93’ Bass Tracker 40hp Prop Suggestions?

[JakeTheSnake8]

Hey Everybody!

I have a 93’ 40hp evinrude 2 stroke (TE40ELETB) on the back of my 93’ Bass Tracker Pro 17. The Prop I believe is OEM and is pretty beat up. It is a 11 3/4 x 17 Aluminum 3-Blade. WOT right now is 5500RPM which is max of manufacture recommended 4500-5500. Speed is in the low 20’s.

I would like to see more stern lift with a new prop as the back end prob has 80% of the boats weight and really dogs with 2 people riding at anything less than 100% throttle. Open to any suggestions that wont put too much stress on the engine or push WOT RPM over 5500...

SS?
4-Blade?
Diameter/Pitch change?

Thanks!

 

[WesNewell]

First thing I'd do is set the trim tab back straight. It appears to be way off to one side at aboiut a 45 degree angle. that's going to rob you of a lot of power And you are under powered to begin with. might then try a 4 blade prop, same pitch.

 

[JakeTheSnake8]

First thing I'd do is set the trim tab back straight. It appears to be way off to one side at aboiut a 45 degree angle. that's going to rob you of a lot of power And you are under powered to begin with. might then try a 4 blade prop, same pitch.

I am assuming you are referring to the top of the picture below? It came this way when I bought it, I can loosen that bolt and adjust back straight though. Why would someone turn it? This is my first outboard motor boat so trying to learn the different parts..

Also, I have heard when switching from a 3 blade prop to a 4 blade, you'll usually need to decrease the pitch by 1 or 2 inches to keep the engine RPM in the same range. Any truth to that since I don’t want to gain any RPM?

 

[WesNewell]

yes, the trim tab is to compensate for prop rotation trying to turn the engine one way or the other mostly during acceleration. As for lowering pitch going to a 4 blade, you are correct. But you're running at max rpm now, so going to a 4 blade at same pitch shouldn't be a problem to lower max rpm a bit. the other thing which can cause a big loss of power is the engine mounting height. Mounted too low causes increased drag and loss of rpm by the lower unit of the engine. With the av plate in line with the hull the av plate should not below the hull bottom. If it is, it can reduce power by as much as 20% depending on how low it is mountedand also loss of rpm.I can't tell from those photos how low it is mounted. Just something else you need to check for max performance. With a light load and your setup, you should see speeds of at least 30 mph at wot.

 

[JakeTheSnake8]

yes, the trim tab is to compensate for prop rotation trying to turn the engine one way or the other mostly during acceleration. As for lowering pitch going to a 4 blade, you are correct. But you're running at max rpm now, so going to a 4 blade at same pitch shouldn't be a problem to lower max rpm a bit. the other thing which can cause a big loss of power is the engine mounting height. Mounted too low causes increased drag and loss of rpm by the lower unit of the engine. With the av plate in line with the hull the av plate should not below the hull bottom. If it is, it can reduce power by as much as 20% depending on how low it is mountedand also loss of rpm.I can't tell from those photos how low it is mounted. Just something else you need to check for max performance. With a light load and your setup, you should see speeds of at least 30 mph at wot.

Thanks for the tip! Just checked and it looks pretty inline with the bottom of the hull (see pic) so I think we are good there. The main issue I am running into is the prop is so small for the little 40hp engine that there isn’t a lot of options for replacement. Per the pics below, they don’t make a 17” pitch four blade. The highest pitch I can find is 14” (diameter can’t be over 12”)...

Should I just go with a new SS 12x17 and see if that helps performance at all?

Thanks again!

 

[JakeTheSnake8]

First thing I'd do is set the trim tab back straight. It appears to be way off to one side at aboiut a 45 degree angle. that's going to rob you of a lot of power And you are under powered to begin with. might then try a 4 blade prop, same pitch.

One additional note on this... Just adjusted it back to “straight” and noticed there is numbers on the fin. It was set past 6 and putting it straight was at 3 (putting it to zero made it slant the other way). However, this fin is actually cupped as you can see in the last picture, does that make and difference?? Thanks!

 

[ahicks]

I have a very similar boat (17' Polar Craft) I use for testing 40 and 50 hp Honda outboards. I think 17" pitch is way too much, which might also explain why the boat is so doggy. I use 14" and 15" props when testing.

If you are getting 5500 from that prop, it may have been cut down or repitched at some point.

4 blade not a bad plan, but there's NO reason to pay for stainless. They will have nothing over an alum. prop, other than the big "clunk" when they're put into gear due to the extra weight.

That trim tab is used to counteract the steering wheel pulling at your favorite cruise speed. Agree, when way over to one side like that it's going to be more about drag than counteracting steering wheel pull.

Last, I would get the boat weighed to see how close it is to the manf. listed weight. It's pretty common for boats this age, especially the Trackers, to have water logged foam flotation, which can add a couple hundred pounds of weight pretty easily - and most of that will be in the back....

 

[WesNewell]

What's the gear ratio for that engine. if it's the same as a 40 hp Johnson, then it should be 2.42. And at 5500 rpm you should be doing about 30 mph at 10% slip at wot. Personally i like ss props because they don't damage as easily as aluminum and i fish the woods.

 

[JakeTheSnake8]

I have a very similar boat (17' Polar Craft) I use for testing 40 and 50 hp Honda outboards. I think 17" pitch is way too much, which might also explain why the boat is so doggy. I use 14" and 15" props when testing.

If you are getting 5500 from that prop, it may have been cut down or repitched at some point.

4 blade not a bad plan, but there's NO reason to pay for stainless. They will have nothing over an alum. prop, other than the big "clunk" when they're put into gear due to the extra weight.

That trim tab is used to counteract the steering wheel pulling at your favorite cruise speed. Agree, when way over to one side like that it's going to be more about drag than counteracting steering wheel pull.

Last, I would get the boat weighed to see how close it is to the manf. listed weight. It's pretty common for boats this age, especially the Trackers, to have water logged foam flotation, which can add a couple hundred pounds of weight pretty easily - and most of that will be in the back....

Thanks for the info! I am leaning towards the 4 blade just having a hard time finding one that fits. When you find one in the 11-12” diameter range, they are all like 10” pitch. The best I can find so far is the SS 11.5x14 I posted above but I’m kinda afraid it will increase the RPM over 5500 and cause extra stress on the engine... Boat and trailer are gettin weighed next week for trailer registration so I’ll check the numbers, thanks!

 

[JakeTheSnake8]

What's the gear ratio for that engine. if it's the same as a 40 hp Johnson, then it should be 2.42. And at 5500 rpm you should be doing about 30 mph at 10% slip at wot. Personally i like ss props because they don't damage as easily as aluminum and i fish the woods.

Gear ratio is one of the few things I don’t know on this engine but I would imagine it would be the same as a Johnson 40. Motor model is TE40ELETB if you have a way of looking it up? I was out last week and believe with me and one other in the boat we were doing about 23 WOT. I fish a lot of flooded timber so SS might be the way to go... lol

 

[JakeTheSnake8]

So... after much research they basically don’t sell a 4 blade prop in the 11.5” to 12” range. They jump from 10 to 13. Anyways, if that forces me to stay with the 3 blade should I just get another 12x17 or drop to a 12x15 as suggested above and hope the prop I had was just so beat up it was causing irregularly high rpms? Any other way to lift stern with a 3 blade? Thanks!

 

[WesNewell]

If you're maxing out rpm at wot you do not want to drop the pitch. That would put you above max rpm. Make sure your engine is at it's lowest trim before taking off.

 

[JakeTheSnake8]

If you're maxing out rpm at wot you do not want to drop the pitch. That would put you above max rpm. Make sure your engine is at it's lowest trim before taking off.

Ugh, guess I’m stuck with just getting a new 11.75x17 then? The engine trim is all the way down.