Donald Propst

Donald Propst

Recruit
Joined
Jul 2, 2009
Messages
3
I have just acquired(cheap) a 16 ft pontoon boat with a 40 hp force engine. It currently has a 121/2x8p prop. I dont have a tach, but it appears I have either cavitation or prop slip. The prop doesnt appear to be one with a rubber hub, so I am thinking caviatation, ecpecially with the 8 pitch prop. anyone have a similar setup and a prop recommendation.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Donald Propst

Donald, we will try to help you as much as we can, but there is certain information that is needed in order to help you. The following form has all of the information that is needed to help you with your problems in finding the right prop. If you do not know all of the information that is asked for on the form please give us the most information you have available as I have a program I designed to find the right prop for any planing hull boat that needs this information, and most other people who are trying to help you will need the same information. It requires time to find all this information when we have to look for it and in my defense I expect you to be willing to expend as much effort in finding the right prop as I do. We hope to be able to help you get the exact prop you need for your particular uses, and this information is required to do that.
It is not as simple to pick the right prop as most people coming to this forum think it is, that is why we ask so many questions, it is for your benefit we ask all these questions. And if you have a stainless steel prop or are changing to one the blade geometry of the prop can make a lot of difference in speed and RPM.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor
8. Manufacturer?s recommended WOT range
9. Antiventilation Plate height above keel of boat if it is an outboard in inches
10. Make, model, diameter, pitch and whether SS or aluminum prop
11. WOT RPM and speed from each prop if more than one prop
The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H
 

Donald Propst

Recruit
Joined
Jul 2, 2009
Messages
3
Re: Donald Propst

the boat is a 1986 Slyvan pontoon, the engine is a 1996 Force. Currently the prop is a 12x8. Problem is either cavitaionor prop slipping It is a thru-prop exhaust, but hard to tell if it has a replacable hub). Am looking at replacement props and they range from 8-17 pitch. Boat does not have a tach. Currently has one 12 gal. tank on port side and I battery also on port side in back, nothing on starboard side in back.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Donald Propst

Donald, I happen to have a 1995 40 HP force engine myself, though mine is on a flats boat. So I assume your has a 2:1 gear ratio like mine but I am not sure it has the same RPM of 4,750 to 5,250. I have looked for a Sylvan 16' pontoon but I don't have any information on the weight of that vessel, could you please give that to me, and can you tell me how many people you normally run the boat with and is it a two pontoon rig or a monohull. Can you also send me a picture of the stern at about the level of the anti ventilation plate so we can see if the motor is deep enough in the water to know you aren't getting ventilation.


H
 
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