Thru hull transducer

chasn_sunset · Post by **chasn_sunset** » Feb 14th, '06, 23:00

Ok, I have installed my Hummingbird depth sounder, per many recommendations...The transducer is in a mineral oil bath affixed to the hull near the old transducer mount. Trouble is, it ony registers 1.5 ft, wont shoot thru the glass, any ideas here???

CapnDave · Post by **CapnDave** » Feb 15th, '06, 00:35

Is it in the water, or on the hard? I know that is probably obvious, but most transducers won't give a correct reading through the air from what I've seen.

Doug Fallin · Post by **Doug Fallin** » Feb 15th, '06, 06:49

I affixed my transducer to the hull with epoxy putty. Lightly sand the paint from the inside of the hull where you want to place the transducer. Kneed the epoxy putty as instructed, make sure all air bubbles are removed. Place the putty on the hull, press the transducer into the putty making sure it is level. Mold the excess that is pressed out the side and your done. The putty hardens and gives you a solid mass to transmit through. Mine works great and is very accurate.

polyphemus · Post by **polyphemus** » Feb 15th, '06, 08:05

what kind of epoxy did you use?

thanks
sean

Sandy D. · Post by **Sandy D.** » Feb 15th, '06, 08:19

Doug, did you use a flat puck,or one that is at an angle to compensate for hull angle?

Dan, How did you go about mounting the unit in the mineral oil,any chance you have any pictures?

I installed the HD600 unit last year,worked great when I tested it (shooting through mineral oil ) So I got the bright idea to mount the transducer permantly to the hull with the included epoxy.

Every thing worked great! My first project on my new boat,a sucess,life was good. Until I ran aground w/the depth sounder reading 8'!! Not so good,really impressed the girlfriend and her mom!

So back to square one this spring,with three choices;
1)Set the tranducer up to shoot through mineral oil( Does anybody have pictures of this set up? )
2)When I order the new transducer,order one that is at an angle to compensate for hull angle.
3) Since a new transducer will cost me 50 bucks or so,do I invest that money in a fishfinder.(same transducer issues,but for an extra $100 I get a spiffy read out of the bottom)

A few questions for the board;

1) Has anyone mounted a transducer to their hull using anything other than epoxy,something less permanent?
2)can anybody share methods/pics. of how to set up to shoot through mineral oil?
3)Any feed back on the use of fishfinders?

Thanks folks,springs right around the corner......right?.......I hope

-Sandy

marilou · Post by **marilou** » Feb 15th, '06, 08:38

I mounted tranducer in PVC pipe & cap, filled with mineral oil. Used 3M 5200 to mount pipe to hull. Drill hole thru cap for cable and seal with silicone sealant. Has worked fine for 25 years.

polyphemus · Post by **polyphemus** » Feb 15th, '06, 09:17

Marilou

when you put the transducer in the pvc pipe with mineral oil, does it simply float or sink in the mineral oil? Or do you also affix it within the PVC pipe someway?

Sean

Doug Fallin · Post by **Doug Fallin** » Feb 15th, '06, 12:27

I use the two part epoxy putty that comes in a tube. Its like modeling clay. My transducer is flat. In my CD25 I mounted it on the port side center, behind the thru haul about 12 to 16 inches.

Oswego John · Post by **Oswego John** » Feb 15th, '06, 14:25

Hi all transducer installers,

Just a word or two about leveling the transducer in your hull. Level is nice, is good. But don't sweat it if it isn't level to the nth degree. Let's face it, the only time your hull will be level in all planes is when it is on jackstands on the hard.

You can install it as level as can be, and then your big, fat brother in law plops his can on the port coaming. Even in a 5 MPH zephyr, the boat heels out of level. Never mind a 15 MPH breeze with the bow crashing through the waves.

What some boat owners do is pitch the transducer a little so that it tells them what is ahead, what's coming shortly. They feel that that is more important than what is directly below. And then some don't.

Good luck,
O J

Carter Brey · Post by **Carter Brey** » Feb 15th, '06, 16:09

Sandy D. wrote:
1) Has anyone mounted a transducer to their hull using anything other than epoxy,something less permanent?
2)can anybody share methods/pics. of how to set up to shoot through mineral oil?
3)Any feed back on the use of fishfinders?

Thanks folks,springs right around the corner......right?.......I hope

-Sandy

Sandy,

I mounted a Uniden QT-206 transponder in my CD25. This unit came with a hull deadrise adaptor, which is just a fancy way of doing what the other guy did with a piece of PVC pipe cut at an angle. The transponder twist-locks into the adaptor, which is filled with mineral oil.

The instructions, as I recall, recommended against both epoxy and silicone for reaons having to do with bad chemistry involving the plastic housing on the one hand, and with the mineral oil on the other. I wanted to be able to remove the unit fairly easily, so I used Boatlife Lifeseal, which supposedly combines the good qualities of silicone and polysulfide, without being injurious to certain plastics as polysulfide (e.g. 3M 4200) can be.

It's important to prepare the mounting surface by sanding if there's roving print-through. I neglected this step the first time I attempted it and had a very leaky unit on my hands (literally). I had to replace the oil every time I went sailing. Needless to say, this was impractical, wasteful, and compromised my sweet smelling, immaculate bilge. I sanded and wiped down with acetone the second time around and never had to refill for the entire season.

It also helped that I found a slightly less convexly curved place for the mounting.

Good luck,
Carter

Not the final installation, but close enough. The unit aft of the depth transponder is the self-sealing through-hull for the speed log paddle wheel:

[img]http://pws.prserv.net/cbrey/aug-19-2003-013.jpg[/img]

George Shaunfield · Post by **George Shaunfield** » Feb 17th, '06, 03:33

I used silicon sealer for temporarily mounting a new transducer and it has worked fine for 8 months. Obviously, you want to avoid air bubbles. And it should be fairly easy to remove when I get ready to mount it more permanently.

George

Neil Gordon · Post by **Neil Gordon** » Feb 17th, '06, 06:55

Oswego John wrote:What some boat owners do is pitch the transducer a little so that it tells them what is ahead, what's coming shortly. They feel that that is more important than what is directly below. And then some don't.

Doesn't anyone use a chart anymore?

If you're in water thin enough to worry about "what's coming shortly," pitching a transducer a bit ahead might get you a boat length's warning. That's about enough to say "Oh $%&#!!!" before your bottom gets crunched.

tartansailor · Post by **tartansailor** » Feb 17th, '06, 11:53

It is hard for me to understand how a transducer / depth sounder can be relied on in a boat that heels.
A prudent skipper would assign:
Piloting 99%
Depth gauge 1 %
IMHO.
Now a fish finder, that is another story.
Dick

Neil Gordon · Post by **Neil Gordon** » Feb 17th, '06, 12:13

tartansailor wrote:It is hard for me to understand how a transducer / depth sounder can be relied on in a boat that heels.

The signal goes out in a cone shape and so even if the boat (and the transducer) are not flat with the bottom, the signal still hits the bottom under the boat and bounces back. I've found that the depth guage is fairly accurate, with the exception of interference from fish, churned up water in the wake of powerboats and perhaps the effect of thermal layers presenting a false bottom.

As for relying on depth for navigation, it's just one more piece of the puzzle. Better than seeing when you are going to crash (a milisecond before), set the alarm so that it will tell you when you've arrived at a partiular fathom curve. See how that compares to what you see by looking around.

Carter Brey · Post by **Carter Brey** » Feb 17th, '06, 12:39

tartansailor wrote:It is hard for me to understand how a transducer / depth sounder can be relied on in a boat that heels.
A prudent skipper would assign:
Piloting 99%
Depth gauge 1 %
IMHO.
Now a fish finder, that is another story.
Dick

10 4 on that, Dick, but don't forget that the boat is level when you're motoring, and very often you'll be motoring in thin water, about to anchor. Obviously you're a fool not to be conversant with your chart data, but, as Neil points out, it's all part of the picture. I never mind a little confirmation of what the chart tells me. Would you disapprove of a pre-electronics skipper who swung a lead line to augment his chart information? Of course not. And in tracing a depth contour in fog, as part of good piloting, the electronic depth finder is your friend.

I can also confirm what Neil says about the heel having little effect on readouts. I tested this one day by passing over the same ground on alternate tacks. I had expected varied readings, but my suppositions were not borne out empirically. Go figure.

Cordially,
Carter

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