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 Westsail 42 was introduced in 1974 by Westsail Corporation as a no-compromise long-distance passagemaker for the cruising couple. It was a time when cruising sailboats had captured the imagination of the American public propelled by a 1973 Times Magazine article featuring a double page spread of a salty Westsail 32 anchored in an exotic tropical island. Westsail found itself on the forefront of a cruising sailboat boom with its Westsail 32 selling in huge numbers.
Historically, the relatively tubby Westsail 32 traces its roots way back to a 1925 Atkins 32 foot design called Eric which was later adapted by Bill Crealock to take advantage of fiberglass production methods. In contrast with the Westsail 42, he was given free reign to design his ultimate cruising sailboat for a couple.
Crealock continued with the 32’s tried and true full keel and heavy displacement formula but gave the new hull a canoe stern to make it fuller in her aft sections than the double-ended Westsail 32. While the Westsail 42 was penned as a center-cockpit, it was followed up with a rear-cockpit variation dubbed the Westsail 43 a year later which was built from the same hull molds.
The Westsail 42 like its smaller 32 foot sibling was offered for sale as fully completed boats or as kits for owners to complete. The original list price of the Westsail 42 was $130,000 by comparison a hull/deck kit and hull/deck/ballast/rudder kit went for $20,000 and $30,000 respectively. Rigs options were available in both ketch and cutter sail plans with the cutter being more popular.
Percentage-wise more 42s were factory completed than the more budget minded 32s. Of notable fame, “the most believable man in America”, Walter Cronkite purchased a Westsail 42 for himself.
Westsail Corporation fell into bankruptcy with a sour economy and dated business practices in 1977, it survived through to 1979 with a buyout operating as Westsail International. When Westsail finally closed operations the molds for the 42/43 was purchased by Jomarco, a boatbuilder in Santa Ana, CA who continued with a small production run. In total 119 Westsail 42 hulls were produced, hulls 1-116 (1974-1979) by Westsail and hulls 117-119 by Jamarco.
Much of the Westsail 42’s heavy displacement comes from its sturdy and overbuilt hull and deck. The hull is constructed in two pieces. Each half consisting of 12 layers of hand laid fibreglass mat and roving which are bonded together. A two inch flange is molded in place along the sheer line for the hull to deck join. The deck molding is cored in half inch plywood. Both deck and hull were cured for a month where any defects would show up during this time.
The lead ballast was cast in three sections and bedded into place with a mix of asbestos and resin and then glassed over.
With long-distance liveaboard cruising in mind, the Westsail is spacious belowdecks with plenty of stowage. Quality construction abounds.
Undersail the 42 is spirited, sea kindly and stable. And with both cutter and ketch sail plans, the yacht is easily trimmed and balance under all wind conditions. In particular shorthanded sailors will appreciate the ketch rig option with its club footed inner forestay sail which gives a huge variety of sail configurations making shorthanded sailing a breeze.
» Westsail Owners Association at Westsail.org
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