timed off circut for boat

Wiring up my newer boat and adding all my toys.
The other day when I moored boat overnight I forgot to turn off stereo, and killied the battery.
I started to think that I will do ths more than once, and the lights may also be left on.

So is there a timed relay out there that I can put on my acc, wires from my switch panel, that would work alot like the on till door open circut.    Where if boat is running I can turn on tunes, get to fishing spot, Turn off the 1 position key switch, which then starts a countdown say approx. 30-60 min.  Then any thing connected to this circut would automaticly shut off if I screw up again.

Does anyone know of a relay that would do this?

I figure worse case I could use a seperate timer to supply the "door trigger" to shut off the on till door open relay circut.
But only timers I know I have access to are for stuff like House alarms, access control.  They often are not sealed just a circut board.

Google Velleman Kits though I think the longest you will get is 15 mins.