The "shot" angle is determined by the frequency used. You will usually have a choice of 50Khz, 125Khz and 200Khz.
Any transducer can be mounted inside a glass hull. There are two methods. One is to build a box and fit the transducer inside it. Then fill the box with
oil. The other is to
epoxy the transducer directly to the hull. I have had success with both methods.
The glass hull will attenuate the signal to some degree. The thicker the hull, the more it is attenuated. But it is not so much that it will render you finder useless in 60ft or less. You will still have very good soundings down to a considerable depth.
The only possible problem you could have is an air void in the glass
layup. These days that should be rare. The easy way to check is to place a grease like substance like KY gell on the transducer and place it where you want to mount it. That way you can test to insure it sends through the hull OK. Then bond it down. The ease of using
Epoxy is that you can either use a ready nmade thick glue, or add a thickening agent to resin and then you can place the transducer on the hull at the angle you want it to aim straight down.
The only other comment I can make is to make sure you are not sitting over or too close to a
keel. If it is too close, you can get eroneouse readings bouncing off the
keel. Once the sounder gets into too deep a
water, the sounder will lock onto the keel reflection and give you a false reading. The
danger is, this reading may not be just a foot or two as the keel maybe away from transducer. The reflection can sometimes be something much different and you maybe fooled into thinking you are good
water depth till it shallow enough for the sounder to once again lock onto the bottom and then it maybe to late.