I hope some one can help me out here. I am only getting 24 mph WOT 5300 rpms 4 blade 14.5x17 i tried a 15x17 stainless prop. 3 blade 15x17 got me up on plane faster and 24 at about 5900. I think i should be l closer to 35 40 mph. Any one have this same setup or any advice on prop size Thanks.
Please HELP 89 overnighter Honda 150
- Thread starter Mattyoung152
- Start date
Bloodweiser
Well-Known Member
- Joined
- Feb 10, 2020
- Messages
- 650
- Reaction score
- 168
- Points
- 43
- Age
- 51
- Location
- Northern Cal
- Model
- Seafarer
Maybe not your prop, how long have you had the boat ? What does the motor height look like ? How is the motor running?
Not an expert on the boat. But I had a 19ft aluminum with a 150hp di 2 stroke that barely scraped 42mph wot. Props are not going to give you an extra 15mph when your engine is at proper rpm at wot. If your trimming correctly, the engine is installed correctly, your bottom of boat is clean and not fouled. I think that is all your going to get out of it I'm afraid.
The fact that you got on plane faster with the 3 blade is not what I would expect. I would also expect a lower top end speed on the 4 blade prop. Something is not right.
How are you measuring your speed?
I suggest you call a prop shop like
propgods.com
and ask what they recommend.
I suspect the pitch is too small. Maybe a 15-19 is a better match based on one of the online prop selector tools
How are you measuring your speed?
I suggest you call a prop shop like
Propeller Testing Services | Prop Gods
Reach out to the dependable team at Prop Gods to ensure that your boat engine’s propeller is in peak condition.
propgods.com
I suspect the pitch is too small. Maybe a 15-19 is a better match based on one of the online prop selector tools
MooseheadDoc
Well-Known Member
- Joined
- Sep 16, 2020
- Messages
- 59
- Reaction score
- 12
- Points
- 8
- Location
- Moosehead Lake, ME
- Model
- Adventure
How long have you had the boat? Is this a sudden change in performance, or is this your starting point?
First question is to confirm you numbers if possible, as suggested by others. MPH should be easy (does GPS match speedometer). RPM might be harder, but if your tachometer is significantly off it will confuse the picture.
Assuming the MPH and Tach are correct, then you have a horrible prop slip mismatch on any of those props (I'm in a similar situation. see link https://www.greatgrady.com/threads/doing-the-prop-math-on-my-adventure-208.31044/)
Lots of factors to consider- high rpm with low mph + slow hole shot could be spun hub, but should be corrected with new prop. Similar problems with all props could be some combination of rough bottom, poor engine placement (too high or too low), heavy boat (waterlogged foam/transom), and other factors.
With the 17" pitch at 5300rpm your calculated speed at WOT (assuming a gear ratio ~1.9) would be 44mph with 0% prop slip (theoretical top end), or 35-40mph with a more typical 10-20% prop slip. If you're only getting 24 @WOT there is more going on than just prop selection. Good luck trouble-shooting, and please post any progress/solutions! I'm out of the water until Spring and will be tackling the same issues myself. Good luck............JB
First question is to confirm you numbers if possible, as suggested by others. MPH should be easy (does GPS match speedometer). RPM might be harder, but if your tachometer is significantly off it will confuse the picture.
Assuming the MPH and Tach are correct, then you have a horrible prop slip mismatch on any of those props (I'm in a similar situation. see link https://www.greatgrady.com/threads/doing-the-prop-math-on-my-adventure-208.31044/)
Lots of factors to consider- high rpm with low mph + slow hole shot could be spun hub, but should be corrected with new prop. Similar problems with all props could be some combination of rough bottom, poor engine placement (too high or too low), heavy boat (waterlogged foam/transom), and other factors.
With the 17" pitch at 5300rpm your calculated speed at WOT (assuming a gear ratio ~1.9) would be 44mph with 0% prop slip (theoretical top end), or 35-40mph with a more typical 10-20% prop slip. If you're only getting 24 @WOT there is more going on than just prop selection. Good luck trouble-shooting, and please post any progress/solutions! I'm out of the water until Spring and will be tackling the same issues myself. Good luck............JB
I would assume ( and maybe incorrectly) that when the OP changed the 3 blade for the 4 blade, the hubs were different and therefore a spun
hub would be eliminated as a cause. Of course, it is possible that props with adapter hubs were tested and the hub was reused.
As mentioned, it is important to understand how the speed numbers were measured.
Finally, I think the Honda may be a 2.14 ratio gear case.
To be honest, there could be a lot of other things causing a problem and we don't have a lot of info. Did the OP have this issue for the entire 300 hours of use since he got the boat? Has the hull been looked at for growth?
Where does the cavitation plate sit in the water when at cruise speed? Is the hull sitting low in the water?
hub would be eliminated as a cause. Of course, it is possible that props with adapter hubs were tested and the hub was reused.
As mentioned, it is important to understand how the speed numbers were measured.
Finally, I think the Honda may be a 2.14 ratio gear case.
To be honest, there could be a lot of other things causing a problem and we don't have a lot of info. Did the OP have this issue for the entire 300 hours of use since he got the boat? Has the hull been looked at for growth?
Where does the cavitation plate sit in the water when at cruise speed? Is the hull sitting low in the water?
agree with bloodnut I have a 19 ft tournament with a 150 2 stroke and the most I have ever got out of it was 44 knots and with your heavier boat and heavier 4 stroke I do not see you going that much faster maybe high 20 Knots my nieghbor has a 150 Honda on his 20 ft Sea Ray Cuddy and on a good day he will hit 30 knots
Last edited: