"diesel is more where im leaning towards. The fuel efficiency is a lot better."
Cruising speed is about the square root of the waterline length, so about 6K for a 35-40ft boat .
A diesel that will push a boat up on the plane at 30K will be 350=400HP and will indeed suck fuel at a wallet busting rate.
Get down to 6K and you will only need 35-50 hp at the most.
A gal of diesel fuel will create about 15 hp when operated slow (inefficient) the gal of gas will create 10+ hp most times.
A 400hp diesel dies rapidly from a large number of causes when run at 1/10 of its rating , and burns way more fuel than it should.
Gasoline does not suffer from this hassle , so the 440 Chrysler or whatever will be not dieing a rapid death from underloading.
At 30 -45 HP it takes a long time to pay for a diesel tune up, compared to a gas one.
A new gas crate engine can be had for 1/6 - 1/10 the price of a diesel.
Spark plugs are $3.00 each injectors run $75 for a rebuild to over $1,000 each new , depending on the engine.
6 quarts if oil? ,,,,6 Gal of diesel rated oil? $5.00 filter / $35.00 filter?
If you were a commercial operator and ran thousands of hours a year a diesel of proper size , well loaded would be first choice.
Most rec boats seldom see 200 hours a year .
The cost of boat ownership is what is known as the round trip.
Initial cost , repairs, operation expense , up keep (like PM) , deducted from sales price at the end.
Usually gas will be far less expensive (if all the required maint is carried out) than a diesel boat with its diesel required maint.
AS diesel maint is expensive , many owners do not bother to follow "Da Book".You get to pay for what they saved on as later owner.
Bigger boats , no big deal, only carrying over 6 passengers for hire is a big deal.