1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Optimizing the performance of Boston Whaler boats
jimh
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1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Sat Jul 13, 2019 2:23 pm

It has been several years since I gathered any performance data on my 1990 Boston Whaler REVENGE 22 Walk-Through Whaler Drive boat with a 2010 Evinrude E-TEC 225. Below is data from a recent test. The engine is now in its 11th season of use.

Performance Data

BOAT, ENGINE, PROPELLER

Boat: REVENGE 22 Walk-Through Whaler Drive, 1990

Engine: E-TEC 225, Evinrude, 2010-model-year
Recommended WOT RPM Range: 4500 to 5800-RPM
Optimum WOT RPM Range: 5500 to 5700-RPM
Gear ratio: 1.86:1

Propeller: Mercury MIRAGEplus 17-pitch three-blade stainless steel
Diameter 15-inches
Length 6-3/4-inches
Exhaust port flare diameter 4-7/8-inches

TEST CONDITIONS

Date: July 12, 2019
Air Temperature: 77-degrees
Wind: 5-knots
Current: none
Humidity: unknown, probably 50- to 70-percent, a nice Summer day
Waves: small with some boat wakes mixed in
Crew: two aboard; total crew weight 360-lbs
Canvas: Flying Top deployed
General gear: normal non-overnight cruising gear.
Fuel: 35-gallons (half-full tank)

TEST RESULTS

Upwind into small waves:

SOG RPM MPG LOAD TRIM NOTES
23.2 3736 2.52 34 35 Not yet optimized for this throttle setting
24.5 3536 2.76 34 36 Optimum fuel economy
27.8 3918 2.66 37 36 Nice cruising speed
29.1 4051 2.66 37 36 Same LOAD as above, but faster speeed
32.9 4456 2.66 41 36 Now 5-MPH faster with same fuel economy
36.5 4921 2.49 46 47 Fast cruising speed
42.6 5605 2.09 100 40 Maximum throttle

Downwind with small waves:

SOG RPM MPG LOAD TRIM NOTES
28.0 3894 2.77 37 35 Optimum fuel economy
28.0 3793 2.81 36 35 Optimum fuel economy
29.2 3949 2.76 37 36 Optimum fuel economy
29.7 3937 2.84 37 25 Optimum fuel econonmy--cherry picking the data
35.7 4690 2.61 44 34 Fast cruising speed with minimum effect on economy
35.8 4708 2.63 44 33 Fast cruising speed with minium effect on economy


Slow speed data
SOG RPM MPG LOAD TRIM NOTES
2.9 503 10.2 0 35 To burn 1-gallon takes 3.5-hours at this speed

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Sat Jul 27, 2019 10:19 am

Recently we were underway with the boat very heavily loaded:

  • 65-gallons fuel
  • a 96-quart cooler packed with ice, beer, and food
  • a cabin filled with mattress, sleeping gear, dry goods, clothing, and book and charts for a week of living aboard
  • all weather canvas rigged and up
  • four adults aboard instead of the usual two adult crew

Best boat speed was reduced to 40.9-MPH. I did not note the engine speed. Fuel economy at best cruising speed was about 2.2-MPG

Later with our two extra passengers gone, and going upwind into moderate headseas, the best fuel economy was only 2.4-MPG.

An hour later heading downwind in smaller following seas, fuel economy was back to a steady 2.6-MPH and 2.7-MPG on occasion.

The boat was at its heaviest loading when this data was collected.

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Tue Jul 30, 2019 1:24 pm

Regarding the heavy-load performance data above: while cleaning the boat after our cruise, I just noticed that while underway last week the aft cockpit live well had about 15-gallons of rain water in it. Add another 100-lbs to the already heavy cruising load.

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Fri Aug 16, 2019 9:44 am

While running the boat in very light load state, with no canvas up, only 22-gallons fuel, and in very calm seas and no wind, the boat speed hit 44.5-MPH at an engine speed of 5,700-RPM. Fuel economy was also very good, and we saw 2.8-MPG at many boat speeds.

The effect on performance of boat weight, air resistance from canvas, sea state and wind, and other environmental influences continues to surprise me.

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Tue Aug 20, 2019 8:54 am

I have tested a new propeller, an Evinrude CYCLONE 17 TBX. I had previously tested a CYCLONE 17 propeller and found it to be a good performer. An opportunity arose to buy one at remarkably low cost. The CYCLONE TBX propeller I bought is a newer model that uses the Evinrude TBX hub kit system, and I also wanted to try a TBX hub. I was able to get a TBX hub kit at a very good price, too, so I couldn’t resist the opportunity to purchase and test this propeller.

The CYCLONE 17 TBX propeller is a polished stainless steel four-bladed propeller made by Evinrude specifically for the legacy E-TEC engines. The blades have the typical sharp-edged thick trailing edges. The leading edges are thin but have a smooth and rounded entry. There is a modest rake to the blades. There is the typical blade cup. This particular propeller was previously used but in very good condition. In shipping there may have been a minor nick or two in a blade edge due the hub kit parts becoming loose from their box and rattling around. A few minutes with emery cloth and the blades were all smooth and like new.

The marked pitch is 17-inch (same as the three-blade propeller tested above) and the diameter is 14-1/4-inches, about 3/4-inch less than the three-blade MIRAGEplus propeller. The length of the CYCLONE hub is 6-inches, or 3/4-inch shorter than the three-blade propeller. The exhaust port flares to a 4-3/4-inch diameter, slightly smaller than the three-blade.

Installing the TBX-style propeller took a few minutes. The plastic coupling between the propeller shaft and the long brass splined coupling to the propeller required a bit of work to assemble. I pre-fitted the plastic coupler into the propeller hub as deeply as I could, using a small block of wood and a hammer to seat it. But the coupler was still not bottomed out. Several revolutions of the propeller nut were needed to fully seat the coupler into the tapered square bore of the propeller hub.

Environmental conditions for this test were similar to prior testing: fair weather, high pressure, clear skies, air temperature high-70’s, and water temperature 73-degrees. The wind was 7 to 10-MPH. Waves were 1-foot or less.

The four-blade propeller produced a different engine vibration frequency than the three-blade, as expected. I don't have any measured frequency or amplitude data about the vibration. This summer I have noticed a cockpit coaming panel has had a tendency to rattle in sympathetic vibration with the engine and three-blade propeller. That panel was not excited into vibration by the four-blade.

The boat was in a light weight configuration as before, and fuel was now only 16 to 19-gallons during the test. We did have the Flying Top canvas up.

The first change I noted was the maximum engine speed of the E-TEC was limited to 5,500-RPM, about 100-RPM lower than with the three-blade propeller of the same pitch. This is a reasonable outcome, as in general a four-bladed propeller will be harder to turn than a three-bladed propeller (although the smaller blade diameter will tend reduce that effect).

Hitting my usual benchmark of 2.7-MPG fuel economy was difficult. I was finally able to coax a reading of 2.7 while running down wind and down sea, and at a boat speed of 27 to 30-MPH.

The maximum boat speed was about 42-MPH, again a bit lower than with the three-blade.

Overall, maximum engine speed, maximum boat speed, and maximum fuel economy were all lower than the three-blade propeller.

I did not observe any remarkable changes in the boat’s handling. There may be a slight improvement in controlling the bow rise, but bow rise on a Whaler Drive boat is always very limited in range; the Whaler Drive acts like a giant trim tab and won’t let the bow come up very much.

I will keep the CYCLONE on the boat for the rest of the season and spend more time evaluating it and collecting more data.

Here are two data points.

Evinrude CYCLONE 17 four-blade propeller
For both measurements the throttle position and trim position were
LOAD=36
TRIM=33 to 34

UPWIND
RPM=4000 MPH=28.4 MPG=2.6

DOWNWIND
RPM=3950 MPH=28.5 MPG=2.7

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Tue Aug 20, 2019 11:05 am

A remark on propeller testing in general

In both reports above, the propellers tested were not new propellers. Both were in like-new condition. Both propellers are products of outboard engine manufacturers, and one might assume, perhaps, that propellers from outboard engine manufacturers are generally high-quality and well-designed for the outboard engines of the specific manufacturer. The prices of propellers from outboard manufacturers are generally higher than for propellers from aftermarket providers.

Even assuming that the two propellers were in perfect, as-new condition, consideration has to be given to the fact that these are mass-produced propellers. They are not delivered from the manufacturer as new in perfect balance with every blade carefully checked and nudged to be in the exact same pitch. Getting a finely-tuned and balanced propeller generally means paying about double the cost of a standard production propeller (or more) for a "lab-finished" propeller. On the basis that the tested propellers are both standard production parts and were slightly used, an assumption that each is an absolute perfect specimen is not justified. Inasmuch as the reported differences in performance are rather slight, to assume that if the tests were repeated with a different pair of these propellers the exact same results would be obtained is probably a risky assumption.

For example, the difference in observed fuel economy is only 0.1-MPG in a value of 2.7-MPG. This is a variance of onl 0.1/2.7 or 3.7-percent. The small difference may a result of testing errors, testing conditions, testing bias, and natural variation in the products being tested, and not due to a fundamental difference in the nature of the two propeller designs. Holding all test variable to be identical and to cause less than 3.7-percent influence on the results is really extremely difficult to achieve, in my opinion, in propeller testing.

The best methods of testing propellers should include blind testing, that is, testing where the boat driver and the person recording the data have no knowledge of what propeller is being tested. The propellers should be tested on the same propeller shaft, on the same engine, on the same boat, and within a few minutes of each other, so that influences due to variations in the engine power output, the hull fairness, weight, and wind resistance, and air and water environmental conditions can be held to a minimum.

A further consideration in propeller testing is the engine fuel. Today the gasoline fuels available vary in their ethanol content, from no ethanol to perhaps 10-percent or more ethanol content. Fuel octane also varies. Engine power output will be affected by the fuel being used. An engine will produce more power output on pure gasoline fuel of higher octane than it will with a fuel consisting of a blend of gasoline and ethanol and lower octane. In order to have comparable test data, the engine fuel should be consistent throughout all tests.

jimh
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Re: 1990 REVENGE 22 W-T Whaler Drive, E-TEC 225

Postby jimh » Wed Aug 28, 2019 3:38 pm

Here is more data on my testing with the Evinrude CYCLONE four-blade 17-pitch propeller:

Performance Data

Propeller CYCLONE 4 17-pitch

TEST CONDITIONS

Date: August 22, 2019
Air Temperature: 74-degrees
Wind: 10-knots to perhaps 15-knot gusts
Current: none
Humidity: unknown, probably 50- to 70-percent, a nice Summer day
Waves: 1-foot or less
Crew: two aboard; total crew weight 360-lbs
Canvas: Flying Top deployed
General gear: normal non-overnight cruising gear.
Fuel: 37-gallons (half-full tank) mostly all fresh REC 90 pure gasoline

Downwind

LOAD=37
TRIM=41
RPM=4078
SOG=29.7
MPG=2.72

LOAD=39
TRIM=36
RPM=4340
SOG=32.5
MPG=2.76


Upwind

LOAD=39 (same as downwind run immediately prior)
TRIM=37
RPM=4288
SOG=31.8
MPG=2.70

LOAD=8
TRIM=55
RPM=1074
SOG=5.4
MPG=6.58


After more time underway with the CYCLONE propeller, the best fuel economy with this propeller seems to occur at a higher cruising speed. Boat speeds in the 28 to 32-MPH range seem to have the best fuel economy in MPG.

We found the propeller had reasonably good reverse thrust at low speeds. We also had to go into reverse and apply a lot of throttle in order to stop the boat very rapidly when we came up on a barely submerged but completely unmarked breakwall. The record-high-water-level in Lake Michigan had completely submerged the rock rip-rap of this breakwall, and we were lucky to be going slowly and could stop in time before running over it.