book value is an accounting calculation. In this business, the vessels are huge capital asset that are depreciated. I would guess, having not seen the financials, that the book value is derived from newer vessels, (higher cost) less depreciation - yields greater book value. FRO's assets are probably older so they've had more depreciation booked to them and cost less. This metric probably isnt the best comparison - probably similar to airlines. It's accounting and not true company value. Hope that helps.