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Sonar - it don't work like it did


Steve S
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I've got a Airmar transducer fitted to my aging Raymarine kit (DSM 300, E120).

 

When the boat in freshly launched the sonar will work up to just about 25knots if flat, but now, after a season in the water (10 months) it will barely work at all. The last couple of trips it has been no use at all as even on the drift the bottom comes and goes. This happened last year as well, the first year I got the boat.

 

Clearly the transducer cover is being fouled up over time and I've no doubt that when it goes back in after relaunch it will be fine for while, I'd just like to extend that while to 10 months.

 

Is this the problem you get? 

Any suggestions on keeping it free of fouling for longer?

I have heard that you can buy special anti fouling paint to go over transducers, any view of whether this is worth getting?

 

Steve

 

 

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Steve, Redfin is coated with a product called cooper coat which is guaranteed for 10 years from experience and research I have done this seems to hold true so you could try that if you can get hold of a small quantity. I know Marinetec at Portland have some as they did a minor repair for me recently but that probably doesn't help,you in Lymington!

Peter

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Thanks for the suggestions guys, barnacle/s is I think the most likely cause. I will know soon as she comes out Wednesday, let the work begin...

 

Apparently shooting through a copper coat or a copper based antifouling paint degrades performance but to what extent I don't know and rather hard to test.

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If shooting through paint degrades it that much I would not try shooting through the hull.

 

Mine is simply the standard lowrance skimmer transducer, that has been epoxied on the inside of the hull. It is shooting through the hull, 5 coats of epoxy and many of antifoul paint.

 

tracks the bottom at cruising speed [mine not Steve's] and picture improves when we slow a bit

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Sounds like affect of antifouling paint in degrading the sonar performance may be overstated.

 

Simrad do say this: http://www.simrad.com/www/01/nokbg0240.nsf/AllWeb/E41103520A769E0AC12575540048CB60?OpenDocument

 

The location of the transducer is pretty good in my opinion, certainly in the full flow. I'll take a good look at the fouling round that area when it comes out and see if I can smooth the area round it the transducer so are a less nooks and crannies (i love those words) for fouling to take a hold.

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Haha, well I think it does work of any least it is a help as I didn't loose much speed over the season, hardly a knot and more importantly my fuel consumption per N/M which I religiously record hardly went up.

 

But here's the thing, there is plate over the sonar, ultrasonics work very poorly through joints so I fear it won't be effective on the plate.

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RESET!  :rolleyes:

One of the issues of buying a thirdhand (or more) boat is that the person you buy off often doesn't know what he has got, such is the case with Tigerfish. I keep discovering things even now.

The new discovery is a pleasant one. The MFD E120 was configured for a through hull Airmar transducer, which I ASSUMED must live in the yellow box in the engine bay and the wedge shaped thing which seems to be underneath was the outside of the transducer. Wrong wrong wrong! The wedge shaped thing is an earth 1ft to starboard from the yellow box. I have in fact got an inhull transducer, there was no fouling underneath it so no problem there.

 

On opening the box I discovered it is liquid filled and the transducer appears to take up nearly the whole of the box!! :o , The liquid level was clearly low and appears to hardly touch the transducer, clearly that is the problem  :) . I’d better check if there is a leak.

 

A check of part numbers revealed that it is an Airmar R199, a 2kw!! transducer that should be capable of clear pictures at 30 knots or more, a top of the range device that never made it onto the boat sale particulars and I didn't realise what it was as I’d never seen one that big. So reconfigure the MFD to R199 and fill with propylene glycol and it should work great.

 

Thanks for all your suggestions, sorry to give you a bum steer on the problem.

 

post-1166-0-66282400-1424117175_thumb.jpeg

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Well done Steve, great result.

 

Interesting about the fluid to use in the box, so much so I looked it up and you are dead right about propylene glycol

 

For others here is a response to the question direct from Airmar:

 

What type of liquid do I use to fill my in-hull tank/base?

Non-toxic propylene glycol (RV antifreeze/coolant) should be used to fill an in-hull tank/base.

 

 

M260 tanks should only be installed with fiberglass resin, Marine-tex epoxy putty, or Fusor T10 EZ. On our newest tanks that have "gf nylon" printed in raised lettering on the sides, 3M's 5200 may also be used to adhere the tank to the hull.

 

The P79 base may installed with silicone sealant, fiberglass resin, 3M's 5200, or Marine-tex epoxy putty.

 

 

NOTE: Do NOT use mineral oil to fill a tank that is secured with 3M's 5200. Mineral oil may weaken the bond. Only use non-toxic propylene glycol (RV anti-freeze) when using this adhesive.

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