I get tired of hearing fuel isn't the biggest cost of boating. For a very high number of people it's a very big expense. If I had the boat I'd like and cruised a lot more it would sure be enough to whine big time on TF and elsewhere. But out of necessity I don't have that boat and have no need to whine.
But as trawler people taken as a whole this fuel burn issue is big for many. Couldn't be otherwise w all the verbage, posts and threads directed at fuel consumption. There's even a thread on fuel prices. I'd say fuel IS a big expense and those that say it's not could be bragging a bit about how much money the've got. Generally speaking of course.
I agree with what you say for the most part. When one says it isn't the biggest cost, they are trying to imply it isn't an important cost. Yet, it obviously is to a lot of people as much as it's talked about here. A huge percentage of those posting here run their boats at the speed they do to conserve fuel vs a couple of knots faster.
In our case, we have a detailed line item budget so maintenance isn't lumped but we have separate categories for engine vs gens vs stabilizers vs thrusters vs painting, etc. Now the largest line item of our budget is depreciation. Ignoring depreciation and salaries, fuel is our largest single expense. It ranges from 8% to 25% depending on the boat and usage.
Just because fuel usage might not be important to us or someone else doesn't mean it's not a significant expense for serious cruisers and I would guess it gets mentioned in more posts here than any other single subject. I think it's fair to say in most cases that fuel is a relatively small percentage of total costs, but it's still significant.
Whether it's a big enough expense to influence one's boating is for each individual boater as it depends on their financial situation. However, if we were looking for a way to cut costs, the easiest way for us would be to slow down and save fuel.