You are going to resist covering anything with epoxy because you will begin to think that it will ruin your craftsmanship! You might just want to keep everything natural and never put that thing in the water! Just roll it out in the driveway every now and then!....or drive it to the boat ramp and just let it sit there for a while!

That looks great! (You might want to put some saran wrap over those gauges though!

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Reading your blog I love the fact that you used the half-lap joints in the framing. I think it is a much better "looking" job and is very professional. My only concern, as is yours I am sure, is: will they hold up over time. I think the gusset provides most of the strength, however, once all of the parts come together I still think it will be fine. Gussets provide for additional grain orietation to gain even more strength. When you look at structural framing members in a house, trusses for instance, the gussets provide all of the strength practically. (Some of the gussets are metal nailing plates). The butt joints of the timbers are actually engineered to allow for gaps because the nail plate/gussets provide so much of the strength.
In the end I like your method for aethestics and size considerations. I wish someone would do an actual engineered load test on the two different style frames to prove what the actual difference in strength would be and find out what the failure mode would be with each design, that way others could incorporate the same method into their builds with total confidence.
Hell, I can't build a good dog house so I am impressed with all of it!
Great job! ....
Steve