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Kayak fishing the Lone Star State...

By Number19
I have an older model Ocean Prowler Trident 11. I'd like to mount a fish finder (my first) inside the hull with a shoot-through-hull transducer.

According to instructions found on the Net, the unit has to be located on a flat section of the bottom.

That's my problem. No part of my kayak's bottom is truly flat. At the location where I'd like to place it, it is the most near to being flat. But it still has a very shallow Vee profile; no more than 5 deg, but possibly slightly less.

Right now I'm stumped. Anyone have any comments or suggestions?

The only thing I can think of is to forget about placing the transducer inside the hull, but this would be a last resort.
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By Neumie
I would place it on the flattest possible location you can reach and install it there. The main thing you need to watch out for is making sure there are no air bubbles in between the transducer and hull.

Note that your temperature readings will be off and internally mounting a transducer will not work with side imaging (and possibly down imaging).
By Number19
Thanks for the two responses. I've continued researching and I'm all over the place on what I'll end up doing.

I've now found several comments, instructions and illustrations that the bottom does not need to be perfectly flat. One set of instructions said that as long as the Vee does not exceed 15 deg the installation should be OK. My Vee is very shallow, no more than 5 deg, so I no longer have this concern.

The vast majority of instructions seems to favor Duct Seal to secure the transducer. Many comments warn about the air bubbles.

With duct seal, I see no way not to have air bubbles. Several posters said this can be seen by pressing duct seal against a car window. Also, common sense tells you, when you press the duct seal against the hull, or press the transducer into the duct seal, you are going to trap some air in the interface between the two.

So I'm giving some consideration to a waterbox.

The waterbox I'd be using is to attach a PVC pipe to the hull using duct seal. After filling with water and installing the transducer, I'd further seal the top of the box with duct seal, making it a closed system. Comments?

Using duct seal is clearly the most simple; but a water box may give better readings. Comments?

I'd initially favored a Lowrance, but it seems they actually do not recommend using "shoot thru hull" and have no transducer for this mount. Humminbird does and this is now my choice. Initially I leaned to the Helix 7, but the 5 is now my choice at 1/2 the cost.

The question I now have out to Humminbird is whether their included Transom Transducer can be used for "shoot thru the hull" or do I need to upgrade to their transducer made specifically for this. Comments?

Having never used a fish finder before, I had no idea there was so much to consider.

Thanks for comments.

(edit) I just now saw the link to Tom's Tips. Good link. Good instructions.

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