Well there's not really any need for venturing out to deep waters because:
One: Your poles are no more than a few meters long.
Two: how are you supposed to spear something that is further than a meter from the surface?
And three: Who ever said you wouldn't be able to find good enough fish in the shallows?

With your raft you could drift around and hopefully not scare the fish off until if is too late for them.

So you sit down at the edge of the water with one of your pointy sticks and try to be as still as possible.