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 Tashiba 31, designed alongside her larger 36 foot sibling, represents the last of Bob Perry’s full-keeled production double-enders. Though outwardly compact, the interior is spacious with a luxurious finish that’s been a hallmark of the Taiwanese builder, Ta Shing.
Ta Shing commissioned Perry for the design of the boat and launched it in 1986. That year marked nearly a decade since the Taiwanese boatyard started a rise to prominence with the release of the popular and closely related Baba 30 double-ender (also Perry designed). It’s interesting to note despite the years that span the two designs the Baba 30 and the Tashiba 31 are mistaken to be variations on the same boat.
Make no mistakes however, the lighter and faster Tashiba 31 is wholly a different animal under scrutiny. Her hull form is a derivative of the Baba 40. Perry tells us the Baba 40 was a radical departure to his previous full keelers, the 40 was really a full-keeled evolution of the famously fast fin-keeled Valiant 40. It proved to be such a success in terms of performance and handling that Perry took the elements that worked and pushed them further. The leading edge of the keel was moved further aft, turn of the bilge got even firmer and the bow entry became finer.
In his book Yacht Design by Perry he reflects, “I think the Tashiba 31 and 36 mark the best boats I ever designed with modified full keels. The boats were fast, close-winded, stiff, and well balanced. I constantly got calls from owners telling me how they had “beat” a local contemporary design.”
The Tashiba 31 can be found in three variations. Two aft cockpit versions were offered; one with a seagoing quarter-berth (most popular) and another that had a forward stateroom and the head located aft (we’ve yet to see any of these). There was also a pilothouse version, something that’s unusual to see in a boat of this length, of which only two were built. All told, they did not sell as well as expected, at last count we found 26 boats listed in the owners registry (kindly put together by Alan Sugarman of the Baba / Panda / Tashiba owners group).
These boats (like all boats from the Ta Shing of that era) have garnered a loyal following. The build quality is exceptional and you’ll find most are in very good condition being well maintained by their owners.
» Yacht Design According to Perry, by Robert H. Perry (p97-p98)
» Baba, Panda, Tashiba sailboat Yahoo Group, information and owner discussions
Great choice! Your favorites are temporarily saved for this session. Sign in to save them permanently, access them on any device, and receive relevant alerts.