unit turns off than on with engine startup



I have had this unit mfd8 for almost a yr and this issue is new. On initial startup of engine no problems because I start the engine than turn on unit. But sailing the engine is turned off and if I need to start the engine, the unit will turn off momentarily and turn itself back on.

Is this a indicator that my batteries are on the way out the door, they are wet cell and now about 5 yrs old, time to replace with AGM????
It sounds like your unit is shutting down (rebooting) due to improper power being provided to the unit. In cases of starting your boat motors; this is normally because the batteries don't have enough amps to make both your starter and the unit happy. If power drops, or has noise on it, during the motor start process; the unit will experience problems. You should fix the power issue because if it continues it can damage the unit. Some users put a power filter/booster like a Newmar StartGuard to protect the electronics.

http://www.newmarpower.com/DC_Power_Con ... oners.html

Overall, it sounds like you have a power issue that needs to be addressed.
So this does indicate that the batteries don't have enough juice to do the job.

Putting on a startguard makes sense but it is just covering up the fact that the batteries are failing.

So if I just get a startguard, the problem goes away or if I get new batteries without a startguard, the problem goes away also????

Or if I get new batteries and a startguard, no worries for along time.

Does my logic make sense????????
It could be your batteries. It could also be your starter throwing RF noise all over your power system when you start your motors. It might be that your power demands have now exceeded what your batteries can support without dropping voltage. It would take a tech on the boat to find the root cause. As you point out, the “Start-guard” is more of a band-aid. You would still have a root problem. The power conditioner is still nice even when you don't need it because it offers some noise filtering and protection. I can't tell you much more than you have a power problem that needs addressing.