Hi Dan- I was a yacht broker for around five years, so I didn't write the book on the business. During my time, I did my best to level with my listing customers regarding how to improve selling chances. If you haven't done it already, ask the listing broker for honest feedback regarding showings, etc. I remember one of our boats that had a bad odor. I didn't succeed in getting the owner to deal with it. More than once, I sold a different boat to the customer because of the odor problem. Most brokers want you to declutter the boat as much as possible. They show best when the storage spaces are mostly empty. If you won't listen to that broker, then find one you can listen to. Most owners have trouble being objective about their own boat.
I looked at your writeup and it presents the boat nicely. There are a lot of Gulfstar 50's on the market, so people shopping for one may be finding better deals elsewhere. Of 15 I saw on Yachtworld, yours is among the 5 most expensive. I'm not really in a position to determine if you have it priced right. It may truly be more turnkey than the next boat, but many buyers don't understand how much it can cost to get a poorly maintained (and low priced) boat ready for cruising.
More likely is the simple fact that the vast majority of people shop for boats smaller than yours, especially in a fragile economy. I would not recommend a 50 foot boat as a starter boat and mostly, I would not try to talk a person into buying a larger boat than what they were looking for unless I thought they had the skills to manage it.
If you can't wait, then lowering the price will probably help.
The open listing is probably a disincentive for most brokers to make a big effort. You might just be using the brokerage to help price the boat and then sell it to someone in a private sale or cut a listing deal with another brokerage. Open listings don't generally get much of an advertising budget.
When I was in the business, I showed our own listings probably more than 5 to 1 compared with boats at other brokerages. If I had to make a half day commitment or more to show a boat elsewhere, there had to be a strong likelihood that the boat was a strong candidate. To the extent that I developed a good bond with the customer, I would search all corners of the earth for what they wanted and do my utmost to help them understand their real needs. If a Gulfstar 50 was one the list, I'd start by showing the one close by to see if the customer liked the breed. I don't know the Miami area very well, so don't know how many brokers are within 10 minutes of your boat. I consider it a liability that the listing broker is an hour away from where the boat is moored. Brokers, like all sales people, ultimately need to make a living and how they split up their time and effort depends on where the likely rewards are. Fortunately, there are lot of brokers who balance that with a true love of boating and a desire to help their customers.
Patience and good luck to you Dan. I hope this helps.
If you want to have a phone chat, or email followup, just let me know. We're still enjoying our time here in La Paz.