Samar class is listed as having 6000 nmi range`and Samarth as 6000 nmi at 12 knots. DN-2000 is listed a 5000nmi at unknown economic speed. You don't need more range for greater 'reach' but you might need it for sustained presence in an area i.e. 'endurance'. Recall the example of the Phillippines that Carlosa gave earlier: if you have to leave before the opponent has to, they might get the area. Also, it is not unheard of that coast guards ships of different nations get physical, so you might need sufficient mass to match some ships. Moving from big a$$ to bigger a$$ ships.
See
http://www.vietnambreakingnews.com/...rejects-chinas-east-sea-wrongful-allegations/
This puppy is 3000 ton.
These are 4000 ton
And vice versa too!
For the Dutch Navy, the Holland class OPV are an economy measure as similarly sized M-frigates are much more expensive to operate and use in anti-piracy (rather than actual warfare) and so all but 2 (of 8) were decommissioned, replaced with 4 OPV's and let go to foreign navies e.g. Belgium (2) , Portugal (2), and Chile (2). The size of the ship has to do with our need to e.g. patrol against drugs in the Caribbian (autonomous overseas parts of our kingdom) and international commitments in support of anti-piracy ops e.g. in the Arabian Sea.
I'd like to point out that the latest chinese coast guard vessel is a 10,000 ton vessel, so the chinese strategy is very clear. They want to be able to muscle out everybody.
That's why Vietnam had to get into the DN-2000 and 4000 vessels. Bigger ship will ram you real bad as was shown during the oil rig episode.
For the Dutch Navy, the Holland class OPV are an economy measure as similarly sized M-frigates are much more expensive to operate and use in anti-piracy (rather than actual warfare) and so all but 2 (of 8) were decommissioned, replaced with 4 OPV's and let go to foreign navies e.g. Belgium (2) , Portugal (2), and Chile (2). The size of the ship has to do with our need to e.g. patrol against drugs in the Caribbian (autonomous overseas parts of our kingdom) and international commitments in support of anti-piracy ops e.g. in the Arabian Sea.
There you go, thank you very much.
You just illustrated my point about why I advocate for what I call a "missile armed OPV" for Vietnam.
As you said, such OPV vessels are much cheaper to buy and operate, which also means that you can have more.
My definition of a "missile armed OPV" is a hybrid between a coast guard vessel and a light warship. It needs to keep all the attributes of a coast guard vessel such as the fast boat for boarding, the water cannons, the search and rescue capabilities, etc coupled to a light sensor and weapons suit, something like what is in the Molniya class.
Example, just imagine a DN-2000 with a modified superstructure to house a 76mm gun, 8 KH-35 missiles, some AK-630s, Sigma-E CMS, etc plus the radars and sensors of the Molniya.
Vietnam pays $90 million for the DN-2000 and I estimate that by adding all these other stuff it would cost $130 million total. See my point? You can have many ships like that and you can build them fast. They are for peacetime duties, patrol and to slog it out with the chinese.
@Penguin has explained it very well. With coast guards it is important to have different classes of vessel to support one another, the large OPVs (>3000 tons) can be "on station" for long periods of time and the smaller classes can support when needed and undertake patrols closer to shore thus creating a comprehensive, layered, patrol arc. The Indian Coast Guard has followed this policy for a long time, why else are they inducting 3,000+ ton OPVs?
Exactly, I would even say that with respect to the chinese, for Vietnam the coast guard is actually even more important than the navy, but need to have both, of course.
When you are playing with the chinese, you are playing the
numbers game and the
size game. Size does matter !!!!