Asking alot of a little outboard. best prop pitch?

[Bman1337]

Got a pretty large barge. Its a Lowe 2200 Deck boat, had a suzuki 140 and it unfortunately blew a piston and never got repaired, well a few weeks ago i unintentionally bought a 40hp Force. a Mercury Marine era. It seems to run decently. The prop i got with the boat is a 12 1/4 x9pitch prop. Came off a larger pontoon so i figured it would have a lower pitch prop,

Now i know thats ALOT of boat to ask it to move. 22ft i believe. Im not expecting anything more than a motor just to putt the boat around and swim off it etc thankfully most of the hot spots for hanging out are close to ramps, That 9P the best chance prop wise its got? or is there a better pitch? not all to versed on prop pitch other then lower means more grunt and higher means more top end.

 

[jimmbo]

Welcome to iboats

You are going to need to know the Engine WOT Rpm Range, and some way of measuring Engine Rpm. I don't know what Range of Pitch is offered for a 40hp Force. Perhaps there is a lower pitched 4 blade. This is one place where a 4 Blade would be of Benefit. But you will need to have the other info, to know figure out then next move

 

[Bman1337]

looks like you can get from an 8p up to a 17p. motor WOT is i believe 4700rpm to 5200rpm. ill have to look into a tach. never installed one. I know the motor isnt up to the task power wise i just want to make sure i keep it as happy as it can be will putting along,

 

[Bman1337]

I'm guessing Forces(by mercury) use a mercury tach?

 

[Scott Danforth]

Got a pretty large barge. Its a Lowe 2200 Deck boat, had a suzuki 140 and it unfortunately blew a piston and never got repaired, well a few weeks ago i unintentionally bought a 40hp Force. a Mercury Marine era. It seems to run decently. The prop i got with the boat is a 12 1/4 x9pitch prop. Came off a larger pontoon so i figured it would have a lower pitch prop,

Now i know thats ALOT of boat to ask it to move. 22ft i believe. Im not expecting anything more than a motor just to putt the boat around and swim off it etc thankfully most of the hot spots for hanging out are close to ramps, That 9P the best chance prop wise its got? or is there a better pitch? not all to versed on prop pitch other then lower means more grunt and higher means more top end.

Welcome aboard

your deck boat would have been marginally powered with the 140. depending on year, there was also I/O versions with a lot more power

the 40 hp force even with the 9p will not get you anything but idle speed. the 9P is only 1 step up from the bottom. I would leave the prop on the boat and continue to look for a bigger motor

 

[Texasmark]

looks like you can get from an 8p up to a 17p. motor WOT is i believe 4700rpm to 5200rpm. ill have to look into a tach. never installed one. I know the motor isnt up to the task power wise i just want to make sure i keep it as happy as it can be will putting along,

Check out Tiny Tach. Wraps around a spark plug wire....crude but once you have your number you don't need to monitor it. Lawnmowers use them. I don't know if they have a 2 stroke adaptation or not. Cheap form of info.

If you don't prop for mid to upper RPM (recommended range) WOT your engine won't last very long.

 

[Bman1337]

From my understanding the 140 was 20 over the transom rating and I believe most of them came with a 120hp Johnson. And currently idle speed is all I really need it to do. All of our kids between me and my buddies are 4 or less years old. So even if I had 150hp I probably wouldn't go much faster than idle with the kids on board out of an abundance of safety. At the moment this boats just gonna be like a big floating dock/swim platform.

 

[airshot]

If running right and right prop ut should move you along at a decent pace. Your not gonna ski or pull a tube but slow cruising speed should work ok. I had a 22' cuddy cabin and had a 9.9 kicker motor on the back. With a low pitch prop I could reach almost 12 mph in calm conditions.. Your 40 should push you along over 15 mph...

 

[QBhoy]

Hi. Wishing you the best of luck in getting her propped suitably…but can I strongly and with the best intentions meant, urge you to try and think of this a temporary solution ? I’m sure there are some of these force engines that have managed to be reliable…but the vast majority of them have been problematic, to my knowledge. I’d think that this might be amplified a little, should you ask too much of it and make it work harder than it likely should be. I may be wrong on this too. But just check that the particular one you have acquired, isn’t actually a standard or short shaft. I have an incline in mind that some of these were. Instead of the usual long or XL shaft that you will no doubt require.

 

[Bman1337]

its 100% not staying there forever, but for now if i can get around with it a bit ill give it a go. I hadn't considered the shaft length so not sure what mine is, but it looks like its setting fine so far as foot length. this Lowe deck boat doesn't have a terribly tall transom.

If it manages more than 15 ill be shocked haha.

 

[Bman1337]

Looks to be sitting okay to me?

 

[aspeck]

Because of the angle of the picture, we can't tell for sure, but it does look at least close to the correct length and setting. Get a tach and check your RPMs, that is the biggest thing you need to worry about. The rest is gravy ... enjoy your moving swim dock! May it give your family much enjoyment as they grow!

 

[dwco5051]

I would invest 10 or 15 bucks into one of the "tiny tachs" to just check out what rpms you get with the present prop, When I got my present boat I installed one primarily as an engine hour meter but checking it out I found that is was surprisingly close to my shop tach and more expensive tach I also installed. Going from a 9 to an 8 will only give you 2-300 more rpm.

 

[Bman1337]

So update. Took it out for the first test. I managed to adapt the Suzuki controls and cables pretty nicely. saved me some money there. and let me tell you I'm shocked at how well it actually did. Now mind you I was only expecting 10-15mph tops. Like best case scenario. But it actually not only managed to plane out. It ran 20mph. Now that's just me on the boat and I'm sure a load of people is gonna slow it down, but I'm still very impressed. And yeah I need to get a tach as I'm sure that force was working it. but from the ole ear tachometer it actually didn't sound too strained. For a 100 dollar motor I'm more than satisfied.

 

[Texasmark]

If you got 20 out of it and snappy response you are pretty close on pitch for the load for the test. Yes more folks mean more strain on the engine but you can get the tach and check RPMs where you boat the most....prop for that and when running light, pay attention to over revving.