50′ Aluminum Motoryacht

Design Number: 84-501

The design of this vessel was recently completed by this office for a Vancouver yachtsman and the anticipated launching date is set for early summer of 1986.

The layout is of the midships wheelhouse configuration with accommodation below and forward with an aft saloon, leading to an open cockpit and walk around side decks.

It should be pointed out that this is a custom design and as such has many features which reflect the needs of the client .

These features may not have universal appeal and can be modified on future vessels.

Hull Form
The hull is of a moderate deadrise ‘V type semi-displacement hard chine with moulded in spray rail above the water-line. This particular hull form was first developed by us in 1972 for a 33’ cruiser and we have used it on several designs since. It is most suitable for vessels operating at moderate speeds (speed/length ratios of 1.5 to 3) and offers good performance potential with economy of operation as well as good tracking and seakeeping properties.

The hull is of welded marine grade aluminum with scantlings in compliance with American Bureau of Shipping rules. Framing consists of longitudinal ‘T’ bars spaced approximately 14″ on center supported by transverse web frames spaced approximately 45″ on center. We have used a full conical developement on both bottom and tops!des to facilitate plating and to minimize the use of fairing compounds in finishing.

The superstructure is of welded aluminum similar to the hull with special attention to fairness and corner detailing.

Painting & Finish
All exterior surfaces are to be finished using two part linear polyurethane such as supplied by U.S. Paint (“Awl Grip”). Underwater areas are to be protected by a passive cathodic protection system to e l i m i n a t e electrolysis.


All out-fit and finish is to the highest marine standard and in compliance with the regulatory bodies concerned. Special attention is paid to the reduction and/or elimination of structural and airborne noise and vibration through the use of floating floors, isolators, and high density/low mass panelling.

The hull and superstructure are to be insulated with non-combustible sprayed in place urethane insulation to facilitate temperature control and eliminate condensation.

The first vessel will be fitted with twin Cummins MT-555<BC) diesels developing 320 BHP at 3000 rpm turning 30″ diameter 4 bladed stainless steel propellers. Gears are Twin Disc MG507(3:1 reduction ratio) and fitted with hydraulic bypass trolling valves for fishing and slow speed manoeuvring.

The power selection for future boats is optional and at the discretion of the owner. To fully utilize the benefits of this hull form, we would suggest that the total installed power range from 900 bhp to a minimum of 300 bhp.