What I oppose is the idea that in order to mitigate the threat for the assault ships and to be able to achieve some surprise one develops the EFV. This vehicle is going to be so gold plated and expensive that the Marines will never get enough of them if they get it at all.
Why not design a new AAV which is less ambitious and save the money.
Heck, surprise on undefended beaches can be achieved by LCACs and helicopters. If you just buy some more LCACs and bring them along if the need ever arises might be much more useful. And the vehicles a LCAC can bring to the beach are much more capable than an EFV ever will be.
Let’s crunch some numbers.
Assumptions
2 scenarios. One with the landing force located 10 miles offshore, the other with it located 30 miles offshore.
An initial beachhead perimeter with a minimum radius 8 miles / 10 km must be established ASAP to protect the landing area from mortar fire. In most cases the perimeter radius will need to increase to 20 km for protection against 105mm artillery, or 30 km for 155mm, within 24 hours.
A Wasp class LHD with maximum assets:
-- 24x CH-46, each of which can deliver up to 25 infantry or 2½ tons of material. Let’s assume a round trip time of 30 minutes at both ranges. The Wasp can only spot 9 helicopters at a time.
-- 3x LCAC, each which can deliver a 75 ton load. Round trip time for each load is 1 hour at 10 mile and 1½ hours at 30 miles, including loading and unloading. The LCAC has to dock inside the LHD in order to accept the next load for the beach, which is a major bottleneck. You may be able to squeeze a 4th LCAC in without the AAV / EFV compliment, in effect giving the same rate of delivering supplies to the beach in the 30 mile scenario as the 10 mile scenario, but due to the bottleneck will confer little advantage beyond redundancy in the 10 mile scenario.
-- 40x AAV, each capable of transporting 3+21 infantry – or -- 40x EFV, each capable of transporting 3+17 infantry
Case 1 -- No AAV / EFV
At the end of the first hour you have delivered the equivalent of a battalion of light infantry, with another still onboard. A beachhead perimeter will not be complete until at least 2 hours. But it will be at least another day, probably 2 or 3, will be needed to get enough vehicles on shore to break out of the beachhead, unless the intent is to march out on foot.
Case 2 -- with AAVs
At the end of the first hour you have delivered the equivalent of a battalion of light infantry, with another battalion of mechanized infantry on board the AAV still inbound on the water, arriving in hour 2 for the 10 mile scenario or 5 hours for 30 miles. A beachhead perimeter will not be complete until at least 2 hours. The big difference is the number of infantry vehicles [AAV’s] that arrive under their own power, permitting the LCACs to concentrate on support vehicles and equipment (fuel, artillery, tanks, etc.). Break out from the beachhead can probably take place 1 or 2 hours after the bulk of the AAVs arrive.
Case 3 -- with EFVs
For the 10 mile scenario, by the end of the first hour you have the equivalent of 2 battalions, one light infantry/airmobile and a second mechanized on shore. The beachhead perimeter is complete, and the break out from the beachhead is ready to go. In the 30 mile scenario things just take an hour more.
One more final item, the EFV can keep up with modern tanks and IFVs, the AAVs are 1/3 slower.
Now let’s look at it from the defenders perspective:
For the defender the single most critical thing is
time.
Time to find out that the attacker is landing, and where. Yes, I know the attacker has taken out the coast watchers and lookouts, and is knocking out or are jamming all the regular communications, but someone will always, eventually, make it back to headquarters when they start send out people to find out why they cannot contact anyone in the area.
Time to mobilize their forces and contain, disrupt, or counterattack the beachhead before the invading forces can break out and start a battle of maneuver.
Summary
Case 1
Because of the slow buildup of vehicles means that it will be several days before a land breakout can be mounted, this case is only workable if:
the enemy is so weak that his response cannot effect the outcome,
or the objectives are limited so that so that they enemy does not have time to respond before the attackers forces plan to withdraw,
or local air defenses (especially MANPADs) are weak enough to permit unrestricted airmobile close assault without ground vehicles,
or the landing location has only limited, and highly defensible access, which will also make the breakout phase difficult
or no surface vehicle (except LCAC) access is available or required.
Case 2
The 10 mile scenario may allow sufficient time for local forces to intervene in the breakout, but probably not to counterattack the beachhead.
In the 30 mile scenario the defender may have time to attack the beachhead before the arrival of the AAVs with local forces, naval fire support could prove critical to success. General reinforcements will be available to counter the breakout.
Case 3
In the 10 mile scenario EFV forces should be able to move directly from the landing to the breakout phase, leaving the airborne forces to establish the perimeter. High probability that local forces can be overrun before they can organize, possibly before they can be alerted.
The 30 mile scenario is midway between the 10 mile scenario and the Case 2 10 mile scenario, and could go either way.