Inheritance Tax or Capital Gains Tax on boat sold over probate value

Hello helpful people, Currently dealing with someone's estate after their death. The probate valuation has gone in and the value is currently under IHT threshold. Part of the estate includes a boat which was independently valued at £3,000 and that's what went down on the probate documents. We're now being offered £6,000 for the boat by a buyer because of some unique features of the boat that make it desirable to them. If we realised a sale of £6,000 what would be the implications of this? If the boat had originally been valued at £6,000 the estate would still not have surpassed the IHT threshold. I have read it could be considered capital gains because of the difference in valuation and realisation, but I also saw that boats with an engine are considered depreciating assets and so not subject to CGT. Do we need to submit IHT documentation regarding the difference, would there be CGT costs to the estate? Any guidance appreciated!

Hi 

If classed as a wasting asset under  CG76909 - Wasting assets: yachts, ships and other vessels then no gain arises.

Thank you