Transducers have a cone measured in degrees or what might be called a beam angle or beam spread. A transducer does not need to be pointed straight down as long as a portion of the acoustic cone points at the bottom. The problem with a sailboat, especially a monohull
, is that they heel and sometimes significantly.
Lets say the beam angle is 30 degrees for example. This leaves you 15 degrees for a port tack and 15 degrees for a starboard tack. If your boat heels more than 15 degrees and your transducer is pointed straight down with respect to your hull
, then you will get no sound signal back..or worse yet a degraded signal from things that are not directly below you giving you a false reading that the water
is deeper than it actually is.
You can buy or make a plastic wedge with a hole in it so that the transducer points downwards....but then you do take an increased risk of it shearing it off if say a log hits it. I have seen guards on large transducers on the upcurrent side of the transducer head
specifically designed to protect it...but that may be going through more trouble than it is worth for you. I have four very large transducer heads located on my research
boat that are flush mounted, eliminating the problem of them getting hit by something, but again, flush mounting may not be worth it for you.
If you have the option of a bronze transducer head
then I would consider one because of the decreased risk of it being sheared off if something large hits it.
The manufacturers specs have the beam angle of your transducer....so that should help in knowing with certainty what you can and cannot get away with.
Transducer Beam Spread