H'Bird won't read bottom at high speed

[PFUNK]

Was hoping someone might be able to add some insight as to why my dad can't seem to get his transducer to read at speeds over 15 mph. Got a Humminbird 385ci for ice fishing that he just moved over to the boat. Installed the transducer per the Humminbird manual but once he hits 15 mph or so it loses the bottom. Also is throwing a rooster tail but H'Bird is sending a rubber plug to block the space between the bracket arms that cause the rooster tail. Any idea why this thing isn't keeping a lock on the bottom? Here are some photos of the transducer mounted too. It is the one on the right, the other one is an old one.

[scott b]

Might be because you are out running the return signal. Tip the transducer down a couple of degrees so it shoots the signal forward. This should help you get a better return reading. Might make more of a rooster though if the transducer is too far below the bottom of the boat. I'm no expert but that's what I would try. Good luck.

[PFUNK]

The thing is if you tip it forward one click it goes too far forward and I don't think that it would give an accurate reading once the speed is reduced to a trolling speed. I just think there has to be a way to make it work. If they can work on boats doing 40 mph or more, they should easily be able to work on one doing a top speed of 28. I thought maybe lowering it down a bit might solve the problem, but we'll see. I sent the pictures to an H'Bird rep as well so I will have to see what he says. I was thinking some other H'bird owners have had this same issue and would have some advice.

[PerchJerker]

The problem is in the transducer mounting. Get it adjusted correctly and you should be able to hold bottom at the speeds you're talking about.

I can't tell from the photos, but the transducer should be in a location where it is getting as "clean" of water as possible off the hull --- ie. no rivets or seams or ridges in the hull ahead of the transducer, etc. If the transducer is running through water that has been diverted by these types of obstructions, there will be cavitation (air) in the water and you'll lose the reading.

Lowering the transducer may help.

Also, I would push the back of the transducer down a click or two (back goes down, front goes up). This should result in a smoother flow of water going over the transducer and that solves many problems. I'd try this first, before I tried moving the transducer.

Good luck getting it figured out.

[scott b]

At trolling speed my boat is at a 25 degree angle with me in the back. Just a thought.

[Ed Carlson]

You have a strike right in front of the ducer. For optimal bite at plain you need to move it to the center clear of the strike and angle it down 10 to 17 degrees to bite at plain. If the drain plug is in the way you may need to move it to the right. Or, epoxy a ducer mounting board on the back and drill out a hole to accommodate the drain plug so you have a wider range to adjust the mount to the center of the boat.

I think your getting turbulence from the strike that is distorting the water flow over your ducer.

[PFUNK]

Thanks Dave... he is going to try that before moving anything around. I believe the photo may be a little deceiving in the way it makes that strike look like it is right in front of the transducer. I'm pretty sure the transducer is actually to the right of that strike. He told me he avoided as many rivets and ribs as possible, so I am guessing that the transducer is actually not right behind it. He tried as best he could to look over the transom while driving the boat to check for cavitation coming from where the transducer was, but said it looked like it was in a good dark area of water. He is going to try playing with the angle and if that doesn't work, might drop it down a little lower and see. I will update if he gets it figured out. Not sure when he will have time to get the boat wet next. Thank you all for the tips.

[CAMAN]

The strake actually looks 3-4inches to the left of the 'ducer. The problem I see is it is getting pretty far out from the centerline of the hull. I would relocate it so its between the strakes, best place looks to be where the old ducer is.

[Ed Carlson]

Ah..ok...it is the one on the far right, I should have looked closer I thought that was a speed censor. Plain enough if I looked closer....I should wear my glass's more often.

Yes I agree, it should be moved closer to the center. That hull is fairly flat yet I too suspect cavitation causing problems that far out on the hull.

[Cliff Wagenbach]

I agree. Move it to where the old transducer is mounted and move it down a little. A rooster tail with a decent high speed reading is better then no high speed reading!

Had to settle for that on my boat!

Cliff

[Deitz Dittrich]

Just to echo others, you have it mounted right on the strake.. its not getting clean water at speed.. Hence why you are not getting a reading.

[PFUNK]

The reason he has it mounted so far off the the right is that they state in their manual it must be at least 15 inches to the side of the prop. Sure would make sense that if the old one worked fine where it was the new one should work there too. PS... you guys are good!! Rep from Humminbird took a look at the pictures and got back to me today... said try moving it closer to the center because of this being a very flat hull. Also said try tilting the back end of the transducer down just a bit.

[Nick Kuhn]

Mine works fine and it is pretty darn close to the prop. And yes, mine is low enough that it throws up a bit of a tail, but not nearly as bad as before I installed the rubber plug.

[1750FH]

make sure its on 200 hrtz wont read bottom at higher speeds on 83 hetz

[PFUNK]

Yup.. got it on dual frequency.

[Bigtom]

I just installed mine as it says in the instructions except the transducer is about 10 inches from the motor. I tested it today and it worked flawlessly 0-38mph. I was so happy that I ordered another one.

[PFUNK]

So an update on this problem. The transducer was moved to the left side of the boat much closer to the motor like the old transducer is mounted. It now picks up the bottom at any speed, but the signal gets very weak. Rather than a nice strong reading, the bottom appears as a very thin line. This doesn't sound normal and I am worried it wont be picking up the most important things, fish close to the bottom. Anybody else have this problem?

[TurnUpTheFishing]

Ive got a 798 and it doesnt read well over, about 12mph. Im ok with it though, when Im running WOT and on plane Im not really in search mode Im just going to different spots. I can use the gps chart or my knowledge of the lake to navigate shallow water.

I can understand someone wanting to have their unit run perfect even at high speeds but personally I dont mind it, the trade off of having to do a bunch of in-and-out of the water and putsing with the trandsducer isnt worth it to me.

[Cliff Wagenbach]

Is your depth finder in auto or manual mode? I always run it in manual mode so that I can max out the ping speed and increase the power so that I can pick up more on it.

Cliff

[PFUNK]

I don't think you can change ping speeds on humminbirds. Unless you can and I just don't know how to.