*UPDATE* Test results, 08 Merc 90 ELPTO prop swap.

[eastcoasthd]

I recently completed some preliminary performance testing prior to making the prop swap from the 3 blade to a 4 blade Solas 12.5 X 19P.

2008 Lowe 165 F/S powered by a 2008 Merc 90 ELPTO 2S. QuickSilver Alum. 12.75 X 21P. Recommended operating range 5000-5500 rpm.

Test 1.
Motor mounted top hole (this is the original rigged position), zero wind, water flat, temp 70ish, D.P. 60ish%. Max speed via GPS 41.6 mph. RPM 5200. Very heavy steering torque while fully trimmed.

Test 2.
Same as above, Motor raised two holes. Max speed 38.8 mph. RPM 5300. Trim limited to approx. 2/3 of previous test before severe blowout.

Test 3.
Lowered motor one hole (split the diff. between two previous tests). Slight wind increase, very light chop (more like ripples) temp. 85ish, D.P. 60+.
Max speed 40.9 mph. RPM 5250-5300. Max. trim was 2-3 taps less than test #1. Noticeably less steering torque while fully trimmed.

In all the tests, the boat jumped onto plane in 3-4 seconds, estimate.

In test #3, I picked up 50-100 rpm, reduced steering effort while trimmed up and really didn't give up much if any top end. I presume weather conditions are probably the biggest factor in the reduced max speed.

Now that I have a baseline, I can install the 4 blade and see how it shakes out. I'll post the results later this week.

I have included a few pics.
Pic.#1 is test #1, motor top hole.
Pic. #2 is test #2, motor raised two holes.
Pic. #3 is test #3, motor raised one hole, you can see the bolt head that attaches the trim tab. The bolt head is apprx. 1" above the vent plate. You can also barely see the orange tape under the spray.

 

[eastcoasthd]

Re: *UPDATE* Test results, 08 Merc 90 ELPTO prop swap.

I recently completed some preliminary performance testing prior to making the prop swap from the 3 blade to a 4 blade Solas 12.5 X 19P.

2008 Lowe 165 F/S powered by a 2008 Merc 90 ELPTO 2S. QuickSilver Alum. 12.75 X 21P. Recommended operating range 5000-5500 rpm.

Test 1.
Motor mounted top hole (this is the original rigged position), zero wind, water flat, temp 70ish, D.P. 60ish%. Max speed via GPS 41.6 mph. RPM 5200. Very heavy steering torque while fully trimmed.

Test 2.
Same as above, Motor raised two holes. Max speed 38.8 mph. RPM 5300. Trim limited to approx. 2/3 of previous test before severe blowout.

Test 3.
Lowered motor one hole (split the diff. between two previous tests). Slight wind increase, very light chop (more like ripples) temp. 85ish, D.P. 60+.
Max speed 40.9 mph. RPM 5250-5300. Max. trim was 2-3 taps less than test #1. Noticeably less steering torque while fully trimmed.

In all the tests, the boat jumped onto plane in 3-4 seconds, estimate.

In test #3, I picked up 50-100 rpm, reduced steering effort while trimmed up and really didn't give up much if any top end. I presume weather conditions are probably the biggest factor in the reduced max speed.

Now that I have a baseline, I can install the 4 blade and see how it shakes out. I'll post the results later this week.

I have included a few pics.
Pic.#1 is test #1, motor top hole.
Pic. #2 is test #2, motor raised two holes.
Pic. #3 is test #3, motor raised one hole, you can see the bolt head that attaches the trim tab. The bolt head is apprx. 1" above the vent plate. You can also barely see the orange tape under the spray.

*UPDATE*

Today, I finally completed my testing after installing the Solas 14.5 X 19 four blade.

Temp. 93*, D.P. 68. Slight variable winds 0-5 mph. 1 person on board. ? tank of fuel.

Top speed of 40.8 mph via GPS, turning around 5700 ? 5800 rpm. Jumped onto plane in around 2.5 secs. Noticeably less bow rise and reduced torque steer while trimmed up.

I was a little concerned with the speed that I lost with the 3 blade after raising the motor, but the 4 blade seems to like this position (mounted high) and I can trim up the same amount as the 3 blade with the motor mounted to the lowest position (top hole).

This prop is perfect for my needs. I have gained much at the expense of less than 1 mph, which under better weather conditions I'll bet I could make some of that back. I'm not concerned with the 200-300 rpm increase over the recommended 5500, I think when loaded as I normally do, 2 adults, full fuel, plus gear, it should come back into range. I very rarely run at WOT anyway.