Stereo ideas for my fathers boat???

My dad has a 42 Ocean Alexander and I think it has the original Stereo from1989 or so when the boat was built. Needless to say it sucks ballz. Actually, I don't know if it even works. Here is what he currently has:

Deck-looks like a regular single DIN tape player located in the head space above where the lower helm would be if he had a lower helm.
Speakers-There are 3 or 4 sets of speakers total in the boat.
-Main Cabin-has a set of home type looking speakers that are in a rectangular shape and recessed into the ceiling.
-Master Stateroom-a set of 6.5's I believe. Easy peasy to replace.
-Guest stateroom-same if there actually is some in there.
-Flybridge-a set of plates that that have seperates in them.
-Amp? I am not sure if there is even an amp or if it is all running off the deck with switches to go from one set of speakers to another?

So obviously I need to do some more research on my end and find out exactly how it is setup but then again mayeb it is better to start over from scratch.

My questions.

-What deck would you guys recommend? I would want something that has a wireless remote, the ability to have at least one remote(to run up to the fly bridge) that has a screeen on it and can control an ipod, mp3, etc... and maybe even the ability to run a second wired remote to the cockpit but if it has a wireless remote that may be sufficient? I don't think I need a marine deck as it is located in the cabin and if it were to get there would be a lot bigger problems to worry about.
-Amp/deck power-What are the options for running an amp or deck power but being able to power 4 sets of speakers and being able to control them? I think at the minimum it would be nice to have the ability to turn up/down/on/off the flybridge speakers from the rest of the speakers. Actually it would probably be nice to have the inside speakers be able to be turned off/down while the flybridge speakers are cranked. What are my options for accomplishing this?
-Speakers-I would like to stay with the same speakers throughout the boat. I figure the 2 or 4 in the staterooms can just be replaced with 6.5's. I think it might be easier to replace the cabin speakers(rectangular hoem looking speakers) with the same 6.5's and just figure out a way to mount them under the grill to the existing speaker frame. For the flybridge I suppose I can just make my own rectangular boards and cutout for 6.5's. Would DB651's be a good choice? Maybe Exile or Wetsounds less expensive speakers?

I am going to try and get some pics of the current components but that at least gives you guys an idea of what I am looking for. Here is a picture of the exterior of the boat.

I also forgot that I am guessing he doesn't care about having a crazy, loud, over the top stereo. Probably no subs. I would like to find some speakers that have a nice warm sound with some midbass to make up for not have a sub.

Brett,
I'm not familiar with the Ocean Alexander but alot of the larger boats, like Hatteras for example, have AC and 24 volts DC systems so I would verify early that this is a 12 volt boat on the DC side.
Also make sure that there are no common ground wiring schemes on the speaker wires from that vintage of boat. If so you can work around it but its not something you want to be surprised with.
Alpine makes a couple of marine decks that will provide for wireless remote control operation and also include a dual zone control function. Ipod functionality is great.
Any exterior speakers on an ocean going boat need to be a true marine speaker with a polymer basket, coated tinsel leads, synthetic spider, etc. Stay clear of metal speaker baskets outside. I'd narrow it down to either Wetsounds or JL Audio for 6.5" and 7.7" marine coaxials that have excellent midbass and can handle the elements. Polyplanar has plate speakers but they aren't impressive in the midbass or for overall sound quality.
That's a start.

David
Earmark Marine

Thanks David, I didnt' even think of it potentially being an AC stereo setup. I am thinking because of the DIN deck right now that at least that portion is 12v. Could it be a 12v deck that has RCA's running to an AC amplifier?

Obviously I need to do some more research on how it is setup currently.

The other idea is to just buy a bose sound dock and move it up stairs or downstairs depending on where he wants to listen to music.

Brett,
Its rare that they would interface AC components with DC components because that usually results in noise. In fact, everytime the AC TV audio outout connects to the auxilary of the DC 12 volt stereo you have to use an isolation filter.
There's no real consistency between the big boats even within the same brand during the 80s and 90s. And it is most likely all 12 volt DC from your description. Just calling a few things out in advance to be eliminated.

David
Earmark Marine