how large is your boat?
If your looking at a "ship board" repeater, it's expensive, and is generally 
used on large container or tanker ship/cruise ships for communication over 
say a 1000 or 1500 foot long ship.
I'm not really sure what you are after, but connecting radio gear into the 
cellular network is a real long shot, and would also be highly expensive to 
do.
The GPS stuff is probably availible off the shelf at typical marine 
electronics supply places.
Your really asking the wrong group for all of this stuff as most of what you 
are looking for isn't ham radio related.
You can legally run a modified amateur radio on marine frequencies as long 
as you are licensed to operate on both bands in the jurisdiction you are 
operating in.
Also, you really didn't mention what part of the world you are in, or any 
other pretty important information regarding the context for the gear you 
want.

73
Colin, V A6BS

----- Original Message ----- 
From: "T. Joseph Carter" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 27, 2011 5:20 PM
Subject: Re: anyone have contact / info?


> Opening up a ham rig for the marine band is probably not what Julie=20
> wants since she's describing things like GPS and other digital modes=20
> you're just not going to get on a radio designed for our usage.
>
> Julie, if you're looking for HTs to be able to relay through a larger=20
> radio for a boosted signal, Gary's right that what you're after may=20
> not exist.  But if you're just looking for the ability to communicate=20
> on-ship above and below decks, there are marine HTs that'll do the=20
> job when set to low power mode.  You can even get them designed for=20
> harsh environments.
>
> I can't recommend the FRS/GMRS solution because outside the US, it=20
> may not be (and in fact usually isn't) legal to operate on those=20
> frequencies.
>
> Off the rack ham gear isn't likely to do what you're after, but of=20
> course with the right bit of tinkering you can certainly get whatever=20
> you want, including a ship-board repeater or crossbanding into marine=20
> frequencies, or anything else you could imagine.  How to do all of=20
> that is well beyond the scope of what you're asking for, though, and=20
> I have no idea how you'd go about making it all legal=E2=80=94certainly t=
> he=20
> communication would have to be non-commercial and everyone using the=20
> HTs would need to be licensed somewhere or other.
>
> Interfacing with cellular phones is another thing I'm not sure about. =20
> There are commercial providers who set up roaming services in=20
> stadiums and the like, and then block all other transmissions so that=20
> you're forced to use their service.  That's despicable IMO, but=20
> apparently legal if the FCC says you can do it.  There are also some=20
> consumer devices that boost cellular signals in problem areas or even=20
> provide a "personal cell tower" looking much like any other WiFi=20
> router that connects to a cellular provider's network using an=20
> internet connection.
>
> Some marine radios can pair with bluetooth headsets.  In fact, you're=20
> more likely to find the feature on a marine radio than a ham radio.
>
> Hope some of that is useful.  Because I'm not a mariner, I cannot=20
> give specific advice on radio equipment.
>
> Joseph - KF7QZC
>
>
> On Tue, Sep 27, 2011 at 05:12:06PM -0400, Gary Tillinghast wrote:
>>Hi Julie,
>>To find one radio to cover your wants might be impossible.  You can take=
> a
>>regular 2m/70cm and have it opened to receive and transmit marine channe=
> ls.
>>As for the handhelds, it might be best for FRS or GMRS type of radios.  =
> The
>>GPS functions would have to be a type that will receive a Satellite sign=
> al.
>>May be others will have some ideas.  73. Gary KB2YAA
>>----- Original Message -----
>>From: "504 area" <[log in to unmask]>
>>To: <[log in to unmask]>
>>Sent: Tuesday, September 27, 2011 3:20 PM
>>Subject: anyone have contact / info?
>>
>>
>>Hello,
>>
>>I am hopeful to gain a contact regarding my need for a radio for my
>>boat.  Specifically I need a main radio VHF, UHF and basic operational
>>functions.  acess to marine and weather channels is obvious.  I also
>>need to handheld units which interface with the main unit below deck
>>and with other radios.  Waterproof... Interface with cellular phones
>>is a plus!  A need is for each handheld to be able to interface with
>>one another (this may now be two radios or a walk and talk) as when on
>>deck in moderate to high winds I am not able to see / hear the other
>>individual on deck.  Finally integration with satelite (GPS), AIS,
>>radar/sonar would be added bonus.  This is not a complete list but a
>>start as we are replacing nav equipment.
>>
>>If anyone has information please contact me off list or on list - I
>>thank all in advance.
>>
>>Respectfully,
>>Julie