osjak
19.05.2021 2:09:52
Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311
Hull Speed = Max Speed/Length ratio x √LWL more
See full version: Columbia T-23
Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311
Hull Speed = Max Speed/Length ratio x √LWL more
Columbia T-23 is a 22 ′ 6 ″ / 6.9 m monohull sailboat designed by Alan Payne and built by Columbia Yachts between 1973 and 1977.
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.
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.
"The bow shape has been chosen principally for it's effect on steering. The U-shape reduces weather helm when the Yacht is heeled and makes the boat much easier to steer in a following sea. On top of the veed stern there is a fairly wide spreading out transom in the style of the early American yachts like the schooner 'America'. This stern confers useable deck space and acts as a very good pitch dampening device when the yacht is heeled over." [links]
"The final satisfactory result was achieved by combining a wide beam, a flat-bottomed shape amidships with firm bilges, and bow and stern shapes which are different to the shapes adopted nowadays in rather thoughtless imitation of shapes which have been developed to fit the geometry of racing rule." [links]
Summary: Classical Glass is a strong seaworthy vessel with a beautifully balanced helm. Designed by acclaimed Australian America�s Cup yacht designer Alan Payne, she is fast and forgiving and handles heavy air beautifully. In the local phrf fleet she has won her class and never finished lower than 3rd.
Comments by her designer: " There has always been the thing that cruising yachts were a kind of watered-down version of current racing yachts. The amount of design thought that has gone into cruising yachts was nowhere near what it should have been. The Super-Cruiser design is intended to be a balance of good handling qualities, safety and ability in rough weather and speed. The interesting and special thing about this design is the very good performance which has been achieved over the whole range of cruising requirements." more
"The net result of the bow, midships, and stern shapes is a boat which imparts tremendous confidence in rough weather. It keeps going fast, it has an easy motion, it is dry, and it is easy to steer. It is also stiff and stable and carries it's sail well. It's a boat with which the owner can go on board and find that she is particularly easy to manage in all sailing conditions."
The fiberglass revolution in boats really hit its stride in the 1970s. Builders experimented, learned, and improved construction processes during the 1960s, so by the early 1970s, there were a lot of big- time builders pumping out a lot of good boats. In the East was Pearson Yachts; in the Midwest was Tartan Marine; in the South, Hunter Marine and Irwin; in Canada, C&C Yachts flourished; and out West were Jensen Marine (Cal), Ericson, and Columbia Yachts, to name just a few of them.
Stanchions, double lifelines and double stern and bow pulpits were standard. Stanchions are though-bolted, but backed only by washers, not backing plates of fiberglass or aluminum, which do a better job of transferring loads and preventing cracking of the gelcoat, and possibly the deck laminate, in way of the stanchion bases.
Tartans enjoy very active owners groups, especially in the Chesapeake Bay area. T30 owners’ websites have much useful information on troubleshooting and upgrading. [links]
Classic hull speed formula:
The biggest problem has been corrosion in the aluminium fuel tank which is buried in the keel directly under the engine. It needs to be fully glassed over to protect it, or excavated and replaced if already corroded. Similar corrosion problems have occurred with the sleeve cylinder in the early model 9hp Farymann diesel engines which also must be rebuilt or replaced but the engine is apparently easy to remove. The later Farymann model 32W has a cast iron cylinder and is not so susceptible. No other significant weakness have come to light.
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. more