this is the cheapest way but you have to drain the water out every time you check it. you can put it right on the down rigger cable.

http://vexilar.com/pages/products/products_deptherm.php

that's a great idea forry but i was hoping for something a bit more creative/accurate.

the vexilar device is just what i was looking for - cheap and hopefully fairly accurate...thanks!!!!!!!

I guess I am an old yankee. that is a great looking rig. it must tell you how deep you are by measuring the pressure??? not really sure. but it looks good and no need for velcro or tape.

i have a really old one, the water fills up to a certain point and you read the depth from that water level mark. they are not perfect but it will get you close. one side reads the depth with the water level mark, the other side has the therm and with the water in there the temp reading doesnt change much as you reel it up.

the water pressure must equalize with the spring tension that opens and closes as the unit goes deeper

The Fish Hawk TD looks like a real good option for the price.

http://www.fishhawkelectronics.com/shop/category/handheld-temp-meter/

Mac