That isn't bad at all. As a comparison, my father's '82 Sceptre ran 40mph/35 knots at it's best with a full enclosure and bottom paint, and that was with both a '89 Evinrude 225 looper and '96 Yamaha 225 SWS.

I have a 23 Tsunami, full top with a df 250 on a 12 inch set back aluminum bracket. I'm running a 20x16 suzuki 3 blade and getting 40 knots at 6100 with an offshore dive load and a couple of buddies. Can you trim the motor and gain speed and rpm? If so keep moving her up. This photo was before I changed props.

5650 was all I could squeeze out of her trimed up w/light load.There is only one hole left to go up.
I bought a 16x17 prop but didnt get to try it out yet.I'll raise her one more hole and see what happens before I change props. At least I have a spare now.

http://img.photobucket.com/albums/v6...0515111755.jpg

That is a 30 inch motor.... right? also, are you running a 4 or a 3 blade prop?

Yes 30 inch motor on a 30 inch new transom. Running a 3 blade suzuki prop.
6100 rpm at 40knots with a 20 inch prop
are great numbers.
Why did you put a jack plate on your Tsunami ? Was the motor on the transom at one point?

The transom was built for 25 inch motors so the plate not only made up the difference, it gave me some cleaner water to run in and left me lots of room to walk in from the dive ladder. I'm almost wondering if you should do a compression check. I had power issues with my motor due to carbon build up on the valves. (Crappy ethynol gas) I ran a bunch of ring free through it and have been running maintainance levels of Lucas and have regained full, like new compression and power.

Another problem may be that someone changed the pitch of that prop. I have run into that with other boats and it really through me for a loop. It sounds like your getting close to the expected speed but the rpms are off. Somethings up but I don't think its a big issue.

I will try some ring-free but I mostly use Val-tech fuel at my marina that claims to have all the additives for ethanol in it.The prop came from the dealer with the motor so I don't think the pitch was changed.I should have my new prop by this weekend.If I loose a little top end that's fine as long as I'm in the upper rpm range Ill be happy.Thanks for your help.