US Navy News and updates

[StobieWan]

Yup. And if folk had perspective - Spruance and OHP all met the same criticism.

Oddly, one of the civilian contractors on board was wearing a Spruance cap, which had me cracked up.

In comparison, one of the Batch 1 Type 22's in the Falklands war actually went to *war* with a contractor on board, and apparently he got to shin up the mast to fix a microswitch more or less in the shooting zone.

Hull comparisons, on space for mission bays and aviation, Indy wins every time. I think in terms of the rest of the ship, Freedom seems to have more room to swing a cat in most areas.

There's definitely bags of room to stuff things into, and that's a significant cause for celebration - all that ASW, MCM stuff, it takes up room, LCS1 and 2 both have space for that, carry on, nothing to see here.

I was very impressed with how easy it was to move stuff around as well - Indy just rolled up, moored alongside, dropped a hatch/ramp and they ran a tractor inside with the heavy parts they wanted. It seemed about as easy as a ferry transfer..

 

[swerve]

Just caught a Disco channel doco on the two LCS ships - while ignoring anything the commentator said I have to say, I was really impressed at the size of the mission bays and hangars on each - Indy in particular is stunning - for a ship of that size, the scale of the aviation facilities is amazing, followed by that enormous mission bay was incredible..

Ship of that size? Independence is 127.4 metres long, with a beam of 31.6 metres. That's 95% of the length of a Type 23, & 195% of the beam.

 

[StobieWan]

Indy displaces just under 2800 tons full. Or you can go with the alternative that, she's nearly as big as a Type 23 and had a pad four times the size. Take your pick I guess.

 

[alexsa]

Ship of that size? Independence is 127.4 metres long, with a beam of 31.6 metres. That's 95% of the length of a Type 23, & 195% of the beam.

But displaces a lot less and has less load capacity (dead weight) for gear. The ships was max out on weight long before they run out of space. This is a critical issue for those suggesting the ship can replace a multi role frigate as each mission package uses up weight.

 

[swerve]

Indy displaces just under 2800 tons full. Or you can go with the alternative that, she's nearly as big as a Type 23 and had a pad four times the size. Take your pick I guess.

Neither. She's bigger than a Type 23 - but lighter. Lots of space (she can fit in lots of light stuff), but as alexsa says, less load capacity (she can't carry as much weight).

I have a 56 lb weight, which I use for holding things down sometimes. It weighs a lot more than my printer - but my printer's bigger, in every dimension. Weight does not equal size.

We often use weight as a proxy for size with ships, because the relationship of size to weight is less variable than for other objects, but we should be aware of its limits.

 

[StobieWan]

But can we agree that for a 2800 ton ship, they have really good aviation facilities and plenty of internal room to store, and work mission relevant kit ?

I'm just used to looking inside non amphibs and barely finding room to swing a cat and there they are driving tractors around inside to get kit moved around - it was impressive and you can see what this module routine is driving at. Obviously, on a multi-purpose frigate that space is going to be permanently full of VLS silos and stuff so there's your margins committed.

 

[db2646]

But can we agree that for a 2800 ton ship, they have really good aviation facilities and plenty of internal room to store, and work mission relevant kit ?

I'm just used to looking inside non amphibs and barely finding room to swing a cat and there they are driving tractors around inside to get kit moved around - it was impressive and you can see what this module routine is driving at. Obviously, on a multi-purpose frigate that space is going to be permanently full of VLS silos and stuff so there's your margins committed.

This question for Alexsa, Swerve and StobieWan: Did you guys take into consideration that the Independence is probably 80% made of Aluminum therefore it is an 2800 ton ship? Would a lighter ship made of Aluminum has a lower weight capacity than for example the Freedom which is made of Alloy Steel? Also, being the Independence is an Trimaran, equating to more space, therefore it would be able to carry more load?

 

[ASSAIL]

This question for Alexsa, Swerve and StobieWan: Did you guys take into consideration that the Independence is probably 80% made of Aluminum therefore it is an 2800 ton ship? Would a lighter ship made of Aluminum has a lower weight capacity than for example the Freedom which is made of Alloy Steel? Also, being the Independence is an Trimaran, equating to more space, therefore it would be able to carry more load?

The capacity to carry "load" equates to weight. Archimedes principle applies to carry weight you must displace water. As LCS 2 has very little wetted surface ie hull in the water, it's capacity to displace water is limited therefor it can't carry weight.
As any mariner who has operated tri hulls or cats knows, their freeboard disappears very quickly when you load them compared with a conventional ship, meaning they start to settle at an alarming rate
All that empty space is good for the sort of bulky but light modules they were designed to operate with.

 

[justsomeaussie]

Isn't this their similar design?

http://www.austal.com/Resources/Del...1-22e4-6f5b0532faca/austal-trimaran-270-1.pdf

That's still some pretty impressive capacity and this is 100m not 125 of the LCS.

 

[ASSAIL]

Isn't this their similar design?

http://www.austal.com/Resources/Del...1-22e4-6f5b0532faca/austal-trimaran-270-1.pdf

That's still some pretty impressive capacity and this is 100m not 125 of the LCS.

620 deadweight tons is not impressive for a conventional ship of those dimensions. Take out fuel and water and your left with only about 450 tons of cargo!
I have been Master of a 42 mtr pearling vessel with max DWT of 300T

 

[db2646]

The capacity to carry "load" equates to weight. Archimedes principle applies to carry weight you must displace water. As LCS 2 has very little wetted surface ie hull in the water, it's capacity to displace water is limited therefor it can't carry weight.
As any mariner who has operated tri hulls or cats knows, their freeboard disappears very quickly when you load them compared with a conventional ship, meaning they start to settle at an alarming rate
All that empty space is good for the sort of bulky but light modules they were designed to operate with.

I am not a marine engineer but I understand the Archimedes principle also. This is counterintuitive; if the Independence is made of steel and weighed more, then it displaces more water and therefore able to carry more load? Then the advantage of building the ship with lighter materials is lost or a disadvantage?

I read this somewhere, General Dynamics stated that they can fit any armament the US Navy would like into the Independence, i.e., bigger gun, VLS, Harpoon, etc. meaning the ship is capable of carrying more weight than is actually specified? There must be a factor of safety (what I call factor of ignorance) applied in the design of the ship as far as total load capacity? Perhaps 10 to 15 percent?

 

[StobieWan]

I read this somewhere, General Dynamics stated that they can fit any armament the US Navy would like into the Independence, i.e., bigger gun, VLS, Harpoon, etc. meaning the ship is capable of carrying more weight than is actually specified? There must be a factor of safety (what I call factor of ignorance) applied in the design of the ship as far as total load capacity? Perhaps 10 to 15 percent?

The quote is in this thread and there's one further line that's relevant:

""We can make a ship that looks and fights just like any other cruiser out there, but is that the right path? If we hand over all the available margin on LCS to legacy weapons … do we risk losing the opportunity to exploit the changes that are coming in the war at sea?""

Basically, add all that stuff in there and your margins go away, eaten up by the extra kit permanently embarked. You couldn't then start shovelling mission modules on board or the ship would quickly become unworkable or actively dangerous. They're talking about the existing margins.

 

[ASSAIL]

I am not a marine engineer but I understand the Archimedes principle also. This is counterintuitive; if the Independence is made of steel and weighed more, then it displaces more water and therefore able to carry more load? Then the advantage of building the ship with lighter materials is lost or a disadvantage?

I read this somewhere, General Dynamics stated that they can fit any armament the US Navy would like into the Independence, i.e., bigger gun, VLS, Harpoon, etc. meaning the ship is capable of carrying more weight than is actually specified? There must be a factor of safety (what I call factor of ignorance) applied in the design of the ship as far as total load capacity? Perhaps 10 to 15 percent?

Yes of course extra and heavier weapons can be fitted but the weight limit is finite and the heavier the weapon load the less reserve buoancy available for other loads.

Having stated this, the modules designed to be fitted in Indy are not heavy (relatively) and the extra weapons would not compromise her role but take note of Stobie's answer above.

 

[justsomeaussie]

I read this somewhere, General Dynamics stated that they can fit any armament the US Navy would like into the Independence, i.e., bigger gun, VLS, Harpoon, etc. meaning the ship is capable of carrying more weight than is actually specified? There must be a factor of safety (what I call factor of ignorance) applied in the design of the ship as far as total load capacity? Perhaps 10 to 15 percent?

Except they can't upgrade the 57mm on the bow as a 76mm wouldn't fit vertically.

There is a mission module space directly behind the 57 though.

Is it all a moot point about weight though? As operationally they won't be required to be moving anything too dramatic like Abrams around. Too many mission modules over weighing it doesn't seem possible.

 

[db2646]

Yes of course extra and heavier weapons can be fitted but the weight limit is finite and the heavier the weapon load the less reserve buoancy available for other loads.

Having stated this, the modules designed to be fitted in Indy are not heavy (relatively) and the extra weapons would not compromise her role but take note of Stobie's answer above.

Yes, I understood what Stovie's response. However, nobody has responded relative to whether the Independence being made of steel and therefore will weigh more gives it the capacity to carry more load against what it is made currently of aluminum? There is something missing in this equation that I can't find the answer?
Lighter material would then be a disadvantage? I would think it is NOT in aircraft or vehicle designs? Please respond. Thanks.

 

[StobieWan]

Assuming your wetted surface area (the bit of the boat that's in the water and available to push down on) stays constant, then making the structure of the boat of heavier materials simply takes up more of the load carrying capacity of the ship.

For instance, grab a bucket made of plastic and try and push it into the water - that force you have to apply to immerse the bucket is proportional to the displacement of the bucket - ie, how much water you have to push out of the way.If you make the bucket out of steel, it's heavier and will be easier to push down into the water - but will displace the same amount of water, assuming the bucket is the same (and has the same wetted area as a result) As a result, your load carrying capacity just went *down*.

That's my school boy "ugh, grunt..me do physics today" understanding of it. Otherwise, you'd have this displacement equivalent of perpetual motion.

 

[db2646]

Assuming your wetted surface area (the bit of the boat that's in the water and available to push down on) stays constant, then making the structure of the boat of heavier materials simply takes up more of the load carrying capacity of the ship.

For instance, grab a bucket made of plastic and try and push it into the water - that force you have to apply to immerse the bucket is proportional to the displacement of the bucket - ie, how much water you have to push out of the way.If you make the bucket out of steel, it's heavier and will be easier to push down into the water - but will displace the same amount of water, assuming the bucket is the same (and has the same wetted area as a result) As a result, your load carrying capacity just went *down*.

That's my school boy "ugh, grunt..me do physics today" understanding of it. Otherwise, you'd have this displacement equivalent of perpetual motion.

Stobie, I appreciate your good effort and explanation. However, I still believe that General Dynamics found a way to increase the effective load carrying capacity of the Independence with the trimaran hull design. Again I am not a marine engineer or architect or I'm not privy to the detailed design of the ship. However, I would like to offer what I think about what we're discussiong. The Archimedes theory still applies based on direct correlation between weight and displacement, and in addition to the surface area of the ship in contact with the water must also be considered in the equation. The Independence has a big/large contact area with water, and as long as the relative center of gravity is maintain in relation with the load, I think bouyancy is maintained and the ship is able to carry considerable amount of load greater than its dead weight?

 

[RobWilliams]

Wouldn't hurt to bring forward some evidence to prove you ARE right either, if you believe you are right then throw down the "technical and numerical data/evidence" to prove it.

By expecting Stobie to show you the evidence, it's entirely within your capacity to bring forward that same data (or at least technical enough) to prove your point, so get to it.

You've got your opinions, now back them up with the sort of data with the similar level of detail you believe you'd need to change that is basically what I want.

 

[db2646]

Wouldn't hurt to bring forward some evidence to prove you ARE right either, if you believe you are right then throw down the "technical and numerical data/evidence" to prove it.

By expecting Stobie to show you the evidence, it's entirely within your capacity to bring forward that same data (or at least technical enough) to prove your point, so get to it.

You've got your opinions, now back them up, that's basically what I want.

Sorry, I didn't mean entirely for Stobie to prove me wrong. Since it is only my theory, I retract for any evidence to be submitted to prove me wrong and updated my previous post. I can't otherwise provide the data myself since I am not an ship designer or privy on the ship's design. Only an theory that General Dynamics may have found a way to increase the load capacity of the ship not just mainly based on weight, reason why their statement about being able to add bigger gun, VLS, etc., per whatever the USN wants.

 

[StobieWan]

However, I would like to offer what I think about what we're discussiong. The Archimedes theory still applies based on direct correlation between weight and displacement, and in addition to the surface area of the ship in contact with the water must also be considered in the equation. The Independence has a big/large contact area with water, and as long as the relative center of gravity is maintain in relation with the load, I think bouyancy is maintained and the ship is able to carry considerable amount of load greater than its dead weight?

Nope - Indy's a trimaran and Assail pointed out, trimarans have a relatively low wetted surface area -- thats the "surface area of the ship in contact with the water".


Trimarans and catamarans go pretty quick because they're not sticking a lot of metal in the water in proportion to the amount of metal they're made of (I'm flinging technical terms around here like crazy, bear with..)


Take a sheet of metal , batter it into a bowl shape, push down on it, it pushes back quite a bit. Ditto, try and drag it through the water, it presents a lot of resistance.

A trimaran has a narrow hull and a pair of fairly narrow outriggers - look at a fully displacing monohull - there's a lot more in the water in relation to the displacement of the hull - a wider front. More resistance in the water and this is why they're driven more by the speed/length rule - trying to get a fully displacing monohull up to 44 knots in anything like a normal set of dimensions and you'd need to shove the sort of power plant the Ford has inside it.

Coming back to Indy, that low wetted surface area also presents less resistance to being pushed down by the load it's carrying. The two (high speed and low DWT figures) are the two sides of the coin.

In direct reply to your question about exceeding dead weight tonnage, DWT is what it is - there's no question of exceeding it by some fudging. Go past the max DWT figure and the thing will either ride dangerously low in the water or become a submersible.

Again, I see from your earlier post you're referring to the contractors claiming they can add extra stuff. I already covered that by highlighting the quote you left off..that doing so eats into the margins available. There's nothing magical about that.

What the quote was actually about was trying to get across the point that the two LCS are what they are - they're intended to provide space to store and operate mission module kit, not fart around being a mini-burke.