Howard said he and his family weren't told until 1:45 a.m. Friday they had to get off the ship by 7:30 a.m., so they had to rush to pack in the middle of the night.
After disembarking, they boarded one of dozens of chartered buses, which traversed St. Maarten with a police escort to the airport, Howard said.
The captain said remaining passengers could "enjoy another day in beautiful St. Maarten" or stay onboard for a "full schedule" of activities.
"We sincerely apologize for the disappointment this unexpected change has caused and regret we were unable to provide you with the fun and memorable cruise vacation we had in store for you," he wrote.
The letter also offers passengers a three-day refund and a half-price cruise in the future.
Donahue said that in terms of reimbursing vacationers, Carnival needs to take each incident on a case-by-case basis.
"You have to consider brand reputation and what is the risk to brand reputation. You don't want passengers unfulfilled by expectations for the trip and slighted by an inadequate offer of compensation," he said. "If you are facing or trying to recover some perceived brand impairment, you may want to make sure the compensation is viewed as generous."
In a statement, Carnival said the ship's emergency diesel generator failed. The ship's next voyage was canceled, the cruise line said.
Carnival spokesman Vance Gulliksen said Thursday that 4,300 guests were aboard the Dream, along with about 1,300 crew members. Carnival's website puts the ship's capacity at 3,646 passengers, but that's based on only two people per cabin, and some cabins hold more, Gulliksen explained.
There are also three- and four-person cabins aboard.
Carnival said on Friday that it had arranged for a combination of approximately 50 commercial and private chartered flights to fly the 4,363 Dream guest home from St. Maarten. Guests were given the option to return to Orlando -- the closest air gateway to Port Canaveral, where the voyage began -- or their originating city, Carnival said.
On Tuesday, Carnival announced it was conducting "a comprehensive review" of all 23 of its ships after the fire last month that crippled Triumph in the Gulf of Mexico.. Carnival President and CEO Gerry Cahill said the investigation will focus on the prevention, detection and suppression of fires, engine room redundancies, and what additional hotel facilities might be provided and might run off the emergency generators.
The review is a "positive step," Donahue said.
"If they are transparent about results of a review, I think that could go a long way to build confidence back among passengers or any prospective passengers who are reviewing some of the negative media coverage," he said. "But the key is not just that they conduct the review, but be transparent about the findings of the review and the steps they will take to address any gaps."
'Human waste all over the floor'
After Dream's problems began Wednesday, Gregg Stark, who is traveling with his wife and two young children, told CNN that conditions were deplorable.
"There's human waste all over the floor in some of the bathrooms and they're overflowing -- and in the state rooms," he said. "The elevators have not been working. They've been turning them on and off, on and off."
An announcement over the ship's public address system said the crew was trying to fix the problem and was working on the generators, according to Stark. A few hours later, another announcement said the problem was worse than originally believed.
"We are not allowed off of the boat despite the fact that we have no way to use the restrooms onboard," Jonathan Evans of Reidsville, North Carolina, said in an e-mail Thursday. "The cruise director is giving passengers very limited information and tons of empty promises. What was supposed to take an hour has turned into 7-plus hours."
But Thursday afternoon, Carnival told CNN that based on conversations with the ship's management team, a look at service logs "and extensive physical monitoring of all public areas, including restrooms, throughout the night, we can confirm that only one public restroom was taken offline for cleaning based on toilet overflow and there was a total of one request for cleaning of a guest cabin bathroom.
"Aside from that, there have been no reports of issues onboard with overflowing toilets or sewage. The toilet system had periodic interruptions yesterday evening and was fully restored at approximately 12:30 a.m. this morning."
'This needs to change'
Last month, an engine room fire left the Carnival Triumph adrift in the Gulf of Mexico with more than 4,200 people aboard.
As that scheduled four-day cruise doubled in length, food was scarce, and passengers sweltered in the heat with no air conditioning. Passengers also reported overflowing toilets and human waste running down the walls in some parts of the ship.
A class-action lawsuit was filed against Carnival Corp. afterward.