# oops - my depth transducer got painted with two coats of bottom paint



## billsull (Jul 8, 2007)

I hired a kid to paint my bottom and shame on me for not supervising carefully, but my depth sounder got painted with two coats of WM Bottomshield (their hard paint). It's a nylon thru-hull transducer connected to a Raymarine ST60 Tridata.

I've always heard that one shouldn't paint transducers, but I don't know what the real consequences are. Also, what is the best way to remove it? scrape or is their some kind of solvent that won't hurt the 'ducer?


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## ambianceack (Aug 27, 2006)

try using a scrub sponge (rough one side and soft on the other-commonly found in the kitchen) and a water and acetone solution at 1:1. gently/lightly wash and scrub the area. 

You might get some false readings if you leave the bottom paint on. Anything listed in the manufacture spec. about caring for the nylon transducer?


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## Tanley (Aug 20, 2009)

The yard painted ours as well (they don't allow owners to paint their own hulls). Transducer still works fine, no problems.


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## genieskip (Jan 1, 2008)

I just put in a new ST60 depth instrument and Raymarine wants you to paint it. It seemed weird to me so I didn't, but I don't think it will effect your readings.


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## Faster (Sep 13, 2005)

Should be no problem - transducers can be mounted to shoot through the hull skin in certain applications, so a few mils of paint won't matter.


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## Gary M (May 9, 2006)

You are better off with a mil of bottom paint than you would be with several barnacles etc.


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## bljones (Oct 13, 2008)

The concern really isn't the thickness of the coating but the composition of the coating. Clean it off with a paper towel soaked in laquer thinner. 30 seconds and done. In fact you likely won't have to (and shouldn't) scrub very hard, as the paint should still be soft. After all, it wasn't painted very long ago, right? For best results you should be hull wet less than 72 hrs after bottom painting.


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## jarcher (Jul 29, 2008)

You should probably remove that pait as others have said. For those who want anti-fouling paint for a transducer, you can buy water based paint for just that purpose. The manual for mine recomended that a water based anti-fouling paint be used on it.


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## JeffBurright (Apr 22, 2009)

My understanding is that the copper in most bottom paints can lead to a significant amount of signal interference. I had the same issue a couple years ago and opted to dive under the boat with a purple 3M scrub pad. Just be gentle, because apparently you can damage the diaphragm if you scrub too hard.

-- Just another 2 cents of nautical hearsay.


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## eolon (Feb 5, 2008)

Most modern transducers suggest 1 or two coats of bottom paint to prevent fouling. Even the biggest particles of copper in bottom paint are between 20 and 40 um (microns) in size. Your ultrasonic frequency is either 50 kHz or 200 kHz, or sometimes both (for depth sounders that work at depths >400 ft.)

Because these frequencies translate to wavelengths of 68.6 mm and 171.5 mm, respectively, and because both wavelengths are much larger than the copper particles (which are between 0.020mm and 0.040 mm), even the copper-laden bottom paint is perfectly transparent to your transducer. 

This is the same reason that light can pass through glass (different frequency, though).

Anyhow, don't yell at the kid, he was doing the right thing, whether he knew it or not 

Best Regards,


e

.::.


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## hangupndrive (May 4, 2007)

This would be an Airmar transducer. They recommend using antifouling paint in their installation instructions. It should only be a water-based antifouling paint. A solvent based antifoulant can eat through the plastic. I would see if it works. If id does, no harm no foul, and I wouldn't mess with scrubbing the paint off.


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## Omatako (Sep 14, 2003)

I have had several thru-hull tranducers (mounted inside, no holes) and the boats have been antifouled with copper based paint on the outside and I have never had a problem with distorted readings so I don't think the copper has any effect.

As another post said, anti fouling is better than living stuff.


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## FlyNavy (May 14, 2009)

I did a lot of learning as I sought out the right depth finder/transducer combination for my boat. I chose an inside the hull—shoot through type transducer and learned some more.
Transducers are effected by changes in density which eventually yield their depth readings. The changes are critical in determining where the bottom is. 
In an inside the hull transducer, the puck is submerged in a liquid (mineral oil...no bubbles) inside a vessel which is epoxied to the inside of the hull at an appropriate place. It is essential that the transducer shoots through a homogenous density material (fiberglass) and not a mixed substrate (wood, metal and glass etc).
In your case the paint will be fine if there aren’t any air bubbles trapped in the paint as it will be shooting through the homogenous skin of the paint and will not detect any density changes. You will likely have to use the adjustment function to get perfect accuracy.


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## r.furborough (May 28, 2006)

The use of Mineral Oil in transducer resevoirs is no longer recommended as it affect the bonding material used to bond the tanks to the hull and leads to tank leaks or total bond failure. Now RV (Pink) Anti-Freeze is used.


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## billsull (Jul 8, 2007)

Thanks for all of the reassuring posts - I'll be able to test my sounder tomorrow because the Patience is going in! I have a "backup" thru-hull transducer that I can connect to my Garmin GPS/Sounder unit. I think I'll set that up for comparison. I'm going to try the "toilet wax ring" installation method that I have read about for that one.


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