Advice for New Transducer and (Perhaps) Chartplotter

[_Ish_]

Hi all, I need to get myself an operational transducer for my E25+. The original does not appear to work and the transom mounted one that came with the boat when I purchased it does not talk to the Garmin GPSmap 498 that’s… 20yrs old? I am a novice sailor who is eager to get out, explore, and do weeklong cruises. But I currently can’t even anchor up anywhere given that I live in Alaska’s fjords and the depths are typically several hundred feet until you get right up near shore.

Does anyone have recommendations for getting a working transducer without hauling the boat out? I’ve heard that some older boats you can actually unscrew the transducer, cork it with a provided plug, and clean them. A friend did this and was able to swap the old transducer with a new one that fit the threads correctly. Is this an option with the E25+? Is there a way to have a transducer talk to a tablet with Navionics or something similar in lieu of a chartplotter? Since I’m in Alaska, there is very little cell service which means I could not be reliant on anything that requires a consistent internet connection.

With the Garmin is so old, I assume I need a new chartplotter and will perhaps get other sensors if it makes financial sense. However, all the boats I work on have integrated bridge and/or ECDIS systems so I don’t really know what options are for piecing together an affordable system for my little sailboat. When I talked to the guy at West Marine it sounded like my options started at $700 for anything better than a lakeboat fishfinder. Is this really the case? Would I fare better on ebay?

Any guidance or advice will be much appreciated.

 

[peaman]

Does anyone have recommendations for getting a working transducer without hauling the boat out? I’ve heard that some older boats you can actually unscrew the transducer, cork it with a provided plug, and clean them. A friend did this and was able to swap the old transducer with a new one that fit the threads correctly.

Speed transducers which can be removed without hauling are common. Same for combination speed and depth. Newer ones have a built-in valve to greatly reduce the water flow when the transducer is removed, which results in less anxiety while you try to get the dummy plug into the through hull opening. Because most through hull transducers are made by Airmar and sold under various names, it may be possible to install a new transducer in an older through-hull fitting. Just be prepared for the flooding when the transducer or plug is removed, as it can be pretty frightening for the uninitiated.

As for depth transducers, they are available for in-hull installation. Carefully review the installation requirements and pro/con arguments before purchase. There are a few in-hull depth transducers on eBay, for those who don't mind gambling a bit.

With any purchases of new or used electronics, make sure you understand what cabling is needed. Your old Garmin is probably NMEA0186 or even proprietary. Modern stuff is usually NMEA 2000 which simplifies wiring and compatibility between devices.

 

[Slick470]

Hard to say if a new transducer will install in the same hole as the old one without doing some research on what you have vs what you are planning on buying. As peaman mentioned Airmar has manufactured a large percentage of the transducers for the recreational marine market and they sell them to most of the major instrument manufacturers. I have heard of people being able to swap out the transducer without replacing the thru-hull housing but I personally didn't chance it when I upgraded, but it does require a haul out to swap the housing.

The newer thru hull devices are often tri-ducers that combine speed/depth/temp in a single device, so while the overall system may cost more than you are expecting, it can give you a lot more information or flexibility if you want to expand things later.

The little flapper valve that peaman mentioned that is supposed to slow the water ingress while changing out the transducer with a blanking plug on newer style through hulls is a nice thought but they are notoriously fragile and can break off. Mine disappeared not long into it's life. It was nice while it lasted.

 

[peaman]

The newer thru hull devices are often tri-ducers that combine speed/depth/temp in a single device,

I don't know if this issue has been fixed, but a number of those "tri-data" devices, or "DST" (Depth-Speed-Temperature) devices had faulty temperature sensors. I have one from B&G, purchased in 2021, which works fine for speed and depth, but the temperature only worked for a year or so. But then I won't really miss it until I want to cross the Gulfstream.

To install that DST device, I needed to replace the through-hull fitting, which for me was not as difficult as I feared. I wrote about how I did it here.

 

[Christian Williams]

You need a new chartplotter, and a depth transducer. $700 range sounds right. Airmar makes in-hull transducers, meaning no hole, shoots through the hull, so no need to haul. They work for me up to 400 feet or so.

It is deep here, too, and because of that I find little real need for a fathometer. GPS says where I am, which is good enough. A modern chartplotter is much more important than depth in my environment.

 

[Slick470]

I don't know if this issue has been fixed, but a number of those "tri-data" devices, or "DST" (Depth-Speed-Temperature) devices had faulty temperature sensors. I have one from B&G, purchased in 2021, which works fine for speed and depth, but the temperature only worked for a year or so. But then I won't really miss it until I want to cross the Gulfstream.

To install that DST device, I needed to replace the through-hull fitting, which for me was not as difficult as I feared. I wrote about how I did it here.

Ours initially wouldn't display the temp, but found a buried check box in a menu somewhere. I haven't heard about the sensor being faulty on them, but good to know as something to look out for. Ours has been in service since 2014 or so.

I think ours probably would have fit in the old speed log hole and the threads appeared to match up, but I wasn't willing to risk it. I was able to re-use the hole in the boat with out making it larger or needing to fill in, but was left with an extra hole from the old depth transducer that I ended up glassing back in. Overall a relatively easy boat project with a bit of planning.