Hull moisture content – when should you be concerned?

Surveyor’s Tips from Martyn Jenkins of Marlin Yacht Surveys

Don’t necessarily write your vessel off because of a higher moisture content

Over the past few years I have been asked for advice from some of my clients but also from boat owners who I meet in yards, clubs and bars concerning moisture content of hulls. Vessels should not be written off because they are ‘wet’ is what I tell them. I see sailing and motor yachts with higher than acceptable moisture content and generally these are at least ten to fifteen years old but without any signs of osmotic blisters or wicking. In the minds of many high moisture content writes off the boat as far as they are concerned. This shouldn’t be the case.

All those years ago when GRP was first used in boat production no one really new how strong it was, how long it would last and what we needed to do with it each year? Consequently the early production boats were built like battleships, heavy and over the top, but tough. Those boats are still around today. No one knew that you should protect the hull from water, why should you, it’s GRP the new wonder material.

Since those days many lessons have been learnt and huge changes in how boats are made and advancements in what they are made of, has meant that today the modern yacht, although more lightly built is as strong, and less likely to suffer from osmotic problems.

So, the question is that if you have an older boat, as I had, it’s more than likely built well and is structurally sound, but has a wet bottom. What should you do? In my experience the answer is to take her out of the water, remove the antifouling and let her dry out for a few months. In most cases this will bring the moisture content down to acceptable levels. At that point apply a coating of epoxy, there’s lots to choose from so do some research.

A vessel that is fifteen years old now should still be sailing, motoring and giving enjoyment to owners and crew in another thirty years time.

Marlin Yacht Surveys is a YDSA-member yacht survey company based in Palma de Mallorca offering survey, guardinage and both vendor and purchaser support in the sale and purchase of yachts.

Marlin Yacht Surveys represent Grabau International as Strategic Partner in the Balearics.