Can't find stock spec to get baseline for prop

[Wirenut8]

Hey all,

I am new writing on this board. I have been reading for a while. I have a 1987 Four Winns 190 Horizon bowrider. It has 5.0 4bbl GM 230 hp with an Alpha 1. I bought it from a guy who lake fished and wanted to troll as slow as possible. I will try to follow the required questions as best as possible.

Boat type listed above. Not sure of weight
WOT rpm according to gauge is 5300-5500
Fish finder says I am going 38 mph with wife and 4 kids
Current prop: Not sure of brand but it is a 4 blade 14.5"D, 18"P
I was trying to find what prop would come on there stock as I would like to be able to run wide open a little more without risking engine damage. It comes out of the hole pretty good for a bigger tug and would like to keep most of that for pulling me on the knee board, kids on the tube. But by the low top speed and high engine rpm the current prop can't be ideal. Any help would be great!!

Thanks!!

 

[steelespike]

Re: Can't find stock spec to get baseline for prop

While I agree you may need a different prop I don't think the 18 is extreme.
Your wot rpm rating is 4200 to 4600.
Your numbers don't quite add up. if your rpm is 5500 your speed should be about 53.
A gps is better for speed.Its also possible the tach is reading high.Does it seem like its screaming or does it seem more like its just working. A 18" 4 blade doesn't seem like a choice for reduced speed for trolling.It possible that he doctored the prop maybe flattened the pitch or cup.I think you need to verify the tach and use a gps for the speed.Some cells have a gps app.
You may be able to borrow a shop tach.