Re: Making an offer on a boat . . .
iI really doesn't matter. Until there is a leally binding offer and a legally binding acceptance of that offer, you've got nothing and anything goes. And "legally" whatever will vary by state.
Big ticket sales, boat sales, house closings, all fall apart regularly as someone can't get a mortgage, or a board doesn't accept them as buyers, or the phase of the moon changes. If the broker has no interest in taking a conditional offer of any kind, for any reason, there's no way to force it on him.
If you think the broker is screwing around, see if you can run the numbers or the name on the boat and contact the owner directly. Sometimes you can. Otherwise, keep looking elsewhere, and if you call back next week, just bear in mind you're dealing with a player.