Airmar Transducer - Loosing my cool!

[whiteman]

So I've had the Furuno 620 installed for a few weeks with the Airmar P66 hanging off the back. Three test trips and losing bottom at 15-18 knots. Called Furuno and they were polite but essentially it was RTFM as the answer.

So dropped the Airmar a little and angled forward. Big trip to the reef on Saturday as THE test of this gear. At 20 knots in flat water I have a depth but no view of the bottom but this is slightly better.

However, half way out at 20 knots (the sounder has lost it by this stage) in very lumpy conditions I hear BANG, BANG, BANG coming from the rear end. The transducer is hanging on by the cable only. So I tied it off with an occy strap to continue to the reef (me, completely depressed and feeling a lot like NEWBY in his anti-Lowrance posts).

At the reef in calm waters I click it back into place but it looks like the locking cap has gone missing so getting good readings at 5 knots and we bag out on reef fish in two hours. Excellent result, love the sounder.

On the way back in lumpy conditions BANG, BANG , BANG - you know the rest.

This transducer is SOOOOOO touchy. I don't know if I'll ever find a spot where it doesn't get serious "cavitation" or whatever it's called. And now I've gotta get it repaired and I reckon I'll have a warranty fight on my hands. When it is good, it is PERFECT. But I need to cover ground at speed to find good fishing.

I'll try and post results as others may learn from my experience. BTW, it is on the back of a Milleneum hull if you have good advice.

[wiz]

some pics of position of transducer in relation to the hull would be good if you are able cheers

[stabi 659]

Mate,

I have the same set up with the 585 on the Stabi.

Will be able to get a better idea with some pics from the side to see how deep it is sitting.

I am able to read depth and see bottom at 30knts but i have a clean hull with no strakes. Had the same on my last boat and after a bit of playing around it worked well at 30knts. Just got to make sure it is in clean water.

If it is still not working see if you cant get your hands on another transducer. They are prety cheap or someone might have a spare floating around.

As for the locking pin i had very simular recently. Transducer fell off and as i didn't want to swim with the sharks i lost a days fishing. Now i make sure it's all good and the clip is locked in before each trip.

Cheers

[aharding]

You need to stick the P66 really deep in the water colum and with quite an angle on the face to get a good reading at speed (you may find that this will pop off your tdx in the rough but a self tapper through the quick release will fix that or heat and bend the tab) - try this, guarantee it will fix things.

They are a top unit and Airmar are very good quality and reliability wise, I'd imagine you are grabbing some aerated water somehow through tdx position.

[peterbo3]

I had a P66 on an earlier boat & it was fine AFTER I did what aharding suggests. Plus, remove the speed wheel. It is not needed with a GPS & although it sits behind the transducer face I feel that it causes the unit to "pop" up.
In very lumpy conditions you will be pushing to see bottom at 20 knots if you have hull strakes. There is just too much aerated water coming off the strakes.



Not the best photo but you can see how deep it is.

[whiteman]

Some photos that may interest attached. I really can't see how going deeper will help much as it is already way below the hull. I may try centering it between the ribs a little more.

Called Markwell Marine as they are the Australian distributors for Airmar. The guy had heard of a few locking clasps that had broken. BUT - he said I'd have trouble claiming this as warranty (I'll try tomorrow) AND there are no replacement parts - YOU HAVE TO BUY A WHOLE NEW TRANSDUCER! What a racket! You can get the part in the US from here for $US20 ... http://www.blueheronmarine.com/Airma...t-for-P66-6707

I'm starting to get annoyed at this. It's ironic that I switched from Lowrance to Furuno (and Airmar) based upon NEWBY's issues with Lowrance transducers and I may be getting into the same problem.

[trueblue]

I put a small self tapper through one side to stop it flicking up all the time. a bit of sikaflex would do the same, but don't overdo it.

you really have to bury these transducers to get them to work, but this puts enormous strain on the bracket

[peterbo3]

Your problem is looking at you. The planing strakes are the cause, they are too close together & run all the way to the transom. The water coming off them will be a mass of bubbles at speed. At 5 knots you mention good bottom pics which indicates no transducer or head unit problems which only leaves hull location.
Can you move the ducer closer to the centreline away from the strakes? Try raising it first as you seem to be deep enough.


I am running a "through hull" unit on a tab off the centre line & a 1KW unit on a slide. But there is a flat planing plank in front of the tab. That may be an option but you need clean water. A half pipe or box section keel will probably stuff that option..............is your keel a simple V? Some more pics would be good.

[bluefin59]

I notice you have the wedge in ,have you tried it without it thats the way i have it on my fin maybe its shooting a bit far forward when you are on the plane just an idea ...matt

[8astripey]

by the looks of the pics you are getting too much airation from the stakes on the hull. can you move it further towards the centre of the hull away from the stakes and push it a bit deeper. any rib stake etc in a hull will cause probs with any transducer. problem with any trany at speed is as mentioned earlier with a bit of slop you will lose bottom. failing that airmar say a p79 will shoot through an alluminium hull 3mm thick?

[bastard]

I reckon ditch it all together and drill a hole through the bottom and mount a through hull ,would suck if you had a hole and it still didnt work though,ive never had a transom mount that was much chop,i to just fitted a 620 on the weekend and used a wet box and it works fantastic,ive hurd people that reckon theyve shot through the aluminium and been fine and others that say it wont .

[whiteman]

Firstly, a BIG YAY! to BCF who effortlessly swapped the broken transducer bracket with a new kit which they took from a full unit off the shelf. Their supplier will send them a replacement kit. BIG BOO! to Markwell who said the kits weren't available in Australia.

To answer questions....
- The bottom of the Milleneum Quinnie hull has full length strakes around 6" apart.
- There is nowhere at the back to get away from a strake.
- I have tried with and without the wedge. With the wedge is best so far.
- Not interested in through the hull transducer at this stage.

I have a couple of options to try - go deeper at the current mounting position (probably won't make much difference as it is already 30mm below the hull) OR move to an outer edge spot where the flare is flatter and this looks to be my best option. The local Quinnie dealer was no help as they install the small-style transducer which I've had in the past and works well.

Thanks all for your suggestions.

[trueblue]

I filed my wedge down to be about 2/3's of the original angle, it was too much initially, but too little without it

[Out-Station]

Whiteman, as per other comments on here i recon your facing an uphill battle to get the picture your looking for at 20 knots with a pressed strakes hull. Not saying you won't find a sweat spot but imo it will take some finding. I have a p66 on 585 on a smooth hull plate boat and the standard recomended fitup works fine for me. 20 knots of good picture in flat seas. I think you can only keep playing with it and hopefully find the right config for your boat. Only my opinion but i's start by laying the sucker right back just to see what happens. Hope you can get is sorted.

Cheer's, Scott

[testlab]

I agree with the general concensus, it has to go a fair bit deeper. From looking at your pics it may already be below the level of the hull, but it is line with the apex of the pocket formed between strakes. So air or turbulence is going to be at a maximum there.

I went looking for a diagram of this as I can't draw for peanuts, and found an installation manual from Norcross Marine that had this diagram in it.




"I" pretty much matches where yours is mounted now. I would have a look over the back of the boat when at speed and look for clean flat water with no foam exiting from under the transom. Thats the sweet spot and I reckon it will be near the bottom of the strake. Even so you may have to drop it down further.

There is an Airmar FAQ about your problem but its not much more help than what everyone here has said already.

http://faq.airmar.com/index.php?sid=...&highlight=P66

Hope this helps.