Just a note on transducers,
Most of them shoot their signal in a 20 degree cone configuration (imagine an
ice cream sugar cone upside down). Meaning that's why one can get away with
mounting the transducer somewhat close to the keel. This also means with a 20
degree cone angle, the bottom area read will be larger as the depth increases.
Not so important to the Sailor, but critical to think about if you're actually
after fish. The fish you see coming into view at 10 feet may be under or
astern of the boat while the ones at 50 feet may be ahead of the bow. Also to
think about is where the transducer is mounted, towards the bow may be more
prudent for the sailor as the items comeing into view will be shown sooner.
>From my experience, there isn't much point in a depth sounder to keep you off
the rocks as you are sailing. Reason being the cone angle and the fact that
your moving toward your target to avoid, and if you're healing the reading will
be a falso one as the cone will be pointing away from the structures under
the boat. If we were sailing in a larger craft, we would probably opt for a
forward reading sonar. The signal is sent out forward to do an efficient job of
spotting coral heads and rock outcroppings (read expensive).
Also from experience, I'll never be without a depth sounder for the reason
Howard mentioned to get an idea of bottom structure for anchoring and for
spotting schools of fish.
Bill SF Bay
M-17 #496 "Tiperary"
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