Help from Sceptre Owners

[schooner]

Hello,
I have just repowered my '85 Sceptre with a new 225 Johnson-Suzuki 4 stroke and am still having trouble dialing in the prop. Center consoles with equivalent power seem to be getting 10-20% more speed through the range. Should the extra weight of the deck and cuddy make that much difference? Currently swinging a 15.5x19 prop and getting statute 19 mph @ 3500 - slip=28%
23 mph @ 4000 - slip=24%
27 mph @ 4500 - slip = 20%

The motor is mounted as low as it will go and the anti-ventilation plate is about 2 inches above the lowest point of the vee at the transom. WOT is 5600. The above numbers are with about 100 gallons of fuel, 2 POB, and the canvas up.

Would be grateful to hear about the set-up for Sceptres with equivalent power and how performance compares. Wondering if what I am seeing is acceptable. MPG is around 2.5 across the range. Thanks very much.

[JohnB]

I have a merc efi 250, so these numbers might not be much help. Also, do you have a top on the boat, that really drags them down some in speed/etc.

My best cruise/efficiency is 3800 rpm, 13.8 gph, 27 mph, 1.8-2.0 mpg. When setting up a boat, I always look for the best effiency cruise, top end dosen't mean much, as long as your getting all the rpms out of the motor.

I am swinging a tricked powertech 4 blade stainles. The 4 blades really seem to have some lift to help get the stern out of the water.

[joema]

i just put 250 suk on 80 septer 16 21.5 5400 37 knots so so bottom going to try 16 20 ilove it wisper quite those # on full tank

[schooner]

Thanks for the replies. Joema, Please clarify knots or statute MPH. 37 kts is about 42 MPH. Is this correct? I agree on the motor, smooth and quiet.
Thanks again.

[joema]

It is knots by gps looks like a good weekend going to monomy at o dark thiity

[eggsuckindog]

The Zuk's have a lower gear ratio than other motors so props can be difficult to figure, does sound like a 17 would be better. They swing much bigger dia. than other motors so comparing is hard just an FYI. That does sound like too much slip though.

[joema]

16 20 5900 rpm 36knots 80 septor 250 suk