[chrismahon]

I'd contact your nearest Marina to find out about the boat- they usually have a second hand sales area and will know the local market. They may be able to sell it for you or perhaps buy it? Hopefully it's on a roadworthy trailer, otherwise it may cost more to move than it's worth? There should be a manufacturers plate on it somewhere.

[SallyintNorth]

How frustrating!

If you really want to have tried everything to contact the catamaran's owner, the solicitor they used for your purchase should be able to forward a letter?  That really would be everything you could try. 

No idea on catamaran value, sorry.  I suppose you don't want to list it on eBay, understandably.

[Womble]

If anyone knows what a small catamaran is worth I壇 be greatful.

@Melias farm  - does the catamaran have a cabin? If it does, I'm the wrong person to ask. If it doesn't, if you send me some photos, I can probably advise on what it is and what it's worth.