FOREVER YOUNG

I have an 86 Chris Cat with 560hp motors. I haven't been able to reach the top speed I was hoping for (top speed is 80MPH). The props are currently turning inward and the boat gets squirrelly at that speed. I was told that turning the props outward would improve handling. Any suggestions?

ve3lt

Do you have a "Link Bar" joining the two drives?

jeff32

a guy in the classified has an 84 twin hp500. He claims to run in the 90's so something is wrong with your boat and it's probably more than the side of rotation of your props... Are you sure the engines still pulls 560?

FOREVER YOUNG

I Do Have A Tie Bar Between The Drives. The Motors Only Have 17hrs.on Them.the Dynos Show 560hp.i Talked To American Dffshore And They Told Me That This Hull Design Has To Run The Props outward Because inwards The Props Are In Dirty Water. This Is An Old Coast Guard Boat. It Has Two Gas Tanks Of 100 Gallons That Run Farther forward Than The 50 Gallons On Todays Boat. with the extra weight Maybe It's Not Getting Enough Air To Lift. also it has ssmll and borg warner trans.

jeff32

pictures?

bobkatz

Each boat is different on prop rotation, try them out and see what it feels like. Send a PM to Greencard, he has a chris cat, it starts to hop around 70, then he can drive through it. What is the boat doing that is bothering you? Hopping up and down, like its trying to pack air, side to side, etc... Also what kind of water are you on, rough, dead calm?

FOREVER YOUNG

i will try and get some pictures as soon as possible. the lake i live on is fairly calm. i'am in the process of turning them outward. i will keep you posted. our lake is low right now so it maybe a month or so before i will get to try it. it wants to walk around from side to side at around 70 to 80 mph.

ve3lt

Don't know if this will help or not but anyway...

http://www.go-fast.com/Prop_Slip_Calculator.htm

http://www.rbbi.com/folders/prop/propcalc.htm

rdoactive

I had the same boat. My 525SCs got it to 100mph.
First off, check your X dimension. Some people put SSMII drives on boats that came with TRSs. If the prop shaft is several inches below the bottom of the hull, that's your problem.
I've tried both rotations. The "clean" water comes through the tunnel. Turning them in gave great stern lift, faster planing, and 20mph more top. I also as running 4 blade props, they seemed to grab better than the 3 blade.
Gary

FOREVER YOUNG

the center of the prop shafts are even with the bottom of the boat. i'am also running 4 blade props. they are 17in 30pitch.with the formula giving above 1.50 ratio 30 pitch prop 5000 rpm speed was 94mph add 10% slip its 84. i'am running 80mph gps. other people with the same boats are runnig faster with less power. i will keep trying different things till i find the problem. keep the suggestion coming.