Replacing the depth transducer

[BoarX]

Hello all.

Since we have purchased our T28 2 1/2 years ago, our depth sounder kept working erratically. This was no fun while sailing on shallow Midwest lakes. Finally we have been able to confirm that our Raymarine ST60+ Tridata instrument was working properly (I can share how this was done if anyone is interested). Thus we need to replace the transducer. According to the documents I got from the previous owner, we most likely have either Airmar thru-hull P319 or P219 unit. I am not sure which one though - they are a bit different and I am unable to see the markings on ours, except that it is indeed Airmar one.

* Does anyone happen to know which of the two transducers we might have?

* What is involved in routing the cable from the transducer to the instrument?

* Did anyone succeed in replacing the fixed through hull original transducer with retractable one, like Airmar B17? The hull hole sizes for all the three transducers mentioned here appear to be the same

Thanks in advance,
Alex

[Ron]

Alex -

Did you clean the contacts at both ends of the cable and any connectors in the middle? I've had to do this several times for the wind (including the connector at the base of the mast) and some other circuits as well (GPS, etc.). The wet environment (especially salt water) can do a job on these low voltage circuits. Problems were erratic or erroneous readings, or no reading at all.

[ggreen]

II agree with Ron. In fact I replaced the wind connector at the base of the mast. Also if your boat is bottom painted make sure there is no bottom paint on the transducer. The yard accidentally painted over it and it took a couple of days before the paint wore off and the transducer started to work again.

gary g

[BoarX]

Thanks guys, but I have cleaned the transducer several times and since we keep the boat 90% of time on shore, only launching her to sail, my estimate for the chances of the external contamination of the transducer is quite low. I did clean the connections to the instrument thoroughly and from there there is a straight cable permanently attached to the transducer - unless there are some splices/connectors hiding under the panels somewhere. Hence I am wondering how to route the new cable. The plan is to purchase a new transducer and give it a try outside of the hull. This was the advice Ii got from the shop that verified my Tridata instrument functionality. If this doesn't help I can hopefully return the new transducer for a refund.

Best,
Alex

[BoarX]

A question relevant to the transducer installation: is our main hull solid fiberglass or cored one?
Thanks,
Alex

[wooden]

It's a core construction Alex. you will need a through hull transducer. I put a new transducer in mine and it is not difficult. I put it in the storage space as you step into the cabin. Easy access.

[BoarX]

Thanks Steve, that clarifies things a bit. Is the storage space you are referring to next to the water tank, where original transducer is/was or somewhere else?

[wooden]

The original transducer on mine was mid boat just behind the cabin mast post on the port side as it attaches to the bottom of the cabin. Not convenient because the wires were exposed and could be damaged easily, which they were. The storage I speak of, assuming your boat is like mine, is the storage space that the steps to the cabin from the cockpit are resting on. Taking the stairs off and opening the storage hatch gives you plenty of options. The only downside to this location that I have seen is that it is in the aft part of the boat so that a quickly reducing depth may not show up as quickly as you would like. I have had no problem with this.

[BoarX]

Alright, finally got myself retractable model, but prior to that got non-retractable one, hooked it up to my ST60+ TriData and sent floating on a piece of wooden board mounted into 2" diameter hole. Confirmed it working, returned to Amazon for refund and got the retractable one for a few bucks cheaper - go figure. The model is listed as D800/P17, there appears to be the whole gamut of compatible Airmar models, here is the Amazon link if anyone is interested:

https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1

Sealed with 3M 5200, so far no leaks, fingers crossed. The old hole appeared to have solid fiberglass walls, i.e., the core (if there was any) was properly protected from sucking in water. Spent this last weekend checking depths on Clinton lake in IL, already discovered few scary shallow spots I was not aware of, despite having sailed there for many years.

Next step is calibration. Does anyone recall the depth values from the waterline to:

* the hull bottom?
* the lowest point of the fully submerged rudder ?
* the lowest point of the fully lowered centerboard?

Thanks in advance,
Alex

[Ron]

The hull bottom is about 1 1/2 feet under water. There were two different center boards. My 359 hull was supposedly the first with the longer board - about 5 feet down. The older boats were about 4 1/2 feet . Forgot the exact amount of each. I think they all had the same rudder.