There is a strong tendency on my part to be attracted to the latest new, shiny "gee whiz" gadget. I'm pretty sure that I am not alone in this. But you have to go pretty far up the gadget cost scale to get something that can top the good old hand bearing compass.
A recent crossing from Port Madison to Shilshole provides the case in point. Just as we cleared Jefferson Head, a tug and tow became visible, heading south in the southbound traffic lane. I pulled out our trusty old hand bearing compass and took bearings on the bow of the tug and the stern of the barge it was towing. Then after a few minutes I took the bearings again.
The old adage is that if the bearing is not changing, then you are going to collide. And tug-'n-tows are long enough that you need to keep track of both ends of the combination (NEVER try to go between a tug and its tow!).
But when I took the second set of bearings, I noticed that a second tug and tow had appeared from behind the first - he was in the process of passing! The problem just got more complicated.
Clearly one tug was going faster than the other (he was passing, after all). Now the choices had become:
- Pass in front of the entire parade
- Pass between the barge in the first tow and the tug in the second
- Wait for the whole parade to pass and cross behind the last barge.
We did this bit of piloting with a lowly hand compass.
To do it with electronics, you'd need to have a GPS-interfaced AIS receiver, or a multi-thousand dollar radar with MARPA capability.
Or a hand compass.