I have lots of experience with credit card payments between working in hotels and gas stations in my college years. Here are a couple of things to keep in mind.
There is a difference between debit and credit cards. If you can do so responsibly, always use credit cards at gas stations and hotels. Sign up for a rewards cards and get paid to use their card. They also come with much more fraud protection and consumer services (ie roadside assistance like AAA, rental car insurance, etc, depending on the card)
The reason for credit cards has to do with authorizations. It is not coming out of your pocket and they are not holding onto your money with credit cards. It is basically just saying "I am authorizing you to charge up to but not to exceed XXX.XX amount"
Whatever is not charged is returned. Since it is only on your line of credit, you won't miss that money unless you are right at your limit. Credit card Authorizations are usually released after the vendor batches their transactions for the day. Should be within 24 hours, 48 hours if it is a ma and pa place that may not do it every day.
Debit cards are on an entirely different system. Never authorize a debit card. If you have a debit card, pay cash. It is not unheard of for debit card authorizations to be held for 1-2 weeks! If you are in a pinch, tell them to charge the debit card for a specific amount and pump that amount like a cash transaction. They all have the capability to do it, it just takes 2x as long and more work on their end. If you are told no, talk to a manager and they will make it happen.
Back to the OP, marinas will increase the authorization to $250 because of the cost of fuel at a marina, usually an 80-125% markup from the nearest gas station on land. Why? Because lakefront property isn't cheap and they have bills to pay. Can you imagine the big cruisers filling up their 80 gallon tanks $75 at a time with $5/gal fuel? Keep in mind each transaction costs the marina money so they want to minimize the number of authorizations. $250 seems very reasonable for a pre-authorization at the marina.