From time to time and usually at the end of the rowing season, we have customers who experience unexplained surface deterioration problems in the form of small pimples/bubbles on the hull surface, often quite random and localised.
In almost all cases, this has been caused by boats being left or stored for a number of days or weeks in wet boat covers or plastic bags.
This phenomenon is known as Osmosis and a full explanation of this condition is shown in the following link:
Whilst this article is mainly referring to hulls that stay permanently in the water and have greater protection using thicker coatings and additional protective coatings, it is the same phenomenon.
All rowing hulls, no matter which manufacturer or type, have a hull coating of either Gelcoat (epoxy or polyester), or a paint system of the two pack variety. Whilst performance will vary across this range of coatings, all can suffer osmosis given certain conditions set up by leaving them in wet coverings.
Most sculling boat owners take better care of their craft than the average crew rowers, but even then, due to circumstances at regattas etc, boats are often packed up in wet conditions, such as on rainy days so not ideal, and the need to get the boat out of the wet covers asap is critical in avoiding this type of surface deterioration.
In all cases, the hull will need to be repaired by removing the affected coating, drying out and recoating, which is not a simple process.
PREVENTION IS BETTER THAN THE CURE