I did a survey recently on a boat which has sat out of the water on stands for about 8 years. The engine was, for the most part, properly stored and this post is not really about the mechanical side of boat storage anyway. What I want to discuss is the hull. This boat was foam cored fiberglass and was of somewhat light construction. The yard had also not taken measures to match the stands to any sort of underlying frame or bulkhead material where the boat is more stiff. As a result, the boat was observed with intense distortion of the hull right at the boat stands. I measured approximately 1.7 inch inward distortion and this was observed on the inside of the hull as well. The prop shaft was also well out of alignment and very stiff to turn by hand. Unfortunately this specific survey did not go far enough for me to get the opportunity to do some detailed inspection beneath where the boat stands were in contact with the boat but in my experience there are a wide array of possible outcomes for this from needing major work to there being no issues.
In all cases the boat should be put back into the water well before use, from a week to even a month. This allows the boat to rebound back to its original shape as much as it is going to and as the hull shifts back into a final shape then the propeller shaft can be brought back into alignment if need be. A foam cored boat might sustain some damage to the core material as was likely the case with the recent survey and this might require massive and expensive work to restore. For some solid fiberglass boats it might not be as big of a deal to sit on land for such a long time but some distortion of the hull is expected. Do be aware of the issue and if you know the boat has been out of the water for an extended time then make sure your surveyor knows too. The surveyor will already be doing a detailed inspection of the effected area to determine what is needed to make the boat safe for you and your family but we also like any extra info that we can get about the boat’s past. Any information helps us to better represent your interests.