The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.
Classic hull speed formula:
Hull Speed = 1.34 x √LWLA more accurate formula devised by Dave Gerr in The Propeller Handbook replaces the Speed/Length ratio constant of 1.34 with a calculation based on the Displacement/Length ratio.
Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio.311
Hull Speed = Max Speed/Length ratio x √LWL
A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.
SA/D = SA ÷ (D ÷ 64)2/3
A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.
Ballast / Displacement * 100
A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.
D/L = (D ÷ 2240) ÷ (0.01 x LWL)³
This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.
Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam1.33)
This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.
CSV = Beam ÷ ³√(D / 64)
The Whitby 42 is a rugged-looking, full keeled, heavy displacement cruiser designed by Ted Brewer in 1973 but lacking the “Brewer bite” that improved the performance of her sisterships, the Brewer 12.8 and Brewer 44. Although the most commercially successful of Ted Brewer’s designs, and considered a good value, liveaboard shoal water cruiser, opinion is that the Whitby 42 is not as rugged as she might suggest. Although she has completed serious offshore passages, weaknesses in her construction mean that she is not the preferred choice for serious blue water sailors. Not renowned for performance under sail, the accommodations are perhaps the real attraction of this center cockpit cruiser as well as the 5′ draft which is excellent for shoal waters.
The first Whitby 42 splashed out of the yard in Ontario, Canada in 1973. Whitby Yachts, owned by Kurt and Doris Hansen, went on to build 200 hulls from 1973 to 1983. Previous to this, Whitby Boat Works had built the Alberg 30 and Alberg 37. With the 42′ construction quality gradually improved until 1983. Production then shifted south to Fort Myers Shipyard in Florida where another 32 of these ketches were built along with the Brewer 12.8 and Brewer 44. The Myers versions have a reputation as having the highest quality construction. The 12.8 design substituted a cutter rig instead of the Whitby’s ketch rig, added a Brewer bite to the full keel and added a centerboard. The hulls are lighter and stronger, and the weight savings are used to increase ballast and stability. The Brewer 44’s are a stretch version of the 12.8’s.
The Whitby 42 has a modern center cockpit aft stateroom with walk through arrangement. Forward is a large V-berth. There is a forward head with shared shower. In the salon, a L-shaped settee dinette arrangement is offset by two swivel chairs. The swivel chairs illustrate that the Whitby 42 was geared more as a liveaboard than a serious offshore cruiser. A U-shaped galley is aft to port. The walkway has low headroom due to the cockpit lockers. The aft cabin has a full width bunk with en-suite head.
The hull has balsa cored topsides like many Canadian manufacturers of this vintage. Below are alternating layers of mat and woven roving with polyester resin. The hull and deck is secured on most by pop rivets. Enlaid is a molded liner to stiffen the hull and provide interior structure though at the expense of hull access. She has a ketch rig. The engine was a great 67 HP Ford Lehman that provides plenty of punch.
Sailing performance, though better than a Westsail 42, is still a bit of a weakness. Not only does she have a rather full keel with connected rudder, but her buttocks are more rounded so she is more tender than her rugged looks and heavy displacement might suggest. Without a bowsprit she has wicked weather helm. Otherwise she is a stout boat for the trades with her shoal draft of 5-feet able to access the shallowest of harbors.
Owners advise buyers to examine the water tanks which are oddly fiberglass with an aluminum top plate. Another problem is the keel fuel tank which sits down deep in the bilge. The hull to deck is often secured by stainless steel rivets although many took up the option of through bolts. The mizzen mast does not have a solid glass radii and is prone to compression. Look for 42’s with a bowsprit to reduce weather helm and increase performance.
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