Automatic shore power switch?

I have an older boat, when I connect to shore power I have to switch a manual switch down then up to engage it.

If there is any fluctuation in voltage, the switch will flick off like a fuse almost resetting itself to the off position (and our batteries will kick in).

The issue I have is that the batteries drain if we are not home and although the power may have been off for only a second, we manually have to turn it back on.

Can someone give me a brand and name of a switch control that will automatically engage when power is restored.

I'm not quite sure what I am looking for specifically other than the fact that every modern boat seems to cope with this scenario automatically and without intervention.

I'm going to guess what I want is an automatic changeover switch?

I bought one from Germany from a site called Boat24 and it was about as much use as rocking horse manure ! It burnt out, fortunately I was on board and able to shut it off. Currently I have one made up by an electrician but would prefer a factory made/tested unit that I could buy off the shelf.

I'm guessing I am looking for something like this : https://www.ato.com/automatic-transfer-switch-250-to-630-amps

I just have a rotary switch with "Off," "Generator," and "Shore" options. The output of that switch is then fused appropriately. Couldn't you use something like that? Or a heavy-duty On/Off rotary switch? The item at the link you posted seems overkill. Might want to have a marine electrician check it out to determine the best options.

Very simple has no built in horrors.

Fit a proper sized plug inside the boat that plugs in as the source to the electric panel.

Fit one socket that is supplied by the shore power , a second that is fed by the noisemaker and a 3rd fed by the inverter.

Now switching between power sources is easy to perform , with no surprises.

AS there inside, "marine" water resistant plugs and sockets are not required , any 4 prong properly rated will do fine , should be under $100. for everything at a big box store.

I replied earlier with a solution but with a 94 foot boat typical recreational systems may not be compatible. How big is your inverter? The switch you’re describing is typically internal to the inverter. A simple rotary switch can engage and disengage ac sources if it doesn’t also serve as a breaker. You likely need an electrician to look at your boat...

Thanks for the comments team. The issue seems to be that the power switch installed currently is energized to stay on.

Given the simplicity of the setup, the electrician has suggested this can just be changed now to a manual on/off switch.

It's great that the simplest solution is acceptable. Thanks for updating with the resolution.