is this transducer installed too low??

[Five O'Clock]

I installed my transducer, following the Garmin instructions, to 1/8" below the hull line. But after the boat was launched for the season, I thought to myself, is the bottom of the transducer supposed to be 1/8" below, or is the entire transducer supposed to be 1/8"?

I ask, because up to about 10 knots I get perfect readings, up to about 15-18 knots I get readings but I can see the air bubbles on the scree. and over 20 knots I get nothing, not even correct depths.

I tried to take a side picture but I don't think it came out so good...

Any thoughts?

 

[a70eliminator]

Re: is this transducer installed too low??

The bottom should be an 1/8 below, yours is sitting a bit too deep but not awfull, usually there is are height adjustment slots for fine tuneing.

 

[Pez Vela]

Re: is this transducer installed too low??

Your initial thinking was correct, but the performance of transom mounted transducers is problematic due to hull configurations which do not lend themselves to the release of a smooth, clean flow of water over the bottom of the transducer. By varying your transducer mounting height (which appears to be a little low) you may be able to improve upon your performance slightly, but the problem you're experiencing is more than likely due to the hull's configuration and your apparent inability to select a better (horizontal bottom) mounting location. If you wish to experiment with different mounting locations, try a temporary suction cup mount until you find the optimum location. Doing so will save putting any more holes in your transom than is absolutely necessary.

 

[Capt'n Chris]

Re: is this transducer installed too low??

Yes, your transducer appears somewhat low. Use a straightedge, such as a paint paddle taped flat to the bottom of your boat. Allow it to extend aft to intersect the center of your transducer and begin your "at sea" trial and error adjustments beginning flush with the bottom of your boat. Transom-transducers are, without a doubt, the better performing of all transducers, to include "through-hull" and "shoot-thru". Hull configuration (hull design) has nothing to do with the performance of a transducer. As long as you have an unobstructed boat bottom fore of the transducer your slipstream is as good as it gets. Do not; however, mount on a running strake or behind a massive row of rivets, or too far outboard. Otherwise, the transducer will work anywhere on a transom of an outboard or I/O.

 

[a70eliminator]

Re: is this transducer installed too low??

Looking at the photo again I now can see you do have the slotted adjustments and it looks like they are set right in the middle, so you you can move it up at least 1/2" which more than likely will solve your problem.

 

[cpubud]

Re: is this transducer installed too low??

should be relatively flush to bottom of transom to 1/8 inch below

 

[Seon]

Re: is this transducer installed too low??

In reading the Garmin install instructions, it reads "Transducer should extend 1/8" below fiberglass hulls or 3/8" below aluminum hulls". It illustrates the bottom of the transducer is 1/8" lower than the hull. So you're transducer appears to be a bit low.

 

[willamettejeff]

Re: is this transducer installed too low??

Your transducer does appear a little low, but the biggest problem I see is it appears to be angled up from the transom end to the end of the transducer. Should be angled slightly down so that it kind of planes keeping the water in solid contact with the bottom of the transducer at all speeds. Angled up would cause the water to cavitate under the bottom more and more the faster you go until all contact is lost. Installed a few in my time and always in the instructions there has been an angle down adjustment as well as the height one.

-- Jeff

 

[w2much]

Re: is this transducer installed too low??

I too would move the transducer up a bit. Some trial and error but easy to do. I had the same issues you described and moved and moved the transducer but was never satisfied. I finally purchased another fishfinder and new transducer, still had the issues you described. You may be having electronic interference from other electronics or even your engine. I installed a second battery not in parallel with the first. I ran lights and the fishfinder only to it. This cured my problem and taught me a valuable lesson. Also of course be certain that the trailing edge of your transducer is not higher than the leading edge. Good luck. Also noticed some fouling on the surface of your transducer, you need to clean that off ,it too will cause bad readings

 

[Seon]

Re: is this transducer installed too low??

I ... I had the same issues you described...
... I finally purchased another fishfinder and new transducer..

I too bought another unit and upgraded to a 10.5" screen. At that point, I bought a shoot-thru hull ducer which I epoxied in the bilge and am very satisfied with the results

 

[dingbat]

Re: is this transducer installed too low??

Don't matter how high or low you mount the unit you are never going to get a good reading with the transducer sitting that close to the strake. The speed pick-up is probably causing you some grief as well.

Move the transducer over about ? way between the strake and the chine and you should see a major improvement in performance.


There are some good mounting tips at the end of this presentation.
http://airmartechnology.com/uploads/installguide/Miami 2009 Airmar Generic Presentation.pdf

 

[Five O'Clock]

Re: is this transducer installed too low??

It seems as if the speedometer pitot is half way between the chine and strake, what do you think I should do dingbat?

I never look at the speedometer, it doesn't even really work, I need to replace it anyway. I go off of one of my 2 GPS systems for speed.

 

[slasmith1]

Re: is this transducer installed too low??

I have had the same problem with every transom mount transducer I have ever owned. The only solution I have found is to spend a little extra up front and buy a through hull transducer.

 

[dingbat]

Re: is this transducer installed too low??

It seems as if the speedometer pitot is half way between the chine and strake, what do you think I should do dingbat?

I never look at the speedometer, it doesn't even really work, I need to replace it anyway. I go off of one of my 2 GPS systems for speed.

You need to get the transducer away from that strake. Looks like you have plenty of room to work with if you move the transducer toward the chine (right) in the picture. Move the transducer over about 8" to the right and give it another try.

On my previous boat I gave up messing with a transom mount and went to a tank mounted shoot thru arrangement. It provided very good performance but I wanted something better the next time. On my latest boat I wanted to go thru hull. Airmar had just come out with the tilted Element thru hull transducer so I gave it a try.

The element inside the transducers is tilted to match the deadrise of the boat. This allows the transducer to be flush mounted to the bottom and eliminated the need for a faring block (like the transducer shown above) sticking off the bottom of the hull. The flat surface of the Tilted Element transducer has no problem passing over or sitting on rollers so they quickly caught on with the trailer boat crowd.

I?m running a B164 which is a 1kW transducer and probably a bit over the top for your installation. For a 600W installation a B60 transducer would work quite well. Runs @ $200

 

[Five O'Clock]

Re: is this transducer installed too low??

Thank you to everybody for your response. I'm going to relocate the transducer this weekend.

When I move the transducer to the "right" in the picture, I'm going to have a few open screw holes. Can I fill those with 4200 or 5200 or should I be using something else?

 

[Fl_Richard]

Re: is this transducer installed too low??

MarineTex Works well.