How much you will spend on your cat storage will be dependent on where you want to store your boat. Grenada Marine, for example, charges If you have major upgrades or issues with your boat, you can expect to pay more than $10,000 on maintenance (boat gear is extremely costly, especially if you’re in the middle of nowhere). Or, maybe you’d want a more efficient propeller, new ventilation fans, or solar power. Unfortunately, a high-quality marine-grade solar panel can cost you a couple of thousand dollars, although some cheaper ones worked fine for us..55/ft per day for up to 120 days or Also, depending on the boat’s complexity, age, and systems, a survey can take a couple of hours to an entire day. Your surveyor will do a sea trial to test specific problems. This process is necessary when a seller intends to sell his boat to you, or when you own one and need to maintain it, or when you want to sell yours someday..50/ft per day for 121+ days storage. Nanny Cay charges $1.30 per square foot per month for general catamaran storage.