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Author Topic:   Navigation Instrument Resets On Engine Start
ssi_whaler posted 02-20-2009 04:21 PM ET (US)   Profile for ssi_whaler   Send Email to ssi_whaler  
Here's the problem: On my 1983 Montauk 17 I have a Lowrance 520 that resets everytime I start the motor, a Yamaha F100 four-cycle. I would like to be able to arrive at my destination, stop the motor, leave the key in the ignition in the position (middle) to power electronics, and restart my motor without the Lowrance rebooting. Currently, I can stop the motor and the Lowrance will stay on. However, when I start the motor, the Lowrance resets and I have to wait for it to restart, initialize the GPS receiver, and then I have to manually scroll back to the page with the SONAR-Navigation split screen. It is not a big deal - just kind of annoying when skipping from fishing hole to fishing hole. The Lowrance is wired to the original fuse box that came with the boat in the same manner as the marine radio and fm radio. Anyone experience this, have any suggestions? Thanks, Garret
Liteamorn posted 02-20-2009 05:41 PM ET (US)     Profile for Liteamorn  Send Email to Liteamorn     
Your unit is probably shutting down due to it receiving less than 12 volts when you crank your engine over. I would check all of your connections making sure they are all clean and tight. If your battery is older it might be time to replace it. I would step it up a few amps when I did replace it.


Jefecinco posted 02-20-2009 07:25 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
I agree with Litemorn. A dual battery setup could also be worth consideration. It would ensure a good voltage supply to your electronics and decrease the likelyhood of needing a tow at some future time.


swist posted 02-21-2009 08:30 AM ET (US)     Profile for swist  Send Email to swist     
Check the input voltage range on the specs of your GPS, I don't know how old a Lowrance 520 is, but most modern electronic devices have a huge tolerance for swing of input voltage. I've seen things like 8-20 volts.

If cranking the engine is dropping it that low there is indeed either something wrong with the battery, or a weak connection somewhere. It's easy enough to test with a voltmeter during cranking.

jimh posted 02-21-2009 09:31 AM ET (US)     Profile for jimh  Send Email to jimh     
From your narrative it sounds like you have wired the navigation instrument to be powered from the ignition switch of the motor. When the ignition key is moved from the RUN position to the START position, the voltage provided may be interrupted. If this is indeed how you have wired the power for the navigation instrument, it will always reset. To remedy this, move the power leads for the navigation instrument to a direct connection to the battery power distribution.

Even on a small boat like a Boston Whaler MONTAUK 17, there should be a battery distribution wiring block with fused branch circuits. Wire the navigation instrument to that distribution block.

If you already have the instrument wired directly to the battery, and it resets whenever you crank the engine starting motor, then the voltage sag in the battery is too great. This is indicative of other problems.

While not necessarily specific to your Yamaha F100, it is not always a good idea to leave the engine ignition circuit in the RUN position when the engine is not running. In some motors, leaving the ignition circuit in the RUN position without the engine running will cause problems.

By the way, exactly how do you shut off the engine without turning the key to the STOP or OFF position? If your navigation instrument is wired to the ignition circuit of the motor, it must reset whenever you turn the key to OFF.

Chuck Tribolet posted 02-21-2009 08:57 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
There is significant voltage sag when cranking. That's
normal, and you GPS can't handle it. And then there's a big
spike when the engine catches.

Humminbird used to make a device called the SureVolt. Put in
anything from about 6V to about 18V, and 13.8V (IIRC) comes
out. It can run small devices like fishfinders and chartplotters,
but not a VHF radio on transmit. They were about $60, weren't
around long, and were remaindeder at about $20. I've got
one, it's been working for six or seven years, and it was
worth $60.


glen e posted 02-21-2009 11:32 PM ET (US)     Profile for glen e  Send Email to glen e     
google "Newmar Start Guard"
jimh posted 02-23-2009 09:37 AM ET (US)     Profile for jimh  Send Email to jimh     
For information about the Newmar Start Guard, you should just visit the company's website: html

ssi_whaler posted 02-23-2009 08:56 PM ET (US)     Profile for ssi_whaler  Send Email to ssi_whaler     
All, thanks for the suggestions. I replaced the battery about a week ago with a new Group 27 battery which has a little over 800 mca's. Hopefully, it is not my battery already. After reading the above, I completely disconnected the unit, re-spliced the wires to the connectors, sealed those with heat shrink tubing, and made sure the connectors were securely attached to the fuse box. That didn't seem to correct the problem so I used the "data overlay" feature in the unit so I could monitor the volt reading. I noticed that it was around 11.8 with the screen at its brightest and jumped to 12.2 at the dimmest setting. The middle setting was also 12.2. I was able to turn the motor over without it resetting the unit while the display was set on the dimmest setting. Not perfect, but at least I have a temporary workaround until I invest in something like the Newmar Start Guard. Also, it turns out the electronics are not wired to the ignition like I initially assumed (sorry for the red herring). Thanks again for all of the suggestions - Garret
tmann45 posted 02-24-2009 12:21 PM ET (US)     Profile for tmann45  Send Email to tmann45     
If your voltage at the unit changes with the brightness setting, that would suggest a bad connection between the unit and the battery.
jimh posted 02-24-2009 06:30 PM ET (US)     Profile for jimh  Send Email to jimh     
For the cost of the NEWMAR Start Guard you could install an isolated house battery and an automatic combiner relay to provide charging for it. The house battery would also serve as a secondary battery for engine starting if you added a dual battery switch. For a small boat this is a better solution. The Start Guard does not look like its enclosure is weatherproof, which might be a problem in a small boat.

The Start Guard apparently contains its own small storage battery and charger set up, which is how it supplies isolated voltage to the electronics during engine cranking.

Casco Bay Outrage posted 02-24-2009 06:33 PM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
Is that the correct size and CCA rated battery for the motor (check with Yamaha)?

I still think something is wired wrong. There was no standard factory wiring for boats of your year. With the F100, someone re-powered. I am sure the electronics are not original. Often the yard doing the rigging does not do a clean install, splices and piggybacks off existing wires rather than removing the old ones and installing new one.

My boat was re-powered and the yard hacked the wiring. What a complete mess. Trace all your wiring. I would not be surprised if you find something totally wacked.

I would hold off on buying a power conditioner till you have fully assessed all the wiring in the boat.

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