1984 20' Bayliner explorer need prop advice

Joined
Jul 26, 2015
Messages
4
As I mentioned in my title I have a new to me 20' Bayliner Explorer it currently has a 17" x 12? pitch prop. The boat takes a long time to get on plane and won't come up till the engine huts 4100 rpm's. I'm thinking a smaller prop might help. Any input would be greatly appreciated.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
We need your motor and hp.Is your prop definitely A 17" diameter X 12" pitch?
If you do a lightly loaded wot run and get us the rpm and gps speed.
we can help.
 
Joined
Jul 26, 2015
Messages
4
OK. I am heading out to the boat today to have another look at the prop all the reading I have done says that 17 x 12 doesn't make sense. The engine is a 4.3, when it was new it was rated at 170 hp to 190 hp depending on what article I'm reading. My last run my gps was not set properly but it read 53 klm at about 4200 rpm. I will recheck all these numbers today and confirm.
 
Joined
Jul 26, 2015
Messages
4
sorry for taking so long I ran into a, old marine mechanic at the dock and he hooked helped me out. my dad got the numbers for me and he got them mixed up so it's a 14"with 17 deg pitch. He had another prop I tried out that worked real well. it was a 15.8 x 15.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
As you discovered prop size is written Diameter X pitch. in inches Pitch means theoretically a 15" pitch moves forward 15" in one revolution.
Your boat would likely use a 21" maybe e even a 23" if the motor could;d spin them up to the wot rated rpm 4400-4800.
Light load in excellent tune your 4.3 would run right around 50 with a 21 or 23" prop.
a 23 would likely only be good for speed would struggle for hole shot and added weight.
If your 15" can make 4800 rpm your speed would be around 33 mph.
If we are going to get you setup right we need an accurate tach.
If you can do a light load wot test run remind us of the prop size, get us the rpm and gps speed.
Its important to be sure the motor operates within its wot rated rpm.Once we know its right you can run at what ever rpm you choose.
 
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