PROOF OF PERFORMANCE
Clearly the central question, upon which this whole project hinges, is whether or not
Spirit of The Bahamas will be capable of achieving the performnce levels needed - in order to ensure the success of this venture.
Underlying this paramount concern, one suspects, is the question as to why an individual, with virtually no financial backing or formal training, should be capable of designing and building a vessel which meets certain performance requirements that would be considered unattainable by many major boat yards -- staffed by highly qualified naval architects and marine engineers. The suggestion that such a vessel could be constructed at a fraction of the cost of most similar size vessels would appear to make the whole idea even more suspect.
To respond to the latter question first: It just happens that the designer has been blessed (or cursed) with a fairly high level of mechanical aptitude - despite being the world's worst auto mechanic. There is also the fact that he has spent 40 odd years pursuing a single design goal unifluenced by market demands - rather than fiddling about with design details intended to marginally improve (or, in many cases, merely decorate) basically poor designs Some other observations which might shed some light on this question are as follows:
The point, concerning the negative influence that market forces and, in turn, marketing personnsel and boating publications, has had on pleasure boat design, has already been beaten to death in other pages on this web site. This influence, however, is not limited to the pleasure boat segment of the industry, it also carries over to a large extent into the commercial sector.
Throughout all sectors of this industry, and within all profesions generally, from garbage collecting (sanitation engineering) to rocket science, there appears to be a tendency to make one's proffesion more and more complicated and arcane - and thereby, presumably, elevate one's status as compared to the layman. It might well be that this tendency, coupled with the urge to conquer nature rather than coexist peacefully, are major contributing factors to the defficiencies that are so apparent in many small motor vessels today.
Clearly, cutting edge modern sailboat design - as illustrated by "fragile" windsurers "frollicking" in 10 ft. surf or equally "fragile" 100ft sailing catamarans tearing round Cape Horn at 30 knots (during the recent unlimited round the world race) has moved well beyond the latter of these restrictive influences.
It is these highly expensive, high tech, highly complicated racing catamarans, (which the vast majority of the powerboat community have probably never heard of) that have provided the inspiration and set the standards of performance which act as a beacon to the designer in the development of his design concept.
The designer feels strongly that, by "cheating" and employing mechanical power instead of sail power and utilizing all the cost saving strategies previously mentioned on other pages, Spirit of the Bahamas will be able to emulate, in a modest way, the performance of these magnificent much larger creations -- at a small fraction of their cost. At the same time, Spirit of The Bahamas, will hopefully provide a better indication of the possible practical applications of these general design concepts.
Some indication of the likelihood of our achieving our objectives may be found by looking back at her two most recent predecessors: Walk on Water and Little Trick.
Both of these vessels are quite different from each other in regard to hull design and, in fact, represent a span of some years in the evolution of the designer's overall concept. Nonetheless, they give a good indication (and provide concrete evidence) of the performance levels which Spirit of the Bahamas can be expected to achieve.
Walk on Water, the older of the two vessels, with 40ft (12 m.) long, 2ft (0.6 m.) wide, full displacement, deeply vee'd hulls, is in fact closer in concept to Spirit of The Bahamas. Originally powered with a pair of 10 h.p. (7.5 kw.) outboards which provided a cruise speed of 10 knots at approximately 7 (nautical) m.p.g. she is now powered by a pair of 25 hp. (18.7 kw.) outboards providing a cruise speed of 13 knots at approximately 5 (nautical) m.p.g.
She is an extremely sea kindly vessel, considering her size, and shows little sign of wear, after ten years of use as a pleasure boat / inter island passenger / freight boat, plying between the owner's residence in Nassau and their Out Island Inn - some 80 miles away on the Island of Eleuthera.
Little Trick, was built with the main purpose of providing the designer with a home and was built in a rather limited building space. These circumstances led to the choice of more conventionaol, semi displacement, rather short fat hulls (33ft long by 30ins wide). The inherent disadvantages of such hulls, in regard to speed and effficiency, have been overcome, to a large extent, by the addition of a fixed hydrofoil spanning the hulls just forward of the centre of gravity.
Available documentation suggests that the designer was the first to realize the advantages of, and employ, a simple fixed foil on a power catamaran in order to provide partial lift. The result is a substantial improvement in speed, efficiency, and seakeeping without the complications, high cost and vulnerabilities inherent in vessels which are fully supportsd by an extensive, complicated adjustable foil system.
This design concept has since been (presumably independently) developed by another designer and is now utilised in many "cutting edge" fast vessels (particularly in the commercial sector) - both as original equipment and as a retrofit. Nonetheless, we believe that the hydrofoil concept,while very exciting, is neither usefull nor desirable when applied to a vessel with correctly proportioned hulls.
With a single 100 hp (75 kw.)outboard, Little Trick is capable of a cruise speed of 18 knots with gas mileage of 3 nautical m.p.g. and has proven to be a successful weekender / sport fishing boat - and is, considering her size, a very sea kindly vessel. It should be noted that, in order to demonstrate the seakindliness of both these vessels, we have often simply placed a glass of water on a flat surface in the boat.
At no time, during any of these demonstrations, in all kinds of sea conditions, has a single drop of water been spilled. There is no question whatsoever, that, in an extremely high percentage of similar size vessels, operating at similar speeeds, in similar sea conditions, a similarly placed glass of water would end up on the floor in seconds.
Moreover, the development of this design concept is an evolutionary process, and Spirit of The Bahamas will be standing on the shoulders of all of her direct predecessors - plus any other shoulders that are handy and deemed usefull. Indeed the designer has no qualms at all in regard to stealing ideas and concepts, in particular from (in his opinion) the far more advanced sailing catamaran sector.
While Spirit of the Bahamas will reflect many design and construction advances conceived over the last several years, the main advantage she will enjoy over her predecessors is sheer size. To stress this paramount point one more time: Unlike vehicles of all other kinds, length provides a tremendous advantage to water borne vehicles - firstly because of the basic laws of hydrodybnamics - secondly because of the nature of the surface of the sea in common weather conditions - and thirdly because of the "mechanical scale effect".
As an example of the latter, in scaling up a 40ft. boat to 80 ft., if the passengers were also scaled up in the same manner, each passenger would be approx 12 ft (2 m.) tall and would weigh approx. 1,600 lbs (720 kilos) It is easy to imagine the extra structural weight that would be required to stand up to the impact forces generated by a few of these giants tramping around on the deck.
The fact that an 80 ft. vessel does not have to withstand such enormous loads means that it can be built relatively lighter than the equivelant 40 footer. Because of lighter overall weight, the length / hull beam ratio can be increased which leads to less disturbance of the water, which in turn requires smaller engines, lighter fuel load, etc. etc. In boat design, fundamental, basic changes usually generate a snowball effect - for the better or for the worse.
In regard to concrete accurate proof of performnce, a 5ft (1.5 m.) model has already been built and tested (with encouraging results) and a 20ft. (6 m.) 1/4 scale manned model /tender will be built and tested in the near future. This model, besides providing very accurate numbers in regard to speed, horsepower requirements, and fuel consumption predictions, will also give a very good indication of the seakeeping abilities that can be expected from the full size vessel. As soon as the results of these tests are available, they will be published on this page.
CAUTION - DEEP END
All information directly related to this venture has been included on the HOME
page. Those seeeking further, in depth, information on a particular aspect of
this project are invited to click on any of the following links.
2007
For info on current related developments, please vist the
following web sites:
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