Page 28 - WestlawnMasthead17_Mar.11.pub

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Config. A: with bulb, stabilizers, blisters, bi-foils
Very little wave train with significant hollow after the bulb.
Typical long range cruise speed. Shallow wave train with
little disturbance.
Fast long range cruise with appendages working at their
maximum efficiency. The bow wave has just reached the
spray knocker.
Positive bow trim for the first time.
Trim only 2.6 degrees
The maximum practical limit to this hull form and appen
age combination.
The resistance advantage of the appendages has zeroed
and there is no benefit to this technology beyond this
speed/length ratio.
CONCLUSION
The bow bulb work has been retrofitted to over 3 dozen v
sels from 40 ft. to 95 ft. (12 – 30 m) and model tested o
designs up to 160 ft. (48.8 m). It has gone through only
revision to date and currently shows no signs of slammin
and in fact seldom comes clear of the water. The design
parameters and real-time results have been well establis
by feedback from numerous clients and their captains an
crew. These results from the bow bulb are a minimum 3
knot increase in speed or minimum 10% drop in fuel con
sumption as well as a very significant reduction in pitchin
motions.
The midship blisters, which show an initial result of a 6%
drop in resistance, need further study to bring out their fu
potential and determine the exact proportions necessary
create the maximum benefits. The goal is to achieve a si
nificant reduction in the midship wave hollow in combina
tion with the wave reduction of a bulbous bow, which will
bring a reduction in the stern wave through an overall sh
lower wave train. This will also contribute to increased st
bility underway as there is less midship trough for the ve
to heel into.
With the reduction in bow and midship waves it is only n
ral to next look aft to the transom. The large reduction in
bow wave needs to be matched by a similar reduction in
stern wave. How this will be accomplished is yet to be de
mined but there are some areas of work that hold promi
including the stern bi-foil mentioned earlier. As well, ther
has been some very promising, but limited work done on
stern bulbs. If a successful stern type bulb appendage co
Continued next p