Design Concept

We prepared the design of our first passage maker in 1970. At the time it was new ground. The owners brief was for an ocean going vessel incorporating all the tried and true hull design, systems, stability and seaworthiness of our existing commercial designs.

The owner insisted on steel construction for stranding and fire resistance. He was conscious of the risk of total loss in fiberglass and wooden vessels resulting from often minor stranding incidents.

Those no-nonsense characteristics were to be built into an attractive modern hull that could grace any marina. The result was the 67ft MV Hamal , still in her original ownership after more than 35 years and many thousands of miles of voyaging. It is testament to her owner’s original demands for a vessel of such high integrity that Hamal still attracts admiration wherever she is cruising.


The 67ft Hamal was followed by the design of the W72 and W79 again each meeting the highest Classification Society standard: Maltese Cross •Mach. This assures the owner of a vessel that it is able to cope with weather conditions in Unrestricted Ocean Service due to its structural strength, stability, redundancy of systems and more specifically sea keeping ability.

Watson 72

The development of these larger designs has led to interest in smaller models and now our range includes the 48, 54 and 60. These follow in the tradition of our larger vessels; no other passage makers of these sizes are built to such a standard.

Watson 48

All our range are modeled on proven full displacement hull forms derived from many years of involvement by Naval Architect firm T.C. Watson & Sons in trawler, tug and motor yacht design, along with much published research into sea-keeping properties of various hull forms and hull proportions.

Yet even as full displacement hull forms, due to their efficient propulsion systems with large slow turning propellers, they achieve the economy of their lightweight competitors with far greater “staying power”. All achieve cruising speeds allowing greater than 200 NM per day steaming with the ability maintain speed, comfort and safety in adverse weather conditions.

Unlike many of the competing designs now on offer in the passage maker market, the Watson range of vessels are uncompromising in the four main hull properties that are proven for safe unrestricted ocean cruising. These hull design characteristics’ are:

• A high length to draft ratio of 0.15
• Low A/B ratio – this is the ratio of the above waterline lateral area to the immersed area, which       for a vessel intended for ocean cruising should never exceed 2.
• Prismatic co-efficients optimized for the vessels cruising speed.
• Low block co-efficients with rake of keel for good course keeping and propeller efficiency.

As always tied to hull form is the all important question of propeller efficiency, which is poor in any craft that depart from the above, especially in those with restricted or shallow draft.

Our range of vessels have large slow turning, quiet and efficient propellers with diameters at least 7.5% of the waterline length and maximum speed of 600rpm. We have found during more than 60 years of power boat design that only from these propulsion particulars can reasonable cruising economy be achieved.

Our range of passage makers are fabricated from steel to the exacting standards of the Worlds leading Classification Societies; Lloyds Register and Bureau Veritas. The designs have been appraised by structural experts, who apply a rigid set of rules that not only stipulate minimum thicknesses of material but also quantify the sea pressures the hull must withstand in service. Also stipulated is the minimum longitudinal watertight subdivision of the hull. Each of our vessels have four watertight bulkheads. This subdivision, together with large double bottom fuel tanks, makes these vessels practically immune to foundering.

Steel is unmatched in puncture, fatigue and abrasion resistance and is, of course, fireproof. It is also the most superior construction material for any vessel contemplating voyaging in ice.

The fully faired Watson hulls are protected by the most modern epoxy and polyurethane coatings available. When applied over a steel substrate, these extremely durable coatings have far superior weather and abrasion resistance than either vinylester or polyester gelcoats. In keeping with our commitment to produce world class vessels, all areas subject to abrasion are fabricated from polished stainless steel and include beltings, cap rails, fairleads and bollards.

Whether your intention is for extended coastal cruising or trans-ocean passage making, you can be assured that either of these vessels will by far exceed your expectations.

Last Updated (Wednesday, 15 September 2010 09:26)