Sunday, January 29, 2012

The Price of Ice

Last summer while visiting Tracy Arm with our friends the Crowders, we did a tour down to the snout of the North Sawyer Glacier (Crowder visit).

As we were viewing the glacier a nice chunk fell off. We were about a half mile away so I wasn’t worried about the wave but I maneuvered the boat (we had been in neutral just bobbing along) so as to take the wave on the bow. At the time there were “growlers” (see ice sizes) in the water nearby. As the splash waves passed underneath the boat, we began to “hobby horse” a bit. Unfortunately during one of the cycles, some ice was underneath the bow area. We heard the thump but had no concern about damaging our steel hull.

That evening, as we entering the anchorage for the night, I turned on our forward looking sonar (FLS). Unlike a downward facing depth sounder, the FLS is oriented forward and can give you a heads up about what is in front of you (how it works). The FLS display screen simply showed a line at a 45 degree down slope. Having anchored in the same spot the day before I knew that wasn’t correct. Since the FLS worked fine up until then, I feared that it might have been damaged during the ice “thumping.”

Flash forward six months to the middle of January, we had a diver inspect our bottom paint and zincs for wear. We also had him inspect the FLS transducer. Sure enough, the transducer shows its impact with the ice.

Although the transducer is, in theory, replaceable while the boat is in the water, we’ve decided its replacement can wait until we have the boat hauled at some point in the future as part of bottom maintenance or other work. In the meantime, I’ll be more careful around ice.