Well ... call me ignorant ... but how the buyer broker thing works. I never used one ... I always dealt with boat seller's broker myself.
What constitutes or commences the buyer and broker business relation. I can sense it's not a black and white thing, and somehow different than in real estate.
This might be an opportunity to educate the ignorant ...
Your method works but understand two negatives. First, you're really talking to the seller. Not going to do anything to steer you into what is right for you in most cases. His obligation is clear. Second, you're going to be contacting a lot of brokers. In doing so you may not be as important as you should be to some. If you'll only look at one boat with them, they'll think you're just window shopping sometimes. All of them want but some will.
By having your own broker as a buyer there are certain benefits. Let's be clear they are not a buyer's broker as such unless you have a contract saying so. They are a broker chosen by buyer and helping the buyer but their true obligation is to the seller, because that's who is paying them. To change that would take a contract stating they are your representative and responsible to you. Still some will show they feel obligated to help you regardless. They will help you with negotiation, contracting, steps to take, even refer you for documentation, loans, or insurance. But most importantly they'll help you find the right boat. They don't care which it is. Just one, the right one. They should listen to you and talk to you about types and brands, likes and dislikes. Then search, but not just what is on Yachtworld or Boat Trader. They should inquire and qualify the boat. Then take you to the one, two or three that meet your needs best. So the two benefits are (1) you pick up some personal assistance and direction and may make a better decision plus learn of more boats and (2) you may save a lot of time in the process. There is a third I should add. Using the seller's broker you don't get to choose, it's who he chose. Using a broker yourself, you get to interview brokers and find one you're comfortable with.
Now this is when it works as it should. Otherwise it's easier to do what you've done.
In deciding which way to go, I'd consider my own knowledge and experience in the type boat I was searching for, the time I had available, and just my tolerance for having to talk to many brokers as opposed to one.
I personally would never go to all the different selling brokers for one personal reason. I want someone to work with as I go through the entire process, whether I look at one or ten boats. What I don't want is looking at 5 boats and 5 brokers then contacting me constantly about the boat they showed me and others, and probably sometimes about the same boat. I do not enjoy hard sells or talking to a lot of salespersons.
Now I must give one caveat to all this. While I know the process well and have helped friends who bought plus have friends who are brokers, I've not actually been through it as I've never purchased a used boat. But in many ways they work very much like house brokers, just not as many legal restrictions in most areas. Not to offend any broker and I know the good brokers won't be, but in most areas being a boat broker doesn't require any courses nor any apprenticeship of any sort. So while there are many great ones, there are some who have no idea what they're doing and others with no integrity.