Yes it is the vinyl from Cabelas. I bought a 21' roll of it at a tent sale a couple years ago for around $19. It was a return but there was nothing wrong with it. Been sitting in the attic of the garage for a while now.
It feels pretty stable standing on the casting decks, but I haven't had it out yet with the seats installed. I have stood on the front and rear decks though and it feels stable to me. I have done alot of fishing and even bowfishing in a canoe over the years though so stable is relative. If the seats feel unstable in the up position they will still be ok in the low position I guess. I bought the bases, pedastals and seat mounts as kits, since it was about the same price as just buying the seat mount and bases separate.
I love the idea of an open grate over that hole, allows the airflow but still usable deck space. I will pick up a piece of aluminum grate next time I am at the alro metals outlet in town. Thanks for the idea! I may do the side bracing, not sure yet how I am going to proceed on that part. I have some 1.5" square alum. tubing I can use.
The outboard is a 4 stroke. I have never been in a boat this size with a 2 stroke 20hp so I can't give a comparison. Everything I read or hear is that the 2 strokes are quicker off the line for the comparable HP rating (15hp-2 vs. 15hp-4). Two strokes are also lighter, my 4 stroke motor is around 120 lbs. A 2 stroke is most likely going to have more holeshot, just from my experience with 2 and 4 stroke off road bikes. The 4 stroke is very quiet and it has plenty of holeshot for me (up on plane very quick, but haven't timed it) though and it pushes this boat very well (25mph-gps- in under 10 seconds, estimate). I have heard 4 strokes use quite a bit less gas also. I wanted a quiet motor and didn't want to dink with mixing gas any more. Holeshot wasn't a consideration in my decision, noise and fuel consumption were high on the list. As far as powerful goes, the overall output is the same horsepower wise(20HP is 20HP no matter what), it is just the powerband/torque curve and how gearing and prop size&pitch selection are affected by the powerband or output curve, whatever you may call it. I don't know much about prop selection and how that plays in, but I know on motorcycles gearing and torque curve make a big difference and are not the same for 2 stroke vs. 4 stroke. There are alot of guys on here that can tell you all about the differences between the two as far as outboards go. If you want holeshot though, from what I have read I think 2 stroke is the way to go. If you want torque, get one of the 4 strokes with the "big prop" type option! Merc and Yamaha both have them, I am not sure of other brands...