How can I find out the weight of a 26' Oday sailboat with a 4800 pound displacement and a 1850 pound ballast?
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displacement is not the weight
O25 centerboard weight listed at 3900. Displacement is around 4800. O25 fin keel weight is 3850+,-. Displacement is approximately 4760. A one gallon milk carton weighs a few ounces but displaces over 8 pounds of milk. Listed displacement is the weight that results in a boat floating at its designed waterline.
O25 centerboard weight listed at 3900. Displacement is around 4800. O25 fin keel weight is 3850+,-. Displacement is approximately 4760. A one gallon milk carton weighs a few ounces but displaces over 8 pounds of milk. Listed displacement is the weight that results in a boat floating at its designed waterline.
Ed
Sorry. You're wrong. You're quoting various examples of cruising weights (half load and such) Displacement is the water pushed aside (displaced)period.
Sorry. You're wrong. You're quoting various examples of cruising weights (half load and such) Displacement is the water pushed aside (displaced)period.
Fred
you wrote "Displacement is the water pushed aside (displaced)period." Sorry officer. In the wonderful world of Oday trailer boats the water pushed aside is the dry weight plus contents. The trailer weight of an O26 is around 4000 pounds. In the O25-26 size, Oday assumes 750 pounds passenger plus miscellaneous. I don't tell you how to wax your bitchin' Camaro, you don't tell me what an Oday weighs.
you wrote "Displacement is the water pushed aside (displaced)period." Sorry officer. In the wonderful world of Oday trailer boats the water pushed aside is the dry weight plus contents. The trailer weight of an O26 is around 4000 pounds. In the O25-26 size, Oday assumes 750 pounds passenger plus miscellaneous. I don't tell you how to wax your bitchin' Camaro, you don't tell me what an Oday weighs.
I have to agree with fred here. The one gallon milk container Ed
talked about only displaces a few ounces until you push, or weigh it down with a force equal to the weight of water it displaces. If it will displace 8 pounds of (lets say water instead of milk) when it is fully immersed, then it takes 8 pounds to push it down. If you fill it with 4 pounds, it will only be half immersed. Displacement is the weight of the water displaced by the weight of the boat. As you add weight the boat sinks deeper until it displaces the equivalent weight of additional water. Have fun. Joe S
talked about only displaces a few ounces until you push, or weigh it down with a force equal to the weight of water it displaces. If it will displace 8 pounds of (lets say water instead of milk) when it is fully immersed, then it takes 8 pounds to push it down. If you fill it with 4 pounds, it will only be half immersed. Displacement is the weight of the water displaced by the weight of the boat. As you add weight the boat sinks deeper until it displaces the equivalent weight of additional water. Have fun. Joe S
Thanks Joe.
Ed, your feathers are ruffled. Sorry. But your milk carton analogy is what seems to be throwing-off your mindset. Your carton is CONTAINING a gallon of milk, not displacing it. If it's empty and weighs an ounce and floating on water then it will displace an ounce. Displacement on water equals the weight of the displacing object or vessel. An exactly equal weight of water will be moved aside (displaced) A boat trailer weight is taken into consideration because it's part of the load that the towing vehicle has to control. It has NO affect on the displacement of the vessel unless somebody forgets to unhook it after leaving the ramp. Not good.
OK, let me start with your post; "O25 centerboard weight listed at 3900. Displacement is around 4800. O25 fin keel weight is 3850+,-. Displacement is approximately 4760." (You're refering to capacity, the number given by the builder that tells you how much the boat can carry in crew and cargo. Every ounce you put aboard a boat increases its displacement.) "A one gallon milk carton weighs a few ounces but displaces over 8 pounds of milk." (See above) "Listed displacement is the weight that results in a boat floating at its designed waterline." (Again, only in theory. The design-waterline is where the stripe is, not where the boat floats. The float(trim) depends on the cargo and its location. And the total of such equals EXACTLY the vessels displacememnt.)
Ed, your feathers are ruffled. Sorry. But your milk carton analogy is what seems to be throwing-off your mindset. Your carton is CONTAINING a gallon of milk, not displacing it. If it's empty and weighs an ounce and floating on water then it will displace an ounce. Displacement on water equals the weight of the displacing object or vessel. An exactly equal weight of water will be moved aside (displaced) A boat trailer weight is taken into consideration because it's part of the load that the towing vehicle has to control. It has NO affect on the displacement of the vessel unless somebody forgets to unhook it after leaving the ramp. Not good.
OK, let me start with your post; "O25 centerboard weight listed at 3900. Displacement is around 4800. O25 fin keel weight is 3850+,-. Displacement is approximately 4760." (You're refering to capacity, the number given by the builder that tells you how much the boat can carry in crew and cargo. Every ounce you put aboard a boat increases its displacement.) "A one gallon milk carton weighs a few ounces but displaces over 8 pounds of milk." (See above) "Listed displacement is the weight that results in a boat floating at its designed waterline." (Again, only in theory. The design-waterline is where the stripe is, not where the boat floats. The float(trim) depends on the cargo and its location. And the total of such equals EXACTLY the vessels displacememnt.)
If you continue with the example that Joe S. started and load that
jug with gravel you can cause it to sink when the weight of the jug with its load exceeds the weight of the volume of water that it displaces. If you weigh it when it is submerged, the weight that you read will be the difference between the total weight of the jug and its contents minus the weight of the displaced water. An iron aircraft carrier floats because its volune exceeds the weight of the water it displaces when afloat. Fill a bucket brim full with water and place a chunk of wood into the bucket so that it floats. The weight of the water that overflows the brim will equal the weight of the wood. But if you force the chunk of wood below the surface it will displace its volume. Edited for typos
jug with gravel you can cause it to sink when the weight of the jug with its load exceeds the weight of the volume of water that it displaces. If you weigh it when it is submerged, the weight that you read will be the difference between the total weight of the jug and its contents minus the weight of the displaced water. An iron aircraft carrier floats because its volune exceeds the weight of the water it displaces when afloat. Fill a bucket brim full with water and place a chunk of wood into the bucket so that it floats. The weight of the water that overflows the brim will equal the weight of the wood. But if you force the chunk of wood below the surface it will displace its volume. Edited for typos
David understand that the listed displacement
stats for any boat are equivalent to dry weight. That is without fluids (water, fuel, oil), batteries and other accessories. It obviously does not include all the stuff we add to the boats like supplies, appliances, tools, etc.
stats for any boat are equivalent to dry weight. That is without fluids (water, fuel, oil), batteries and other accessories. It obviously does not include all the stuff we add to the boats like supplies, appliances, tools, etc.
Guys- not that complicated
An old Greek named Archemedes ( sp) said" an object immersed in a liquid displaces an amount of the liquid equal in weight to the object" or something like that. I think the story was he discovered this while in his bath tub. Displacement equals weight. And yes listed displacement does not include all the stuff we cart down to our boats every sailing season.
An old Greek named Archemedes ( sp) said" an object immersed in a liquid displaces an amount of the liquid equal in weight to the object" or something like that. I think the story was he discovered this while in his bath tub. Displacement equals weight. And yes listed displacement does not include all the stuff we cart down to our boats every sailing season.
Richard, Actually Archimedes realized that an object immersed
in water displaced its volume. An object floated on water displaces its weight. A ferrocement boat will float and displace its weight of water but when it sinks it displaces its volume.
in water displaced its volume. An object floated on water displaces its weight. A ferrocement boat will float and displace its weight of water but when it sinks it displaces its volume.
I am surprised
RichH... hasn't spoken up. He would set the record straight. He must be on vacation.
RichH... hasn't spoken up. He would set the record straight. He must be on vacation.
Well- maybe it is that complicated!
"Archimedes' principle, principle that states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. The principle applies to both floating and submerged bodies and to all fluids, i.e., liquids and gases. It explains not only the buoyancy of ships and other vessels in water but also the rise of a balloon in the air and the apparent loss of weight of objects underwater. In determining whether a given body will float in a given fluid, both weight and volume must be considered; that is, the relative density, or weight per unit of volume, of the body compared to the fluid determines the buoyant force. If the body is less dense than the fluid, it will float or, in the case of a balloon, it will rise. If the body is denser than the fluid, it will sink. Relative density also determines the proportion of a floating body that will be submerged in a fluid. If the body is two thirds as dense as the fluid, then two thirds of its volume will be submerged, displacing in the process a volume of fluid whose weight is equal to the entire weight of the body. In the case of a submerged body, the apparent weight of the body is equal to its weight in air less the weight of an equal volume of fluid. The fluid most often encountered in applications of Archimedes' principle is water, and the specific gravity of a substance is a convenient measure of its relative density compared to water. In calculating the buoyant force on a body, however, one must also take into account the shape and position of the body. A steel rowboat placed on end into the water will sink because the density of steel is much greater than that of water. However, in its normal, keel-down position, the effective volume of the boat includes all the air inside it, so that its average density is then less than that of water, and as a result it will float." The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.
"Archimedes' principle, principle that states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. The principle applies to both floating and submerged bodies and to all fluids, i.e., liquids and gases. It explains not only the buoyancy of ships and other vessels in water but also the rise of a balloon in the air and the apparent loss of weight of objects underwater. In determining whether a given body will float in a given fluid, both weight and volume must be considered; that is, the relative density, or weight per unit of volume, of the body compared to the fluid determines the buoyant force. If the body is less dense than the fluid, it will float or, in the case of a balloon, it will rise. If the body is denser than the fluid, it will sink. Relative density also determines the proportion of a floating body that will be submerged in a fluid. If the body is two thirds as dense as the fluid, then two thirds of its volume will be submerged, displacing in the process a volume of fluid whose weight is equal to the entire weight of the body. In the case of a submerged body, the apparent weight of the body is equal to its weight in air less the weight of an equal volume of fluid. The fluid most often encountered in applications of Archimedes' principle is water, and the specific gravity of a substance is a convenient measure of its relative density compared to water. In calculating the buoyant force on a body, however, one must also take into account the shape and position of the body. A steel rowboat placed on end into the water will sink because the density of steel is much greater than that of water. However, in its normal, keel-down position, the effective volume of the boat includes all the air inside it, so that its average density is then less than that of water, and as a result it will float." The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.
And his principle applies to
popping the chute to land on Mars! Is that cool or what?! Mars has something like 1/100th of the Earth’s atmosphere and those guys made a parachute work. Of course they were figuring on it opening seven seconds sooner than it did, but @#$% happens. Mars and sailboats, all the same. Wonder if that would hold-up in the 11th dimension? Ah, String Theory.
popping the chute to land on Mars! Is that cool or what?! Mars has something like 1/100th of the Earth’s atmosphere and those guys made a parachute work. Of course they were figuring on it opening seven seconds sooner than it did, but @#$% happens. Mars and sailboats, all the same. Wonder if that would hold-up in the 11th dimension? Ah, String Theory.
an easier method
Park the trailer on a truck scale, move the tow vehicle off, then weigh the boat and trailer. Come back with an empty trailer, repeat the process, then do the math. You can even do dry weight vs. how much stuff the Admiral crams aboard.
Park the trailer on a truck scale, move the tow vehicle off, then weigh the boat and trailer. Come back with an empty trailer, repeat the process, then do the math. You can even do dry weight vs. how much stuff the Admiral crams aboard.
Four Thousand Eight Hundred Pounds
4800 lbs. The ballast is included in that figure. Added gear, equipment, optional equipment, water absorbed into the fiberglass, probably fluids, maybe batteries, and people aboard not included. So, it will be heavier than stated in 'real life'. In other words, the factory 'displacement' is probably light ship, and not the loaded displacement of the vessel. The only way to be sure is to weight it, of talk to someone who has weighed a similar model for an estimate of yours. OC
4800 lbs. The ballast is included in that figure. Added gear, equipment, optional equipment, water absorbed into the fiberglass, probably fluids, maybe batteries, and people aboard not included. So, it will be heavier than stated in 'real life'. In other words, the factory 'displacement' is probably light ship, and not the loaded displacement of the vessel. The only way to be sure is to weight it, of talk to someone who has weighed a similar model for an estimate of yours. OC
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