If you were on a deserted island and wanted to make a raft with coconuts how would you drill out the centers (to make the raft)?

Catch a woodpecker and use him as a hammer drill.

Find two small rocks ... use one to chip the other to make a narrow pointed tip that you can use to drill like a screwdriver ... pick one of the three small round points on the coconut and twist/drill there ... then use a thin stick or bird bone to scrape the inside of the coconut ... then make some fatty wax from the fat taken from some birds and fish so you can seal the hole.

It better be a fairly short trip ... this type of raft would only be good for a little over a week at most in rough sea water, and you would need a vast number of them. It would also be better to contain them in a mesh of lashed sticks, rather than a woven net ... be sure to take along a whole lot of spare lashing material and check all the lashings every few hours.

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With spy satellites they way they are now, you would probably be better off to stay on the island and just keep a large "S.O.S." fire burning at night so either passing aircraft or spy satellites could see and read the letters "S.O.S." ... risking a sea voyage on a coconut raft may be OK to move to another nearby larger island, but would not be good for any long trip.

If you have coconuts on the island, stay on the island. You will live a lot longer on an island than any raft you can make.

I think you should use bamboo, it has chambers of air. Watch "Survivor" on CBS. It's my favorite show.

I would not use coconuts. I would make a stone ax and cut down coconut trees to make the raft. Why would I use coconuts?

Find a copy of the book Kon Tiki. Everything you would ever need to know about making a raft and surviving on one at sea.
As far as your question.. I would find a 1/4-3/8 inch green stick and cut it about 18 inches long. Split one end and find a flat rock about 1 inch by one inch. Using a larger rock, chip the small stone to create a arrow head with point the size you want the hole. (it might take a few trys to find the right type of rock) Then lash the arrow head on the stick with coconut husk fibers. Then create a bow about 2 feet across with more coconut fibers. Find a palm sized flat stone. Wrap the bow string around the arrow shaft 2 or 3 times (Now a drill bit) Put the stone end on the coconut where you want the hole. Use the palm stone to push on the blank end of the drill bit and using a sawing motion move the bow back and forth to spin the drill bit.

i wouldnt drill out the coconuts...but since they do float and are full of nutrition, water and their husks are very fibrous and make good fire material, and ;lashing material, like string, id take as many of them as i could, with me for water and food. and fire for signalling at night and day. id also make a bow and arrow to shoot flares and for fishing etc

id use bamboo.. for the raft.it floats well.
id make some sort of rope bags and make a catamarran type webbing(rope) somewhere in the middle of whatever raft i made.
then put all my coconuts under or in between the webbing for floatation and ease of access. make some sort of sails. and several paddles, several rudders, and several sets of shade and spears..plus several tethers to tie myself and others to the raft.(always take spares).
id survive off the coconuts and whatever else i could gather. and by spearfishing, using baits, for fish, turtles and sharks.

it would be quite comfortable... and could be survivable for months with good shade.

Break the coconut in half over a rock. Eat the innards. How that becomes a raft is beyond me at this time of night.

The island is not truly deserted if I am on it.

Coconuts off the tree are much softer and easier to bore holes in them .

They will provide you with Food and drink and transportation a very useful product you can plait the halves together with the leaves of the tree.

I was amazed at just how different coconuts are when freshly picked.

coconut trees will float for several months. bamboo even longer. coconuts will float better left unopened and also will provide fresh water and food, and material to start fires (husks) for flares or cooking and make good cups and bowls.
make a raft with the trees and bamboo. if you are out at see for more than a few months, highly unlikely, cut free any sinking logs.
take several sails, several paddles, several rudders, many spears, a bow and arrow, rope for lashing to the raft, made of vines , etc, and tons of cocomuts in bags.
take spares of everything.anything that breaks, rudders, paddles, etc, are life saving necessities.
shade and fresh water are the most important. plastic or similar sheeting will enable you to distill condensation and catch rain for fresh water.
spears, for fishing, tether for swimming while fishing. sharks etc taste great and have tons of fresh water.

several folks can live for months if well prepared on a simple raft and be safe and comfortable.

build the raft twice as big as you think it should be.

mirrors and fire work wonderfully for signalling...especially on a high pole or sail etc and fire at night and shootin arrows as flares once a ship is seen