Hi Everyone.
I would like to clear up an old Misconception. There is scientifically no such thing as Dry Rot !
Now that said, let me explain. Wood ,as we all know absorbs moisture. That moisture and constant immersion in salt or frash water eventually leads to natural wood rot .
Wood rot needs two main things to happen .Dark dry places and a presence of water, both clean and fouled. As the wood ages it starts to get somewhat soggy.Not to total softness, but a surface softness.
In this environment, bacteria feed on the cellulose in the wood .Much like Termites on land and Toredo Worms at sea ..
Various coatings were developed such as White Lead ( Many British Ships ),and A form of tar ( The Portaguese " Black Ships ") and many types of oil or other liquified coverings .This couldn't prevent rot though because of standing water ,sometimes with Human waste in it within the bilges of said ships. This created a bacterialogical Smorgasbord in which many ships ( not well cared for ) found themselves .
I have found many modern Wood Yachts Piffy ( soft Wood and Frames ) upon survey .This is usually very prevelant around the bilges and waterline . Now , When you rinse a wood boat out - Pumping all the water overboard,open up All hatches,Ports and such and let her dry she won't rot . Those in Humid areas will stop ,for the most part on dry land .But , remember Humidity equals moisture. MOISTURE Equals rot! You can't see it but there it is .But it isn't dry rot, because when wood is perfectly dry it cannot rot !
Often times ships being " Careened " ( An old fashioned way of cleaning a two or three masted ship's bottom )This is a method of leaning the ship on dry land to clean Barnacles and stuff off the hull. Sometimes they would find a " Piffy " region ,but couldn't do anything about it till a refit.