Transom mounted transducers - a venial sin?

[Duane Dunn, Allegro]

Where it intersects the transom the ballast tank is just a small channel that goes to the transom valve. Depending on your model and year it may be on the port or starboard side. M's are a bit different than X's. Likewise there are numerous places under the aft berth where the hull is accessible. Same under the cooler area on the X as well as under the battery and galley compartment. The X ballast tank is really two tanks connected together. The smaller is under the aft berth. It has a channel to the transom, and two channels going forward to the larger bow tank. The area at the bottom of the companionway steps is pure hull for maximum headroom. The channels are outboard under the head and galley. Where the step up starts going forward is where the forward tank starts. It's full width from there forward under the dinette and the vee berth.

If you take a look at the picture in the brochure showing all the individual parts of the boat near the end you can see the hull with the tank glassed in but no liner. You'll see how it's set up and which area's of the hull itself are accessible. The picture is an early boat with the port side valve. I believe the M brochure has a similar picture that show the tank config on it.

[Andy26M]

I have a Garmin 188C on mine, and I put the transducer (with temp and speed paddle wheel) on the transom. I screwed it right in with 5200 sealing the holes, and she sat in salt water all last season with no leakage. I put the transducer on the starboard side; positioned per the manufacturer's directions it landed right under my swim ladder. The swim ladder didn't quite clear it, so I cut a round disc out of a cutting board and epoxied it to the hull at the point where the ladder touches down - voila, the ladder is at a slightly nicer angle to climb, and the transducer is nestled snugly in a spot where it is practically impossible for a swimmer to step on or kick it.

I get accurate depth readings up to about 30 degrees of heel, at which point things go erratic because the tranducer starts coming out of the water.

I do get growth FAST, though. But, the tranducer can be taken off the mount and with a little slack in the cable can be brought into the transom well and cleaned.

I have not succeeded in finding anti-fouling paint safe for the plastic transducer, but Tripp Girl posted a tip last year: Coat your tranducer with "Bag Balm" ointment and nothing grows on it. This does indeed work, but you need to reapply the ointment at least every 2 weeks.

- AndyS

[Scott]

http://www.raymarine.com/raymarine/Defa ... &Section=2

Check it. We have the first one listed.

A few times every season I have to swim and clean it, I love it. No underwater holes

[Idle Time]

The big toe temp dip is OK unless you have a wife who is willing to paddle around in COLD water with a big smile on her face ..all the time telling you how nice it is....then you dive in...

I wont get away with that one anymore...he now has a fish finder with temp guage.

[Patrick Gilbert]

If you mount the transducer near the water ballast valve on the transom, you don't have to worry about a leak. It is just as WET on the other side of the transom when ballast tank is full.

[norbert]

if you ever drill holes in your hull under the waterline, they imeratively should be epoxy sealed (not only marine sealant!). although i doubt that the rudder bracket bolts are sealed correctly by the factory...

i have transon mount speed + depth transducers. i screwed them on a piece of cutting board epoxied to the transom, so no holes in the hull. they work quite good, the paddle wheel is frequently blocked by marine growth but is easy to reach for cleaning. no problem so far with the sounder. the depth transducer can be protected by those special engine/prop antifoulings.

if i ever redo i ll glue the depth transducer to the inside of the hull. for the speed paddle wheel i see no other option than the transom.

[Frank C]

I removed my transom 'ducers because I wanted ability to beach the stern. I've still never beached stern-to, but I regret the loss of the transom 'ducers. They provided extra info, speed & temp, and the depth readings were much more consistent, and reliable at all speeds.

The cutting board idea is interesting. If one mounted a hinged board, screwed to the transom above the waterline (no leaks), then the 'ducers could be mounted to the board and still raised from the water, either when slipped or for an occasional beaching. Need to get over to see that stern up close, and ponder it some ....

[Bob Zoobricke]

You can mount the tranducer/temp/speed on the transom easily. Epoxy a piece of 3/4 plywood below the waterline, then after it drys cover the rest of the plywood with epoxy. That will waterproof the wood. Now mount your transducer to the plywood. Look no holes to drill below the water line, no sleep to lose and no pills to take!

[sailpsych]

MTC -
I've got a little hand held GPS - Garmin eTrex Vista - the neat thing about it is I can tell how far up and down the waves are taking me with the barometric altimeter. It is almost always showing a faster speed than my depthfinder. Knots or kno knots.

Bruce G.

[Casey]

Mine is transom mounted similar to Norberts. My dealer used Marine Board, which looks alot like a cutting board, on the outside of the transom to help mount the 50hp motor. I use an aluminum adjustable extension mounted into this marine board with screws to mount the the transducer and speed/temp wheel. No holes in the fiberglass.

The temperature and depth works well. The speed gets gunked easily with marine growth. I think a gps works better. My next one will be mounted inside in plumbers gunk.

[mtc]

Bruce,

The RM 500 is supposed to be able to integrate a GPS . . . hmmm, wonder how much one of those little Gs cost and if the combined cost is close to the GPS/Fishfinder?

I'm head-desiging a way to quick disconnect my transponder (trisponder, as RM calls it ) so I can mount when underway, then easily remove when needed.

All in all, I would prefer a GPS with an internal mounted 'ducer, but we all know as Mac sailors, that our game is focused on compromise, eh?

I could just contniue to climb on the cost factor and buy my Fat Cat 38 along with a half dozen through hulls, couldn't I?

Not today.

Michael