In terms of what value you insure for , I believe the are two schools of though / routes insurance companies follow.
a. Current Value
b. Replacement Value
With current Value, then you would need a valuation to equate to the physical value or perhaps be accused of fraud in the event of a total loss. Total Loss brings to light the dangers of this route, as if it occurs you might have to find a substantial sum to replace your " home" to equal standard.
This risk does not occur if you are insured on a replacement basis , which I would suggest would be the better route to go down, because it produces a result that insurance is intended to produce, ie an no cost return to standard ( less of course any excess ). Also if it is partial damage, the question of deduction of depreciation from the claim does not happen as the replacement value of the item (s) would be paid.
In this case of replacement value the amount for valuation could be easily worked out without the cost of a physical valuation by using the current list price of an equal vessel or if not a standard one the new cost price + inflation.
This then leads to the grey area of what equipment fitted = structure and what is content , but that is another subject .
When I had to insure several million pounds of JCB & Cat plant, I used the replacement value method and could sleep at night !
However I am yet to insure a DB and would be interested if any of the current Marine Insurers do a replacement value policy , which I would certainly use when I get afloat next year, despite the extra cost due to the higher valuation.
If there is not an actual dedicated policy, then perhaps a declaration to the insurer that the Value requested to be insured is replacement and not actual might suffice ?
Regards Tim