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Ballast is normally in the keel, but some boats distribute ballast elsewhere.
The displacement figures are normally calculated during the design stage, and are only good for boats in 'as-designed' condition, closest automotive anology is curb weight.
ken
The displacement figures are normally calculated during the design stage, and are only good for boats in 'as-designed' condition, closest automotive anology is curb weight.
ken
Say that in a little simpler language. Why would ballast be distributed?
What is as designed condition?
What is as designed condition?
In modern production boats it usually isn't. With many traditional types, there simply wasn't room in the long shallow keels for the massive amounts needed in heavy boats, even when large cast chunks were incorporated in the keel structure. The result was typically bilges full of lead or iron pigs that had to be hauled out each year, scrubbed and then returned. (An we think waxing is a chore) There was also a belief, the pros and cons of which are too complex to go into here, that boats were more comfortable with a good proportion of their ballast inside and spread well out into the ends. There is no debate though that inside ballast was a major hazard in a roll over and tended to want to keep on going and knock the planks loose in a hard pounding grounding.
Sometimes, a small amount of ballast is put out in the ends of a boat because the other end is low in the water or to correct list. This is known as trimming ballast and could be considered a form of distributed ballast.
What is as designed condition?[/quote]
Designed Condition: What the designer and marketing people hope and claim the boat will weight. Usually with nothing aboard that isn't included in the stripped down base price to make it seem light, fast, and hot in the brochure.
Actually all conditions exist in both designed and actual forms, the first on paper consisting of the above and conditons with calculated amounts of food, stores, fuel, cargo, etc. added. The second in the cold light of careful measurment after construction changes and equipment additions by the marketing guys have taken their toll.
Typical Conditions:
Light Ship: Vessel with all equipment necessary for minimal legal operation aboard, oil and coolant in machinery but no crew, stores, fuel, fresh water, or cargo.
Ready For Sea: Light Ship with everything ommitted above and full tanks.
Half Load: 50% stores and liquids in tanks.
Return: 10% stores and liquids in tanks. Sometimes with 100% Sewage and gray water.
Half Load is usually used for performance predictions. Stability is usually evaluated in each condition. Commercial craft may have many additional conditions calculated for various cargos and deck loadings.
A question concerning sailing cargo ships. Weren't some of them build with minimum fixed ballast and depended on their cargo load for the majority of their ballast? I think that I once read that many of the paving stones found in seaport towns were brought in as ballast and unloaded and replaced with cargo for the return trip.
Ballast Stone
Many of the streets in older cities, Philadelphia, New Orleans, have the streets paved with ballast stone. They were put into the bottom of the empty ships so they would not flip over enroute to puck up their cargo. Ballast, be it permenate or temporary is use to compensate for the upper weight, above the water line, of the ship. When a cargo ship is empty it needs to take on ballast as to prevent it from capsizing. These days the is done by pumping water into its ballast tanks and pumping it side to side to adjust the ships heel.
Displacement is equal to the total weight of a ship, the more you add the more the weight increases and so to the displacement. The term displacement refers to the weight of the volume of water a ship hull replaces when put into the water. If you put a boat into water and it pushed 3000 gallons of water out of its way before it floats, 3000 X 8.34lbs = 25020lbs displacement. Before every one starts, it assumes a given temp and water density, can we not get into that.
Many of the streets in older cities, Philadelphia, New Orleans, have the streets paved with ballast stone. They were put into the bottom of the empty ships so they would not flip over enroute to puck up their cargo. Ballast, be it permenate or temporary is use to compensate for the upper weight, above the water line, of the ship. When a cargo ship is empty it needs to take on ballast as to prevent it from capsizing. These days the is done by pumping water into its ballast tanks and pumping it side to side to adjust the ships heel.
Displacement is equal to the total weight of a ship, the more you add the more the weight increases and so to the displacement. The term displacement refers to the weight of the volume of water a ship hull replaces when put into the water. If you put a boat into water and it pushed 3000 gallons of water out of its way before it floats, 3000 X 8.34lbs = 25020lbs displacement. Before every one starts, it assumes a given temp and water density, can we not get into that.
Re: Ballast Stone
The buildings and roads in Savannah, Ga were made of bricks used as ballast that were unloaded as they loaded the cotton.
The buildings and roads in Savannah, Ga were made of bricks used as ballast that were unloaded as they loaded the cotton.
in simple terms
Displacement is: The actual weight of water moved aside or displaced until the boat floats.
This also happens to be the same as what the boat itself weighs.
Ballast is 1. fixed ballast is how much the keel weights in a modern boat. Ballast can also mean the weight placed in the bilge of a boat. fixed or removable: Lead, cast iron pigs, rocks
water ect:
Displacement is: The actual weight of water moved aside or displaced until the boat floats.
This also happens to be the same as what the boat itself weighs.
Ballast is 1. fixed ballast is how much the keel weights in a modern boat. Ballast can also mean the weight placed in the bilge of a boat. fixed or removable: Lead, cast iron pigs, rocks
water ect:
re: was there a question here?
Yes, Bill, there were actually two... they were just not phrased in "what is...." form.
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