I have sailed my H33 with in-mast furling main and roller furling jib for just over a year. I usually can get the boat to about 5.0 kts. on a close reach with 10 kts. of wind. The boat will accelerate to 6.0 Kts. on a beam reach, and downwind deccelerate to about 4.5 kts. When the wind picks up to 20 kts. I get to 6.0 kts. on a close reach, 6.7 kts. on the beam and 5.5 kts. down wind. I have noticed the sail seems to have very different amounts of draft from the foot to the head. No matter how much I use the mainsheet and outhaul it is difficult to adjust the draft. I was wondering if other H33 owners are getting similar kts. with like wind conditions. Also does your main have a like draft problem?
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You have problems
My H33 will do close to hull speed on a beam reach with a 10 kt wind. Make that a 12 kt wind and it will be at or above hull speed. In 20 kts of wind I would have about half of both sails rolled up to reduce excessive heeling but I would still be near hull speed on a beam reach. It may not be the best method, but the way I adjust the sails is to adjust the headsail first. Then make the main look as much as possible like the headsail. i.e. adjust the mainsheet to get the same angle; then adjust the outhaul to get the same amount of belly in the main as the headsail. Of course it will require some tweaking, but this what seems to work best on my boat. Your relative speeds, close reaching and running, seem in line with the beam reach speed, so maybe there is some other problem. Has your knotmeter been calibrated? When was your bottom cleaned last? How fast can you motor? The H33 is a lot better performing boat than your numbers would indicate.
My H33 will do close to hull speed on a beam reach with a 10 kt wind. Make that a 12 kt wind and it will be at or above hull speed. In 20 kts of wind I would have about half of both sails rolled up to reduce excessive heeling but I would still be near hull speed on a beam reach. It may not be the best method, but the way I adjust the sails is to adjust the headsail first. Then make the main look as much as possible like the headsail. i.e. adjust the mainsheet to get the same angle; then adjust the outhaul to get the same amount of belly in the main as the headsail. Of course it will require some tweaking, but this what seems to work best on my boat. Your relative speeds, close reaching and running, seem in line with the beam reach speed, so maybe there is some other problem. Has your knotmeter been calibrated? When was your bottom cleaned last? How fast can you motor? The H33 is a lot better performing boat than your numbers would indicate.
Above hull speed at 12kt of wind?
Sorry, but unless the boat was surfing, that is physically impossible.
Sorry, but unless the boat was surfing, that is physically impossible.
Impossible?
Whose physics says it is impossible? Quote the book and page, please. Hull speed on the Henderson 33 is 7.28. I'm curious to know; according to YOUR physics book, exactly what wind speed is required to achieve hull speed? Don't assume that the characteristics of your boat and sailing performance apply to every other boat and sailor on the water. I have owned both a 380 (which is essentially the same as your 375) and a H33. While the 380 was a wonderful boat (in its day
), the 33 is a lot more fun to sail because it goes fast, over a broader spectrum of wind speeds, with very little effort.
Whose physics says it is impossible? Quote the book and page, please. Hull speed on the Henderson 33 is 7.28. I'm curious to know; according to YOUR physics book, exactly what wind speed is required to achieve hull speed? Don't assume that the characteristics of your boat and sailing performance apply to every other boat and sailor on the water. I have owned both a 380 (which is essentially the same as your 375) and a H33. While the 380 was a wonderful boat (in its day
), the 33 is a lot more fun to sail because it goes fast, over a broader spectrum of wind speeds, with very little effort.
Larry
you missed the key word ABOVE. It is impossible to exceed hull speed in 12 kts of wind at a beam reach....infact, it's impossible to exceed hull speed in any wind speed at a beam reach. You have to be surfing the waves to exceed hull speed and you can't surf from a beam reach. Note: we aren't talking about COG because current can add to that.
you missed the key word ABOVE. It is impossible to exceed hull speed in 12 kts of wind at a beam reach....infact, it's impossible to exceed hull speed in any wind speed at a beam reach. You have to be surfing the waves to exceed hull speed and you can't surf from a beam reach. Note: we aren't talking about COG because current can add to that.
Franklin
Don't miss the key word THEORETICALLY. Hull speed is theoretically 1.34 times the square root of your waterline. The key word is "theoretically." The formula needs to be adjusted according to the hull design and displacement of your boat. The formula is only a general guide to how fast your boat will sail. Among other things, the formula doesn't consider hull shape. A modern, light-weight, beamy, fin-keeled hull is certainly faster than a narrow, traditional full-keeled hull. In any scientific discussion of hull speed, reference is often made to Froude’s Law. Froude was a scientist who worked in the second half of the 19th Century doing much research work for the British Admiralty. The work was for warships so any references to sailing and Froude are probably distortions even though he did like yachting. He did his basic research on models of 3 ft, 6 ft and 12 ft for two different hull forms. He observed that when models were run at speeds in proportion to the square of their length they created similar wave patterns. In 1876 he gave his famous Law of Comparison which states that the resistances of similar ships are in the ratio of the cubes of their linear dimensions when their speeds are in the ratio of the square roots of those dimensions. This is equivalent to saying that the resistances vary as the cube of the scale when the speeds vary as the square root of the scale. Nowhere did Froude make reference to a maximum speed or an unattainable speed based on the waterline length. The hull speed is only a guide to a speed that should not be exceeded in the interest of fuel economy but then it might as well be 1.3 or maybe 1.4 or 1.2. When a vessel proceeds through the water it creates a wave train at the bow and another at the stern depending on the speed and the length on the waterline. If there is an interaction the resistance is higher than the smooth line ignoring all the interferences. If there is no interaction the resistance is less than the smooth “average” line so there is a series of humps and hollows. Although the LWL is the usual length used in resistance calculations the length actually depends on the pressure variation at the ends and it varies so that LWL is a kind of average used to simplify the problems. Hull speed is not an absolute limit. It is the approximate speed where a significant increase in power is needed to lift a vessel out of the bow wave that has lengthened with increasing speed until it is the same length as the waterline. The actual formula, as popularised by a book on Yacht design published in the early sixties, is: Hull speed in knots = C x sqrroot(waterline length in feet) where C is a constant varying with form. Yachtsman usually take it as 1.34 but it varies from about 1.42 for fine hulls to 1.18 for chunkier ones. It only pertains to displacement hulls and gives an approximation of the maximum speed a hull can achieve before the bow wave combines with the stern wave to dig a trough out of which the vessel would not be able to climb without using inordinate amounts of power. The formula needs to be used circumspectly and applied to hulls within reasonable limits. It cannot be used indiscriminately to prove absolute values for any hulls. The absurdity becomes apparent when a hull of infinte length is inserted into the formula. It is not self limiting. Thus a hull of a few millimetres could almost not move while an infinte one could move infintely fast. In fact the formula is not much use above about 200 feet and is in fact best utilised on small sailing dinghies. In fact the ocean literally teems with vessels exceeding their "hull speed" according to this formula.
Don't miss the key word THEORETICALLY. Hull speed is theoretically 1.34 times the square root of your waterline. The key word is "theoretically." The formula needs to be adjusted according to the hull design and displacement of your boat. The formula is only a general guide to how fast your boat will sail. Among other things, the formula doesn't consider hull shape. A modern, light-weight, beamy, fin-keeled hull is certainly faster than a narrow, traditional full-keeled hull. In any scientific discussion of hull speed, reference is often made to Froude’s Law. Froude was a scientist who worked in the second half of the 19th Century doing much research work for the British Admiralty. The work was for warships so any references to sailing and Froude are probably distortions even though he did like yachting. He did his basic research on models of 3 ft, 6 ft and 12 ft for two different hull forms. He observed that when models were run at speeds in proportion to the square of their length they created similar wave patterns. In 1876 he gave his famous Law of Comparison which states that the resistances of similar ships are in the ratio of the cubes of their linear dimensions when their speeds are in the ratio of the square roots of those dimensions. This is equivalent to saying that the resistances vary as the cube of the scale when the speeds vary as the square root of the scale. Nowhere did Froude make reference to a maximum speed or an unattainable speed based on the waterline length. The hull speed is only a guide to a speed that should not be exceeded in the interest of fuel economy but then it might as well be 1.3 or maybe 1.4 or 1.2. When a vessel proceeds through the water it creates a wave train at the bow and another at the stern depending on the speed and the length on the waterline. If there is an interaction the resistance is higher than the smooth line ignoring all the interferences. If there is no interaction the resistance is less than the smooth “average” line so there is a series of humps and hollows. Although the LWL is the usual length used in resistance calculations the length actually depends on the pressure variation at the ends and it varies so that LWL is a kind of average used to simplify the problems. Hull speed is not an absolute limit. It is the approximate speed where a significant increase in power is needed to lift a vessel out of the bow wave that has lengthened with increasing speed until it is the same length as the waterline. The actual formula, as popularised by a book on Yacht design published in the early sixties, is: Hull speed in knots = C x sqrroot(waterline length in feet) where C is a constant varying with form. Yachtsman usually take it as 1.34 but it varies from about 1.42 for fine hulls to 1.18 for chunkier ones. It only pertains to displacement hulls and gives an approximation of the maximum speed a hull can achieve before the bow wave combines with the stern wave to dig a trough out of which the vessel would not be able to climb without using inordinate amounts of power. The formula needs to be used circumspectly and applied to hulls within reasonable limits. It cannot be used indiscriminately to prove absolute values for any hulls. The absurdity becomes apparent when a hull of infinte length is inserted into the formula. It is not self limiting. Thus a hull of a few millimetres could almost not move while an infinte one could move infintely fast. In fact the formula is not much use above about 200 feet and is in fact best utilised on small sailing dinghies. In fact the ocean literally teems with vessels exceeding their "hull speed" according to this formula.
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