boat sales agreement is far from legal rocket science
Right, they are not like drafting a new constitution. If two parties have agreed, in good faith, and written down their agreement, a napkin would most often work out just fine. I suspect recreational marine P&S contract problems are rare, I've never had one. However, when you do, it can be awfully frustrating. There are two common contract problems.
First, both parties agreed on the terms, but ultimately don't agree with what the vague or boilerpate language specifically means. Usually, as a result of something going wrong. These end up being sorted out in court, if not walking away, because of the cost to pursue.
Second is more insidious. One party refuses to comply with a term and it turns out it is unenforceable, because the counterparty didn't realize some form of law imposes an unmet standard. These are the one's where the blood vessels in your eyes burst. The counterparty renegs and there's nothing you can do about it. While I think obvious, one example could be a clarifying verbal agreement that is later superceded by the written contract that does not include the verbal term. The buyer says, you told me all that stuff would come with the boat. The seller says, not in the contract.
I'm sure these all rarely happen and I'm not suggesting the use of a lawyer to draft one. I would suggest not using outdated forms. The lawyer probably starts with a forms library themselves.
I would offer, however, there is an intersection of art and science in these. You need enough clarity to avoid conflict, but not an encyclopedia of wherefores and whereas, which probably tell the seller you're a pita.