From the U.S. Master Depreciation Guide
Assets used in the commercial and contract carrying of freight and passengers by water (except as noted below) are 15 year property
vessels (eg yachts), barges, tugs and similar means of water transportation, but not used in marine construction or as a fishing vessel are 10 year property
Assets used in the recreation business are generally 7 year property
Fishing vessels are 7 year property
Bless the IRS - you can pretty much pick your poison - unfortunately personal assets like your own private boat, not used in business are non-depreciable for tax purposes. But I digress, that was not the question was it?
From a bored cpa on a friday afternoon