We can always make it better---right???

[karbine98]

Have a 1978 Sea Star Spoiler deep V 888 18 footer with inline 6cyl engine. 2,200 lb empty weight. Engine was new about 6 yrs ago, 3 yrs before we got it. Runs very nice, but with the 15 X 19 aluminum prop WOT revs would reach upper 5,000's and supposed to be ~ 4,300-4,500 per manual. Got a 21 pitch stainless which I'm told was a large jump, but still WOT over 5,500 rpm. Don't really want to invest a lot more $ -who does- but sure liked the extra performance I had when cruising at ~5,200 rpm--before I knew I wasn't supposed to exceed ~4,500. Engine stayed right at 150 degrees. I'll keep my eyes open for an inexpensive (?) 23 or maybe 25 pitch stainless prop. How would 4 blades work--does that lower WOT any? Is it essential to keep WOT below 4,500? Love this boat and folks at marina with big $ new boats always come over and check her out. Thnx in advance for any advice. Greg

 

[flyingscott]

I would give your tach a serious look over that does not sound right at all.

 

[Bondo]

Ayuh,.... Agreed,... Cross check the tach against a known value shop tach,.....

Yer numbers are suspicious,...

What drive is behind the I6,..??

 

[gm280]

karbine98, until you verify you tach is reading correctly, don't buy any more props. If your prop is reading correct, then buy a prop that will put your WOT in the proper RPM range. JMHO!

 

[karbine98]

Great advice as always. I too wondered about the accuracy of the tach as it sometimes goes out altogether. I will get it checked when I get it out of storage--my barn--and get it ready for the coming season. Really purrs and planes well at 5,200-5,400 on my tach. I also need to check my speed per GPS if that's accurate. Speed on the Missouri River with good current gets up to ~40mph when I was at those higher revs. I'll let you folks know how the tach checks out. Oh and the drive is the "Pre-Alpha" MC or MR 1 I believe. Don't think I'd have spent any more on it anyway, but have that nagging habit of wanting to make things better even when they are real fine.

 

[steelespike]

To say your tach is off is an understatement. A quick calculation at 5200 rpm a 21" pitch would make about 55 mph
40 mph with the current is in the ball park.I'm guessing the 21 is too much and the rpm rating is about 4200.
Someone should be along that is better acquainted with the 165 / 3.7