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)
From the prestigious drawing board of the Sparkman and Stephens office, the Columbia 29 was introduced by the Glas Laminates Company of California who were producers of fiberglass camper tops, shower stalls and chemical toilets. The first hull was laid up in 1961 and introduced to the market the subsequent year. The Columbia 29 was successful enough for the company to form Columbia Yachts Corporation and adopt the Columbia name for its entire line of subsequent boats, the company eventually became the highest volume producer of fiberglass yachts by 1967.
Primarily designed for coastal cruising the Columbia 29 is easy to sail and has reasonable comfort for its size. The boat has sleek lines and good performance for her era.
According to the sales material of the time, the boat can sleep 6 (at a pinch) having two quarter berths, a forepeak double, and a convertible dinette. The boat came standard powered by an outboard motor operating within a cockpit well, there was an inboard 8hp Atomic 4 gasoline engine as an alternative option. Early models had 3120 pounds of ballast which got bumped up to 4,100 pounds in later models before the introduction of the MkII. In total 304 MkI hulls were built between 1961 and 1967.
The boat appears in Atom Voyages list of proven boats for offshore voyaging so we’ve included it here. We’ve heard that construction quality was good through to the end of 1967 where quality started to decline. Most of the tabbing was glassed over marine ply which becomes saturated over time.
By 1967 a MkII version was introduced which shared the same hull, rig and sail plan as its predecessor, but a redesigned trunk cabin to keep it cosmetically inline with the rest of Columbia range of sailboats.The new cabin featured a one-piece fiberglass headliner. They also retained the extra 1,000 lbs of ballast which was added to the late MkI models. A total of 383 MkII hulls were produced between 1967 and 1969.
A raised deck version was built as the Defender 29, which offered more interior room and a flush deck. Though some may cite higher freeboard at first glance as a disadvantage, the overall windage when compared the equivalent Columbia 29 cabin profile is actually reduced.
» Columbia 29 specifications and details at the Columbia Yachts Owners Association
» Columbia Yachts Yahoo Group, information and owner discussions.
» Heart of Glass: Fiberglass Boats and the Men Who Built Them by Daniel Spurr, a short history of Columbia Yachts (p182)
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