Mounting a transducer on a dory??? help

[CrazyFish]

My boat is a 21' wood dory with the forward motor well. I mounted the transducer on the back of the boat but the signal dies after about 10mph (I think since the motor is forward of the transducer).

I'm thinking of 2 options to fix this:

1)Mount the transducer in the motor well, but this would put the transducer within a few inches of the motor. So I'm not sure how this would work.

2)Trying a through hull transducer. So far what I've read about mounting a through transducer they only work through solid fiberglass. My hull is made up of 2 layers of plywood and paint.

The FF is a Garmin 160 Blue and I know that it worked great on my last boat at high speeds.

Has anyone run into this before and if so what is the fix.

[Sensei-san]

Mounting a thru hull transducer works on any boat. If you look at the airmar website, http://www.airmar.com/install/install_index.html they have information on installing thru hull transducers.

It sounds like you are getting air under the transducer at speeds over planing speed. A thru hull transducer properly located should solve the problem.

[Mark Mc]

Hello Sensei, how ya been? I think what crazy meant was that setting a transducer inside the hull, without actually penetrating the hull, only works on solid glass. I'd modify that statement to say that solid glass is best, solid aluminum or steel are good too, wood is next, and any material with air in it (balsa or foam core) would not work. Crazy, I can tell you that a transducer in a bag of oil worked fine on my brother's old wood plank boat. So you may as well try it first; doesn't cost you anything. Your idea of putting it in the motor well could work if there's room for it. If it gets it out of the bubble trail, you're home free. Perhaps you could rig a way to try it. If that still doesn't work, then think about cutting a hole & putting a true through-hull with faring block outside the hull. If you have a real flat spot on the bottom one can mount the transducer flush with a hole but that is something (IMO) that should only be done by an experienced boat builder. Good luck....Mark

[fish assassin]

CrazyFish,

You have what is a common problem with dories ... there is NO good
place to put the transducer so that it will pick up the bottom when
you are running. One solution I've seen for this is to mount the transducer
on a pole that slips into a bracket on the back of the boat. This will
put the transducer a little deeper in the water and allow for it to read
when going a little faster. Only problem with this setup is that when
you want to run FAST, you need to pull the transducer up & out of the
water. Also, when you land your boat on the beach, you wanna make
*real* sure it's in the up possition or you'll tear it off the back
of the boat.

Hope this helps!
-assAssin-

[edsr]

CrazyFish - I am facing the exact same problem with my dory. The only solution that makes sense to me would be to mount a tube within a tube on the inside of the well beside the engine mounting bolts. A square tube within a tube would allow you to raise and lower the transducer easily from inside the boat. This would save any through hull problems, and still allow you to adjust the transducer for best reception. The unit I have does temp. and speed as well as depth etc. and so inorder for the speed wheel to turn it must be in the water. The end result might be that we finally do the thru-hull route but it is worth a try. The folks at Rogers marine didn't think shooting the signal thru the hull would be a good option, however each boat is different. The bag of oil trick sounds like it is worth a try. As I understand it the bubbles, i.e. air spaces are what really degrade the signals. Keeep me posted on your experiments and I will do the same.

Sensi-san, MMc, and FA, thanks for your input.
edsr