Here is another option that works for me:
Because I sail OPB

, some with, and some without
chartplotters initially, I wanted a portable
GPS/Chartplotter. Another issue was that of the boats that had
chartplotters, different boats had different brands and models. Each different model, had a different user interface, different features. I couldn't keep them all straight. This was the situation until last year, when all the boats had
Raymarine C80s & depth transducers installed with local
charts loaded on the memory card. This year, some of the memory cards have been erased... thus reafirming my decision.
I also travel for business and my company will not (knowingly

) spring for
GPS in the rental car. I can find my way around Boston, but get completely lost trying to navigate my way to a street address in DC, Montgomery, or Minneapolis.
I therefore needed something portable, that would be useful in any boat, and a rental car. The best match that I could find for my needs was the
Garmin GPSmap 478, which I bought last year. It is water proof (1Meter for 30 min), comes pre-loaded with all US coastal and street maps. I beleive that this unit also does not have a hard drive, but stores data on flash ROM. As a result, it starts, and updates very quickly.
To date, I am very pleased with the decision. I find that when I'm on the road, that my stress from being lost is GREATLY reduced (this alone was worth the price). If I do get lost (which still happens when I encounter a new road / development), I just blame the
GPS.
In March of this year, a friend of mine and I took a motorcycle trip from Boston to Atlanta, to Key West (and back). We both found the local point of interest (gas, food, lodging, etc) invaluable. It also survived torrential rain and the vibration of 4K miles on the bike. Here is a pic (sorry about the grainy pic) of the unit on my bike:
On the water, this unit has ALL of the charts for the coastal US. Tide and celestial tables are pre-loaded. I can also add
Garmin BlueChart g2 cards (for $160 a pop

) if I want to see aerial pictures, or add other regions (like the Bahamas

). It also works fine below at the nav station. If I ever mount it, it supports NEMA 0183, so I could connect it to my
VHF and have DSC capability.
Other options that I could, but do not have include XM Sattelite "antenna" for XM
radio and XM weather overlay ($300 for the "antenna" + monthly subscription of $30-$50), and a depth sounder /
fish finder.
For obvious reasons I did not permanently mount the unit on a boat, but use the "sand-bag" mount and place it in the companionway, under the dodger, or if needed (and conditions warrant), next to me in the cockpit. I can always see the display (even in direct sun), and have infinite options of moving it if the need arises.
Should I ever have to evacuate a boat in an emergency, I like that the unit will run over 8 hours (I've verified this) on Li ION battery power. I have also found it reassuring to set the
anchor drag alarm, and to keep the unit next to me (especially at dinner, and when sleeping), while at
anchor
.
One of the best aspects of having a portable unit is that I can learn what *all* the software functions are whether I am on the boat, in a car, or at home. I can set my waypoints and planned route while I'm at home using the unit, or the waypoint manager software that is included with it. I also like downloading and archiving my tracks to my home PC, so I know where I've been. (It's tough to get old

)
Still, I drool every time I am in a boat and have this nice 10" (or better) display, and compare that to the 3" display on my portable. However, when that display dosen't show Georges Island, and I'm on a mooring 150 yards off the island, I get over it (this happened last weekend).
I wish that the unit was NEMA 2000 (I wish that everything was) so that when I get my own boat I could tie this unit into an overall information system. For now (and the next few years), however, this will suit my needs.
$0.02
Ed