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 Hans Christian 38 MkII dates back to 1978, introduced only two years on from its predecessor, the popular Hans Christian 38 Traditional. They share the same designer and the same Taiwanese boatyard, Shin Fa. To the untrained eye, it’s easy to mistake the two. The 38 MkII continues with the same family looks and configuration; a traditional heavy displacement double-ender, with a springy sheerline, large bowsprit and a cutter rig. However the MkII has some important improvements made to its underbody.
In the interests of more boat speed, the beam was carried further forward and aft, the bottom sections flattened and the turn of the bilge was tightened. The forefoot to the keel was made shallower and the rudder placed further aft. Followers of boat design will note Bob Perry had great success with evolving this kind of hull form in a similar direction with his series of performance double-ended full keelers like the Tayana 37 (1975), Baba 40 (1980), and Tashiba 36 (1985).
In addition to the hull changes, to mitigate its predecessor’s tendency for weather helm, the mast was moved 12 inches forward, and to improve light air performance the rig was three feet taller and carried 11% more canvas. The result was a boat that performed substantially better all round, it pointed higher and could move much better in light airs.
Belowdecks, the 38 MkII can be immediately recognized by her sink which is mounted on an island bench, gone is the U-shaped galley. Another important change worth considering is the placement of the engine to under the companionway stairs, in the 38T this was located under the sink which provided better accessibility.
Although the 38 MkII offered better performance, it’s somewhat surprising that the original 38 Traditional was considerably more popular. We’re told by Craig Beckwith, VP of Sales for Hans Christian Yachts during that period, the better performing Telstar Keel** offered on the 38 Traditional took a lot of the market from the MkII, and for financial reasons the Telstar Keel did not become an option on the MkII. In total 87 MkII boats were built with production ceasing around 1989, roughly the time when Hans Christian Yachts shifted their operations to Thailand. The molds have survived (though in rather bad condition) and in theory the boat could be produced once again, with some investment in refurbishing the molds.
** See article on the Hans Christian 38 Traditional for a full description of the Telstar Keel
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