TRANSDUCER PROBLEM 31 TE

[Coho Spirit]

We have a 31 Albin Tournament Express with a single engine and bow thruster. Recently installed: Garmin GPS Map 7610xsv, Garmin GMR-424 Radar and dual Garmin GT-51M-THP Chirp/down & side view transducers. The transducer before was in the starboard forward engine room. Sonar does not works at cruise speed at new and old locations. At our request we asked Garmin for the transducer placement and were told to place them in the back 4 feet. Does anyone have a similar installation that works? If so where did you place your transducers?

The latest idea is the problem is caused by the bow thruster sending air across the hull. Any help would greatly be appreciated.

Dick

[Pitou]

Dick -
Sorry that you're still having difficulty with transducer readings at cruise. My 31 TE is a single screw with a bow thruster and my transducer placement (as advised by Airmar) and readings hold at all speeds and sea states. It sound like your transducers are aft of the fuel tanks in the rear bilge compartment. Do you have any pictures? You mention that they are mounted in the backward 4 feet of the hull. If you had an outboard boat I could see that, but with a keeled displacement hull I think that Garmin got this all wrong. Between the prop wash coming up against the hull, the center keel, strakes and the engine intake there is an awful lot of turbulence going on at the back of the boat against that area of the hull. As the bottom of the 31 never changed over the years hopefully you can get some other input from other 31 owners and maybe even someone with a dual transducer set-up. I hope that you can get this straightened out to enjoy your new gear.

Here is the Airmar recommendation:
"Displacement hull powerboats—Locate amidships near the
centerline. The side of the hull where the propeller
blades are moving downward is preferred."

Having a left hand turning propeller I am mounted port side. My previous transducer was in a fairing block and the new one installed this spring is a flush mount thru-hull 20 degree Airmar B60. My placement is mid-ship and as close to the centerline as possible on the outward side of the port side stringer next to the engine. See previous discussion: viewtopic.php?f=27&t=8946

[kowal_53]

I was going to post this once I figured out my problem. Since others have placement issues, I thought I would post this information perhaps prematurely.

I have been trouble shooting a B60-20/Raytheon E120/DSM 30 for quite sometime. I have had intermittent depth, and times that the DSM did not communicate with the E120. It got so bad I had to turn off the sonar due to alarms. Given all of the Raymarine components it was hard to know what was causing the issue. I have talked with Raymaine a 1/2 dozen times. I tied to get an expert, but they were busy. So in frustration I sent my DSM back to Raymarine for a second time. They returned a new CP-370 so I installed it. It does work a bit better than the one I sent them. However even the old one work pretty good sometimes. The new one worked right up to 14 knots, were I lost the depth. I brought the speed down and it came back. I went back a forth many times and above it dropped, and below it worked. I intend to go out quite a few more time before I decide I have a issue above 14 knots, other some other gremlins return.

Pitou: I measured my port location, since your link provided a measurement that worked, I though I would measure mine. I am close to your link measurements. Forward bulkhead 47 inches to B60 is 47 inches, 22 inches to the rear bulkhead. (This is about 5 inches further back than your link) Mine is located about 12 inches out from the engine mount runner. (This is about 8 inches further away than yours) If you new B60 is not where the old one was please let me know.

Please remember I might have some other issue, I just don't have enough time on the new unit. I thought I would put this out there just in case someone was looking to install a new transducer. At the moment, I would recommend placing the transduce more towards the keel.

As for me, if it turnout that I loose my depth at high speed, I could consider moving it, of instilling a new unit. I was considering a blade since you used to have one. Now I am not sure, the B60 might be fine. Perhaps a new B60 in your location is my best bet. I was wondering a hail Mary and replacing it all, now I see that even a new equipment can be challenging. Hopefully we will get some others to give us an idea what works.

[Pitou]

Kowal - My new B60 went into the same location of my old transducer that was in the fairing block. No issues and I hold bottom in all sea states and up to full throttle of 21+ knots. I know the location in the link above works .. thru hull flush mount or fairing block. Moving your transducer to this location will bring the result you're looking for.

[amber jj]

Our 31 with twins has the transducer mounted in a fairing block right below the helm next to the stringer.

[djpeewee]

I am not sure if this is applicable to the 31 as ours is a 28 Flush Deck, but the relative placement may be of value. We have a pair of the Garmin GT51M-THP transducers I installed last year. They are mid ships, just behind the transmission. I used the location of the old transducer on the starboard side, and mirrored its location for the port side. We have never had issues with them losing bottom - even at 1000'+ depths at any speed.

For reference, below are some photos during the installation:

Looking forward from cockpit. The top edge is the hinge of the center fish box, which is open, and the transmission shown in the middle.

Transducers.jpg

Looking to port.

Transducers2.jpg

I can provide some measurements if needed.

[Halcyon]

Thanks for the info. I'm going to move my transducer this winter and am trying to find the right place.
Do you have a shot from the bottom showing the distance from the skeg?

Thanks

[djpeewee]

I crawled under the boat tonight and took some measurements. The transducers are port and starboard of the skeg center line 11-1/2 inches horizontally at their centers. They are exactly 8 feet from the aft edge of the hull at their centers. Like I said, I reused the original transducer hole for the starboard side and mirrored it for the second transducer on the port side. No problems.