Centerline, how far above the waterline would this installation be.?..I'm thinking back under the quarterberth as O'day put several easily moved teak hatches back there...I'm not certain the most aft of the two is close enough to the waterline using the pvc pipe as described above.....also, how big is the transducer in relation to the pvc pipe....I'll take it out of the box and try to answer my own question......Patrick
im not entirely sure I understand your question, but I'll do my best to answer.
one thing I want to make absolutely clear is that, we are
NOT cutting a hole in the boat and installing a pvc pipe to put the transducer in.... this is a "shoot thru" installation, without any holes. it works just as well as a direct "water contact" installation, but has many benefits that an exterior mounted transducer does not have.
so.... inside the clean, dry, holeless, hull, the transducer mounting is not above the waterline... the trasnducer should be mounted somewhere towards the center of the boat where the hull will never lose direct contact with the water in rough conditions.
any air bubbles that pass under the transducer can cause it to lose its signal, and sometimes it takes a few seconds for it to regain.... this is very aggravating when trying to read the meter.
as for the waterline that may be
inside your boat
, it doesnt matter because the transducer is waterproof.
the pvc pipe is only a vessel to hold and protect the wax inside of it, because the toilet ring wax can be messy if it is left exposed... it also causes less wax to be needed, as when you pour the hot wax in, the pvc only needs to filled til the top of wax is level inside it, so the transducer will set level on it
the pipe size in relation to the transducer matters little, as long as the transducer will set inside of it..... when I used an older garmin transducer, the pipe was bigger and I formed it into an oval shape so the transducer fit with a very slight bit of clearance all around, I then cut the angle so it fit the hull perpendicular, and then cut it to length. it was only 1" high on the short side and only had about a quarter inch of wax in it on the outer edge....
on my 34 with its compact little nasa clipper transducer, its only about a 1.25" in diameter (round), so I used piece of 1.5" pvc and did not have to form it, but stuck it to the hull and poured the wax in.... and placed the transducer.
I like to place the transducers in a location where I can support the cable above the transducer with a tie, so the cable does not come directly out of the unit and flop/bend over and lay in the bilge, but looks like a professional installation.