I understand, however the fuel
consumption goes up tremendously as soon as you approach
hull speed. We will use my IP 38 for example, she is 41' long, but has a waterline length of 33' which gives her I believe a
hull speed of 7.3 kts.
Her fuel burn at 7 kts is about double what it is at 6.5 kts, because I'm all over
hull speed at 7 kts. Now I am a
displacement hull of course so in reality there just is no real comparison, it's like comparing a Prius to a Ford F250 or something, but bear with me.
To use a ridiculous example, I met a nice couple in a 65' Viking Soprt Fisherman in the
Dry Tortugas this year, their
cruise speed was I think about 25 kts or something, so they were going 4 times as fast as I do, however their fuel burn was 120 GPH, so they burned 120 times as much fuel to go four times as fast. Now that is not apples to apples of course as they are at least twice as big a boat, but planing speeds cost horrendous amounts of fuel.
So then the idea is well, just slow down to less than hull speed, right? Two problems with that, then your likely mostly idling your big Diesels, and your boat is not really designed to operate at those speeds and your
steering is less responsive, and honestly it will drive you nuts. Its like driving your car at 20 mph, you can't stand it, you want to go cause you can.
Now when we would go out
fishing in our 36' Sportfisherman years ago we would go out to the middle grounds from the Panhandle and would take two or three 60 gl barrels of fuel on the swim platform to have enough fuel for the weekend, cause go fast boats go through so much fuel when going fast that they do not have much range, want more range means
ferry tanks or barrels or something.
Go fast boats don't usually have big
water tanks either, but you can fix that with a
watermaker, but that adds at least 10% to what you want to pay for a boat.
Please don't take this as an insult as none is intended, but if you can only afford to spend 50K on a go fast boat, you can't afford to take it to the Bahamas. Years ago it was nothing to go through $1,000 in fuel for a weekend's
fishing, but distances are likely the same as going to the Bahamas.
Now accept that 7 kts or so is an acceptable cruise and look for a nice
Trawler, and burn maybe 1/10 the fuel and gain lots of space that is not occupied with two huge Diesels, you have only one smaller one.