fishfinder powers off when starting engin

I have a new boat, about 1 month old. I purchased a fish finder and had it installed. Works good but when I crank the engine the fish finder powers off. Is there a way to have some type of capacitor and diode combo to keep 12 volts to the device for a few seconds to keep it from powering off when I start the engine? I am not an electronics expert by no means so please post any reply in basic details. Any help would be appreciated. Thanks in advance.

Push starting the boat would solve the problem, but I understand wanting to stay dry or not having big nor flat enough feet.

A cap and diode might work if the diode voltage drop is low enough and cap big enough. That's a combination of the unit's spec (lowest operating voltage) & current, and the voltage dip involved.

It could also be a weak or small battery or if the finder shares the same current path from the battery as the starter motor.


Options include a dc-dc converter or dual-battery system - tho being marine I'd assume a voltage sensing type battery isolator would be required (bad luck; more expensive and not as good as charge-light etc controlled relays).