200 hpdi on a 18

[bigblockdock]

Coyote, That's moving! I'll try raising the motor up a hole at a time and maybe get a few more r's. The rpm for the 150 tops out at 5600, 5300 is a tad low. I had a 93 200 merc on a gambler bass boat, it would turn a 26 inch pitch but the boat would chime walk at about 74. It was a custom prop from NY, 4 blade. Tried everything but solid mounts to get it right, sold it in 95. Try this for your speeds; RPM Divided by gear ratio ( I believe 1.87 for a 200)equals prop rpm, X prop pitch(equals inch per minute) divided by 12 (changes it to feet per minute) X 60 (per hr.)divided by 5280 (feet in a mile) equals your speed, then minus 5 to 15 percent for prop slippage. There is a shorter formula by merc but I cannot locate it right now. My mirage has 7% slippage according to the GPS reading. You are right on the money with your boat so if you got the speed from a speedo, its very accurate. Seems hydraulic steering is the way to go. It's being used on alot of boats now. the cable in the 18 is new but when it gets stiff, I'm switching over to hydraulic. Butch