Before we go any further in terms of qualifications, the "$8,000 (max) & $6,500 (max)credits only apply to purchases after January 1, 2009.
The boat would qualify as a primary residence but the time period as indicated above doesn't fit with your acquisition.
You can read more about these credits at www.federalhousingtaxcredit.com/
Also, see the following information related to your 2008 return (which may be amended using Form 1040X) to see if you might qualify for the prior first time homebuyers credit (limited to $7,500) which in effect an interest free loan which must be paid back over 15 years at the rate of $500. each year, paid with your annual income tax return on Form 1040.
The Housing and Economic Recovery Act of 2008 established a tax credit for first-time homebuyers that can be worth up to $7,500. For homes purchased in 2008, the credit is similar to a no-interest loan and must be repaid in 15 equal, annual installments beginning with the 2010 income tax year.
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