Seafari 25 performance

[seafari25]

Connor

Yes the steel tabs move with the piston and only attached to the bennett tab, no contact with the hull. The steel is sistered to the aluminum each with 4 bolts.

As far as I know, Gramps had the plates made while he was chartering the boat in the mid to late 70's on Lake Ontario. He replaced the original joy stick in the 80's with the double rocker still on now and I had the original actuators replaced a few years ago. Other than being upset that they cut holes in my inner transom when installing the actuators , no problems. Structurally, the steel has held up quite well. I removed the plates about 8 or so years ago and sandblasted them. I had to weld in a small patch on one that I blasted through and I coal tarred them. They'll last a few years yet but I think I might try making them out of aluminum next time.

I'm hoping the boat is out of the water by now and I'm planning to hit the cottage this weekend to pull the docks. My good camera crapped out but I'll try to get some close ups with the blackberry and get them up before she goes to hibernate for the winter.

Brandon

[Gary Hill]

When I repowered a couple years back, I had the four inch extensions on my engine. I looked at several boats and they all had them (of couse mine is a inboard).

[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

[Bushwacker]

Connor

I saw Carl at the OFF2009 Raceboat gathering and specifically asked him about how much water ballast would be appropriate for your boat. He said Potter didn't build the boat the way he designed it, and that he wouldn't bother with the ballast tank. Your observations are interesting though. Sounds like placing gear as far forward and as low as possible would be worth playing with. Did you get those props fixed? Sounds like you could go to higher pitch, now that you found that earlier run did not get to full WOT! I think that vacuum gage will help you find the "sweet spot" combination of optimum throttle/drive/tab trim. Keep us posted on what you find out! Denny

[seafari25]

Well, she was on a trailer awaiting cleaning and winterizing so I got a few shots.[image]http://[/image] [image][/image] [image][/image] [image][/image] [image][/image] [image][/image]

[seafari25]

Connor,Here is a pic showing risers per your PM [image]http://[/image]

[cdavisdb]

Outstanding pics! Just what I needed to show the welder.

Thanks

Connor

[strick]

Brandon-

Interesting that your boat's scuppers are in the stern while mine are a foot or so forward of the stern in the sides of the hull.

strick