'98 scarab sport- completely re-done with brand new 300 HP yamaha- Boat runs 64mph. It has bottom paint and I'm sure this is taking many mph's off at this point. Running 3 blade props. I think getting that boat closer to the 70mph range is quite a feat.

How is everyone trimming their boats to achieve top speed?

Trim motors way way up!

Ok, this is my first outboard boat I've owned.

Can you do anything to make them faster???

I think a 19 pitch on a 250 Yamaha OX66 is too little of pitch?

I have a 1988 scarab sport with 1996 merc 225 EFIs. The best i have seen is about 56MPH but my engines are old and tired. I am running 3 blade mirage 21p props.

I have a 98 with twin 250 Merc EFI's. If I go balls out, trimmed way up, 5900-6100 RPM's, I'm seeing 59- 61 MPH. I'm not happy with those speeds at all. I don't know the pitch or any other crap, but I do know I am a good 6 MPH slower than I was 5 years ago with everything the same. ( I know, it might be time to re-power, but that's alot of cash )

Not sure why every one with a center console fishing boat is so worried about speed, if speed is your desire sell your boat and get a Skater. there are plenty of people looking for good deals on 302 scarab's.

What's the big deal? Nothing wrong with trying to get the most out of your boat, kinda what this site's about right? :rolleyes:

Any truth to lowering tabs some amount creating additional stern lift at higher speed?

Are any of you guys running jack plates? I can tell you where I plane off and cruise is not the same setting on the jack plates where I find the best speed. Trimming the motors up creates bow lift but gives up efficiency by using power to lift the bow.

X-dimension as the I/O guys call it, or transom height of the propshaft in relation to the bottom of the boat, can also make a big difference. By jacking the gearcase further out of the water you reduce hydrodynamic drag which means it goes faster.

Before I went to jackplates, I did some testing with a drilled plate to move the motors up 3/4" at a time. I found that moving them up picked up top end speed to a point. I also found that as I moved them up, it took longer and longer to come on plane. Here's a picture of the plates. Simple T-6061 3/4" aluminum plate bolted to the brakets and the motor bolted to the plate with holes. At the best, I picked up 4 mph just playing with engine height.

http://www.speedcraving.com/scarab/plates/plate-1.jpg