PPM design
This is where (In my opinion) design by committee falls apart. Any
design, and more especially a "Perfect" design will seamlessly integrate
every facet and factor involved (and there are literally thousands of
those). Thus no design decision can be made in isolation from every other
design decision. The choice of construction material dictates the
stability, hull form, speed, displacement, cost, etc, etc, etc.. If
stability is an overriding factor, it's limits will dictate construction
material, hull form, displacement, range, and interior arrangement. There
are numerous factors which are impossible to achieve (realistically) with
certain other givens. Everybody wants a 50' semi-custom aluminum yacht that
costs under $500k. That is impossible without major compromise in every
department.
Once upon a time designer's addressed this dependency problem with what was
referred to as the "design spiral". This exercise involved addressing each
major issue (material, powering, form, weights, stability, etc) in turn,
over and over again as one works around the spiral and narrows the choice of
variables. The first and outermost point of the spiral is the "Design
Statement". This covers what the boat is for, who it's for, speed, range,
crew, cost, rough dimensions, constraints, etc. If the boat must meet
Lloyd's rules for Special Service Craft that's a major constraint. The
completed design is somewhere way down in the very center of the spiral.
Modern design practice refers to a Design "Cone". This reflects design by a
team, each working in their individual area of expertise. Again they work
from a broad outer area into a central point which is the complete design.
One person works on weights, another on hull form, a third on powering. All
are working simultaneously, hopefully informed by the other groups as to
what is happening. This cuts elapsed time considerably from the older
spiral method of continuously revising work already accomplished.
All the best, Tad
www.tadroberts.ca http://www.tadroberts.ca/
www.passagemakerlite.com http://www.passagemakerlite.com/
[demime 1.01d removed an attachment of type image/gif which had a name of image001.gif]
You make some good points, Tad.
To be honest, I'd like to see the price floor raised closer to two
million dollars to make this project fun. At that price, we can do
some cool stuff.
At $500K, existing boats like Diesel Ducks and Nordhavn 46's are
probably about as good as you are going to get.
Besides, custom-built boats always cost a lot more than they seem to
when you start.
John Marshall
Serendipity - Nordhavn 55
Sequim Bay, WA
On Nov 1, 2008, at 3:28 PM, Tad Roberts wrote:
This is where (In my opinion) design by committee falls apart. Any
design, and more especially a "Perfect" design will seamlessly
integrate
every facet and factor involved (and there are literally thousands of
those). Thus no design decision can be made in isolation from every
other
design decision. The choice of construction material dictates the
stability, hull form, speed, displacement, cost, etc, etc, etc.. If
stability is an overriding factor, it's limits will dictate
construction
material, hull form, displacement, range, and interior arrangement.
There
are numerous factors which are impossible to achieve (realistically)
with
certain other givens. Everybody wants a 50' semi-custom aluminum
yacht that
costs under $500k. That is impossible without major compromise in
every
department.
Once upon a time designer's addressed this dependency problem with
what was
referred to as the "design spiral". This exercise involved
addressing each
major issue (material, powering, form, weights, stability, etc) in
turn,
over and over again as one works around the spiral and narrows the
choice of
variables. The first and outermost point of the spiral is the "Design
Statement". This covers what the boat is for, who it's for, speed,
range,
crew, cost, rough dimensions, constraints, etc. If the boat must meet
Lloyd's rules for Special Service Craft that's a major constraint.
The
completed design is somewhere way down in the very center of the
spiral.
Modern design practice refers to a Design "Cone". This reflects
design by a
team, each working in their individual area of expertise. Again
they work
from a broad outer area into a central point which is the complete
design.
One person works on weights, another on hull form, a third on
powering. All
are working simultaneously, hopefully informed by the other groups
as to
what is happening. This cuts elapsed time considerably from the older
spiral method of continuously revising work already accomplished.
All the best, Tad
www.tadroberts.ca http://www.tadroberts.ca/
www.passagemakerlite.com http://www.passagemakerlite.com/
[demime 1.01d removed an attachment of type image/gif which had a
name of image001.gif]
http://lists.samurai.com/mailman/listinfo/passagemaking-under-power
To unsubscribe send email to
passagemaking-under-power-request@lists.samurai.com with the word
UNSUBSCRIBE and nothing else in the subject or body of the message.
Passagemaking Under Power and PUP are trademarks of Water World
Productions, formerly known as Trawler World Productions.
John Marshall said: "To be honest, I'd like to see the price floor raised
closer to two million dollars to make this project fun. At that price, we
can do some cool stuff. At $500K, existing boats like Diesel Ducks and
Nordhavn 46's are probably about as good as you are going to get...."
Grin. Now you understand why I mentioned focusing on something that could
"resale" at an affordable price point. These things get expensive quickly!
Actually, I just did a quick survey to see what used trawlers sell for, and
even used boats cost a bunch of money. As you said, we may want to target
something closer to $2 million.
Used Nordhavn 46: $485,000 to $715,000
Used Nordhavn 47: $905,000 to $1,499,000
Used Selene 43: $499,000 to $725,000
Used Selene 47: $499,000 to $629,000
Used Krogen 48: $775,000 to $1,185,000
Used Nordhavn 55: $1,400,000 to $1,899,000
$500,000 doesn't get you much, even in the used market.
I didn't put much time into this quick survey, and I'm sure there are great
passagemakers out there that I didn't list. Plus, actual sales prices can
vary from online listings (especially in today's market). However, this does
give us a quick sense of what is possible at different price points.
Interestingly, three N46 owners on this list have made the claim that they
already own the "perfect passagemaker", and they may not be fibbing. The N46
is the lowest cost boat on this list, and, yet they rack up a lot of miles!
Nordhavn has been tracking mileage achieved by Nordhavn owners,
http://www.nordhavn.com/distance_pennant, and of the thirty N46s they track,
the average mileage is over 17,000 miles.
I did do a quick check of the pricing on Dashew's FPB 64, since several
people have mentioned it. $2 million.
The more you spend, the more you get. I'm ok with any price point we want to
design for. There are no wrong answers, and even tiny boats can cross oceans
if well designed, and you pick your weather (34 row boats have crossed the
Atlantic...).
-Ken Williams
www.kensblog.com
Sans Souci, N68