Danny
I don't know what the sea conditions are like where your are (apart from warmer than here in the UK!) but unless they are very severe you should be fine.
I used to run a 5.7 metre RIB with a 115 hp outboard, and it coped fine with crossings from the UK to France and the Channel Islands (not your Channel Islands though!) -- 60 to 70 miles of open water.
California sounds like a great place for RIB cruising!
John
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John Kennett
RIBnet