For anyone contemplating a purchase in this size range, the ideal choice becomes rather clear. Remember what I said about operating engines on the edge of their power range. Notice that the diesel engine torque curve begins to flatten near the top. That means that for slower boats, at the very point you need the most power, is the point where it begins to fall off. The Dilemma Most questions of choice arise for boats in the 28 to 34 foot range where either type of engine is available with adequate horsepower.
Gas engines have the advantage that they are cheap to buy and cheap to repair .
For the price of a smaller, in-line 6 cylinder diesel, you could buy two gas engines. The advantage of the diesel comes only at the point where the extra torque is needed because a gas engine would simply be under too much strain to have an adequate service life. If you are planning on some serious long range travel, particularly if fuel stops are not available, then fuel consumption becomes and issue. But considering the cost of the engines versus the amount of fuel you will burn during your period of ownership, fuel savings in monetary terms is a non issue. Cost of Ownership Initially, the cost of maintaining the new diesel engines is low.