Thje Oceon range of yachts were built by Southern Ocean Shipyard located in Poole in Dorset. They are very solid construiction and rely on high quality solid lay up rather than low cost construction with a lightweight core. They were and still are very poular with charter companies because of their space and strong construction. I myself have been building a yacht from an unused hull (Contention 33 ft) moulded by SOS them for the last ten years ( it's almost finished now) and have found that it is very strongly constructed. eg 20 mm thick at the P bracket.
It must be realised that hulls of that age are prone to osmosis as at the time they were moulded technology had not advanced sufficently to prevent it.
It really depends on the general conditionm of the craft as to whether it is worth investing in. Look at Crightons Naturally as an example.
