I have personal experience of the surge in Timaru when I was tied up alongside there on Kiwi many times. Definitely couldn't use the current port facilities, but there is room to the south of the port for expansion. Would involve the building of another breakwater with armour rock, along with a second mole. If that second mole was extended further out than the current one it could with proper engineering slow down or even halt the aggradation of Caroline Bay and prevent sediment deposition within the current shipping channel. If the naval facility was moved further south, say about level with the South Timaru cemetery, and the breakwater and mole built there, then a second sandy beach, a la Caroline Bay would be formed between the naval facility and the current port. The problem would be taking the mole far enough seaward and engineering it and the seafloor around it to ensure that the change in sediment flow didn't cause sediment deposition in the current shipping channel. There's a large gravel sediment stream that flows north from the Waitaki and other rivers towards Banks Peninsula that's just offshore of Timaru. Naval accommodation could be at the mooted air base.
I seriously considered Lyttelton but reached the conclusion that there is no room there for expansion for a naval base. All of the inner harbour is taken up now, mostly by the Port Company; they only other deep water is either along by the coal export terminal and it's mostly sheer cliff; or across at Diamond Harbour and again no flat land for development. The reason why Timaru was my choice apart from that, was it's proximity to army facilities and as such any amphib vessels / logistics vessels are reasonably close to army facilities. That's why I ruled out Dunedin.
I do consider a necessity that we have at least one ship permanently assigned to a South Pacific location. The recent IPV deployments to Fiji were a success and I think that they should be built on. That's where I believe something like the VARD 7-100-OPV, VARD 7-110-OPV or VARD 7-125-OPV would be ideal and in reality it would have to be more than one ship. An aircraft would need to be permanently based as well and not necessarily a P-8A but a long range aircraft with maritime ISR capability. The crews could be swapped out, leaving the platforms there.
We do have to face the fact that DNB will at some stage be forced out of Auckland because the land it occupies is just to valuable and all those Devonport luvvies and Northshore yuppies will be wanting to get their hands on the land for the views etc. Unbeknownst to them Ngati Whatua have first right of refusal on the land.
The west coast of both islands is out because of the prevailing westerly winds and seas along with prevalence of bars into west coast rivers, inlets and ports, apart from the fiords in the south.The Marlborough Sounds and in particular the head of Queen Charlotte Sound around Picton was next considered. Where would such an establishment be built? Most, if not all, of the suitable land is already taken for residential or other use. Same down Grove Arm. As much as the the area is very scenic with good fishing, diving, and other recreational activities, there is not a lot for families and partners with their own careers outside of NZDF. They could work in Wellington, but the bit of water between makes the daily commute something of a problem. There's no bridge.
Napier and Tauranga were also considered but again it was the career problems. Finally that left Wellington and Marsden Point. Wellington was considered to much of a risk of the fleet being severely damaged / sunk / stranded in the harbour due to a major earthquake being generated off the Wairarapa Fault. The last one generated an 8.2 shake with 6m of vertical uplift and 14m of strike slip. The tsunami was a good sized one as well. There are also, from memory, about another four or five active faults running through Wellington itself.
Marsden Point presents fewer natural hazards apart from storms, tsunami and some earthquakes. Unlike Auckland there are no volcanic hazards and there is plenty of available land for the base and an airfield. The water depth is agreeable and for those who have careers outside of NZDF, Auckland is within commutable distance. Well the getting to Albany will be relatively quick. Getting from Albany to the city will probably take longer than Whangarei to Albany.
