Fish Finder Battery Life

Do any of today's fish finders get a good battery life?

While shopping for a new portable fish finder, I asked the clerk about
battery life. It's important consideration for my 10-day Canadian fly-in
fishing trip. My old fish finder could go about 1-week on two lantern
batteries. The clerk told me that about 2-years ago, all manufacturers
converted to "D" batteries. He also told me that according to customer
reports, the Eagle FishMark 320 gets about 6- to 8-hours from 8 "D"
batteries. At that rate, I would have to pack about 80 "D" batteries!

Dave