Lowrance 3500 Replacement with Lowrance LST-3800 & Garmin Transducer

ColoSR

Active Member
Apr 25, 2018
425
Boat Info
2003 Sea Ray Sundeck 220
Engines
MX 6.2L MPI Mercruiser with 2.2 Bravo III drive
Hi All,

My Lowrance 3500 display went bad, and I could not find a used gauge or a new one that would work with the old 192kHz thru-hull transducer. My Sundeck 220 has a 2” thru-hull fitting at a 20-degree deadrise, and neither of the 2 1/8” gauges Lowrance (LST-3800), Hawkeye (D10D), nor Humminbird (HDR 650) had an off the shelf replacement.

I found out that most of the transducers are made by a company called Airmar, and found out that the depth signals would generally work between manufacturers so long as they were all 200kHz. I ended up making a pigtail to mate a Garmin (Airmar) P19/B619 transducer to a Lowrance 3800 gauge. This arrangement does NOT give an accurate water temperature reading because Lowrance uses 5,000K thermistors while Garmin (and the rest of the industry) uses 10,000K thermistors. I decided to get the bronze version of the transducer rather than plastic because I trailer my boat, you can save a few bucks with the plastic P19 version.

Parts List
** Lowrance LST-3800 with WSU-HST 200 kHz Transom Mount Transducer
** Garmin B619 20 Degree Tilt Bronze (200 kHz) Thru-Hull Transducer - 8-Pin – Garmin P/N 010-10217-22 (Note plastic P19 – P/N 010-10218-22 works too)
** Garmin 6-Pin Female to 8-Pin Male Adapter- Garmin P/N 010-11612-00
** Airmar Inline Cable Splice 6 Conductor IP67 Waterproof

I did not cut the connectors off of the B619 transducer nor the LST-3800. I made a pigtail out of the transom mount transducer that came with the 3800 and the garmin adapter wire so that I could sell the 3800 and B619 if my experiment did not work. The wire colors below may not be correct if you connect the 3800 and B619 directly.

To make the pigtail, cut the thicker Lowrance transducer wire approximately 8” from the uniplug connector. Make sure to leave the smaller wire intact as that is the power and ground (see manual). Next, cut the garmin adapter plug in half. From there, use the Airmar cable splice fitting to wire the garmin 8-pin end to the Lowrance uniplug end by connecting the Bare wire to Bare wire, White to Yellow, Blue to Blue, and Black to Black. My pin-out sketch is attached, no guarantees on quality. Then you can use the pigtail to connect the 3800 to the B619 to make a functioning system. Even though the temp is not correct, I think you need to hook it up because the 3800 is looking for the temp circuit.
I would recommend that you build the pigtail out of the boat so that you can put the transducer in a bucket of water for testing. The depth will not read without water, so I didn’t realize that I had some wires backwards until I was on the lake. Happy boating!

Transducer Pigtail Wiring.jpg
 
Hi All,

My Lowrance 3500 display went bad, and I could not find a used gauge or a new one that would work with the old 192kHz thru-hull transducer. My Sundeck 220 has a 2” thru-hull fitting at a 20-degree deadrise, and neither of the 2 1/8” gauges Lowrance (LST-3800), Hawkeye (D10D), nor Humminbird (HDR 650) had an off the shelf replacement.

I found out that most of the transducers are made by a company called Airmar, and found out that the depth signals would generally work between manufacturers so long as they were all 200kHz. I ended up making a pigtail to mate a Garmin (Airmar) P19/B619 transducer to a Lowrance 3800 gauge. This arrangement does NOT give an accurate water temperature reading because Lowrance uses 5,000K thermistors while Garmin (and the rest of the industry) uses 10,000K thermistors. I decided to get the bronze version of the transducer rather than plastic because I trailer my boat, you can save a few bucks with the plastic P19 version.

Parts List
** Lowrance LST-3800 with WSU-HST 200 kHz Transom Mount Transducer
** Garmin B619 20 Degree Tilt Bronze (200 kHz) Thru-Hull Transducer - 8-Pin – Garmin P/N 010-10217-22 (Note plastic P19 – P/N 010-10218-22 works too)
** Garmin 6-Pin Female to 8-Pin Male Adapter- Garmin P/N 010-11612-00
** Airmar Inline Cable Splice 6 Conductor IP67 Waterproof

I did not cut the connectors off of the B619 transducer nor the LST-3800. I made a pigtail out of the transom mount transducer that came with the 3800 and the garmin adapter wire so that I could sell the 3800 and B619 if my experiment did not work. The wire colors below may not be correct if you connect the 3800 and B619 directly.

To make the pigtail, cut the thicker Lowrance transducer wire approximately 8” from the uniplug connector. Make sure to leave the smaller wire intact as that is the power and ground (see manual). Next, cut the garmin adapter plug in half. From there, use the Airmar cable splice fitting to wire the garmin 8-pin end to the Lowrance uniplug end by connecting the Bare wire to Bare wire, White to Yellow, Blue to Blue, and Black to Black. My pin-out sketch is attached, no guarantees on quality. Then you can use the pigtail to connect the 3800 to the B619 to make a functioning system. Even though the temp is not correct, I think you need to hook it up because the 3800 is looking for the temp circuit.
I would recommend that you build the pigtail out of the boat so that you can put the transducer in a bucket of water for testing. The depth will not read without water, so I didn’t realize that I had some wires backwards until I was on the lake. Happy boating!

View attachment 59355
I have connected per your information and testing it in water it just flashes a depth of 60. The menu works but will not read depth
 
I have connected per your information and testing it in water it just flashes a depth of 60. The menu works but will not read depth
No different than if it is not connected to the transducer
 
I would check the connections again, black-black, blue-blue, yellow-white, and Bare-bare. i had some of the wires backwards and it flashed 60.

Can you check that the gauge works with the transom transducer?
 
Thank you. I thought I had checked so carefully but in rechecking I noticed the blue wire was staggered and not in opposition. ‍♂️ It does work in a bucket now. Thanks again
 
Happy to help!
 
So, to get all these parts would cost me around $400 or so correct?

Then just the depth gauge will only work correct? Eventually if I wanted the transducer installed then I could install that and depth and temperature would work?
 
I got a deal on the LST-3800&B619 so that the cost was just north of $200. I found out 4 weeks later that Lowrance will get you a thru Hull transducer with a 20 Degree deadrise on custom order, should be under $400 for matched set.

Either way, still very happy with the garmin/Lowrance splice since it gets me depth. If you are planning to add a fish finder, get an upgraded thru Hull. The B619 is an older unit in the lineup.
 
Well, if I decide to go with all new - what would be the best thru hull transducer and gauge to get (if brand doesn't matter)? I'm assuming other than depth, knowing the water temperature would be nice.

Sounds like there is no way to use my existing thru hull transducer with a different gauge even if its an older model right? So no matter what, I'd need a new gauge with thru hull transducer (with 20 degree deadrise) correct?
 
See detailed response in "Official 280 Sundancer" thread # 7032.

Brand? What other electronics in the way of gps/chart plotter do you have? You might want to consider something that could integrate with what you already own. If you already have something pretty new, like the Raymarine Axiom, or Garmin 76xx, or 86xx family for example, you would only need a transducer as these have built in capability for depth. Similarly, if you have something old and obsolete (vintage 2003 chartplotter) you might want to consider a wider horizon than just depth and upgrade to an all in one MFD that could provide chart plotter with built in GPS, maps, depth and radar capability. There are also other brands, but the big point is the cost difference between an upgrade versus standalone depth set up could be small enough to warrant the larger upgrade.
 
Unfortunately, none of the manufacturers are still using the 192 kHz frequency so the existing transducer can't be used.

Personally I wanted to (1) retain my 2 1/8" depth gauge, (2) reuse the 2" hole in the bottom of the boat, (3) keep the total cost around $300, and (4) find a bronze transducer because I trailer my boat.

I found three different manufacturers with a 2 1/8" circle gauge; Lowrance (LST-3800), Hawkeye (D10D), and Humminbird (HDR 650). I found a new LST-3800 that was used as a demo for $50, so I went that route. Faria and Raymarine had options as well, but they didn't fit my criteria above.

The tough part was the 2" thru hull with a 20 degree deadrise. The 200kHz Airmar P19 / B619 (bronze version) was the only one I could find that met all my criteria, everything else was either a new/bigger hole or transom mount. While airmar builds all the transducers, each company has their own proprietary connectors.

I bought the Garmin B619 and used the splice to create a pigtail to connect the Garmin B619 to LST-3800. As I mentioned before, Lowrance offered to do a custom order for a 20 degree deadrise Lowrance P19 but I had already installed the Garmin when they reached out.

To get all new, I would confirm the diameter of your existing transducer then reach out to Lowrance and find out if they will do the 2" thru hull, 20 degree deadrise custom transducer and the LST-3800. That would get you depth, temp, and one package.
 
The Lowrance 3500 transducer on our 280 was knocked out and replaced with an Airmar/Raymarine transducer. I went originally with the standalone ST40 depth gauge linked to our mfd. I later added a DSM300 and fishing grade in hull RM transducer that worked great for several years. Personally I found the ease of installation and how well it worked to be well worth it.
 
Why is a 20 degree deadrise unit needed?

Mine is mounted flat on the bottom of the hull.

I just need something simple. I'm on an inland lake and don't trailer anywhere but storage and back.
 

Attachments

  • Thru hull transducer 1.jpg
    Thru hull transducer 1.jpg
    96.4 KB · Views: 301
  • Thru hull transducer 2.jpg
    Thru hull transducer 2.jpg
    98.4 KB · Views: 418
  • Thru hull transducer.jpg
    Thru hull transducer.jpg
    6.3 KB · Views: 246
Why is a 20 degree deadrise unit needed?

Mine is mounted flat on the bottom of the hull.

I just need something simple. I'm on an inland lake and don't trailer anywhere but storage and back.

On our 280 the transducer was mounted on the slope of the Vee (deadrise) of hull at the transom end of the boat. Down under the engine about in line with the vacuum generator and water heater. Mounted in front the engine, you are right it’s zero degrees.
 
On our 280 the transducer was mounted on the slope of the Vee (deadrise) of hull at the transom end of the boat. Down under the engine about in line with the vacuum generator and water heater. Mounted in front the engine, you are right it’s zero degrees.

So, doesn't that mean for my 280 Sundancer I don't need a thru-hull transducer with any special angle?

Basically I'd need the Fixed 0° tilted versions for 0° to 7° hull deadrise correct since mine is mounted right in front of the engine?

http://www.airmar.com/productdescription.html?id=140
 
You are right. Mine was offset like Henry’s. Your life is going to be much easier:)

The Hawkeye unit has a 0 degree thru Hull option, I think the P19 with temp is an upgrade from the base model.
 
If you go back through the same hole you are right on the angle. However, I’m not sure that’s the best location given the proximity to the ac water pickup. The distance forward might cause problems at speed with that section at high speed. Did the old gauge act erratically, or cut in and out? If so this might explain that and predict future behavior. If not, go back with a zero degree transducer.
 
If you go back through the same hole you are right on the angle. However, I’m not sure that’s the best location given the proximity to the ac water pickup. The distance forward might cause problems at speed with that section at high speed. Did the old gauge act erratically, or cut in and out? If so this might explain that and predict future behavior. If not, go back with a zero degree transducer.

I'll go with a zero degree transducer - it does make my life easier. My depth finder seemed to work fine in general, unless I was going faster then sometimes it wouldn't read great. Figured that was due to the old technology. I don't plan on filling and cutting a new hole, so it will go back into the previous spot.
 
When you pull the old transducer pay attention to the condition of the plywood. Where it is is located where there is a plywood reinforcement. If it is wet, or spongy you should let it dry out and then scuff out any spongey stuff and recoat with epoxy filling in any voids.
 
Hello all! I have a 1996 300 and I am needing to replace my Lowrance 3500 -- Can anyone tell me where to find the transducer?
 

Forum statistics

Threads
112,950
Messages
1,422,832
Members
60,931
Latest member
Ebrown69
Back
Top