I suppose all of us yachties believe that our boats are more valuable than what the market dictates. For example if a Crowther 32 cat was built in 1986 and valued at $300,000 including tax,
I guess the owner's accountant would apply an annual depreciation, if 10% was the figure, 17 years later the boat's book value might read $50,000.
All that said, multihulls in this era, do hold their value compared to monos. BUT they must come from a good stable and have been well looked after and maintained.