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Prop Comparison - Enertia vs. Revolution 4

Ok I took the boat out this evening. Calm winds. Just myself (the dogs were PISSED). Again, this is the prop I've had on the boat (15.5 x 17P stainless), not the new Enertia which arrives tomorrow: I have a 1.43 gear. All speeds/times are with the outdrive trimmed at optimal level. I have a 55 gallon tank and it was just less then 3/4 full according to the gauge. Full compliment of gear.

RPM's Speed(mph)

1000 4.4

2000 10.6

3000 23.3

4000 33.6

WOT: 4400 RPM's @ 39.3mph (a little faster than last year). Max RPM's for my engine is 5000.

0-30mph: 8.6 seconds - I checked this several times and did an average.

Will probably be the weekend before I get the new prop on and repeat these tests.

Keith
 
Nicely done!!

That would be about 21% prop slip at WOT according to the Merc calculator.
 
It arrived today! Photo to prove it:

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Isn't that a beauty! Now go put it on Keith. B)
 
Very nice. My guess is 42-43mph @4600-4700. Now, like Carl said, get busy!
 
So as I was removing my old prop I noticed that the prop nut was not only finger tight (was supposed to need a 1 1/16 inch socket to remove this) it was even seated all the way down against the thrust washer. When I removed all of that I had a decent amount of fishing line on the shaft (yes I know this can and does occur....and yes I did say shaft Derrik). Would this have been causing some of my slip issues?

Also, after I put the new prop and everything on, my Volvo manual states:

8. Install and tighten the propeller nut until it is seated against the thrush washer.

9. Loosen the nut, then turn it back against the thrush washer until finger tight. Tighten the nut an additional 1/3 to 1/2 turn.

It is pretty much effortless to tighten it that extra 1/2 turn...I say this because of what they say at the end:

10. (cotter pin stuff)

Before your next outing, use a torque wrench to tighten the propeller to 70-80 ft. lb. The thrust washer, nut, keeper, and cotter pin must be installed as show.

So right now I have it all together after tightening that nut 1/2 extra turn past finger tight. Is that good enough or do I need to remove the cotter pin and tighten it farther?

I'm not real sure about taking it out and retesting everything until I hear back from you guys and I will also send this to Propgods. I am wondering if I should have tightened the old prop nut and then retested everything. However, I'm not real sure how tight it really needs to be because after you tighten the prop nut you put on the keeper and cotter pin so it's not like it's ever going to be able to loosen up right?

Keith

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That first line should read, it was NOT even seated all the way down.
 
The fishing line wouldn't cause slip but it can cut your lower unit seals resulting in water intrusion to the grease, so it's good you found that.

I don't know Volvo's, but as far as tightening, follow their recommendations to torque it. The cotter pin is a stop gap to keep from losing a prop if the nut comes loose. If too loose, it might cause other problems like vibration and even damage the bearing carrier, and perhaps a very slight performance loss. Ken will know for sure.
 
Torque it. If you don't have a torque wrench, at least go another 1/2 turn and then the cotter pin. Make sure you grease everything well (splines). Also, the prop should be removed once a year while servicing to grease the splines AND look for fishing line. As was said by Tom, it could destroy the seal.
 
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I have a torque wrench actually. However, I will guarantee you it's going to be way more than another 1/2 turn to get anywhere near 70-80 ft lbs because I actually tightened it with my t-bar a couple of rotations before doing what I eventually did.

What kind of grease do I use on the splines (shaft)? The same stuff in my grease gun in the garage?
 
I use synthetic marine grease. You can get it at Tractor Supply.
 
Here's what Ken at Propgods emailed me back this morning:

When using the Flo Torq 2 hub kit, tighten the prop nut to about 50 LBS of torque.

Put a 2x4 between the prop and the antiventilation plate so it doesn't turn.

Torque it down.

Fishing line is not going to cause a prop to ventilate.

It can screw up your prop shaft seal, and leak water into your lower unit, so you might want to check that.

With the stock Volvo prop, having the prop nut loose isn't going to make it ventilate either.

Once you've installed the new prop, spin it, and make sure it spins easy, and doesn't hit the gearcase or the trim fin.

The most important part is the thrust washer. (large washer between the prop and the gearcase)

Make sure you get your old one off, and the new one on.

I had already decided that was what I was going to do anyway....torque it down to about 50 ft lbs, so I will do that this evening and then retest the boat.....can't wait.

Keith
 
cwag911 said:
I use synthetic marine grease. You can get it at Tractor Supply.
Click to expand...
I called a local marina guy who's walking distance from my house and he also lives across the lake from me....he's been working on outboards for 42 years including setting up racing boats. The guy actually has a PhD in physics. I actually called him to see if he sold the grease because I like to support him. He said he has never greased the prop shaft/splines and has never had a prop stick. Guess I won't bother buying that then.
 
Everyone has there opinions, but I've pried one off that took a couple hours on a used boat I bought. I think the previous owner never had it off, so now I always grease them. If you're taking it on and off every year anyway it might not matter.
 
Here's what Ken emailed me back about it:

I rarely grease them either.

If you have a little grease of any kind, you could put a little on the splines, but thats about all you need.
 
Here are my results with the Enertia (14.5 x 17P). That was a waste of $500 +.

RPM's Speed

1000 4.5

2000 10.1

3000 21.7

4000 34.4

WOT: 4500 RPM's @ 40.4mph

0-30 time: 8.6 seconds.

Pretty darn insignificant. I gained only 100 RPM's @ WOT and gained only 1.1 mph.

I emailed Ken @ Propgods so we'll see what he says. Wonder if he's going to have me try the 14.75 x 16P one....or the Rev 4.
 
Ouch, definitely not worth it. I wouldn't think going down one click is going to give you much either but Ken's the expert.
 
Of the two props Ken suggested, I figured that the Enertia would be a better choice over the Rev 4, since you seem to be more interested in top speed than overall performance. In all honesty, your particular boat / engine / Penta SX outdrive combination may not be capable of much over 40mph. However, I do believe that it is capable of better mid range cruising performance than what the Enertia is giving you. I prefer more diameter/blade area for cruising. If you'll notice, all prop manufacturers are trending in that direction also. There's a reason.

Note: If Ken tries to get you into a Powertec, good luck. Opinions vary, but all I can say is I'm not a fan and leave it at that.

My thoughts: I tend to stick with what works and is more affordable.

The Solas is a great overall performing prop in both aluminum and stainless..........and much more affordable. For the cost of an Enertia, a person could buy 1 stainless Solas and 1 aluminum Solas for backup and still put $100 in their pocket. That's a bargain.

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