Two answers. The friendly one: Sure. It helps defray the cost.
The legal answer: (In the U.S. At least).
Exchanging anything for a ride (fuel, food, money, dockage fees, expenses) makes the 'fee for hire'.
Are you licensed? Is your vessel up to passenger carrying safety levels? Does your insurance cover this?
Very boring, mundane stuff. But, 'if' something happened, you are treated in court in a whole different way as if you just 'brought someone along'.
old news...check with the USCG.....
Guests can contribute...it just can't be a contingency of the voyage...in other words "voluntary"......
From USCG WEBSITE......
The question of when an individual becomes a “passenger for hire” has caused confusion
but is actually straightforward. “Passenger for hire” means a passenger for whom
consideration is contributed as a condition of carriage, whether directly or indirectly
flowing to the owner, charterer, operator, agent, or any other person having interest in the
vessel (46 CFR 24.10-1). For example, requiring strangers to share expenses constitutes
a “passenger for hire” operation.
“Consideration” means an economic benefit or profit including payment
of money or donation of fuel, food, beverage, or supplies. It does NOT
include a voluntary sharing of the actual expense of the voyage (46 CFR
175.400).
Therefore, if a passenger provides any money, fuel, or supplies as a condition for them to
get underway with that vessel, the vessel is operating as a passenger vessel and requires a
Coast Guard-licensed operator. If more than six passengers are carried, the vessel will
require certification as a Coast Guard inspected vessel in addition to a licensed operator.
In both situations, if an individual gives the owner, charterer, operator, agent or anyone
else who has an interest in the vessel any money, fuel, or supplies that the passenger did
not freely choose to share as part of the actual cost of the trip, the vessel is carrying a
passenger for hire and must meet the following requirements: