My island is in the Indian Ocean, surrounded by a ring of very sharp rocks. The water is, at most, a few meters deep.
Since a large ferry could not reach the island, what real-world methods of transporting vehicles could get a few (Let's say 7; 3 Hummers, 1 RV Mobile Lab and 3 Caviga Canyon 500s ) of the machines onto the island?
There are many smooth, flat beaches on the island's coast, so getting them ashore should not be a problem.
Some helicopters are able to transport ground vehicles. Check out the weird Sikorsky CH-54 Tarhe:
And this is how it is used:
You may also be interested in the Boeing CH-47D Chinook:
Or maybe try the Mil Mi 10:
If flying isn't your thing (it happens), you may use a Zubr-class LCAC, which is an obscenely huge hovercraft:
Your regular boats. But first: plenty of dynamite.
Reef demolition before invasion of Peleliu, WW2.
https://oceanexplorer.noaa.gov/explorations/18peleliu/background/assault/assault.html
As careful as the plan was, unless the amphibious craft could get over the reef; avoid the mines; navigate the concrete anti-boat obstacles, the coral heads, and boulders; and land on shore, it was doomed to failure. The Navy underwater demolition teams (UDTs) were formed in 1942 in response to this fundamental problem...
In the run up to the Peleliu operation, UDT 10 scouted the invasion beaches in USS Burrfish. The information gathered in August 1944 revealed an array of concrete tetrahedrons, a double row of wooden posts 75 yards from shore, barbed wire, horned mines and, importantly, in some areas the reef was awash with barely two feet of water at low tide. Three days before D-Day, UDTs 6 and 7 deployed along the invasion beaches to destroy obstacles, but more critically, to blast wide ramps into the coral for the amphibious craft.
So too your rocks. It is the modern day in your world. Stuff is available to blow stuff up. Use that first stuff liberally on the second stuff. Then proceed.
and here I see @RonJohn proposed exactly this in the comments 5 hours ago!
![Ferry with long pier[1]](https://i.sstatic.net/oUXLK.jpg)
Build a pier to the place you can safely dock a ferry or other ship. A pier can be as long as needed.
As an example, in 1926, the Golden Gate Ferry Company began construction of the Berkeley Pier in Berkeley, California. It extends about 3.5 miles (5.6 km) into the San Francisco Bay. It was used to transport vehicles in 1926.
Simply build a pier over the sharp rocks out through the shallow waters until you get to a spot that is deep enough for ships to use.
In addition to @Renan's answer, the Bell Boeing V-22 Osprey has an internal payload of 20 000 lbs. Might take 2-3 trips, or 2-3 planes.
If there's no room to land a plane, and the island is too small for a reliable airdrop, you can also perform a low altitude parachute extraction.
The low-altitude parachute-extraction system (LAPES) is a tactical military airlift delivery method where a fixed wing cargo aircraft can deposit supplies in situations in which landing is not an option, in an area that is too small to accurately parachute supplies from a high altitude.
Note that the plane here doesn't actually land.
You could use a ground effect vehicle, sometimes known as an ekranoplan. These are plane-like vehicles that use the ground effect, an air cushion that forms under the wing at low altitudes, to achieve incredible lift relative to their wing size and power. Then can only fly a few metres above ground or water, but can carry an immense amount.
This is the Lun-class ekranoplan, built by the Soviets as a combination anti-ship craft and assault transport. It could carry a thousand tons of military equipment right up to the shoreline at 550 km/h, and fight with six heavy anti-ship missile launchers that you can see rising from the centreline. On its nose you can see four turbojet engines that provide the primary thrust. It flies up to four metres above the water, so it can avoid all but the largest rock formations.
This fellow is a little heavier duty than what you're looking for. You could probably pack all that gear into this sprightly little fellow, the A-90 Orlyonok:
This chap could carry 28 tons of cargo at the not insignificant speed of 400 km/h and is rather more maneuverable than the previous beast. The front hinges sideways to let vehicles roll right onto the beach. I think this would make for a fun and interesting way to get to Isla de Spikeyrocks; at least, as long as you can build your own or pull one out of the Russian plane graveyards.
Maxim 11: Everything is air-droppable at least once.
Hummers are designed to be air droppable.
If you switch from the RV to M934 Expansible Van Truck, I believe it's air droppable. Certainly at least once.
You could drop the Cagivas (palatalized) as well, or you could use something like this https://olive-drab.com/idphoto/id_photos_m1030_m1d.php and it uses the same fuel as the HMMVs.
https://www.youtube.com/watch?v=oxLi4gKprOo
If that doesn't work for you, the Marines have a bad ass hovercraft that is slightly smaller than the one listed above.
https://www.youtube.com/watch?v=XbXF2B3fHMk
Remember also Maxim 32: Anything is amphibious if you can get it back out of the water.
The USMC has been hitting the beaches with mechanized transport since before WWII, so in addition to simply flying in on helicopters, the Marines can hit the beach in several ways.
The most obvious one is to dispense with carrying vehicles, and simply ride into battle in your own amphibious fighting machine. The USMC uses the AAV-7, which can swim ashore, and then continue inland to battle with a turret mounted .50 HMG and a 40mm grenade launcher, plus 25 armed to the teeth Marines ready to debuss on the objective.
AAV-7
AAV-7 ashore
The Royal Marine Commandos use the "Viking" Marginal Terrain Vehicle (MTV), which is also amphibious, although having lower levels of performance than an AAV-7. It is much more versatile ashore, capable of crossing terrain that no other vehicles can even approach:
Royal Marine Commando Viking MTV
If you really must transport the various vehicles, the USMC uses the LCAC, a hovercraft which can approach the beach very rapidly, and even fly over the beach and move inland so long as the ground it relatively flat. Getting past the sharp rocks might be an issue depending on the size and sharpness, getting the "skirt" damaged makes the hovercraft much less capable of maintaining an air cushion.
Formation of LCAC's
Finally, the US Navy and Marines are experimenting with a new vehicle which has many of the features of a Viking and an LCAC. The prototypes are small, but a full sized version is supposed to take cargo as large as tanks from ships, swim ashore and deliver the payload inland. Meet the UHAC (Ultra Heavy-lift Amphibious Connector)
The enormous "paddles" serve as a track ashore
So if you are looking for alternatives to air delivery, here are how the USMC and Royal Marine Commandos do it.
Depending on the shape of the reef, something like the PTS tracked ferry. Formerly Soviet, so you can easily explain a surplus ferry showing up anywhere after the Cold War.
Being tracked, the PTS might be able to climb over reefs that would endanger the bottom of normal boats. But a sufficiently pointy reef could pose problems.
The advantage is that it is smaller/cheaper than a hovercraft, and it uses less fuel than a helicopter. So the expedition might be able to keep it around, for coastal or river transportation.
Park the dredge over some sandy bottom and pump. Sand slurry can be carried some distance. Deposit the wet sand on the rocks.
Water runs off, combat engineers grade it to suit.
Wind and wave action will eventually restore the shore.
What about a ramp that unfolds from the boat? How wide is the ring of rocks? Think of something like a drawbridge or a loading dock leveler.
What about a crane on the ship?
Use a pontoon bridge (if only needs to be used once, and the rocks are just below the surface), or a Bailey bridge (for extended operations, or rocks above the surface).
These are both kit bridges that that can be built very quickly, and were used for temporary bridges during WWII.https://en.wikipedia.org/wiki/Pontoon_bridge
There's also the medium girder bridge (folding bridge), and the Armoured vehicle-launched bridge. This is a medium girder bridge which is attached to a tank. It is unfolded and laid at an chasm, and then detached. The rest of the division then cross the bridge, the tank crosses last, and collects the bridge. https://en.wikipedia.org/wiki/Armoured_vehicle-launched_bridge
Swim or kayak in and then set up a cable bridge, Bring the vehicles in piece by piece and assemble them on the shore.
Set up your loaded landing craft at the outside edge of the ring of rocks. Generate a small tsunami with a controlled (nuclear) explosive out at sea and surf over the rocky area and run aground on the beach.
How about an icebreaker? Maybe the icebreaker bit would break up the rocks. Or maybe an armored icebreaker so it wouldn't get punctured.
