Waly,
Here's my two cents. We were there in early November, didn't get bit by a single mosquito.

Try to put everything that has been said here into perspective. If you are on a boat for ten days, and especially if you are usually on the boat at sunset, you have a low probability of getting bitten by a skeeter. If you don't get bit by a skeeter, you've got 0% chance of contracting. Bring your DEET bug spray, keep an eye on the kids and watch your sunsets from the boat and there's little chance you'll be affected.

Like I said, we had ten days on the boat and two ashore in November and neither my wife or I can recall getting bitten. But we always watch sunsets from the boat and we always take the furthest available ball from shore (we like the quiet and the breeze) and we don't overnight on the boat at the dock.

Enjoy your trip!!