We are, in general, dealing with boats designed to travel the inland waterways. Their use has evolved from being able to carry the maximum amount of freight to now carrying the maximum amount of comfort. Therefore with regards to shell design requirements in fact not a lot has changed!
Rivers excepted, there are physical restrictions on hull design. The primary considerations are the length and width of locks and the depth of the canal or waterway to be navigated. These physical restrictions also determine the speed at which any craft can comfortably travel (hence the development of low revving, high torque engine & gearbox systems).
As such we have a craft which has evolved to have stumpy front & rear ends and a shallow, flat bottom. A heavy engine, usually in the stern, drives a propellor restricted in size by the minimum depth of the water in which it has to operate.
So, design has changed very little since the 18th century. Complex bow and swim designs are expensive to manufacture. Any efficiencies that may be gained are often negated by the environment in which the craft operates and as such it is almost impossible to design a boat which is able to navigate, lets say, the Huddersfield Canal in its entirety and the Humber Estuary with equal poise.
Bow design originally allowed the hull to overcome some resistance, but with an eye on load carrying capacity. The harsh working life also determined a physically strong design and as it was a horse that provided propulsion there was not a great deal of mind towards economy. Modern bow designs allow for the above capacity and strength requirements whilst the market dictates what “looks good”. A radical design may not be to everyones taste and could affect resale value.
A longer swim will assist in the boats stability but then there are many craft with happy owners whose swim length is restricted due to the short length of the boat. A balance is struck. Equally, an “S” shaped swim with a fine termination will aid efficiency but this has to be balanced with the cruising style of the owner, the propulsion system, the depth of the water, engine efficiency, the weather, hull encrustation and a myriad of other variables, including that bit of rope around the prop that no-one realises is there! Plus it is expensive to manufacture when compared to welding in flat plates.
We would suggest that any potential owner, after deciding on where most of their cruising will be and boxing off any other specific requirements, talks to their shortlisted shell builder
s. In the Products and Service directory section of TheFitOutPontoon we have a number of expert designers and builders who will be happy to discuss any customers needs in more detail.