Which Prop to Buy

[NYGiants]

I have a Johnson 8hp which i used for my sailboat. It has a prop that is meant for a sailboat on it. I plan on using this motor for a 12' rowboat and a Inflatable V-Bottom Dinghy.
The motor is a 1993 Johnson 8hp Sailmaster edition (its a short shaft also)
the motor model is j8srletb. Which prop should i buy for it? I don't know much about prop buying. Thanks

 

[hwsiii]

Re: Which Prop to Buy

Giants, , 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 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 planning hull boat that needs this information, and anyone else who is 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

H

 

[NYGiants]

Re: Which Prop to Buy

Thanks for the info
ill have to take the measurements tomorrow.
The boat has no info plate as its pre 1972

 

[NYGiants]

Re: Which Prop to Buy

. 1976 Lowe rowboat aluminum skiff (according to registration)
2. 11.5 ft by 4.5 ft im not sure of the weight
3. 2 people about 350 lbs and 3 and sometimes 6 gallons of gas
4. fishing, crabbing and toying around in the river and bay
5. Is it a Deep Vee and if so how many degrees of deadrise
6. 1993 Johnson 8hp Sailmaster edition converted into short shaft
7. 8hp i dont know the gear ratio but the info on the motor is j8srletb
8. Manufacturer?s recommended WOT range- Do not Know
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

Do Not Know The Last Three, but im looking at this prop
http://www.ebuyersworld.com/Rascal-Aluminum-Boat-Propeller-Prop-R4-0909-p/r4-0909.htm

 

[hwsiii]

Re: Which Prop to Buy

Giants, I can't verify the gear ratio of your motor, but I do show a 1996 johnson 4 stroke 8 hp with a 2.42:1 gear ratio. If that is correct you should be running an 11" pitch prop on that setup, assuming overall weight to be about 700 pounds and the boat is about 200 pounds of that 700 pounds. Ifr you go with the rascal I would drop 2" in pitch that would mean the 9" pitch should work. But I know that an 11" pitch normal aluminum prop with a 2.42:1 gear ratio will work.

H

 

[NYGiants]

Re: Which Prop to Buy

does it matter 4 vs 2 stroke?
Because my motor is two stroke

 

[hwsiii]

Re: Which Prop to Buy

Not really, just the gear ratio. The four strokes have a different power curve than the 2 strokes.

H