My observation is that boat sales price is often a function of time, especially with trawlers where each one tends to be a little unique vs more recent mass market boats that may be more constantly available and in interchangeable condition.
When a boat is first listed, it may get relatively high offers, because there are some folks out there that have been looking for something exactly like the new offering. These buyers may be willing to pay a little more for something that checks all the boxes vs a better deal on something they want less.
After the initial market exposure, any pent up demand from this type of buyer is gone. Things are in a steady state. New buyers are more likely to be more willing to balance price and desirable attributes. And, even that discriminating buyer opened the adverts and saw at least one matching boat. They haven't been on the market long enough to know it is a rare find and that they should pay a premium or will need to compromise.
The upshot is, I think, sellers might be well advised to be patient for a month or maybe two, depending upon season, to see about the focused buyer. And, more compromising, price-sensitive buyers might be well served not to get frustrated by a turned down offer, and just to let the boat age on the market a bit and try again.
A few months time is a buyers friend and seller's enemy. I think.
I dont think buyers have any reason to be upset at sellers for taking less later. I think they should just recognize that they, themselves, missed an opportunity to try again. Never leave a failed negotiation badly -- just let the seller know you can't go higher right now and are going to keep looking for now. Sellers should do the same.
I purchased my present boat months after making my initial offer -- and for less than that offer (I went down).
The seller was 90% through a major refit. All done, the boat is now a gem. Where it was -- it needed a very sophisticated buyer and one who could put some money in and take some risks
After having the engines professionally rebuilt, he did the final assembly in-boat and missed a timing mark on the auxilary gear shaft that had injector timing off. He also goofed a head gasket leaving a minor leak on the engine. He hadn't bothered to repaint the engines -- and the rebuild paperwork was lost between he and the broker. Most buyers saw a smokey, leaky, dirty engine. Given his life circumstances, he didnt want to finish the job and take care of these or other details.
Ultimately, I did buy a boat that was almost fully refitted. And, I did have to spend some time and money to finish it. It cost me a year of visits that could have been cruises. I had 5 "mechanics" out to the boat before finding one who understood the timing issue -- $253 to fix it. I also got the paperwork -- some he found later,, some I got by calling likely suppliers asking for duplicate invoices until I found the right ones. Anyone buyer with less experience would have been out a mint and unable to later document the refit.
The problem for the seller was that this and other bits were small details in his mind. In my mind they were manageable risks. For most, the risks were show stoppers -- and the reality might have been a mess. Some of those "mechanics" were lost in space, and that is an expensive path.
Time let him understand how buyers were viewing the boat and accept my offer, which worked out well for both of us. No hard feelings.