a suggestion:
Given that you like this particular boat and you seem to have the ability to write using some detail, why not take the time to outline and state specifically what you would like to see happen throughout the survey. It is, after all, your offer.
Say what you would like to see happen and who should bear financial responsibility for that action, from sea trial to commissioning to launching, including what happens after the boat is run out; as in who pays to re-haul and re-winterize, if necessary. It is not necessarily true that the seller should pay for everything or that the buyer should pay for everything, but makes more sense to find some middle ground with each paying for a portion depending on what it is.
The point is to be as specific and complete as possible with each and every step. Oh, and please remember that it is not necessarily true that the language contained within a proposal to purchase is "standard" any more than "this is not how things work where they are". An offer to purchase is just that and is geography neutral, and while much is similar, it should also be as unique as you need it to be in order to express your specific requests.
So, good luck with this negotiation, and please keep us apprised.