I'm 6'2" at 240lbs and wonder if I should stretch it out to 18' or 19'? Or even widen it a bit? Any thoughts would be greatly appreciated.

The design displacement is 250 lbs. Figure 40 lbs for boat and cargo and you need a displacement of about 290. Here's a couple options:

1. Lengthen it by spacing the forms, leaving the beam and height stock. To reach a displacement of 290 you'd have to stretch it to 20.6' (290#/250# = 1.16 times 17.8 design length). It's actually the waterline that is important but on the Yukon it's nearly the same as overall. Just change the form spacing by a uniform amount.

2. Scale the entire design by about 5%. (290#/250# = 1.16, cube root is 1.051). The overall length is now 18.7' and the beam is now 23". But doing so you've increased the wetted surface area by 10% (squared function), the resistance by 16% (cubed), and the stability by 22% (quad).

3. Build it stock and sink about a 1/2" more into the water (just an estimate as Nick doesn't list the sinkage per inch but it's usually around 90#/in).

4. Look at a different design.

5. Talk to Nick...