Noise Suppression

[DangerDan]

I just finished installing some new electronics on my boat and things seemed to work well with exception of when I ran above 3,000 RPMs. The fish finder gave irratic readings and the bar to the right was indicating constant clutter as opposed to a mark here & there. I'm figuring it's likely ignition noise. Also my Speed & Temp seems to be getting some interference as well but at lower RPMs, say 800 or so. <br /><br />My electronics run off of my house banks and that circuit is seperate from my starting circuit which runs off of the single starter batt. I use a BEP switch to isolate and charge the two systems. My transducer lines run along the gunnel alone with no other wiring and the power goes to a fuse panel which is supplied by my house batts. Can anyone give any input on this? Is there some sort of noise suppresion I can consider in cleaning up the interference?<br /><br />Any advice would be appreciated.

 

[WillyBWright]

Re: Noise Suppression

If your motor doesn't already have them, install supressor sparkplugs. If the electronics are running off the same battery that the pumps are on, those could also cause interference.

 

[Boatist]

Re: Noise Suppression

I think your problem is more likely your transducer mounting. When the boat planes your getting air under the transducer. <br /><br />Transducer may have something ahead of it making bubbles. Transducer may be too high so when boat comes up on plane it not deep enough in the water.<br /><br />Also at speed it is normal to have a lot more surface clutter. Some units have a surface clutter suppresion setting.

 

[DangerDan]

Re: Noise Suppression

The FF is the Humminbird 981C. I was pretty careful in regard to where and how it was mounted as this unit also has the "side scan" feature. The instructions indicate the bottom of the transducer be approx. 1/8" to 1/4" below the hull. This was how I installed it. It's installed in an area (between the strakes) where no abnormal turbulence should be. I found out Saturday my Alernator was not charging properly and suspect a diode as the culprit. As I said more than one electronics unit was compromised by the problem. After repairing the Alt. I'll do another adjustment on the ducer if necessary. <br />Thanks

 

[Boatist]

Re: Noise Suppression

Dan be aware the biggest killer of alternators diodes is battery switches. If it turned thru off with the motor running the alternator diodes will be blown. If it is not a MAKE BEFORE BREAK it will also bolw diodes when switching between batteries. If you add a battery isolator then it will stop alternator diodes from blowing.<br /><br />Sounds like you did a good job of installing your transducer. I will tell you a few years back that Humming bird units were almost impossible to get to work over trolling speed. Have not herd of any problems with the newer units.<br /><br />Two thing to try when out on the water next. One is to try turning the gain down when running at the problem speed. also try turning it up. If the unit has a surface clutter control turn it up. Another thing you can try at the problem speed is to do a slow turn in each direction. This may cause the transducer to run deeper and the water to flow different accross the transducer. Watch the right side of the screen and see if it helps.<br /><br />Good LucK and please come back and tell us what fixes your problem. That will help the next guy.

 

[DangerDan]

Re: Noise Suppression

As suspected the diode seems to be the problem. After having the Alt. checked it was repaired and re-installed. Both the FF and the Speed & temp now work without a problem. FF works great even at higher speeds with no interference at WOT and RPM of 4900 RPM. Lets Fish!!!!