Generally I recommend against the 401k loan route unless you are CERTAIN of your job security. In most 401k plans, if you separate from service, the outstanding loan (which usually has a 5 year maximum length) becomes immediately due
or is treated as a pre-retirement distribution and is taxable as income plus a 10% penalty if you are under 59 1/2 yrs old. I'm an investment manager with 20 years experience & have seen this happen on 2 occasions to people, with VERY bad consequences for them.If the boat qualifies for getting "2nd home" treatment for a tax deduction (based on the previously stated boat criteria), you don't need to monkey with cost and closing expenses of home equity loans, just a regular loan will do, and you can deduct the interest.
That being said, debt is bad... unless managed very carefully. Always keep your loan to value in consideration and don't get upside down.
That also being said, we are at historically low interest rates and money is "cheap" to borrow. I did not hesitate taking out a loan for part of our recent Meridian purchase, even though we can't deduct it (have 2 houses already). It will be the first thing I pay off, and sooner rather than later.
Just my 2 cents...