(i) The following is a guide and pertains to the services of J. Simpson Ltd. The policy of other design firms or Naval Architects may differ.
(ii) Due to existing ongoing contract work each job will be assessed on an individual basis and may be accepted or declined if it is determined that work cannot be performed in a timely manner.
The following is a brief explanation of a custom design. Greater detail may be obtained from our article on the subject( available by request).
The custom design is a big step and many times more expensive than stock plans. For this reason we encourage clients to review all sources of stock plans available and even if not ‘perfect’, most good stock plans can absorb some minor alterations without compromising the functionality.
If, after a thorough review, it is determined that a suitable stock plan is not available, the next option is a custom design- a design developed specifically to meet the client’s requirements.
The following is a
guide and pertains to the services of J. Simpson Ltd. The policy of
other design firms or Naval Architects may differ.
Sailing Vessel Rig and Sail
On-site Consultation (Owner's
The following is a
brief description of some of the most frequent types of consultation
we provide to the marine industry. The contents of the subjects
addressed should be considered as non-inclusive in that each
vessel must be reviewed on its own merit. Limiting work to rigid
formulae might not be in the best interests of the client or the
Although we will work on designs other than our own, we strongly
recommend that questions and services should be addressed by the
original designer of your boat. If for some reason this is not
possible, we would be pleased to assist. Out of courtesy, we may
request authorization from the designer unless there is a compelling
reason not to do so.
You want to know if
your boat can go faster or how fast it might go with a new engine.
We have standard forms available and with complete information we
can predict the speed of your vessel. Accuracy is often within 10%
and sometimes 5%.
The most common reason for this calculation is to verify the
existing installation. Example: a review of a 42 planing hull
determined that the incorrect reduction gear was fitted and no
reasonable adjustment of the propeller would make the boat go
You may or may not
have the correct propeller. This is related to the speed estimate
but often the problem can be insufficient diameter (& resulting low
blade area) or a poor installation.
If you are going
offshore or cruising in higher risk conditions a thorough review of
the stability can be valuable and reassuring. In addition to the
initial, stability we also look at the range plus other matters that
might limit or compromise stability. For standards we use several
criteria with one being the I.M.O. (International Maritime
Organization). Calculations are done for still water only since
trying to predict what waves a vessel may encounter is highly
speculative and almost impossible.
Self-righting: A well designed, built, and maintained sailing vessel
will invariably self right after a capsize. For powerboats, the
configuration of the hull and superstructure is different and self-
righting and intact recovery may not be possible. Vessels claiming
to be self-righting (positive stability through a 180 degree
roll-over) will require special attention to the structure, outfit,
and interior storage. Arranged as such, items like broken windows,
backflooded engine exhaust, and flying interior objects would not be
of concern. Unfortunately, such arrangements can be expensive, very
invasive, and may detract from the habitability of the vessel.
Vessel Rig & Sail Plan
Some owners may want
to alter the rig (cutter to ketch, etc) or increase its size (sail
area). With correct information we can review and furnish the
appropriate information and drawings.
Owner may need an
alternate or new layout to satisfy special needs or requirements.
Work may be limited to one area (or drawing) or may encompass the
Alternate or new
details to satisfy special needs or requirements. Sometimes a part
or detail shown may not be available or suitable. We can offer
suggestions and guidance.
Estimate (Mass Analysis)
As a part of the
design process, the weight estimate (sometimes called a Mass
Analysis) is a crucial calculation. Unfortunately, it is also
tedious one of the less pleasant chores that a designer must
perform. The boat is floating in a fluid and therefor affected by
weight; each and every item that goes into building, equipping, and
operating the vessel and has weight (mass) must be accounted for.
This includes often over looked items like paint and in the case of
plates on metal boats, over-rolling. We have had the privilege of
reviewing designs in which it was quite obvious that a weight
estimate was never done or if done, was perfunctionary at best. It
is not a pleasant task to inform a client that his boat will be 40%
to 60% heavier than quoted and float 8 to 12 lower in the water.
In an existing
vessel, improving the way it handles is sometimes very difficult.
Sometimes the problem can be attributed to the design, sometimes the
way in which the boat is outfitted. A thorough evaluation of the
vessel may offers some clues as to how problems can be lessened, if
not eliminated altogether.
Check (a second opinion)
This is a review of
a design in its entirety and may range from a quick revue to a
detailed assessment. If a fair amount of time is required, the
design check can be a fairly expensive and in the case of a design
from a competent designer, is probably not necessary.
How do you know if a design check is warranted. Even to the
untrained eye, sometimes a small item can stand out. A good example
is a client who questioned if a ¼ plate deck was needed on his 58
steel cruiser. Unless he was expecting heavy deck loads (wheeled
traffic, cargo, etc.), the use of 3/16 plate (or possibly 10 ga)
would be quite sufficient. This small revision saved him some money
and improved the stability by eliminating about 1700 pounds of
Obviously, the check is done by someone other than the designer of
the work under review. For this and other reasons, some designers
may not appreciate their work being scrutinized by others who, in
most cases, would be the competition.
While the design check is not commonplace in small private vessels,
it is quite common on government projects involving public
(taxpayer) money. If you suspect a problem (or even if you dont)
there is nothing wrong with a second opinion from a qualified
person. After all, its your money, your boat, and your life: a good
design it will stand up to scrutiny.
In additional to our
own designs, we can also provide this service for clients of other
designers. The purpose is to provide some on-site verification that
the builder is following the plans, the intent of the design, and
good shipbuilding practice. In some cases we might be asked to
furnish technical assistance to the builder on behalf of the
designer. In all cases the designer must approve all work and be
kept informed of the vessels status.