Have you seen the prices of apartments in SF?
My $300 apartment in my Podunk college town would cost $1500 there.
The boat will cost more per month once you factor in the payment for the loan, but at least we would own something for our monthly payment. The boat has the added advantage of being mobile and easy to move to near the next job site (we would likely both be working as construction engineers). Plus we can have a bit of fun.