97 gti
I only have the manual for the '99 GTI:
160 W at 6,000 RPM
4.0A at 6,000 RPM.
From your post, it looks like you will be mostly listening while the engine is OFF...
that means there should technically be 0 load additional on the system...
the amp should have an on/off wire.
an amp that small you could even put in an on / off for the + wire
Long as you only use this system while the engine is OFF there would be no problems that I could see...
it would be the same as pulling the battery out of the craft, draining it 1/2 then putting it back in.
the charging system is only doing what the factory asked of it... charging a battery...
Like you said, no subs / etc... the load should be very small...
I'd only play say 15 - 30 min at a time until you know how this will affect starting your ski.
I would also make sure the amp is OFF when you do go to start the ski.
I'm no expert, my dad's an electrician, and I've been doing car 12v and boats for years, but IMO you should be fine.
My only concern is with the size of these batteries, you may end up being unable to start your ski after a few hours...
They make high performance batteries if you need, but I would test it, like I said 15-30 min at a time... see if it starts ok, then another bit, etc... each time you start it and don't let it run keep in mind, uses a lot of power as well... you need to hit 3,000 RPM for a while to charge the battery...
Not to complicate things, but if your really worried, get a 2nd battery that's JUST for the radio...
ie charge it at home, drop it in the craft, then listen to the radio till it dies!
then, you are not touching anything on the ski at all... nor risking a dead battery while you and someone you care about are floating down river towards a 6' over head dam!
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