About

87 Port Road, Whangarei, N.Z.

BACKGROUND

Originally commencing business in 1934 when Walter Watson senior set up as a yacht builder having until then primarily been a small craft builder. The first large vessel commission was the auxiliary yacht “Wayward”.
The design office was established by the founding principal T.C. (Ces) Watson in 1946. This practice has been responsible for the design of the most diverse range of motor and sailing vessels of any design office in New Zealand.
These craft have ranged from 30ft sail boats to Ocean Going Tugs, car ferries and include the largest vessel ever launched in New Zealand a 9000 DWT Barge.
Commissions have included such unusual projects as an “HMS Bounty” replica built in 1978 for the Dino de Laurentas film corporation. This included working drawings not only of the HMAS Bounty but also of the Bounty’s long boat, both of which required extensive research of the British Admiralty archives.
Over the years we have prepared designs in all the available building materials including wood, steel, G.R.P. and aluminum and have a good understanding of the strengths and weaknesses of each.
The design office has always had a particular interest in the design and construction of small steel and wooden trawlers, tugs and other work boats up to approx. 80ft and was one of the pioneers in the expansion in these fleets from the mid 1950s to the late 70s.
Many of these vessels were required to operate in very severe conditions requiring a high standard of hull strength, stability and sea keeping ability. Their propulsive machinery and systems had to have an unprecedented degree of reliability. This is influenced largely by conditions due to New Zealand’s geographic location which are summed up by Captain Cook’s 1769 comments on discovering the country:
“The coast of this country is pounded almost ceaselessly by a procession of great hollow swells and gale force winds which leads me to believe no other land lies within this latitude for fully 200 degrees longitude of the earth’s circumference”.
T.C. Watson’s expertises in these types of craft lead to design commissions for both coastal and ocean capable private motor yachts incorporating many of the characteristics of these earlier designs.
At this time the present principal, Wally Watson, joined his father in partnership after studying at the Institute of Technology and spending four years in ship design in New Zealand’s largest shipyard.

MOTOR YACHTS

In 1970 the design of the first Watson expedition yacht was commenced. The 67ft “Hamal” a twin screw steel ocean capable vessel was completed in 1974 and is still under original ownership.
The first Watson 72, the “Pescadora” followed. This vessel was designed for “unrestricted ocean service” with a Trans Pacific steaming range. Since then four further motor yacht designs have been prepared, a 79ft twin screw vessel, also with Trans Pacific steaming range. A 48, 54 and a 60ft, each of which are pilot house type and also designed for “Unrestricted Ocean Service”.
All these designs are prepared for steel construction with epoxy/polyurethane paint systems. The office has now had over 50 years experience in steel design and our observations over that time have shown the special suitability steel has for this type of craft.
At an early stage a decision was made to design all our range of passagemakers and expedition yachts to meet a recognized standard; Classification Society with a “Deep Sea” notation or equivalent.
The purpose of this was to ensure integrity of the structure. Namely, correct watertight subdivision of the hull and in particular a correctly located strong collision bulkhead, along with the provision of scantlings and design pressures required for the fabric of the structure.
Also, building at this level would answer the question of whether the vessel could be used for charter or easily converted for charter, where the answer is usually “no” or “yes, at great cost”. However, apart from the safety reasons alone one of the strongest arguments to have such a costly asset designed and built to a known standard is in the eventual resale of the craft.
Supplementary Rules have progressively been in troduced aimed at improving the stability and sea keeping ability of motor vessels engaged in long coastal and offshore voyages. The following are examples of these:
Torromelinous Stability Criteria; this IMO regulation was aimed at improving survivability of fishing vessels, but in our view is equally applicable to motor yachts engaged in offshore voyages.
Severe Wind & Rolling Criteria; this IMO criteria is derived from an analytical approach to the sea keeping ability of a vessel in a seaway.
This criterion is now mandatory in commercial vessels exceeding 80ft in length but in our view all craft engaged in long coastal or offshore voyages should meet these criteria. This is not easy to do in many vessels. Particularly in any that have a high top hamper combined with a shallow draft. We have found that a vessel whose A/B ratio exceeds about 1.75 has little chance of meeting this stringent regulation.

THE DESIGN PROCESS: Offshore Motor Yachts

To meet all these sometimes conflicting requirements the design office works from a set of in house design standards to apply to each new design as it progresses. These standards are eventually embodied in each vessel written specification and working drawings.
The design sequence is as follows:

• General Arrangement

This drawing is produced to illustrate the external appearance of the vessel and the internal layout and ergonomics.
In our view the external appearance is the overriding initial consideration and the famous naval architect K.C. Barnaby could not have put it better:
“Ugliness is never an asset and is very definitely a drawback for yachts…Much the same applies to warships. In peacetime they have to “show the flag” abroad and considerable attention should be paid to appearance, so long as it does not conflict with fighting efficiency.”
“Raking masts and severe straight lines give an impression of speed; curved lines indicate grace and sea-kindliness.
“Freakishness is a quality hated by seamen, who are usually very conservative in their ideas. For this reason, excessive streamlining should be avoided. It suggests an undue straining after novelty rather than exceptional efficiency and is also extremely costly”
“Consistency is particularly valuable. A power yacht should not look like a fast warship at the bow and a river steamer at the stern. All curves or raked straight lines should be similar in character and not suddenly chop and change…”
Ironically, Mr Barnaby was involved in the design of some of the world’s ugliest craft, namely the L.S.T.s and L.C.T.s for the D-Day landings in WWII.

• Layout & Ergonomics

This is usually the main interest of owners who have to actually live aboard the vessel.  We have learnt that accommodation layouts have to be flexible to a degree and one must keep this in mind when designing the structural fabric of the vessel. The usual demand is for at least two full double berth staterooms with ensuites, along with two further single berth bunks.
In larger vessels such as our 72 and 79 designs, an owner’s stateroom and two guest staterooms, all with ensuites is usually the requirement, preferably with the owner’s accommodation full width of the hull and separated from guests by the engine room. We have also managed this with our 54 & 60 designs. However as the larger vessels often carry a paid hand, quality self contained accommodation is required for one or two. The smallest vessel capable of this arrangement seems to be in the 60ft range.
The layout should always be planed to show a distinct separation between cabin spaces and between cabin spaces and service areas. Also a minimum of vertical separation between these spaces is desirable along with a separate, dedicated engine room access opening into a service area only.
The engine room, particularly in an ocean going craft, should be spacious and uncluttered and must have headroom of six feet minimum down both sides of the main engine(s) for the full length of the engine room.
Where possible a large amount of under deck storage should be planed for. The longest passage to be encountered in a circumnavigation is from Hawaii to the US West Coast. If we allow twelve days steaming time (12 x 200 NM = 2400 miles including an arrival margin), this is what determines the fuel and water to be carried along with stores for a crew of say four.

• Lines Plan

Great care must be taken in the preparation of the lines plan. Not only does this define the shape of the vessel but also the propulsive performance, sea keeping ability, directional stability, rolling and pitching period and a host of other hydro-dynamic considerations. What’s more, it can never be changed again!
The hull shape is defined with a set of limiting hull coefficients which we have learned through experience suits the vessel being designed. These are:
Length/breadth Ratio                           (L/B)
Length/draft Ratio                                 (L/D)
Displacement/length Ratio                 (D/L)
Block Coeff.                                            (Cb)
Prismatic Coeff.                                     (Cp)
Midship Coeff.                                        (Cm)
Longitudinal Centre of Bouyancy        (L.C.B.)
Longitudinal Centre of Floatation       (L.C.F.)
Centre of Lateral Resistance              (C.L.R.)
The lines plan is drawn manually with splines of varying stiffness and offsets lifted from this faired drawing. These offsets are than “micro faired” with a computer fairing program. We do not simply draw the whole thing in a computer program as we have found it impossible to design a pleasing shape using the programs available. So have many other designers, yet many persist with less than great results.
The lines plan is really everything in the appearance and performance of the completed vessel, and while working on a drawing board may seem “old fashioned” unless the vessel is a very simple shape, it is in fact more productive, giving a far better result.

• Construction Drawings

These follow the production of the lines plan and illustrate all the hull scantlings and shell thicknesses in the hull structure. The structural detailing is always incorporated into the faired computer model of the vessel.
To determine the scantlings the designer must calculate the pressures and forces acting on the hull in a stipulated sea state. These forces vary depending on the location on the hull and are of greatest intensity in the fore ship. The best calculation methods are stipulated in the Classification Society Rules; Lloyds, Bureau Veritas and American Bureau of Shipping.

• Engineering and Mechanical Drawings

These details follow the construction drawings and are guided again by Class Rules which apply to all the virtual systems within the vessel. In small vessels we have found there is little or nothing to gain from preparing these in computer detailing. The engine room can quickly become a “bird’s nest” of systems and equipment without proper planning, so we have found it is best if only one organization is responsible for the overall design of the entire area.

• Outfit and Furniture Drawings

The first step is the preparation of large scale drawings of each accommodation area showing furniture locations. Here is where computer detailing is taking over completely. Floors and bulkheads are prepared accurately inside the 3D model of the vessel. The entire interior can be detailed and finalized prior to manufacturing. The accuracy that can be achieved means that almost all the interior can be made outside of the vessel giving scope for far greater efficiency and quality.

• Trim & Stability Data Book

The final job of the design office after the launching of the vessel, is to conduct an inclining experiment and produce a trim & stability data book.
All told there are some 200 drawings and details required to build a vessel in the 50ft range and 350 required for a vessel in the 70-80ft range. The investment in a design is very large! Of these, if the vessel is to be built to any standard such as American Bureau of Shipping or Bureau Veritas, then approx 75% of the drawings are required to be submitted for Plan Approval.