Challenge 53 MT: Wet Navy Part 1 Help needed

[snrdg082102]

Morning all,

I have Challenge (C) 53, pp. 16-25, which has the first part of three articles for designing water borne vessels called "Wet Navy," for MT. After reading through the article I set about to automate the process by using a spreadsheet. The first phase, which has 10 steps, determines the fluid displacement of a standard hull from MT: Referee's Manual (MT: RM) p. 62. Steps 1 through 7 went smoothly, unfortunately Steps 8 to 10 confused me when I tried to create a message indicating if the hull floats or sinks in the selected fluid. From the article:

Summarized Units used by Ship Design sequence found in C 53 p. 18

UCP Displacement tons (dtons): 1 dton of hydrogen = 13.5 kiloliters or 13.5 m^3
Metric ton of displacement (mton): 1 mton of water = 1 kiloliter or 1 m^3 = 1 mton of mass
Kiloliter is the standard measure of volume. 1 kiloliter = 1 m^3 of volume 1 kiloliter of water = 1 mton, 13.5 kiloliters of hydrogen = 1 metric ton = 1 UCP displacement ton of volume.

I am using the following as my test for creating the spreadsheet:

Step 1. Select hull size (MT: RM p. 62) and hull material (C 53, p. 19 Hull Materials Table):
UCP - 60; Volume - 810, Weight - 31.6, Price - 84.20
Material - Lightweight Composite laminate, Hardness - Mod. 1, Weight Mod. - 0.35, Price Mod. - 1.6

Step 2. Decide hull thickness, minimum of 0.25 cm:
Thickness - 1 cm

Step 3. Calculate "true" hull weight = (Basic Hull weight) x (weight mod.) x (hull thickness in cm)
Basic Hull weight from Weight in Step 1 = 31.6
Material Weight Mod. from Weight Mod. Step 1 = 0.35
Hull thickness Step 2 = 1 cm.

True Hull Weight = 31.6 x 0.35 x 1 = 11.06

Step 4. Calculate hull's armor value: (Material hardness mod) x (hull thickness in cm) = Armor Mod
Material hardness mod from Step 1 = 1
Hull thickness Step 2 = 1 cm.
Armor Mod: 1 x 1 = 1

From MT: RM Step 9 Armor Protection Table: Column 2 Mod, p. 63, lookup calculated armor mod 1 = Armor Factor 4.

Steps 5/6. Calculate Inoperative/Destroyed Damage values by using volume from MT: RM Small Craft Hull Table, p. 62 or Step 1.
Inoperative Damage = Volume/15 = 810/15 = 54
Destroyed Damage = Volume/6 = 810/6 = 135

Step 7. Determine hull type from Hull Type table (C 53, p. 19 Hull Type Table)
Type: Surfaced Submarine, Resistance - 1, "% of Hull Displacing Fluid" - 90%, Price Mod - 2

Here is where my confusion starts:

Step 8. "Multiply the hull's UCP displacement tonnage (dtons) by the "% of Hull Displacing Fluid" figure for the selected hull type. This yields the tonnage of hull that displaces fluid and the tonnage of fluid displaced." UCP dtons x "% of Hull Displacing Fluid" (% HDF)
UCP dtons from Step 1 = 60
% HDF from table in C 53, p. 19 or Step 7 = 90%

60 x 90% = 54 dtons

If I understand Step 8 correctly the submarine hull displaces 54 dtons of fluid.

Now I get totally confused.

Step 9. "Multiply the UCP tonnage of the displaced fluid by 13.5, then multiply the result by the appropriate modifier from the Fluid Density Table below. This yields the weight of the fluid the vessel displaces. If the displaced fluid's weight is greater than the vessel's weight the vessel floats; if it is less, the vessel sinks."
Displaced Fluid Weight (DFW) = Displaced fluid tons (DFT) x 13.5 x Density Multiplier (DeMod)
DFT= 54 from Step 9
DeMod for Sea water = 1 from Fluid Density table C 53 p. 20

DFW = 54 x 13.5 x 1 = 729

Isn't the calculated figure of 729 the volume in kiloliters?

Which vessel weight is compared the Displaced fluid weight? Base weight = 31.6 (MT: RM p. 62) or True Weight = 11.06 from Step 3.

If DFW is measured in mtons then the Displaced fluid weight of 729 mtons is greater than either of the hull weights 31.6/11.06 mtons the vessel floats.
If DFW is measured in kiloliters and the base weight is used 31.6 mtons = 810 kiloliters the vessel sinks.
If DFW is measured in kiloliters and the "True weight," from Step 3, is 11.06 mtons = 149.31 kiloliters the vessel floats.

Step 10. "Compare the weight of the hull with the weight of the displaced fluid. If the fluid weighs more, the vessel will float; if the vessel weighs more, it will sink. In that case build a bigger hull or choose a lighter hull material."

Step 10 is basically a repeat of Step 9.

Can someone, perhaps kaladorn, get me straightened out?

 

[snrdg082102]

Morning all,

I have Challenge (C) 53, pp. 16-25, which has the first part of three articles for designing water borne vessels called "Wet Navy," for MT. After reading through the article I set about to automate the process by using a spreadsheet. The first phase, which has 10 steps, determines the fluid displacement of a standard hull from MT: Referee's Manual (MT: RM) p. 62. Steps 1 through 7 went smoothly, unfortunately Steps 8 to 10 confused me when I tried to create a message indicating if the hull floats or sinks in the selected fluid. From the article:

Summarized Units used by Ship Design sequence found in C 53 p. 18

UCP Displacement tons (dtons): 1 dton of hydrogen = 13.5 kiloliters or 13.5 m^3
Metric ton of displacement (mton): 1 mton of water = 1 kiloliter or 1 m^3 = 1 mton of mass
Kiloliter is the standard measure of volume. 1 kiloliter = 1 m^3 of volume 1 kiloliter of water = 1 mton, 13.5 kiloliters of hydrogen = 1 metric ton = 1 UCP displacement ton of volume.

I am using the following as my test for creating the spreadsheet:

Step 1. Select hull size (MT: RM p. 62) and hull material (C 53, p. 19 Hull Materials Table):
UCP - 60; Volume - 810, Weight - 31.6, Price - 84.20
Material - Lightweight Composite laminate, Hardness - Mod. 1, Weight Mod. - 0.35, Price Mod. - 1.6

Step 2. Decide hull thickness, minimum of 0.25 cm:
Thickness - 1 cm

Step 3. Calculate "true" hull weight = (Basic Hull weight) x (weight mod.) x (hull thickness in cm)
Basic Hull weight from Weight in Step 1 = 31.6
Material Weight Mod. from Weight Mod. Step 1 = 0.35
Hull thickness Step 2 = 1 cm.

True Hull Weight = 31.6 x 0.35 x 1 = 11.06

Step 4. Calculate hull's armor value: (Material hardness mod) x (hull thickness in cm) = Armor Mod
Material hardness mod from Step 1 = 1
Hull thickness Step 2 = 1 cm.
Armor Mod: 1 x 1 = 1

From MT: RM Step 9 Armor Protection Table: Column 2 Mod, p. 63, lookup calculated armor mod 1 = Armor Factor 4.

Steps 5/6. Calculate Inoperative/Destroyed Damage values by using volume from MT: RM Small Craft Hull Table, p. 62 or Step 1.
Inoperative Damage = Volume/15 = 810/15 = 54
Destroyed Damage = Volume/6 = 810/6 = 135

Step 7. Determine hull type from Hull Type table (C 53, p. 19 Hull Type Table)
Type: Surfaced Submarine, Resistance - 1, "% of Hull Displacing Fluid" - 90%, Price Mod - 2

Here is where my confusion starts:

Step 8. "Multiply the hull's UCP displacement tonnage (dtons) by the "% of Hull Displacing Fluid" figure for the selected hull type. This yields the tonnage of hull that displaces fluid and the tonnage of fluid displaced." UCP dtons x "% of Hull Displacing Fluid" (% HDF)
UCP dtons from Step 1 = 60
% HDF from table in C 53, p. 19 or Step 7 = 90%

60 x 90% = 54 dtons

If I understand Step 8 correctly the submarine hull displaces 54 dtons of fluid.

Now I get totally confused.

Step 9. "Multiply the UCP tonnage of the displaced fluid by 13.5, then multiply the result by the appropriate modifier from the Fluid Density Table below. This yields the weight of the fluid the vessel displaces. If the displaced fluid's weight is greater than the vessel's weight the vessel floats; if it is less, the vessel sinks."
Displaced Fluid Weight (DFW) = Displaced fluid tons (DFT) x 13.5 x Density Multiplier (DeMod)
DFT= 54 from Step 9
DeMod for Sea water = 1 from Fluid Density table C 53 p. 20

DFW = 54 x 13.5 x 1 = 729

Isn't the calculated figure of 729 the volume in kiloliters?

Which vessel weight is compared the Displaced fluid weight? Base weight = 31.6 (MT: RM p. 62) or True Weight = 11.06 from Step 3.

If DFW is measured in mtons then the Displaced fluid weight of 729 mtons is greater than either of the hull weights 31.6/11.06 mtons the vessel floats.
If DFW is measured in kiloliters and the base weight is used 31.6 mtons = 810 kiloliters the vessel sinks.
If DFW is measured in kiloliters and the "True weight," from Step 3, is 11.06 mtons = 149.31 kiloliters the vessel floats.

Step 10. "Compare the weight of the hull with the weight of the displaced fluid. If the fluid weighs more, the vessel will float; if the vessel weighs more, it will sink. In that case build a bigger hull or choose a lighter hull material."

Step 10 is basically a repeat of Step 9.

Can someone, perhaps kaladorn, get me straightened out?

 

[snrdg082102]

Morning all,

I have Challenge (C) 53, pp. 16-25, which has the first part of three articles for designing water borne vessels called "Wet Navy," for MT. After reading through the article I set about to automate the process by using a spreadsheet. The first phase, which has 10 steps, determines the fluid displacement of a standard hull from MT: Referee's Manual (MT: RM) p. 62. Steps 1 through 7 went smoothly, unfortunately Steps 8 to 10 confused me when I tried to create a message indicating if the hull floats or sinks in the selected fluid. From the article:

Summarized Units used by Ship Design sequence found in C 53 p. 18

UCP Displacement tons (dtons): 1 dton of hydrogen = 13.5 kiloliters or 13.5 m^3
Metric ton of displacement (mton): 1 mton of water = 1 kiloliter or 1 m^3 = 1 mton of mass
Kiloliter is the standard measure of volume. 1 kiloliter = 1 m^3 of volume 1 kiloliter of water = 1 mton, 13.5 kiloliters of hydrogen = 1 metric ton = 1 UCP displacement ton of volume.

I am using the following as my test for creating the spreadsheet:

Step 1. Select hull size (MT: RM p. 62) and hull material (C 53, p. 19 Hull Materials Table):
UCP - 60; Volume - 810, Weight - 31.6, Price - 84.20
Material - Lightweight Composite laminate, Hardness - Mod. 1, Weight Mod. - 0.35, Price Mod. - 1.6

Step 2. Decide hull thickness, minimum of 0.25 cm:
Thickness - 1 cm

Step 3. Calculate "true" hull weight = (Basic Hull weight) x (weight mod.) x (hull thickness in cm)
Basic Hull weight from Weight in Step 1 = 31.6
Material Weight Mod. from Weight Mod. Step 1 = 0.35
Hull thickness Step 2 = 1 cm.

True Hull Weight = 31.6 x 0.35 x 1 = 11.06

Step 4. Calculate hull's armor value: (Material hardness mod) x (hull thickness in cm) = Armor Mod
Material hardness mod from Step 1 = 1
Hull thickness Step 2 = 1 cm.
Armor Mod: 1 x 1 = 1

From MT: RM Step 9 Armor Protection Table: Column 2 Mod, p. 63, lookup calculated armor mod 1 = Armor Factor 4.

Steps 5/6. Calculate Inoperative/Destroyed Damage values by using volume from MT: RM Small Craft Hull Table, p. 62 or Step 1.
Inoperative Damage = Volume/15 = 810/15 = 54
Destroyed Damage = Volume/6 = 810/6 = 135

Step 7. Determine hull type from Hull Type table (C 53, p. 19 Hull Type Table)
Type: Surfaced Submarine, Resistance - 1, "% of Hull Displacing Fluid" - 90%, Price Mod - 2

Here is where my confusion starts:

Step 8. "Multiply the hull's UCP displacement tonnage (dtons) by the "% of Hull Displacing Fluid" figure for the selected hull type. This yields the tonnage of hull that displaces fluid and the tonnage of fluid displaced." UCP dtons x "% of Hull Displacing Fluid" (% HDF)
UCP dtons from Step 1 = 60
% HDF from table in C 53, p. 19 or Step 7 = 90%

60 x 90% = 54 dtons

If I understand Step 8 correctly the submarine hull displaces 54 dtons of fluid.

Now I get totally confused.

Step 9. "Multiply the UCP tonnage of the displaced fluid by 13.5, then multiply the result by the appropriate modifier from the Fluid Density Table below. This yields the weight of the fluid the vessel displaces. If the displaced fluid's weight is greater than the vessel's weight the vessel floats; if it is less, the vessel sinks."
Displaced Fluid Weight (DFW) = Displaced fluid tons (DFT) x 13.5 x Density Multiplier (DeMod)
DFT= 54 from Step 9
DeMod for Sea water = 1 from Fluid Density table C 53 p. 20

DFW = 54 x 13.5 x 1 = 729

Isn't the calculated figure of 729 the volume in kiloliters?

Which vessel weight is compared the Displaced fluid weight? Base weight = 31.6 (MT: RM p. 62) or True Weight = 11.06 from Step 3.

If DFW is measured in mtons then the Displaced fluid weight of 729 mtons is greater than either of the hull weights 31.6/11.06 mtons the vessel floats.
If DFW is measured in kiloliters and the base weight is used 31.6 mtons = 810 kiloliters the vessel sinks.
If DFW is measured in kiloliters and the "True weight," from Step 3, is 11.06 mtons = 149.31 kiloliters the vessel floats.

Step 10. "Compare the weight of the hull with the weight of the displaced fluid. If the fluid weighs more, the vessel will float; if the vessel weighs more, it will sink. In that case build a bigger hull or choose a lighter hull material."

Step 10 is basically a repeat of Step 9.

Can someone, perhaps kaladorn, get me straightened out?

 

[kaladorn]

I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[kaladorn]

I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[kaladorn]

I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[snrdg082102]

Evening kaladorn

Thanks for the prompt reply and the non-mathematical explanation, which does help some. However, I am having difficulty in understanding how Steps 8 and 9 work mathematically. No hurry, when you have the time will be soon enough. Again, thanks for the reply.

Originally posted by kaladorn:
I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[snrdg082102]

Evening kaladorn

Thanks for the prompt reply and the non-mathematical explanation, which does help some. However, I am having difficulty in understanding how Steps 8 and 9 work mathematically. No hurry, when you have the time will be soon enough. Again, thanks for the reply.

Originally posted by kaladorn:
I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[snrdg082102]

Evening kaladorn

Thanks for the prompt reply and the non-mathematical explanation, which does help some. However, I am having difficulty in understanding how Steps 8 and 9 work mathematically. No hurry, when you have the time will be soon enough. Again, thanks for the reply.

Originally posted by kaladorn:
I don't have time for a full persusal right now, but here is what it boils down to:

A ship has a mass. Think of this as the real weight
in kilograms, even though weight really implies a particular value of gravity...

A ship has a volume. This is l x w x h (more or less) and is how much internal space the ship has in cubic meters. We translate this into kiloliters, but I don't recall if a liter is defined as being related to water (I thought a liter was 1 kg of water... but that seems very imprecise given various water densities so there is probably another definition that is more precise and non-liquid dependent). But at any rate, ship's volume should be a fixed amount.

A ship has a displacement. Displacement is 'relative to a given fluid'. Normally, in nautical terms, this is water. In traveller ship design, this tends to be liquid hydrogen. LH displaces 13.5 kiloliters (which I think is also 13.5 cubic meters) per ton. Water has a different rate (which is probably what the density table refers to).

So, something which displaces (in a Traveller ship design sense) X kiloliters will displace Y kiloliters in another liquid, where Y bears a relationship to X based on the density of Y compared to the density of X. Put more simply, something that will float on liquid parafin may well sink in normal water. Displacement assumes full immersion, but the mass of material you displace (though a particular hull shape l x w x h will displace some set amount of cubic meters) in varying mediums will have varying weights, hence you have a varying displacement (in each medium, since the displacement measures the *mass* of displaced material by your ship's volume).

And then we come to bouyancy. An object is neutrally bouyant (won't ascend or descend) if its volume displaces an equal mass of fluid as its own mass. If its volume displaces less of a mass of fluid than its own mass, it sinks (negatively bouyant). If its volume displaces more of a mass of fluid than its own mass, it rises (positively bouyant)

So, what you end up doing is probably:
1. Figure out the ship's weight (mass)
2. Figure out the ship's volume
3. Figure out the ship's displacement (from the volume) in tons of liquid L.
4. Knowing how much L you've displaced (in tons), and knowing your own mass (from 1), determine if you are positively, neutrally, or negatively bouyant.

I don't know if this helps, but I'll take a more detailed look later if you remind me (you know where I live in e-space...).

Tomb

 

[TheDS]

I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[TheDS]

I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[TheDS]

I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[snrdg082102]

Evening (PDT) TheDS,

Thank-you for your assistance. One thing I forgot to mention is that I do understand positive, neutral, and negative buoyancy since most of my 20-years in the USN was spent in the submarine service. Even with your and kaladorn's assistance, I still am not sure what the value of 729 is being compared to. Is the value being compared with the weight derived from MT: Referee's Manual Small Craft Hull or the True Weight calculated in Step 3 of the article in Challenge 53?

Sorry to be so dense

on the matter, but thank-you again for the assistance.

Originally posted by TheDS:
I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[snrdg082102]

Evening (PDT) TheDS,

Thank-you for your assistance. One thing I forgot to mention is that I do understand positive, neutral, and negative buoyancy since most of my 20-years in the USN was spent in the submarine service. Even with your and kaladorn's assistance, I still am not sure what the value of 729 is being compared to. Is the value being compared with the weight derived from MT: Referee's Manual Small Craft Hull or the True Weight calculated in Step 3 of the article in Challenge 53?

Sorry to be so dense

on the matter, but thank-you again for the assistance.

Originally posted by TheDS:
I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[snrdg082102]

Evening (PDT) TheDS,

Thank-you for your assistance. One thing I forgot to mention is that I do understand positive, neutral, and negative buoyancy since most of my 20-years in the USN was spent in the submarine service. Even with your and kaladorn's assistance, I still am not sure what the value of 729 is being compared to. Is the value being compared with the weight derived from MT: Referee's Manual Small Craft Hull or the True Weight calculated in Step 3 of the article in Challenge 53?

Sorry to be so dense

on the matter, but thank-you again for the assistance.

Originally posted by TheDS:
I remember reading that when it came out... Couldn't make much of it then, and can make even less of it now. Here's what it is probably trying to say:

The definition of whether or not something floats is if its weight is less than that of the water it displaces. Put another way, an object must be less-dense than what you want it to float on.

When you see "displacement" for a naval vessel, this refers to the weight of the water, in tons, that it is displacing. This is a MASS, not a VOLUME. Traveller introduced the idea of the Displacement Ton, and set its value equal to 13.5 kl, which is its true value. (Later editions have rounded this to 14.) It is a volume, and not a mass. (btw, 1 kl = 1 cubic meter, and 1 liter = 1 cubic decimeters, and 1 ml = 1 cubic centimeter.)

The %HDF figure of 90% is intended to tell you that the sub's overall density must be .9. (Water is 1.) Your sub will have ballast tanks, and when those tanks are empty, you should be at about .9. When they are full, your density should be at about 1, perhaps slightly over or under.

So you must figure out the volume of your craft, in kl. This will also be the weight of the water you will displace when fully submerged, in tons. The sub itself, however, should weigh 90% of that, so that it floats when surfaced.

With Traveller dealing so much in Displacement tons, they had to make sure you multiplied by 13.5 to get kl, and by extension, tons.

 

[kaladorn]

Okay, I think I've got it.

You're staring with a 60 dTon hull.
It's nominal weight is 31.6 tons.
But, made out of fancy laminates, 0.35 times that.
A standard 1 cm hull thickness doesn't change anything.
So you have a hull weight of just over 11 tons.
That hull weight wraps a space that would (normally) be 100% of 13.5 meters cubed per dTon, or 810 kl. Because it is a sub, 10% is actually ballast tanks which can be water filled, so you count 90% of that. Which means 729 kl. That displaces (assuming the only slightly bogus rating of) 1 metric ton per kiloliter for seawater. So that means it displaces 729 metric tons worth of water.

So, we have an 11 ton object displacing 729 tons of water. Methinks it floats.

Note, I wouldn't have actually used the 11 ton weight though, myself, because that only includes hull weight. Once you populate it with combat systems, a power plant, a propulsions system, crew quarters, etc, it ought to be one *heck* of a lot heavier than 11 tons. Still probably won't reach 729 tons, so it'll probably still float. But just using the hull weight is a bit dubious.

That clear things up at all?

 

[kaladorn]

Okay, I think I've got it.

You're staring with a 60 dTon hull.
It's nominal weight is 31.6 tons.
But, made out of fancy laminates, 0.35 times that.
A standard 1 cm hull thickness doesn't change anything.
So you have a hull weight of just over 11 tons.
That hull weight wraps a space that would (normally) be 100% of 13.5 meters cubed per dTon, or 810 kl. Because it is a sub, 10% is actually ballast tanks which can be water filled, so you count 90% of that. Which means 729 kl. That displaces (assuming the only slightly bogus rating of) 1 metric ton per kiloliter for seawater. So that means it displaces 729 metric tons worth of water.

So, we have an 11 ton object displacing 729 tons of water. Methinks it floats.

Note, I wouldn't have actually used the 11 ton weight though, myself, because that only includes hull weight. Once you populate it with combat systems, a power plant, a propulsions system, crew quarters, etc, it ought to be one *heck* of a lot heavier than 11 tons. Still probably won't reach 729 tons, so it'll probably still float. But just using the hull weight is a bit dubious.

That clear things up at all?

 

[kaladorn]

Okay, I think I've got it.

You're staring with a 60 dTon hull.
It's nominal weight is 31.6 tons.
But, made out of fancy laminates, 0.35 times that.
A standard 1 cm hull thickness doesn't change anything.
So you have a hull weight of just over 11 tons.
That hull weight wraps a space that would (normally) be 100% of 13.5 meters cubed per dTon, or 810 kl. Because it is a sub, 10% is actually ballast tanks which can be water filled, so you count 90% of that. Which means 729 kl. That displaces (assuming the only slightly bogus rating of) 1 metric ton per kiloliter for seawater. So that means it displaces 729 metric tons worth of water.

So, we have an 11 ton object displacing 729 tons of water. Methinks it floats.

Note, I wouldn't have actually used the 11 ton weight though, myself, because that only includes hull weight. Once you populate it with combat systems, a power plant, a propulsions system, crew quarters, etc, it ought to be one *heck* of a lot heavier than 11 tons. Still probably won't reach 729 tons, so it'll probably still float. But just using the hull weight is a bit dubious.

That clear things up at all?

 

[kaladorn]

Originally posted by Thomas Rux:
in the spreadsheet. Again thanks to both of you for your assistance to this slightly dim witted broken down old submarine sailor.

I can do a bit of math, a bit of computer stuff, and even a bit of surface sailing (taking Coastal Nav course right now). But I have a lot of respect for the Silent Service. That takes something I don't know if I have... but I know that I respect.

Any more questions, you know where to find me.

 

[kaladorn]

Originally posted by Thomas Rux:
in the spreadsheet. Again thanks to both of you for your assistance to this slightly dim witted broken down old submarine sailor.

I can do a bit of math, a bit of computer stuff, and even a bit of surface sailing (taking Coastal Nav course right now). But I have a lot of respect for the Silent Service. That takes something I don't know if I have... but I know that I respect.

Any more questions, you know where to find me.