Originally Posted by Standpipe
Hey, I was reading an old article from The Rudder (1904), a How to Build by Charles Mower for a power dory called "Bonito". This can be found and downloaded in PDF form on Google Books for free; however, I'll summarize the info I think may interest you.
Namely, that the article begins with a history of power dories to that time and mentions sea keeping issues.
Firstly, early power dories were fishing dories adapted with "small" motors of the day to cut back on effort rowing. Mower describes how early successes led to a series of larger craft. He continues:
"After seeing the fishermen come and go in all sorts of weather, yachtsmen took up the idea and the New England dory builders found their trade in power boats gradually developing into power dories, with a decided falling off in the demand for sailing or rowing boats. The dories could be built and equipped with a simple two-cycle motor at a price which the builders of regular launch hulls were unable to meet, and the dories had the advantage of not only being eminently seaworthy and safe in rough water, but it was also found that they were almost invariably able to outdistance regular launches of the typical stock model, fitted with motors of the same size."
So far so good and all sounding rosy.
Yet details about these early boats he subsequently speaks of addresses the development process for pleasure craft from the fishing types. If I understand him correctly early power dories were like their fishing counterparts in being wide at the base, "about one half the extreme breadth" and these boats he later calls "cranky" being the basis for the type developing a bad reputation "among people not accustomed to the type".
I mention this because he notes that the Swampscott, or clipper dory, was of a better type for sailing AND the design he presents, being narrow at its base (less than a third of breadth) is probably of this type ... which makes sense of the mention of the Swampscott variant.
Of this design he says:
"The boat shown in the accompanying design will be stiff and steady and buoyant in rough water and will be suitable to any use to which a small launch can reasonably be put."
The Bonito design itself is an 18' clipper type. You can get the file to reference her particulars.
My own observation is that a modern engine will be significantly lighter than those in 1904 for the same power and it is likely his assessment of the traits of the craft take into account the weight of those old engines (which should agree with statements about ballasting in this thread).
I hope that helps you.
It seems to indicate to me that for a pleasure boat the type with a narrower base may well be the better choice ... or at least I would hope so given that the design is presented after noting the crankiness of the boats with wide bases.
Edit: I looked around a bit more and in the same year there was another dory design, a much larger auxiliary cruiser also of the narrow bottom type by Schock, called Fish Hawk. More to look at for comparison purposes, I guess.