Most of the 26's have vinyl (Like naugahyde facing out, with a thin foam backing. The problem with this is that the foam/vinyl/to fiberglass delaminates, and gets mold in the foam. This may only be a problem in the hotter climates. But I don't like mold in my boat. I considered buying a 26 a few years ago. That boat had only been used for about 1000 miles--had mold in the headliner/foam delaminated. There was an undetermined leak, which kept filling up the bilge (under the floor in the cabin) with water. (The 26 has a cabin floor over the bottom of the hull; the 25 has the cabin floor as the bottom of the hull. Part of the reason for this is the slightly deeper "V" of the hull in the 26. I have seen the boat a number of times since at gatherings. Wooden batten pulled the foam/vinyl back to the top. There is still mold in the boat. Last I saw it, the puzzle of the water in the bilge was not solved.
I just just spent 2 days getting mold out of the boat--I will spend another day--in the 25 you just scrub, and then rinse (I use a pressure garden sprayer to direct the rinse water). You cannot clean the 26 the same way.
I have ridden in several 26's, and they do ride very slightly better than the 25's--but most folks will not be able to tell. A good skipper who knows how to run the 25 will get almost an identical ride. The difference in "Deadrise"--the amount of "V" at the transom is only a few degrees. A true deep "V" is 24 to 26*. The C Dory 25 is about 4*, the 26 is about 8*..The amount of variable deadrise is probably deeper in the 26 at the helm station--and that is what gives the slightly better ride. Neither of the boats have any significant keel. The tracking is essentially the same. Both can pound going into a chop.
As noted the cockpit in the 26 is a few inches longer than the 25, but the 25 is slightly wider. Both boats are 8'6" wide (Max trailerable width without a permit).
There is only 4" Length over all. The number of strakes in the hull is more in the 26, but that was only for looks, when the boats were first made as a competitor to C Dory, and to get around the no compete clause (didn't work, C Dory won, and the copy cats forfeited the molds--short version).
Recently I bought my second 25--it was a 2007, intentionally, because it was the first year of the fiberglass interior. My close friend who has a 2004 saw my boat yesterday, and commented on the definite differences between the 2004 and 2007.
The fuel mileage and range will be pretty close. The 26 weight is a bit more. They both have 100 gallons of fuel, They both can carry up to 200 hp, although in general most of the 25's have 150. With a heavy boat, and 4 stokes getting lighter, the 200 is a better choice.
To the credit of the 26, one has made a number of runs from San Francisco to Catalina and back--this can be one of the roughest stretches of water on the West Coast. True they have taken as much as a month (most waiting for weather). I believe that they made the run several times only stopping for fuel. A 25 could do this also--but I am not aware of any that have. The vinyl/foam insulation may give less condensation, and there is a little insulation factor there for the colder climates.
Ideally the boats would all have a perfectly smooth glossy interior and thus far less likely to have a mold issue. This would make the boats much heavier and more expensive.
Foam bottom core vs balsa bottom core: There have been some of the older boats --mostly 22's--which have had some balsa core rot. These have had the core replaced. There are reasons that balsa is a better core material--this involves both shear strength and compression loading. The newest boats have basically no penetration of the bottom core. I believe that most all of the boats now have foam core transoms. The C Dory's do not have the core delimitation problems that many other boats (Sea Ray, Bertum, etc) have had. All boats have some core penetration. Only the most expensive (Hinkley etc) put any core penetration thru solid glass, or undercut/remove core and put in epoxy plugs properly. This should be done for the C Dory--but it boils down to the individual owners to do this if necessary. There are a couple of places in my "new" boat which will require this--but nothing significant. (you find these issues with a small phenolic hammer and moisture meter). I spent almost a full day surveying the boat I just bought.
I am happy to answer any specific questions--obviously I tend toward the 22 and 25 line--but the 23 and 26 are equally as well built boats, and many like them better. I just feel that for the South--the utilitarian raw glass interior is better.
Good luck in your quest. I suggest that you try and get a ride in both of the hulls. C Brats are very accommodating, and you should be able to get rides. A good way to get involved is to go to one of the gatherings. Most have a "Cruise" involved and members are happy to take you for a ride. Also you get to see many of the boats and modifications.
