i just got a 30' chris cat. I've got #3 drives with extension boxes. i installed 900sc that dynoed right at 900 hp could get 1000hp. the motors have been moved 2' forward. what speed will this boat do?

I would imagine you would see 105+

If you're making a LEGIT 900 HP, you'll see more than that. The boat can be weight sensitive, and some of them were potentially heavy (particularly the balsa-cored boats of 1984 and early 1985). Not sure what year you have, and if it is a pleasure or race version. Prop shaft height is also critical: with standoff boxes you would want the prop shaft to be approximately 2" above the bottom of the boat. From the photos, that seems to be about right, but the setback doesn't look like all that much, so it is hard to tell. You may have to play with shaft height.

We had a 1986 full pleasure version with #IV drives on full stand off boxes. With about 800 HP (guesstimate- never dynoed) she saw 112 MPH in a measured kilo run in Key West. My guess is you should see 110-115 with the prop choices that you have available today, maybe more.

Good luck and be safe!

Tom Caruso
Total Marine

mine is an 86 i dont know if it is a pleasure or race. it looks like fiberglass hull with some kind of foam board that has been fiberglassed over for the transom and interior peices.

faster then 105. Look up the threads posted by greencard. He has a similiar setup with a little less HP and runs quite a bit better then 105. He gives the specs on his in some of his posts.

Those are either #4's or #5's not 3's !!!!!!!!!

Cool, i think they are 4's but easy 110 + MPH with the right props , i would go with some 4 blades and 17.5 diameter.

My 85 Chris Cat is running low to mid 90's with 600's so i think 110-115 should be easy for you.

what drive set-up do you have ,gears and props?

nice older set-up....have fun!

why is everybody saying how heavy these boat are? i weighted mine and its only 10000 lbs on the trailer. my trailer has to weight 2000 lbs.