Hi Fred and welcome to the MOA,
The newest M425 will now be 30 years old so as you know boats, I guess you know that the condition of sails, rigging, furlers, electronics and engine are matters that need looking into.
The hull and deck were hand laid in a temperature and humidity controlled shop using Isophthalic resins, so is more proof against osmosis than most but no polyester boat is immune to this. The hull is solid grp with cored floors and engine bearers (I don't know what core material) and marine ply bulkheads / part bulkheads tabbed in position. If you get to look behind the cabinetry, you will see there are also some galvanised cach bolts associated with the tabbing - they will be looking a bit rusty by now, but that doesn't seem to cause any problems and I suspect they were put there to hold the bulkheads in place while the tabbing was done, i'e' a construction aid. By modern standards the hulls are thick - the cutouts we made to install a bow thruster were 40mm minimum thickness. The deck is end grain balsa cored for stiffness and lightness. The core is marine ply in way of deck fittings but it's worth taking a close look where any further fittings have been added as they may be letting water into the balsa core.
The chain plates penetrate the side decks where they are sealed by small stainless steel plates screwed to the deck with self tapping screws. Over the years, the sealant under these plates dries out and tends to crack, so prudent owners lift the platesand reseal them every few years. If this seal starts to leak, the water runs down the chainplate to where it is bolted to one of the marine ply part bulkheads, promoting rot in the marine ply. You cannot see this because the bolted joints are hidden behind the beautiful cabinetry but, if left unattended, it can result in the bolts tearing through the rotten timber. A sure sign of approaching failure is a bulge in the side deck around a chainplate penetration - you can check for this with a straight edge on the deck. It's good to ask the vendor when he last resealed these plates.
The long and wide hull to keel joint is made with carbon steel studs, nuts and backing plates. If these have been left bare and water sloshing arund the bilge, they will look very rusty, which seems to concern any surveyor under 50 years of age. Owners who have drawn studs for inspection generally find that itis only the visible parts in the bilge that are corroded the working part of the stud being as new. However, if the mastic joint has failed, letting seawater get at the stud , then it may be a different story. If you get a chance to watch while the boat is put down on its keel after being lifted out, watch to see whether water oozes out of the joint - if you see that, the joint is at least failing, if not failed. remaking the joint is not difficult, but requires access to lifting machinery which can handle the hull and the keel separately, remembering that each weighs several tons.
The original water tanks were aluminium, a strange choice. and if they have not been replaced they probably have some unpleasant looking corrosion inside. The fuel tank, under the starboard side of the aft berth was originally mild steel so may suffer from corrosion (internal or external) leading to leakage through welds.
The teak seats and sole in the cockpit were originally made with teak faced ply - most of which will be delaminating by now in a boat which is used. Most will have been replaced by now with solid teak or one of the synthetic teak materials such as Flexiteek.
These boats are getting older so there condition is more dependent on how succesive owners look after them than how they were built, but they are comfortable and surprisingly good performers for cruising yachts, so a well kept one is a great find.
Peter.
