else is working so it's time to go to a back up. For most folks that's a hand held GPS, many times with charting capability. Nowadays that can be an iPad or iPhone. Oft times it's both. If you have to go deeper than that then I go to a hand held "dumb" gps unit that just gives me lat & lon, and that bit of information with the accuracy we have now I'd have killed for 20 years ago. With that and a paper chart I still know where I am. And in the case of a complete electrical failure I always carry a hand held back up compass. If the main nav system went up in smoke then the KVH compass is still sitting there on the dash doing its thing. It's easier to read (for most folks) than a small compass and it doesn't swing all over the place so it's easier to stay on course.

As always...use what you're comfortable with but make sure what you're comfortable with isn't lying to you.

Also, this has zero, nada, squat to do with offshore work, everything I'm talking about here is in the context of small inland based power boats.

Les