Seafari 25 performance

[cdavisdb]

Riser extensions will go on the boat in the next couple of months when I change manifolds, 4 inch for sure, maybe 6.

Made another discovery, there was something blocking the throttle lever and removing it increased the WOT rpm to 5200 with one person and a full load of fuel.

Had a bunch of people on the boat today, 4 adults, 2 kids and 150 lb of ballast forward. Not quite a Bahama load, but reasonably close. Re-ran some vacuum, rpm, speed data (see below) and found some interesting stuff. Putting the extra (~800lb) load in the boat dropped the speed in the 3000-4000 rpm range by right at 1 knot. The most efficient rpm dropped from 3400+ to 3200, roughly. Max rpm dropped about 150rpm with the increased load, 5050rpm heavy, 38.3 knots. I discovered that the most efficient cruise and amount of vacuum was highly dependent on the amount of tab and drive trim, which I had not been paying close attention to. To really dial in most efficient cruise, I will have to fix the trim indicator so I know exactly how much trim is on the boat and get a better tab system(the tab part is coming, soon). I did not have time to rerun the fuel economy, but my guess is it dropped to 2.4-2.5 nmg.

Previous comments about this hull needing weight to run right and Carl M's original plan to put a water ballast system in this hull seem right on target. The boat is so sharp and narrow in the forward sections that there is very little beam in the water. The chines at the transom are barely in the water when it is very light. Adding some ballast forward made a noticable diffence in how lively the boat was when at "rest" Putting a heavy load in it did not change how it handled when moving(at least, not much), but improved it when at "rest" or going slow. The roll was much less "quick"

Data with heavy load

rpm a------- vacuum---------knots

3000-----------10.1---------19.2
3200-----------10-----------22.6
3400-----------9------------25.1
3600-----------8------------27.1
3800-----------7------------29.5

Max rpm full fuel, one person 5200
max rpm with above + 800 lb 5050 38.3 knots

Connor