General Concept
We have developed three
basic types of Power Cat. This one is essentially a mono-hull with a 'tunnel' between the two halves of the hull. The purpose of this configuration is to produce an easy motion, and to avoid any wake interference between hulls. The
one shown here I have preliminarily called the 'Fast Cat' mainly because it would be...!
This "tunnel hull" type has often been outfitted with hydrofoils in between the hulls. The Fast Cat can
be driven at planing speeds even without the foils. But with the foils
and with around 25% more horsepower, the speed potential is almost double. This
is an extremely rare case of getting something for nothing...!
The hydrofoils work well in rough
water as well, since the foils lift the hull about halfway out of the
water. Being between the hulls, the foils are well protected. The 'sub-surface' foil types used for this purpose are self-regulating, in other words they do not need to dynamically articulate for attitude / trim control. The
aft foil can however be arranged to articulate to various 'set' positions,
allowing corrections for variations in load - say for passengers or varying
fuel loads, etc.
While this configuration is certainly
very fast, being foil borne is not a suitable mode of operation for long
range, as there is way too much fuel required...! Instead, it is
an ideal type for extending the daily range of operation, allowing a
wider variety of day trips, and much quicker voyages.
The
model shown here is 50' overall length, but can be sized to whatever
beam or length is suitable to the intended use. Although this
configuration is ordinarily intended for planing performance, long
range cruising is also a possibility, although if long distance voyaging
under power were the overall goal, a model such as the Wave
Cat would likely be more suitable.
Construction
The Fast Cat will be best
if kept relatively light in weight. With this hull type, steel is probably not a viable option until the size approaches somewhere around 90 feet. Aluminum will therefore be ideal, as will GRP. If
built in aluminum, the greatest construction efficiency would be achieved
via NC Cutting of the structure.
What is NC...? It simply means 'Numerically Controlled' and implies that the plates and internal structure will be defined by computer modeling, and will be pre-cut by plasma jet or by water jet cutting. This
has the potential to save a considerable number of fabrication hours,
and offers the benefit of extremely accurate fit-up of the parts.
One of these 'Fast Cat' models - at 35' LOA - is now being built here in Port Townsend, called the Twee Schoenen. On
the 35' Twee Schoenen we
also provided sufficient fuel capacity for the trip from the US West
Coast, out to Hawaii. As with a number of our other metal boat designs, a complete set of NC cutting files were developed and the
entire structure was cut out by water jet. This method of pre-cutting
all the metal parts is extremely accurate, and saves the builder quite a
lot of fabrication time.
Ordinarily NC Cutting is most conveniently applied to metal structure, although it is a technology that is just as readily adapted to plywood construction.
For a vessel built of fiberglass,
computer modeling can still provide an excellent means to achieve the
mould shapes. Many builders have taken advantage of this technology, where either a plug (male) or mould (female) will be cut out of foam by a large 5-axis router. This
eliminates the complex and labor intensive mould-building step, entirely
eliminates lofting, reduces shop space requirements and builder lead-in
time - ultimately saving the builder's labor and the customer's overall
boat cost.
Further Development
Since
it is our routine to work with new designs on a custom basis,
we are able to develop just about any type and size. As a boat becomes larger, naturally there are a much greater variety of cabin arrangements possible. This
is entirely up to one's preferences, with the result that the hull
and superstructure
will be given the best shape in order to fit the required
accommodations.
For example, a much larger Power Cat of this type can be reviewed at our
90' Tunnel CAT web page, which illustrates
rather well that this type can be scaled upward and even re-styled very
nicely. Yet another unusual adaptation of the Tunnel CAT type is the
Nemo - Nautilus combination, where a 70' Tunnel CAT
acts as the mother ship for an 80' Submersible. When mated, they act
as one single ship. When deployed, the Sub and the mother ship are
autonomous.
For more information, please please inquire.
