lose bottom signal above 20mph w/104c

[eyechsr]

I cant seem to figure out why I lose my river bottom signal when I get above 20mph? I have tried changing the angle of the transducer,adjusted my sensitivity and even changed shich side of my transom I had the ducer mount too, nothing seems to help.
I also have a 19c in the back of the boat for when I use the kicker and it seems to work great. And I have turned the 19c off so it didnt interfer with the 104c.
Any ideas?

[Guest2]

Chances are the interference is cause by turbulence coming off of the underside of the boat. Mine acts the same way. I think all you can do is tweak the placement of the transducer.

[icatcher1700]

Make sure your transducer is submerged in a 'clean' flow of water. If it is inline to a row of rivets or anything else producing a stream of bubbles, moving readings can be affected.

I had the same problem with an X-51 last year. After going thru all the transducer moves and stuff, it turned out the transducer itself was f.u.b.a.r. Lowrance replaced it for free, and upgraded it to include temp. - I thought that was pretty good.

[fishhunter]

That has been the only problem I've had with lowrance. In all the graphs I've used lowrance is the hardest to get set right for reading at speed. You just have to keep adjusting on the transducer until you get it in the sweet spot.

[Dave S.]

I had this type of problem last year and it was convinced it was transducer placement. After a couple extra holes in the transom and a lot of wasted time and testing Lowrance sent my a new transducer and it worked great.

That may be your problem. They act real goofy like that when they are bad.

[REW]

Your problem is not uncommon with the transducer placement on many boats - this is true both for glass as well as aluminum boats.

The problem that many folks have is placing the transducer in an area that is not in "clean" water flow.

Before you ever drill the first hole in the boat (too late for you), you need to take the boat out on the water and see where clean water is for you on your boat.

Have a driver and a tester in the boat.
Have both folks wear life jackets.
Then, with someone driving, and the tester looking over the transom - observe the water flow - as the boat moves from an idle, to mid range to wide open.

Have a black marker along, so that you can make a mark on the back edge of the transom to mark where the clearest water flow is located.
You might find that you have no clear water flow. Hopefully this is not the case. You might find that you have to mount the transom on the extreme edge of the hull, which is contrary to the normal mounting instructions.

Then, when you have the location located, you can screw the transducer to a 2X4 and use a c clamp to clamp it to the transom. Repeat the test before drilling holes, to insure that everything is ok.

Bottom line - if you get the transducer located in clear water flow, and if you have no bubbles or turbulance flowing over the transducer, you will get good readings at every possible boat speed.

p.s.
If you have a glass boat, you can epoxy the transducer inside the boat to avoid all of these problems.

Take care
REW