No Depth Reading

[jimh]

my bidata depth sounder flashes (no reading) when I reach planing speed and only stops when my speed drops to about 12 kts which is a bit of a worry to say the least. My current thought is that the transducer is not mounted correctly, however doesn't look like this can be moved - any views ??

incidently, is this a problem I could go back to the broker with??

thanks

Jim

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[Tiger Rag]

I would suggest that the transducer is positioned wrongly and when you are up on the plane it is getting too much disturbed water (i.e. air bubbles) passing over it so will not register anything.

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[hlb]

Alot will depend on your type of boat and the conditions. But I would expect most depth sounders not to register at times above 20 knots. Because of all the air under the boat. This is not a problem as of course you wil not be doing 20 knots in areas where your not sure of the bottom. Will you?? In any case, even if it is regeristering. With a Bleep, bleep BANG, your hardly going to miss anything are you!!....../forums/images/icons/smile.gif

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Haydn

 

[Deleted User YDKXO]

If your boat is new, I would go back to the broker with it but it is a difficult problem to crack. As Russell says, its caused by disturbed water flow under the hull at speed
I've had this problem on a couple of boats and solved it by repositioning the transducer. Get yourself another transducer, connect it up to the display and place the transducer in a small water filled plastic bag. Ask some brave soul to position themselves in the bilges whilst you drive the boat at planing speed and have them move the bag/transducer to different positions on the hull until a consistent/correct reading is displayed. Its best to start close to the existing transducer position and you must ensure that the water filled bag is always in contact with the hull - no air underneath
Once you've found a position that works you have a choice. Either put another hole in the hull for the new transducer or use a special in-hull transducer which some echo-sounder manufacturers offer eg Raymarine. Alternatively, if you cant get an in-hull transducer, you could find a piece of plastic pipe which is a tight fit to the through hull transducer, glass the pipe to the hull, rigidly fix the transducer inside the pipe and fill the void between the transducer and the hull with castor oil
If you dont want to do this yourself, any competent marine electronics company should be able to do the job

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[jimh]

yes i agree, however I got quite acustomed on my previous boat checking the depth was what it should be at various stages during a passage - I now feel like i've 'lost an eye'

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[hlb]

Well. Do like me and buy a fish finder. Then when one stops working the other is usually ok or maybe the other way about, depending on conditions. But depending on bottom and many other things. Occasionaly both dont work. Course yours might also be fitted badly.

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Haydn

 

[DavidJ]

Agree with Russell to likely cause but it's a tricky problem which the manufacturers must know about (the broker probably won't!!) chat to them. Does the transducer go through the hull or is it surface mounted (on the inside)
David

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[Solitaire]

Firstly, I'm assuming that your transducer is fitted externally to the stern on the transom. If this is the case, then it will always be a problem. As has been outlined earlier, the movement of the water under the hull and the prop wash will have a direct effect. I have both a fishfinder with the transducer mounted on the stern and a depth guage with the transducer mounted so it reads "thru" the hull at a point where the water turbulanace is least effected and this reads perfectly when on the plane. The fishinder depth guage however will not register at speeds above 6 knots and even takes time to settle down just after starting the engine during the warm up period.


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[jimh]

I think that it is surface mounted - although I'm not sure. It's about 2" in diameter and sits about an inch or two proud inside the hull. I didn't get an oppurtunity to see the boat in dry dock..

Would a through hull fitting look similar to the speed 'wheel' - with a threaded retaining collar? beacause I have one of those and it's not the same..

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[DavidJ]

My guess is it would look the same as your 'wheel' if it was through mounted, but that's only a guess.
I think the important thing is to dump the problem on the dealer and not attempt to solve it yourself. We all like to solve problems but you can easily invalidate the warrentee by experimenting with 'fixes' ourselves.
Again, have a chat to the manufacturers he must have a drawing of recommended positions.
David

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[MickJ]

I had exactly the same issue with a new boat with a transducer fixed to the inside of the hull. The dealer refitted it to no avail. I even bought my own fixing kit (oil bath) from NASA marine but it is still intermittent. I've since been told that depending on the hull construction (solid GRP or cored with and foam or balsa etc), it may never be perfect. The core layers distort and weaken the signal too much.

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[Deleted User YDKXO]

It should look similar with a retaining collar, maybe 2-3" high if its a through hull unit. If its an in-hull one the whole thing will be larger and sit in some kind of tube and you should be able to remove the transducer

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[duncan]

firstly there have been a a fair few long and detailed posts on PBO about transducers and positioning that would be worth a look
secondly there are some general statements made here that I would take issue with - maily because they appear to contradict manufactures advice! A properly designed 'skimmer' transducer, transom mounted in the right place on a planning hull is considered best for image in most applications. Bass boats would expect to run at in excess of 50knots and still get a reasonable image! Lowrance rate some of their transducers as suitable to 60knots. I never had any issues with my last boat except when it came out of the water! Getting it knocked off/back by twigs etc was however a problem and I ended up epoxying it inside the hull (quite thin GRP) and got an acceptable image up to around 30knots that way - again as long as smooth water kept the hull in contact. Many competition fishing boats do use thru' hull fittings but go to extreme efforts to ensure an absolutely smooth hull/transducer/hull exterior finish but suffer from deadrise issues and forward part of hull being clear of the water at speed. Fairings etc all cause problems.
Do not rule out the units electronics and settings causing the 'loss of established bottom' - in shallow water, silted water or deep sea water the unit may well loose contact and not establish it again easily for a number of reasons. I often get this in Poole Harbour because the unit, on auto sensitivity, can increase gain if it looses the bottom momentarily and end up uncertain if the top or bottom of the silt is the bottom - and end up flashing away but showing a reasonable picture until it sorts itself out - if you only have a digital numerical display you will just get the flashing last know depth for a bit. Finally, if the boat is new and the hull is in the water (you know what I mean!) whatever fittings have been installed should give you a depth reading pretty much regardless of speed - in fact the unit suplied should suit the hull and it's design speed etc

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[BrendanS]

Or do like me and win one! /forums/images/icons/smile.gif

Just had a letter from IPC informing me I won a prize from MBM's April competition, and am about to be proud owner of an Echopilot. Echopilot phoned today, checking where to deliver, and offering advice on installation!

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[oldgit]

Old boat (regal 23), would reach 25 knots. The naff old seafarer depth thingy worked without any problems at all at that speed.

<hr width=100% size=1>My little Princess/forums/images/icons/laugh.gifthe 33 of course.

 

[BarryH]

I've got an Eagle Supra Pro with transom mounted skimmer transducer. Never had the probs that you mention in Poole harbour. Its always given consistant readings with a good picture right upto full speed, about 35 knots. Even when following in another boats wash with lots of airated water passing under the skimmer.

Did have a nasa that would give irratic readings until you played with the gain control. But then that was an old whirlygig unit, so fairly basic. I just leave the Eagle in auto mode and it looks after itself.

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