I'd just finished reading John McPhee's excellent book, when I had to go looking for a ship myself.
I am a member of the Clipperton Project, which embarks from La Paz, Mexico for Clipperton Island this March.
We have one boat, the Lucia Celeste, which is a sturdy craft, but as the numbers wax and wane with camera crews, turtle savers, ham DXers, and others whose functions I don't understand, we might want some additional capacity.
We stayed aboard the Lucia Celeste while in La Paz, and we were quite comfortable, but it's hard to imagine her loaded down with fifteen of us, five tons of fuel, and all the scientific gear.
A second (or even third) boat would be nice for additional capacity, and for safety in numbers. Since our expedition is environmental in nature, a sailboat would be more fitting, and better for photos opps than a stinkpot. We checked out several vessels around La Paz, and one lovely ketch we saw would be more than adequate. The owner is apparently like-minded, which is good because the project wouldn't properly charter the second boat, but pay for fuel and expenses. The rub is that for a sailboat it's a downhill tradewind run to get there; a slog against the trades to get back. Clipperton is in the middle of nowhere and not on the way to anywhere.
We spent a lot of our time devising creative ways to get people and gear in through the surf, as Clipperton has no pass and can be beset with breakers for weeks. The Lucia Celeste just got back from Clipperton, and their method was to clothe people in protective wetsuits and send them tumbling onto the reef. We came up with a plan involving an inflatable with special d-rings, a taut line between shore and a buoy anchored offshore, and lines led from the bow and stern to pull the boat in and out. I envision scientists clad in protective wetsuits bouncing off the reef while trapped under an overturned inflatable, but it'll be interesting to see the whole works in action.