Well dang Bucky! I was tied up with some eBay stuff and just caught a break, so I figured I'd see if there's anything on the net regarding your problem. Damn! The very first site I brought up almost mirrors persactly what I've been saying! I've "been there, done that" so many times with both cars and boats, I guess the experience actually means something. This is from a boating forum ... the initial post could be YOU talking!

Here's the initial post and the very next two responses:

Hi to all,
I am having a problem with my Humminbird FF/GPS losing power when I switch the key to start the motor. Started as an occasional problem but now happens almost every time.

Current wiring: Two batteries to selector switch (1 & 2) Common power to the motor and 2 feeds to the console.

What I have done: At the end of last season I was curious as to whether I may have corrosion in the selector switch dropping power to the FF while engaging the ignition switch so I ran direct to the battery and seemed to not lose power to FF while engaging switch; so I bought a new selector switch and installed. This season, (with new selector switch installed) I lose power to FF every time that I engage ignition switch. So, I examined all pos and negative connections near the batteries and noticed some corrosion in the wiring. I cut back the two pos and neg feeds to the console until I didn't see any corrosion and replaced the ring terminals with sealable connectors, and replaced the heavy battery to selector switch cables. Still no change; lose FF power every time that I key the ignition switch. I was hopefull that I had a poor pos or neg connection and that the heavy draw of the starter was causing a disruption of power to the FF. I do not seem to notice any other power disruption to any other electronic components.

I am hopeful that someone may have experienced this and or further advice as to where the problem may lie. All systems had been working properly since my ownership of the boat. I hope to resolve the problem but I suppose in the meantime I may bypass the selector switch and connect the positve lead (providing power to the console and FF) directly to the battery as a possible short term fix. I will welcome and investigate any suggestions. Thanks in advance.

Response #1: The problems lies with you starting the engine while your electronics on. Eventually, a spike or surge with get your electronics. All electronics should be on a master switch and it should be off until your engines are started. Turn on your master switch and then repower your electronics.

Response #2: Hi, As an electronics tech I see problems like this all the time. What is happening is when you crank your starter (and there is nothing on your boat that draws more amps than the starter) the overall voltage in your electrical system is probably dropping down. When the voltage drops in a system with everything else staying the same, the amps go up. For example if you drop the voltage from 12 vdc to 6 vdc with everthing else staying the same, the amperage doubles! So while your ff is on when you crank the starter (as previous post said, it shouldn't be) you are dropping the voltage and increasing the amperage throughout the entire electrical system. Not just the ff. Keep it up and the stereo, tv, etc will be next. Also too small a guage wire supplying the power will cause voltage drop. Depending on the wattage of the fish finder you prob should use 12 ga high stranded at the least. Long runs use 10 ga.. Joe