Hi Tonyrome69,
Irishfield is right; colour monitors do kill the batteries in portable devices very fast. If you are not dead set on a colour display, I would suggest you take a serious look at a Hummingbird 535 or 565 portable.
http://www.humminbird-gcomm.com/humminbird...35-Portable.htm
They have great displays, the battery life is great, they show temperature, and have optional speed upgrade. The carrying cases are very rugged and the units are just a tough. I purchased the 535 protable last year and have no complaints. The refresh rate it great; it even gives you clear picture even when you boat is moving, and it gives you clear indication on the hardness of hte bottom structures etc.
Regardless of what you choose, I hope you find one that works for you.