Lowrance 3500 Depth Finder

[gibbywmu2000]

Hi Everyone,

I've had the original Lowrance 3500 Depth Finder in my boat (Its a '97 Powerquest) since I bought the boat in 2002. I don't really think it works anymore. I've tried setting the shallow and deep alarms many, many times, but all it does is seem to flash. I'm sure it needs replacing. Now, where is the transducer for it? My boat is on the trailer, and I don't see it anywhere? Is it hiding under one of the trailer bunk? (I hope not, won't be able to replace it).

I'm really not sure if the display is bad, or the transducer, or both. Honestly, I don't even remember seeing the transducer underneath my hatch. I guess its possible that its directly next to my bilge pump, but I've never even messed with it. All it does it flash, no matter what setting I put it on for shallow/deep water.

Need a recommendation for a low cost unit, just need depth. Nothing fancy. Seems like an easy replacement? I'll attach pics. Sorry for the "red" tint, I took the pics with my red cockpit cover on.

 

[21BaylinerCC]

The transducer is most likely inside the boat, along the bottom of the hull. Personally, I am not a fan of those types of depth finders - that may just be because I fish and those do not show any underwater structure!
If you cannot find the transducer, I would look on the internet for a cheap/used depth finder. Best of luck!

 

[gibbywmu2000]

I thought I read online that these transducers are thru hull? So, it should be in the engine compartment somewhere. I don't have access panels that have storage or anything throughout the entire boat, so I would think it would be in there. I didn't see anything on the bottom of the hull. Worst case, I'll have to trace the transducer wire back from the gauge all the way to the engine compartment. Hopefully I can find it then!

 

[Offrddrver]

Gibby,

I have the same Lowrance 3500 unit in my 1992 Four Winns 190 Horizon.
On my boat you can't miss the transducer.
Mine is literally built into the bottom of the boat.
From the inside of the boat you see a couple inch in diameter and couple inch tall black tube with what appears to be a screw down compression type cap.
This is located under the motor in the bilge area.
On the outside/under the boat, you can see a black circle (on an all white bottom boat). Flush with the gel coat.

Kind of interesting to think they drilled a hole through a boat to mount an electronic device. (electronics in water will ALWAYS fail at some point)

Best I can tell these are obsolete. Also, I read the transducer won't work with other units as they no longer use the same frequency on new units.
Best to go with an aftermarket and attach the transducer to the back of the boat.

My 3500 unit got blown when my battery shorted out internally. Along with my stereo, base AMP, and fish finder. Never did figure out why, as all factory fuses were good even though all components were blown. I now keep a close eye on my battery liquid level.

Offrddrver

 

[gibbywmu2000]

Thanks Offrd!!! I'll probably buy a new one next spring and install, so late in the season here to even worry about it anymore. I found the transducer, must be glued on to the bottom near the bilge. Wont budge at all. I have to move my speakers in the engine area to get to it. I'll probably have to take a putty knife and hammer to knock the thing off. I could have sworn I checked the bottom of the boat and there is nothing there..........is that possible? Maybe this type of transducer is ultrasonic and doesn't need any exterior components?

Or, I could just leave that old one on, and stick the new one on right next to it? Thoughts?

 

[smokeonthewater]

Yes if it's simply epoxied in the bilge you could leave it and epoxy in a new one...

Myself tho that would but me n I'd grab a chisel n pop it out

 

[gibbywmu2000]

Thanks smoke! I'll for sure do that next year.......or at least order it now and then install it in the off season or next spring.

 

[Offrddrver]

Gibby,

I re-read my comment above and wanted to clarify the mounting of my transducer.

The whole unit is epoxy'd or some type of resin based glue mount. However, around the transducer is the nut with the compression part inside. However, removing that nut doesn't appear to allow anything to move, and I don't dare try to force it out as I can clearly see the black circle under the boat (flush with the white gel coat), meaning some part of this is drilled and mounted through my boat hull. (either the transducer or the mounting plate is drilled through the boat)

Therefore, I'm wondering on my boat if the threaded mount/base is glued/epoxy'd into the boat, and maybe the transducer sits in that base and is locked down by the compression nut.

Let me get to my point...... I'd be very careful chiseling out anything from the bottom of your boat. If it is embedded into the boat like mine is, you might end up with a hole. Maybe on yours the builder gel coated over it so that it matched the bottom of the boat or maybe it is just epoxy mounted inside the boat???????? You won't know until the chisel cuts through. If it's not in your way, I'd leave it and add a new one to prevent any chance of making a hole in the boat.

Best of luck, please let me/us know what you find out, even if it is months up the road.

Offrddrver

 

[gibbywmu2000]

Offdriver,

Thanks so much! Helpful info! I'll make sure to check. I'd hate to leave a hole also, but like I mentioned I inspected the bottom and saw nothing on the underside of the boat directly below where the current depth finder is. I think the best thing to do is just put a new one right beside it..........you don't think the old one will cause any interference if I leave it do you?

 

[lmuss53]

The flashing indicates the unit is not seeing the transducer, so the transducer is probably the failed component.

The unit is obsolete I'm sure, so you will probably be looking for a new one, but the transducers are around, as new old stock on ebay.

Look at the original and see if it looks like they just put it in a little epoxy on the inside of the hull. If they did that will probably work fine for the new one. I would not pull the old one out if you don't have to. If there is room just epoxy the new one in close to it. You need a solid void free puddle of epoxy to set it in. There are good instructions with the unit on how to prep the area.

The new transducer won't be bothered by the old one laying there at all. You might be able to cut the old wire off at the transducer and use it to pull the new one through the hull to the dash.

 

[lmuss53]

Another option to consider would be to put something else, or a cap in that hole in the dash and buy a small free standing, color GPS/Sonar unit when they go on sale shortly, that may be your best bang for the buck. You can still mount the transducer to shoot thru the hull if you want to, and the GPS antennas are mostly internal on these units.

 

[Offrddrver]

Gibby,

Sorry, I've been away for awhile. I'm just going to say that I agree with Imuss53's posts.

If you find something to replace it that you really like, please let me/us know, because I'm interested in something new also. I'm mostly at the same lake all the time, and I know the shallows there, but I'd like to go on some other lakes and would like to find the bottom before it finds me.

Best of luck.

Offrddrver