The starter went out on my friend's 2008 210 last month - along with parts of the boat's distributor. The local cc dealer covered the starter under warranty, but told him that PCM's position was that the distributor, distributor cap, and plugs (that apparently also needed to be replaced) were all "maintenance" items that were not covered under the cc/pcm warranty. My friend needed his boat back for an event on the lake, so he just paid for everything and then called PCM. He explained to PCM that a distributor, rotor and plugs should not need to be replaced this often, considering he bought his boat new (it was a leftover boat) in '10 and it only had 46 hours of freshwater use on it. Because the boat had been repaired and the bill had been paid, PCM ended up sending my friend another set of plugs, a distributor cap and rotor as a "good faith" gesture. My friend had to take the parts to the dealer to get a refund for the cost of the parts. He had to eat the labor though, which we both think stinks.
Long story short, you probably need a new starter or need your starter rebuilt (pull it and look at the bendix to see if it is worn and/or stuck in the non-engaged position). Hopefully it is under warranty. If not, pull the parts yourself and take them to Autozone or Napa. One thing my friend said was that, had he know he would end up spending a month dealing with warranty issues and paying a couple hundred dollars in labor to swap plugs, a rotor and a distributor cap, he could have bought all of the parts he needed to fix his boat at a local parts store and done the work himself. He checked, and the parts he needed were all common, locally available, parts.