[Yachting newbie]

I know I know, I was urge to buy a pre-owned trawler ( DeFever, Marine Trader, etc at $250,000 range ) instead of a motoryacht ( ChrisCraft '70 Commander at $50,000 range) the argument is, fuel cost and sea worthyness . But I see it this way (1) If all things beng equal, say both vessels will need a $50,000 refit , that wil bring the cost to $300,000 and $100,000 respectively, say the diesel engine on the trawler will cruise at 3 gallons per hour , and the motoryacht runs a gas engine or even twin gas engine at 15 gal per hour but may be double the speed. Won't the lower cost of the motoryacht be able to offset that of the trawler and more? As for seaworthynesss, I know the motoryacht won't match that of a trawler, but for $200,000 cheaper to acquire, may be I won't be so adventureous and head toward higher sea instead? My bottomline is if I can get a boat of a compatable size and at cheaper initial acquiring cost, I am willing to tade fuel economy and seaworthyness to a certain point. Do you guys see any holes in my thinking? I am playing the devil's advocate here , so do forgive me. But I do value the advices from you, the more experienced folks.