Gnasher Posted February 21, 2006 Report Posted February 21, 2006 Hi Guys, I have bought a great Garmin set up a while back, both fish finder and Gps (thanks Bob F). When the boat is moving slowly (upto say 10 knots) the fish finder reads perfect, but as soon as i pick up the revs the screen wont pick anything up, instead it will just flash and give the same reading that it gave at say 10 knots. Is this due to the extra turbelent water caused by the extra speed from the engine? Possibly the transom in the wrong position? Any other ideas? Quote
plaicemat Posted February 21, 2006 Report Posted February 21, 2006 I wouldn't think the transom is in the wrong position. It's usually found just sitting there at the back of the boat! Quote
Afishionado Posted February 21, 2006 Report Posted February 21, 2006 I wouldn't think the transom is in the wrong position. It's usually found just sitting there at the back of the boat! ROTFLMAO I am so tempted to say 'move the transom further forward' but that would be a cheap shot Dan your problem is almost certainly the manner and position of the transducer head. I guess you didn't have the little instruction book about fitting a transducer? Is it through the hull or transom mounted on a bracket? Is it forward of any prop wash or hull cavitation? Is the angle of attack correct so that turbulance bubbles flow away instead of building up? Is the lower part of the head low enough below the transom bottom edge? Why do mummies and daddies sleep in the same bed but I can't sleep with my cousin even though I want to Mad Mike Quote
Swainiac Posted February 22, 2006 Report Posted February 22, 2006 Mikey...............personal problem.....see the Padre. <gg> Rich Quote
Gnasher Posted February 22, 2006 Author Report Posted February 22, 2006 sorry, transducer....was tired....lol...there was a mounting bracket, and it is fitted about about 1 inch lower than the bottom of the boat. I would of thought it was in the right position, but may have to trial and error to get it in the right position Quote
alankirby Posted February 22, 2006 Report Posted February 22, 2006 Hi, 1" below is far too much !!! The transducer face should be 1/8" below the hull bottom and should be parallel with the bottom of the boat or very slightly tilted back.It should be on the starboard side and at least 3" away from the swing of the propeller.Starboard mounting assures minimal aeration from the turbulance of the propellers, which can degrade performance.You will find you may have to make a few adjustments to get just the right position. You could always epoxy the transducer inside the hull and shoot through which is what i do now. Having fitted quite a few transducrs over the years i have yet to fit a transom mounted one and have it work very well. I have fixed the transom mounted transducer that came with my Raymarine DS500x inside the hull and it shoots trough great, and unless your going in 800 feet of water you shouldn`t notice any loss in performance. I wrap the transducer tight with electrical tape and then epoxy it in place,that way you can always cut the tape and remove the transducer if you want. Alan Quote
Newboy Posted February 22, 2006 Report Posted February 22, 2006 Tranducer is usually fitted 12-18" to either side of middle of outboard. Quote
alankirby Posted February 22, 2006 Report Posted February 22, 2006 Never known a transducer to be fitted on the port side of an outboard ! Have a look at the link for fitting instructions of an Airmar transducer. Its a .pdf file. Transducer fitting instructions Quote
Paul D Posted February 22, 2006 Report Posted February 22, 2006 Presumably fitting to the port side does not make sense because the lead then has to be run over to the helm position on the starboard side. So might as well start with the starboard side. Quote
Seamouse Posted February 22, 2006 Report Posted February 22, 2006 Never known a transducer to be fitted on the port side of an outboard ! Quote
Seamouse Posted February 22, 2006 Report Posted February 22, 2006 Oops, somehow managed to send the last mail early. Premature communication Mine's fitted to port side, Garmin instructions said nothing about a starboard restriction and I have no problems with loss of signal at speed etc. Guess I'm simply positioned sufficiently clear of the prop for it not to matter. With respect to Paul's point about the transducer cable run, port side seemd better for two reasons. It meant the transducer wasn't same side as the Z step, so not getting regularly kicked, and it avoided the power feeds from the engine/main battery forward, which route down the stbd side. Running 16ft of transducer cable tight alongside the main power feeds seemed to me to be asking for trouble?? Steve Quote
alankirby Posted February 22, 2006 Report Posted February 22, 2006 Your quite right about the cable. Keep the transducer and battery cables apart. I wondered why when i first fitted one why the screen went crazy when i increased engine speed and it was because the cable was tied to the battery cable for about 3 feet. We all learn by our mistakes !! Quote
Newboy Posted February 22, 2006 Report Posted February 22, 2006 The intruction for my fishfinder simply says min 12" from centre of outboard. It doesn't restrict it to port or starboard. Paul, it makes sense if your helm is on the starboard side, but what if your helm is on the portside? Quote
Paul D Posted February 23, 2006 Report Posted February 23, 2006 Kam, Helms are usually on the port side for reasons of cancelling out the torque from the propellor ( so I read ). Come to think about it, have you seen a boat with the helm on the port side ? Quote
Newboy Posted February 23, 2006 Report Posted February 23, 2006 Shetland does. Some of the older shetland boats (and boats which shetland nicked the hull from)has the helm on the left hand side. However, they only ever have small outboard so torque from the prop was never going to trouble it. Quote
Afishionado Posted February 23, 2006 Report Posted February 23, 2006 Kam, Helms are usually on the port side for reasons of cancelling out the torque from the propellor ( so I read ). Come to think about it, have you seen a boat with the helm on the port side ? Yes loadsa port side helms about. The main reasons for transducer blur at speed are depth below the transom and angle of attack. The smooth lower surface of the transducer head should slope very very slightly forward (not backward as this will induce vortex turbulance) so that the flow of water past the head is swept clean of bubbles. Which side of the engine it is is purely a matter of choice. Mad Mike Quote
Bob F Posted February 24, 2006 Report Posted February 24, 2006 Hi Dan, Sorry to hear you're having a problem. If it's speed related it will be the positioning of the transducer, as the others have said. To check that it is not engine interference, rev the engine in neutral and check that the display is ok. BF Quote
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