GPS Chartplotter

A Chartplotter is an absolute must for comfortable and safe navigation.

I decided to purchase the EchoMAP 50 from Garmin, had some “bells and whistles”… first, in literal sense. I installed an audible alarm (connected two small 12 V beepers in parallel, and two - for redundancy, in case on failed… plus the two made a much more shrilling noise than just one… I would wake up within about 3 seconds when the alarm goes off, no matter how tired…). The beepers can be disconnected via a switch. The chartplotter has a 100 mA alarm output, each beeper consumed about 30 mA, so there was no problem to connect them directly. The Chartplotter has many useful alarms, two of which I use constantly: anchor dragging and minimum depth. This gives you really a peace of mind and allows you to sleep well when the conditions are not in your favor (wind/waves ashore, tight areas, etc). When navigating, I set the depth alarm threshold to about 16 meters, and when on anchor I set both the depth alarm (usually to a couple of meters above the actual depth where I am anchoring) and the anchor dragging alarm (usually to about 60 meters).

I installed the chartplotter on the startboard side. I think a much better location would have been on the port side, because of two issues:

When there is no strong wind (i.e. the boat does not list), I prefer to sit on the port side, because I have a better view of the starboard side where I have to give way to other boats and I do not have to turn my head around so much.

In waves, I often must sit close to engine, to be able to cut-off the accelerator should the propeller come out of the water and engine start overspeeding. So while sitting there, I cannot watch the Chartplotter.

However, the halyard winch and all the lines are led to the port side, so it was not possible.

Chartplotter Installation Location.

I installed the ecosounder of the Chartplotter (the sensor) inside the hull in the bow part. It works perfectly well and did not require any perforations thanks to the single-skin design of Catalina 22. Initially I was skeptical it would work, but I get a firm numerical reading of up to about 50 meters (depending on conditions, between 35 and 90 meters), and when I visually follow the depth graph, almost always one can get down to 150 meters before loosing the signal. I felt that it was much better this way, having slightly reduced depth range, than having a through-hull and even worse, an outside-mounted sensor.

By the way, the standard sensor which came with the Chartplotter was for the outside mounting. I grinded somewhat the hull skin inside and embedded the sensor in regular clear silicone. Although the installation in the central rear part would have been easier, I decided to route the cabling to the bow.

There were several reasons for that: first, it was about 3 meters forward, and that is about 1 second earlier warning at full speed (5 knots). May save me some day... Second, it is placed in front of the keel, so when you are feeling your way through very shallow rocky water, it obviously better to have the sensor in front… Finally, it is naturally inclined somewhat towards the front, so I hope that I would get a slightly earlier warning if rocks are ahead…