Voltage Sensative Relay Question

Ok so spent last weekend cleaning the boat as it is going to be my 1st weekend out for the season this weekend (New Zealand)
While i was cleaning it i decided to start the boat up and make sure it was running fine so i connected the starting battery and the boat fired up fine.
As i have had the start battery connected i turned on the stereo thinking it would only come on with the rear speakers as i have the fronts and tower and sub running of a amp that is connected to the 2nd battery (that was not there) through a volt sensative relay, But to my suprise the whole system started...

So i have Start Battery connected to SENSING BATTERY on the relay and the the Amp battery connected to SECOND BATTERY on the relay. I have my earth connected from Amp Battery to the earth on starter battery and i have the Earth from relay connected to the Earth on starter battery.. When i wired it i followed the instructions exactly..

So is my Amp still meant to get power going to it when it is not connected to a battery ??

I tried this in reverse and only connected the Amp battery up and there was no power to anything else apart from the amp..

Should this be the other way around or does this sound right ?

That actually make sense. When you started the boat you began charging the battery. When the voltage got high enough it was trying to charge your stereo batteries or in your case provide voltage to your amps. I'm guessing if you stopped the engine it would be just as you predicted.

When you reversed it there was nothing to start the boat, thus nothing to charge and close the relay.

Sounds like its working fine.

It also sounds like you have a live, probably unfused 12v+ battery terminal dangling from the vsr? It'd be a bummer to burn your boat down before you get it on the water this season....