topglock
Seaman Apprentice
- Joined
- Oct 29, 2011
- Messages
- 30
Hi folks,
I wanted to follow up on the Stainless vs Aluminum thread, but thought it would be better in a new thread. I've been in search of the best prop for my setup and think I've found it. SteelSpike, thanks for your patience and help in this project. My original post was to see if we could come up with some kind of correlation that could be used as a crossover for aluminum vs stainless. The following is what I found:
The application:
Boat is a 1992 NITRO 170 TF, your basic 17' fiberglass Bass boat of the time. Engine is a 2011 Mercury 75ELPT, 75 HP 4 Stroke, bolted to the hull with no jack plate. Cavitation plate is about 2" above the lowest point of the hull. Set up was tested with two batteries, one forward and one at rear, 20 gallons of gas, also in the rear, and two adults, with fishing gear. There was also a spare prop and small tool kit, forward. I make people and gear at about 450lbs.
Props:
Solas Amita 3 aluminum - 13.25 x 19
Solas Amita 3 aluminum - 13 x 21
True Turn Hustler aluminum - 13.25 x 21 vented (approx 1/4" vent hole)
Merc Laser II Stainless Steel - 13.25 x 20, also vented, with medium vent plugs (approx 1/4" dia. holes)
Here's what I found:
The 19p Solas was difficult to get on plane, however, this was before I moved one battery, spare prop and tools forward. That said, once on plane the engine quickly went to 6000 rpm, the max limit. Max speed was 44mph, GPS.
Tried the 21p Solas next, also before moving the weight forward and experienced the same hole shot problems. RPMs dropped to 5600, what I consider the sweet spot for the engine, and speed was again 44mph, GPS. This prop was damaged, beyond repair, hit a submerged stump, and subsequently scrapped. I'm including these first two props in the evaluation just to show where I started. The following props were the true test, for me.
Next, after moving about 70lbs forward and at the recommendation of SteelSpike, I tried the Hustler 13.25 x 21. Gotta say, I was impressed. Hole shot, from dead stop was still very poor, but from an idle speed of about 4mph I was able to get on plane in 4-5 seconds. Top speed, again at 5600rpm was 44mph, GPS. I'm feeling better...
I made a deal on eBay for the Laser II that I couldn't pass up. Bolted it on and went to the water. Basic configuration was pretty much the same. From a dead stop, the boat was on plane in 3-4 seconds. Engine went to 5800rpm, which I kind of expected, with 1" less pitch, and the boat made 45mph, GPS.
Both props got the bow well out of the water, with the stainless prop lifting the hull to the point where I actually had to trim slightly down to stabilize the boat. With the aluminum prop, I achieved the same stability at full up trim.
Conclusion:
For my setup, I found that, performance wise, there was not a great deal of difference in the props I used. The stainless prop sent the engine 200rpm higher, but it was 1" less pitch (Pretty much what you'd expect in like props), lifted the bow higher and ran 1mph faster. . Hole shot was definitely improved with the stainless prop, but again, 1" less pitch.
From what I've learned, if I ever have to replace the Laser II, I'd buy the same prop in a 21 pitch, if available. However, in my case, the difference in stainless vs aluminum is pretty much straight forward. In sizing the prop to the boat, there was really no difference. What I'd recommend, to those considering changing from aluminum to stainless, or vice versa. Consider your needs/wants. If you're looking for maximum performance consider the stainless prop. If you boat in the swampland, like I do, stainless will probably survive the stumps better than the aluminum. But, for everyday boating, the aluminum, with it's lower pricing, has a lot to offer. For me, the metal used in the prop made on difference in engine RPM. The difference, though, was in the performance...
Thanks again for all the help this forum provides. See ya'll on the water...
I wanted to follow up on the Stainless vs Aluminum thread, but thought it would be better in a new thread. I've been in search of the best prop for my setup and think I've found it. SteelSpike, thanks for your patience and help in this project. My original post was to see if we could come up with some kind of correlation that could be used as a crossover for aluminum vs stainless. The following is what I found:
The application:
Boat is a 1992 NITRO 170 TF, your basic 17' fiberglass Bass boat of the time. Engine is a 2011 Mercury 75ELPT, 75 HP 4 Stroke, bolted to the hull with no jack plate. Cavitation plate is about 2" above the lowest point of the hull. Set up was tested with two batteries, one forward and one at rear, 20 gallons of gas, also in the rear, and two adults, with fishing gear. There was also a spare prop and small tool kit, forward. I make people and gear at about 450lbs.
Props:
Solas Amita 3 aluminum - 13.25 x 19
Solas Amita 3 aluminum - 13 x 21
True Turn Hustler aluminum - 13.25 x 21 vented (approx 1/4" vent hole)
Merc Laser II Stainless Steel - 13.25 x 20, also vented, with medium vent plugs (approx 1/4" dia. holes)
Here's what I found:
The 19p Solas was difficult to get on plane, however, this was before I moved one battery, spare prop and tools forward. That said, once on plane the engine quickly went to 6000 rpm, the max limit. Max speed was 44mph, GPS.
Tried the 21p Solas next, also before moving the weight forward and experienced the same hole shot problems. RPMs dropped to 5600, what I consider the sweet spot for the engine, and speed was again 44mph, GPS. This prop was damaged, beyond repair, hit a submerged stump, and subsequently scrapped. I'm including these first two props in the evaluation just to show where I started. The following props were the true test, for me.
Next, after moving about 70lbs forward and at the recommendation of SteelSpike, I tried the Hustler 13.25 x 21. Gotta say, I was impressed. Hole shot, from dead stop was still very poor, but from an idle speed of about 4mph I was able to get on plane in 4-5 seconds. Top speed, again at 5600rpm was 44mph, GPS. I'm feeling better...
I made a deal on eBay for the Laser II that I couldn't pass up. Bolted it on and went to the water. Basic configuration was pretty much the same. From a dead stop, the boat was on plane in 3-4 seconds. Engine went to 5800rpm, which I kind of expected, with 1" less pitch, and the boat made 45mph, GPS.
Both props got the bow well out of the water, with the stainless prop lifting the hull to the point where I actually had to trim slightly down to stabilize the boat. With the aluminum prop, I achieved the same stability at full up trim.
Conclusion:
For my setup, I found that, performance wise, there was not a great deal of difference in the props I used. The stainless prop sent the engine 200rpm higher, but it was 1" less pitch (Pretty much what you'd expect in like props), lifted the bow higher and ran 1mph faster. . Hole shot was definitely improved with the stainless prop, but again, 1" less pitch.
From what I've learned, if I ever have to replace the Laser II, I'd buy the same prop in a 21 pitch, if available. However, in my case, the difference in stainless vs aluminum is pretty much straight forward. In sizing the prop to the boat, there was really no difference. What I'd recommend, to those considering changing from aluminum to stainless, or vice versa. Consider your needs/wants. If you're looking for maximum performance consider the stainless prop. If you boat in the swampland, like I do, stainless will probably survive the stumps better than the aluminum. But, for everyday boating, the aluminum, with it's lower pricing, has a lot to offer. For me, the metal used in the prop made on difference in engine RPM. The difference, though, was in the performance...
Thanks again for all the help this forum provides. See ya'll on the water...