Lots of great information especially from Kushtaka and Jay. 6 HP is plenty of motor for you 25. My father's sailboat was 26 feet, and very similar in hull profile to the C Dory 25 (Arc bottom, with hard chine), and weight about 50% more than the C Dory 25, and about the same freeboard, and slightly less cabin windage. ) A 5 hp outboard with low pitch prop served that boat better for 20 years better than a latter acquired 9.9 hp outboard. If you loose power in rapids or swift current (which you really don't belong in, in the first place), the well running and used 6 hp will get you out of trouble.
Bear spray and bears. Be sure and buy your Bear Spray in Canada, or get a bear spray which is certified in Canada. They will not accept some of the US bear sprays. We always carried bear spray when going ashore in the dinghy. We had two labs with us, and also carried a .44 mag. revolver in a chauffeur's type of cross draw holster with us, in the dinghy and when going ashore. I am not starting a debate about firearms, but probably not necessary, with good situational awareness--which is key in any wilderness situation. We had our firearm shipped from our firearms dealer to a dealer in AK, so it was there when we arrived, same for going home.
There were very few days we did not feel that the weather was fair enough for movement. However, if you feel that there is a question, as local fishermen, or don't move. A radio capable of shortwave reception can get the Alaskia ham nets, or better yet if you are a ham, take both HF and 2 meter gear with you--you will be in for a real treat meeting some folks in AK who are hams.
EPIRB/PLB. We carry PLB for each person. I do not feel that a Delorme or spot is equal to a PLB, because the EPRIB (&PLB) go directly to a intergovernmental/international SAT/SAR agency, who is sure to get a search started immediately. I do consider the Delorme in reach system with the 140 (?) character messages a great way to communicate with the folks back home, and to allow them to track you (especially the grandchildren)
I agree with Kushtaka's personal items, but I also carry an additional survival bag, This includes some of the personal items, as well as basic tools, including my favorite Gerber multip tool, small vise grips, extra spark plug and shear pins for the dinghy outboard, Flares, light plastic tarp, extra mylar space blankets, cig lighter, waterproof matches, A waterproof VHF, with AA battery tray, and a dozen extra AA batteries, along with a small GPS(containing topo or marine charts of the area). Hand bearing compass, Paracord, strobe and flash light and small first aid kit--bandaids, swabs in sealed containers, triangular bandage, and gauze/telfa pads, and maybe some Quick Clot. all of this in a clear waterproof bag. (I also carried a set of sweats rolled up tight in a waterproof bag which I kept in the dinghy if we went any long distance. As pointed out, if you are prepared both with gear, physically and mentally for survival, the chance you will have to face a ultimate situation is already far less!
Also there are some areas, which I would not miss, such as Ford's Terror, where you may not get good satellite reception, no VHF reception and even poor HF reception because of the very high fjord type of walls.
One "chart" which puts everything in context is the Inland Passage Cruise Guide by Coastal Cruise Tour Guides.
http://www.amazon.com/Alaska-Canadas-In ... 0961143800
This is a 6-foot long by 12-inch fold out map of the inside passage from Glacier Bay to Seattle which costs about $13.50. Great for planning and showing folks after your trip! We still have one bought in 1992, and used on each trip we have made since.
Based on what you say about your engine--you are really lugging it. I would at least drop the pitch down to 17"--you may find that you have to drop another 2"--but 17" is a good place to start. You want several props anyway.