RE: What scale is standard?
Even cars and trucks are moving away from a standard, it seems they they are either going huge or mini and micro now but I know where you're coming from as when I raced the 4-wheelers 1/10 was the size that we raced the most.
As far as mass-produced RTR boats sold in hobby shops you might say that 1/12 scale would be closer to a norm. This will vary as to the type of boat. A scale ship could be a larger or much smaller scale than a racer or sailboat.