I have no idea what would b best but, how'a'bout a transom mount transducer?
That is where ours is now and probably where it will stay. When we got the boat the ...
...depth finder on the boat had....
...... its transducer mounted just ahead of the ballast tank in the bow. The depth finder was hard to read from the tiller as it was on the port side of the cockpit up by the cabin.
I also believe you don't want the transducer on the ballast tank for the reasons stated. The problem up in the bow is that the sides of the boat slope so sharply there that the transducer is shooting at an angle and showing depths greater than what they are. You usually can set the off-set for this, but you still aren't shooting where you are going.
That depth finder is still in place and works most of the time. We added a second one last fall. A Cuda 350....
http://purplesagetradingpost.com/sumner/macgregor-navigation/Cuda 350.html
...that also has GPS and can send the GPS coordinates to another device and we use that function as we have a VHF that has DSC and the GPS sends our current location to it at all times. If we had an emergancy the DSC would send out a repeating distress call along with our present location and we could concentrate on the problem.
I considered locating the transducer for it aft of the ballast tank, but then you loose the temperature feature, so just decided to try it on the transom....
....and so far we like it there. It is a little further from the prop than the instructions call for but occasionally it will loose the bottom for a minute and I think that is because of air stirred up by the prop. At some point I might move it over by the ladder.
I don't think there is much difference than up by the bow in most instances, especially in Florida where the depths usually change so slowly. I doubt most people watch the dept continuously. We don't even with it right next to ....
...the person on the tiller. Above it was slid forward away from Ruth on the lifeline to where I had been sitting prior to taking the picture. If I'm not watching it we slide it back next to her. We love it mounted on the lifeline. If we are getting in shallower water we start looking at it more often, but don't feel having it 20 feet further back is that big a deal.
If we are anchoring and are trying to get into as shallow water as we can we are on the outboard and moving forward very slowly as we approach land. Ruth calls the depths out to me and I'll decide when to lower the anchor. Works for us.
Besides having the temp with it on the transom it is also easier to clean or replace if needed. The negative is that if you are in water with growth, you will have to clean it. Inside it stays clean.
Our original one seems to work fine and whoever installed it used the wax that you use to set a toilet in place and did not use epoxy. I'd try that approach first myself,
Sum
Our Endeavour 37
Our Trips to Utah, Idaho, Canada, Florida
Our MacGregor S Pages
Mac-Venture Links