This topic arises about three times a year. The usual proposal is a split along power/sail lines. Each time the concensus, with a growing number of dissenters, is that (a) much of what is discussed here would be crossposted to rec.boats.sail and rec.boats.power if they both existed, (b) many topics, like maintenance, moorings, coast guard regs, boat shows, the grounding of the QEII, large oil spills, etc., are of (passing) interest to almost anyone who goes out on the water, (c) we all learn something about the folks with whom we share the water by reading what they have to say, (d) the volume of postings is rapidly increasing and is growing too large, but a power/sail split will not necessarily address this.
Recently rec.boats.racing and rec.boats.building have been formed, and they seem quite successful; I personally attribute their success to the lack of overlap in interests between the folks in those groups and ``the rest of us.''
Analysis of the traffic on rec.boats suggests that between 1 and 10 percent of the traffic is devoted to discussions of splitting. All such discussion should take place in (or at least route followups to) news.groups.