Thinking of dealing with a Thru Hull Transducer

[Bad Obsession]

I have an old thru hull depth transducer that no longer works. The Previous Owner cut the cables on it flush with the old transducer.

I have a Garmin 441s. I can hook a six pin transducer to it. It is the dual GPS/Depth unit.

Currently, I have a small humminbird depth finder that just shows depth. The transducer is placed in the boat near the other transducer but it is a transom mounted transducer bedded in silicone. This works fine.

I am thinking of getting a thru hull transducer and replacing the old thru hull transducer with it. It seems like it is a big job though. I have read several posts on the internet about removing the old thru hull. One method that I think sounds the easiest is to take a hole saw that this the same diameter of the transducer and using it to remove the old one.

The big debate is to do or not to do? There is a good sale on the transducer and I must confess that I am a bit nervous or removing the old transducer. I am sure that it was installed with 5200. I do have a working depth finder so this isn't a have to, more like a want to.

What do you think?

 

[Benny17441]

What do I think? First comes to mind, why? You already have a working depth meter. The GPS function will continue to work in your plotter. Seems you are set. To install a new transducer seems like an additional expenditure to end up where you already are and there is the risk of ending up with a water leak or worse which you do not have now. I would not bother until the current one failed. I assume you would be doing this on the hard; if you are thinking about it in the water I would definitely not even consider it. There is also the option of abandoning that through-hull and drilling a new cut to size hole.

 

[Joe]

Go for it.

 

[Stu Jackson]

Don't bother. You have limited $$ and time.

Or, have Joe come and do it for you! OOPS, he's too far away...

 

[Davidasailor26]

I agree with Benny. What's really to be gained by going through the cost and time, vs what you already have in the in-hull version?

 

[Joe]

Don't bother. You have limited $$ and time.

Or, have Joe come and do it for you! OOPS, he's too far away...

Buy me a ticket.... I'll be there tomorrow with my hole saw... well maybe in a few months but before hurricane season. It's way easier than you think, though. That said... if you don't really know why you want it, other than having a depth number on your chart plotter screen... I'd wait.

 

[Tripaddle]

I'm in a similar state except my depth finder doesn't work. It has an in-hull transducer that looks to be epoxied in. I can remove it with a little work. There is a thru hull with a cable coiled up from a previous depth finder. I've bought a Garmin chart plotter/fish finder that has a transom mount. I do not want it hanging off the back. Next time I'm at the boat I will determine the angle where the old thru hull is and order the correct Garmin thru hull. I was under the impression this wouldn't be to hard to replace. Surely I shouldn't cut another hole in my boat.

 

[31seahorse]

Hello Members and Happy Valentine's Day,
We have used a Garmin 441S and a 541S GPS with the "transom mount" transducer. For many reasons we could not imagine a transducer hanging off the stern. The two methods I found best for us were (1) set the transducer inside the hull and secure it in a bed of caulk or (2 and by far and away the better choice) set the transducer inside the hull and secure it in a bees' wax bed. I purchased a toilet bowl seal and mushed it into a pancake. The wax is a natural product and can be removed from the hull with a bit of scraping. The transducer can be pulled out of the wax bed and replaced or moved as necessary. The caulk installation (1) had the nasty habit of not working for some reason. There are instructions with the transducer that warn about avoiding the keel when choosing a place for the transducer. Best Wishes on your project.

 

[Bad Obsession]

The transducer would give me depth and temp. It would also let me use the fish finder part of the 441s.

Then the school of thought of hold off and wait because it isn't a half to. I also hate the idea of trying to remove the old one. Still I was intrigued by the idea of having a working transducer for the 441s.

The other part to this that I am working on a place on my bulkhead. I was tempted to take the old depth finder off of there so I didn't have hole through my bulkhead there. I am replacing a wooden cover for old instruments that are no longer on the boat (previous owner did this). The wooden cover is leaking, slightly, and it is plywood that is exposed to the elements. The replacement is starboard.

I am still thinking of this. The biggest hurdle is removing the old thru hull transducer. This seems like such a big job and if it is a problem then it could cause a lot of problems.

 

[Tripaddle]

A transom mount will work inside the hull? In a bed of bees wax?

 

[31seahorse]

A transom mount will work inside the hull? In a bed of bees wax?

Yes. We have been using it that way for 3 years. I got that idea from an old pirate who moved ashore and had bees in his bonnet!

 

[Ken Cross]

I'm in a similar state except my depth finder doesn't work. It has an in-hull transducer that looks to be epoxied in. I can remove it with a little work. There is a thru hull with a cable coiled up from a previous depth finder. I've bought a Garmin chart plotter/fish finder that has a transom mount. I do not want it hanging off the back. Next time I'm at the boat I will determine the angle where the old thru hull is and order the correct Garmin thru hull. I was under the impression this wouldn't be to hard to replace. Surely I shouldn't cut another hole in my boat.

I also used a Garmin 441S with a transom mount not mounted outside. I simply used some wax from a toilet wax ring ($.99) and just stuck it to the inside of the hull under a drawer. If it doesn't work, pick another location and try again. That was on our old boat. Our current boat has a cheap greyscale fish finder from my drift boat where I also stuck the transducer down with wax. It works great.
Ken

 

[Ward H]

When I bought my 547XS Garmin chart plotter it came with the P79 transducer. I did the toilet bowl wax ring mount trick and it works well but doesn't read as shallow as the Hummingbird HDR650 depth sounder which has it's transducer epoxied inside the hull.
The P79 is accurate to about 4-5Ft. The Hummingbird reads as shallow as 2Ft. My draft is something like 2.6Ft so
I still use the Hummingbird as my main depth sounder and keep the Garmin as a back up. I shut it off via the Garmin's settings to save some battery juice.
The round brass transducers run a couple hundred bucks. The P79 is around $80. I too thought it would be neat to watch the bottom and maybe fish but that got old real quick. Of course I sail in max 15Ft depth with mud bottom so not much to see.
I don't see changing out the transducer as a big deal but think there is little benefit unless you already have that type of transducer to install.

 

[Bad Obsession]

If you take a transom mounted transducer and you use the silicone or wax ring method, what temperature does the transducer show. Surely it isn't an accurate one for the water.

 

[pateco]

I have a similar issue. A friend gave me his old Raymarine C-80 with the DSM300 Sounder with combined transducer and knot meter when he upgraded to a new touchscreen . However, I will need to haul and drill to install the new-to-me transducer/knot meter. I have a functioning depth sounder, but my current knot meter is dead. The current sounder works fine, but the new one does the whole 3d fish finder thing, and it would be nice to have speed over water again, combined with a nice chart plotter display. I am thinking of removing the old knot meter through hull and re-drilling to fit the new combined device. would you leave the old sounder in place or yank it and patch the hull?

 

[Ken Cross]

If you take a transom mounted transducer and you use the silicone or wax ring method, what temperature does the transducer show. Surely it isn't an accurate one for the water.

Our temperature readings are clearly warmer than the water, particularly in winter when the boat is heated. I'd say this method is only good for depth readings and the like.
Ken

 

[Ken Cross]

I have a similar issue. A friend gave me his old Raymarine C-80 with the DSM300 Sounder with combined transducer and knot meter when he upgraded to a new touchscreen . However, I will need to haul and drill to install the new-to-me transducer/knot meter. I have a functioning depth sounder, but my current knot meter is dead. The current sounder works fine, but the new one does the whole 3d fish finder thing, and it would be nice to have speed over water again, combined with a nice chart plotter display. I am thinking of removing the old knot meter through hull and re-drilling to fit the new combined device. would you leave the old sounder in place or yank it and patch the hull?

If it were me, I'd install the new and leave the old for backup depending on space for the display. (Our old boat had a bulkhead mounted depth display that I left in place.) If they need to mount in the same location, I'd certainly remove the old unit and put the new transducer in the same hole.

Ken

 

[rbringle]

We upgraded from a fish finder for depth to a chart plotter w/ depth and temp. We used plumber's putty to secure the transom transducer to a spot on the hull about half way front-to-back and within two feet athwarthship of the keel. If it is too close to the keel, the keel can block the signal on a tack. We kept the fish finder as a back up--its transducer was installed the same way. My only complaint with this system is that when we are in waves (>3') and the wind is on that side of boat, the signal is sometimes lost due to turbulence and I have to reboot the plotter (no big deal). The temperature detected is the temperature at the transducer, which is insulated from the water temp by the hull and putty. We have an alternative way of determining temp (but you can get used to adding or subtracting a few degrees from the transducer's temperature reading).

 

[druid]

I've always used the transom-style puck embedded in epoxy (or in a container filled with oil or water) and they work fine - one less hole in your hull! As for temp, if you go the epoxy method the temp is not too far off (measures the temp of the hull, which is pretty close to the temp of the water surrounding it!).

druid

 

[pateco]

If it were me, I'd install the new and leave the old for backup depending on space for the display. (Our old boat had a bulkhead mounted depth display that I left in place.) If they need to mount in the same location, I'd certainly remove the old unit and put the new transducer in the same hole.

Ken

New C-80 display will not require removing the old one. which is in a globe off the left side of the pedestal as shown in the photo below. Still haven't figured out where to put the new display as the rail on my pedestal is not tall enough to add a standard nav pod. I may have to get creative. Any Suggestions?