075 LHD thread

[Richard Santos]

Izumo class is far faster than either Wasp or Type 075. To enable this higher speed to be achieved without exorbitant power requirement, Izumo’s hull has to have smaller block coefficient than either Wasp or 075. In other words, the shape of Izumo’s hull must be such that its underwater volume represents a smaller percentage of the volume of a box defined by the length, width and draft of the hull than the hulls of wasp or Type 075.

So Izumo’s 30 knot speed explains why on a similar length, beam and draft as wasp or type 075, it has substantially less displacement.

 

[Intrepid]

Really, shouldn’t it be the top of black stripe?

Anti-fouling paint / underwater hull paints / bottom paints extend slightly above the waterline. If there is a black "water pass" between the red underwater part and the gray hull, the waterline may be somewhere in the middle of this strip.

 

[Tyler]

The curved clipper bow on the type 075 is totally unlike those on any other Chinese warship. It suggest to me this ship’s hull is based merchant design, and not warship standard. Whether that is actually so might be shown once we actually see the underwater hull form around the screws and propellers.

Building amphibious assault ships to merchant standard is not uncommon. For example the Iwo Jima class amphibious assault ships were built to merchant hull design. The British “commando carrier” helicopter assulat ships converted form “light fleet carriers” were somewhat closer to warship standard, but was still designed so yards with only large merchant ship experience can build them.

What is the difference between merchant standard and military standard?

 

[Intrepid]

What is the difference between merchant standard and military standard?

Watertight sections, armour, stability, etc. A hull in military standard has less room available and weights more. It needs longer to be build, needs more resources, needs more powerfull engines, consumpts more fuel and costs more money.

 

[Tyler]

Watertight sections, armour, stability, etc. A hull in military standard has less room available and weights more.

Why would they build a military ship with a lower standard?

 

[Intrepid]

Why would they build a military ship with a lower standard?

They can build more ships in less time to carry more troops. Quite normal for amphibious ships.

 

[proelite]

Why would they build a military ship with a lower standard?

Because the idea is that these ships don't participate in direct conflict like fast attack carrier groups. There is no need troop transports to have the speed nor survivability as a fleet warship.

 

[asif iqbal]

btw I get a length of apporx. 230m for the LHD

bit longer than the 225 previously quoted

this LHD is certainly not 30,000 tons

 

[Blitzo]

The curved clipper bow on the type 075 is totally unlike those on any other Chinese warship. It suggest to me this ship’s hull is based merchant design, and not warship standard. Whether that is actually so might be shown once we actually see the underwater hull form around the screws and propellers.

If by "clipper bow" you're talking about the concave overhanging part of the bow, I think it's reaching quite a bit to interpret that as a sign that the ship is not built to a warship standard and based on a merchant design?
(Also, yes, the bow can be argued to be "unlike those on any other Chinese warship" -- but 075 overall is also a type of warship that is unlike any other previous Chinese warship in general)

US LHDs of the America/Wasp class have a near identical bow geometry, and in fact for most ships with large flight decks extending to the front (including aircraft carriers) the bow geometry is of a clipper design.

To suggest that a clipper bow (or any other sole external design feature, for that matter) is somehow indicative of a warship being a merchant design is a little bit ambitious of a claim to make IMO, unless you are talking about something else.

 

[Iron Man]

What makes the Chinese and US boats displace so much? The Izumo apparently has a beam of 38 meters (vs 32m for Wasp class), length of 248m and draft of 7.5m (8.1m for Wasp) but displaces just 27000t vs 41000t for Wasp. America class (32m beam) without a well deck displaces 46000t.

I count 4 standardish height decks for the Izumo. The 075 looks like it has a 3-deck high well deck and a 2-tall-deck high hangar deck; the well deck and hangar decks are in turn separated by a standard height deck. So a total of 6.5-7 decks total, which is what we could expect from a ship that has both a well deck and a hangar. There is where your displacement difference comes from.

The 075 looks pretty fabulous. RCS discipline is quite a bit higher than for previous PLAN warships, excepting the 055. We can see that (almost) all vertical surfaces are sloped and to the same extent. The bow and a few small platforms and electronics are straight up vertical.

The few small gripes I have with the design is that while the HHQ-10s provide overlapping 360 degree coverage, the 2 Type 1130s do not. There is maybe a 20 degree blind spot for the 1130s at 0-20 degrees starboard bow. This could have been reduced to nearly zero if the rearmost sponsons had been flared out a little bit more. The 2 tall decks used for the 075's hangar may possibly be insufficiently high for a future V/STOL or STOVL fighter, though looking at the elevators this eventuality may never have been intended at all.

Can anyone identify that new (presumably) surface search radar on top of the secondary mast?