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Author Topic:   REVENGE 22 W-T WD with 225-HP, Three Propellers
jimh posted 10-05-2009 06:51 AM ET (US)   Profile for jimh   Send Email to jimh  
Here are some data from tests with a REBEL 17 propeller on my 1990 Boston Whaler REVENGE 22 Walk-Through Whaler Drive boat with 2010 E-TEC 225-HP

RPM     MPH     GPH     MPG     SLIP
3550 25.4 8.6 2.95 17.8
3600 25.8 8.9 2.90 17.6
3750 28.0 9.6 2.92 14.2
3850 28.3 9.8 2.88 15.5
4200 32.2 11.6 2.77 11.9
4750 37.0 14.4 2.57 10.5
5450 42.8 20.3 2.11 9.7
5500 43.3 9.5

This data was collected with the boat canvas rigged and running upwind into small head seas.

jimh posted 10-05-2009 07:04 AM ET (US)     Profile for jimh  Send Email to jimh     
The engine is mounted one-hole up. Crew was two people aboard. The overall boat weight was a bit lighter than our normal heavy cruising load, as there was no cruising gear in the cabin and no coolers in the cockpit. The temperature of the air and water was in the low 50-degree range. Speed data is from a GPS receiver. Fuel flow rate is from the engine's EMM data. SLIP is calculated using the Propeller Calculator at

http://continuouswave.com/cgi-bin/propcalc.pl

I am particularly pleased with two measurements. First, the fuel economy at a moderate planing speed of 25-MPH is excellent, almost 3-MPG. Second, the propeller SLIP declines to less than ten-percent at maximum speed, which is a good indication of proper propeller selection. The REBEL 17 looks like a good candidate for a propeller for this combination.

Peter posted 10-05-2009 07:26 AM ET (US)     Profile for Peter  Send Email to Peter     
I agree with the Rebel 17 assessment on. Fuel efficiency looks very good in the 25 to 30 MPH range. Based on those results, I would consider testing the Revolution 4 in 15 and 17 inch pitch sizes and the 4 blade Cyclone TBX also in 15 and 17 inch pitch. While it would be of little surprise to learn that the 4 blades propellers were a little less fuel efficient at cruise, I think a subjective "seat of the pants" ride into a chop evaluation would be interesting to hear.
Tom W Clark posted 10-05-2009 12:34 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Boy! I would love to get 3 MPG with my boat. The nice thing about the E-TEC is that it yields its best fuel mileage at useable speeds and does not encourage you to go faster than condition may allow to just to save money on fuel.

I disagree about the desirability of the calculated propeller slip being below 10 percent. Prop slip is often given too much weight in the propeller selection process. It is not a useful value in the absolute sense, but *is* useful when comparing the same propeller in different applications.

The REBEL yielded 9.5 percent prop slip on Jim's boat then yielded 20 percent slip on another, that would be a red flag that something was wrong in the other application.

On the other hand, if a boat's performance with one prop is better than any other prop, yet the slip is very high, then so be it. There is nothing wrong with high propeller slip by itself and there is nothing magic about getting below a slip value of 10 percent.

jimh posted 10-05-2009 05:32 PM ET (US)     Profile for jimh  Send Email to jimh     
I agree with Tom's observation on the SLIP number on this basis: SLIP as a calculated value is greatly influenced by the entered value for the PITCH. In the case of the REBEL propeller, if Bombardier had said its pitch were 18-inches, then the calculated SLIP would have been much higher.

It is widely known that most modern propellers no longer have a constant pitch to their blades, and the actual pitch of the propeller is typically a progressive pitch which changes with position on the blade surface. In addition, the introduction of cup on the blade also affects the performance in the same way that pitch does. The result is that the notion of a propeller's pitch is somewhat of an aggregation of influences. Some propeller manufacturers designate their propeller pitch in accordance with their own systems, and we cannot really make absolute comparisons of propellers among many different manufacturers.

jimh posted 10-10-2009 10:23 PM ET (US)     Profile for jimh  Send Email to jimh     
Here is some data from tests with a BRP CYCLONE 17, a four-blade propeller, on my Boston Whaler REVENGE 22 Walk Through Whaler Drive.

Downwind
RPM MPH GPH MPG SLIP
3800 26.7 9.7 2.75 19.3
3850 27.4 9.8 2.8 18.2
4200 31.9 11.4 2.8 12.7
5500 44.0 21.3 2.07 8.1
5550 44.4 21.2 2.1 8.1

Upwind
RPM MPH GPH MPG SLIP
2600 12.9 6.3 2.15 43.0
3250 19.6 8.3 2.4 30.7
3500 26.6 9.9 2.7 12.7
4150 30.6 11.5 2.7 15.3
5350 42.3 * * 9.1

Crosswind
RPM MPH GPH MPG SLIP
5450 44.4 20.4 2.2 6.4

Test conditions were different than in the tests with the REBEL. The boat had no canvas rigged, so wind resistance was less. The fuel load was 7/8-FULL tank. Wind was about 10-MPH.

jimh posted 10-10-2009 10:35 PM ET (US)     Profile for jimh  Send Email to jimh     
The CYCLONE results are somewhat unexpected. First of all, the boat seemed really fast with this propeller. It hit a new high-speed mark, 44.4-MPH. This was probably influenced by the lower wind resistance from having all the canvas down. Second, the fuel economy did not seem to be as good as expected. The MPG topped out at 2.8, which is not bad, but not as good as the REBEL had shown. The problem may be I did not get good data below 25-MPH. The boat seemed so fast with this propeller that it just did not want to run at that speed.

I am remarking about the data because generally you'd expect a four-blade propeller to be a bit slower than a three-blade, and also to give better mid-range fuel economy. This test seemed to produce the opposite results.

Today's run was really more for the purpose of getting stabilized fuel to circulate through the fuel system, and the propeller testing was not done as extensively or carefully as in the past. We were running on an inland lake, and at 40-MPH you run out of lake rather fast, so we did not always get the trim optimized.

Peter posted 10-10-2009 10:37 PM ET (US)     Profile for Peter  Send Email to Peter     
Performance of the Cyclone looks pretty good. How did the ride feel relative to the Rebel?
jimh posted 10-10-2009 10:49 PM ET (US)     Profile for jimh  Send Email to jimh     
It is hard to quantify the ride. Looking at the data, it seems like the boat didn't want to run under 25-MPH very much.

I also like to look at the boat wake. I use the size of the boat wake waves as an indicator of stern lift; the smaller the wake the more stern lift I assume I am getting. I'd say the CYCLONE has some stern lift, but perhaps not as much as the REBEL. It is really hard to say--it would be better to compare them on an A-B basis with very little time interval. A week in between tests is too long.

jimh posted 10-10-2009 10:57 PM ET (US)     Profile for jimh  Send Email to jimh     
The CYCLONE propeller I tested uses a TBX hub kit. The thrust washer on the TBX hub kit is smaller in diameter than the standard thrust washer. I assume this means that the central portion of the propeller hub is also smaller in diameter. The implication of that change in dimension means there is more room for the engine exhaust to pass through the propeller.

I'll plan to take a few measurements and a picture or two to illustrate what I mean.

number9 posted 10-11-2009 04:09 AM ET (US)     Profile for number9  Send Email to number9     
Are you attempting to determine/judge any differences is slow speed, close to idle maneuverability in forward and reverse gear similar to what one may encounter in a docking situation while testing the different props? Realize it would be rather difficult to measure and present data but some first-hand accounts may be be of some help to many here. Thanks.
jimh posted 10-11-2009 09:42 AM ET (US)     Profile for jimh  Send Email to jimh     
I have not collected any data about the slow speed performance of these propellers, nor have I noted anything about their influence on boat handling around the dock.

As a general observation, however, I will say that the ability of the E-TEC to operate at engine speeds of 500-RPM permits a nice slow boat speed at dead slow idle, around 2.5-MPH. Being able to maneuver close to the dock at 2.5-MPH permits very easy docking.

One difference between the REBEL and CYCLONE propellers I have noted: there is a slight clunk when shifting with the REBEL. Generally the shifting on the E-TEC gearcase is terrifically quiet, and shifts do not announce themselves with a loud CLUNK as so often happens on outboard motors. With the REBEL there is a bit of a thud or clunk when shifting in some situations, where with the CYCLONE (and with my old SST propeller) there is none.

jimh posted 10-12-2009 09:03 AM ET (US)     Profile for jimh  Send Email to jimh     
An additional factor which changed in the two tests is the fuel used. In the earlier test (with the REBEL propeller) the fuel used was a mixture of gasoline and gasoline blended with ethanol, and I estimate that over 60-percent of the tank volume was non-ethanol gasoline. In the later test (with the CYCLONE propeller) the fuel used was again a mixture, but now the ethanol fuel was likely more than 60-percent of the tank. It is hard to give these figures with much precision, because due to the lack of proper labeling of gasoline fuels, the ethanol content of gasoline purchased in Michigan is something of a mystery, unless greater than 10-percent. (A few years ago, in a drive concealed as an environmental movement, the ethanol lobbyists succeeded in modifying the existing labeling requirements in the State of Michigan for gasoline to remove notice of ethanol when blended at less than 10-percent. Don't let this happen in your state.)

The difference in the observed fuel economy at similar boat speeds, and again, the data is a bit imprecise, seem to be on the order of a variation of 0.1 to 0.2-MPG in a range of 2.7 to 2.9-MPG. This variation represents a change of about 3- to 7-percent in fuel mileage. Some of this change may be due to the influence of the gasoline. It is widely known that the energy content of gasoline diluted with ethanol is lower than pure gasoline. E10 has only 0.9672 as much energy as pure gasoline. The influence of this has been estimated for E10 fuel to be a reduction in fuel mileage of 3-percent. It is possible that a change in fuel played a role in reducing the fuel economy observed with the CYCLONE propeller. In making fuel mileage comparisons, the data would be more useful if collected using the same fuel for the engine in all tests.


Cf.: http://pubs.ext.vt.edu/442/442-884/442-884.html

jimh posted 10-14-2009 09:41 AM ET (US)     Profile for jimh  Send Email to jimh     
A plot of the data from the REBEL 17 test:

A plot of data from the CYCLONE 17 test:

I like to plot the data because it helps to see if the data is reasonably consistent. These curves are all nicely smooth, so one gets the feeling the data is reasonably accurate. If any of the data points were invalid, you would see it when plotted like this.

acseatsri posted 10-14-2009 07:15 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
My results are nearly identical on my Outrage w/t-top and same prop (2006 225 Etec), but at about 10% better mileage, probably due to less weight in the bow. My best cruise is at 3400 RPM,25-26 MPH @8 GPH.

The one complaint I have with the Etec is that the throttle is too sensitive- it's tough to get on plane gradually without lurching forward. Hopefully when I get the 300 hr check done (currently 390 flawless hrs), an upgrade will be available to help rectify this condition.

jimh posted 06-13-2010 11:45 AM ET (US)     Profile for jimh  Send Email to jimh     
Here are some data from tests of a 15.5 x 17 Mercury MIRAGEplus propeller on my Boston Whaler REVENGE 22 Walk-Through with Whaler Drive and a 2010 Evinrude E-TEC 225-HP motor. The data was collected in calm water condition on Lake Michigan near the northern end of Grand Traverse Bay. The boat had over 1/2-FULL fuel tank, all its canvas was up, and there was a heavy load of cruising gear. The boat speed was taken from GPS data. The engine speed was taken from a digital tachometer. The fuel flow was taken from the engine's own instrumentation.

June 2010
MIRAGEplus 15.5 x 17

RPM MPH GPH MPG
500 3.2 0.21 15.2
600 3.6 0.34 10.6
900 5.2 0.58 9.0
1000 5.5 0.68 8.1
1000 5.8 0.70 8.3
1100 6.2 0.81 7.65
1350 6.9 1.2 5.9
1550 7.8 1.7 4.5
3350 18.5 8.1 2.3
3400 19.8 8.3 2.4
3450 23.5 8.5 2.76
3450 24.0 8.5 2.8
3550 25.0 8.7 2.85
3800 27.4 9.88 2.78
3800 27.6 9.9 2.8
3800 28.1 9.85 2.85
3950 29.2 10.8 2.8 Trim at 23%
4000 29.8 10.7 2.8
4000 30.0 10.7 2.8
4250 32.3 11.8 2.7
4500 34.1 12.5 2.7
4750 36.0 14.1 2.6
5000 38.1 16.0 2.4
5450 42.1 20.2 2.1
5500 42.8 21.0 2.0
5550 43.2 20.6 2.1

Here is a plot of that data:

Plot: Boat speed, fuel flow, fuel economy as function of engine speed

jimh posted 06-13-2010 12:19 PM ET (US)     Profile for jimh  Send Email to jimh     
As you can see, the slow speed fuel economy data is off the chart. At idle speed, 500-RPM, the fuel economy is about 15-MPG. It takes five hours to burn a gallon of fuel at that speed.

The optimum cruising speed is between 25 and 30-MPH, where the fuel economy stays fairly constant at 2.8-MPG.

The boat can stay on plane as slow as 18-MPG, but the fuel economy is not good.

The MIRAGEplus propeller was run with the Performance Ventilation System holes filled with full plugs. The engine was mounted one-hole up. The MIRAGEplus propeller did not show any signs of losing grip or "blowing out" at any time. We intentionally took some high speed turns with the engine trimmed out, and the propeller did not ventilate.

We ran the boat is a variety of sea conditions. The MIRAGEplus propeller did not ventilate when running into larger head seas while on a slow planing speed of around 14-MPH.

We had the propeller on for four of the five days we were out boating last week. Here is a typical day:

On Thursday, June 10 we were in the harbor at Leland, Michigan, on the eastern side of Lake Michigan. The previous day the wind had been blowing at 20 to 25-knots from the southwest, and the lake had well-developed four-foot waves. In the morning, the wind hauled to the west and then northwest and decreased to 10 to 15-knots. A number of transient boats were in the marina and planning on heading south, but decided to wait for the wind to decrease further, as was predicted for later in the day, and to give the waves a chance to lay down from yesterday's height.

About 10 a.m. we decided the conditions were not that bad, and left the tranquility of the harbor, heading north. We ran about 20-miles north along the coastline, staying offshore in water about 50-feet deep. We had two-foot waves from the northwest. After we made about five miles passage north, we left the lee of the Manitou Islands (about eight miles offshore), and we picked up a three- to four-foot beam sea from the southwest, mixed into our other head seas. We ran in this at a slow planing speed, around 14 to 16-MPH. As mentioned above, this is not an optimum speed for fuel economy, but we were willing to burn more gas in order to maximize our comfort. Once we reached the tip of the Leelenau Peninsula, we turned east then south. We then reduced speed to about 5-MPH and enjoyed a nice downwind ride in two-foot seas. At this low speed the engine idle sound is very low and we listened to the sound of the boat moving in the waves. It was reminiscent of sailing and made for a very relaxing and enjoyable ride after the bumpy and windy run north.

About five miles down the bay, the northwest seas disappeared and we were in very calm water. We collected some of the data on speed and performance shown above, then got back onto an optimum plane about 28-MPH, and ran south to Northport, where we entered the break wall and tied to the courtesy dock for lunch.

The day's run so far, Leland-to-Northport, was 29.2-miles, and we burned 11.75-gallons, giving us an average of 2.48-MPG.

After lunch we cruised at a leisurely pace further south to Suttons Bay in much calmer water, running another 19.3-miles and burning 5.63-gallons, for 3.42-MPG on that leg.

Our overall trip for the day in a variety of seas and at a range of speeds--including some wide-open-throttle runs--saw us travel 48.5 miles and burn 17.4-gallons, giving us an average fuel economy for the day of 2.8-MPG.

I liked the performance of the MIRAGEplus propeller, and I think I will keep it on the boat for a while for some further testing.

jimh posted 06-13-2010 01:44 PM ET (US)     Profile for jimh  Send Email to jimh     
In case you were wondering how we got to Leland when the day before the lake had 20 to 25-knot southwesterly winds and four-foot seas, it was a matter of good timing. We left Northport about 10:30 a.m., rounded the Grand Traverse Light before noon, and found Lake Michigan with two to three-foot waves from the west. In those conditions we drove on plane at about 18 to 20-MPH, until we ran into a set of three big waves that changed our minds about running at that speed. Shortly after that we ducked into Cat Head Bay for a lunch break, were we could relax in the lee of a little point and eat a sandwich. When we went back to the lake, the wind was almost gone, and the seas were laying down. By the time we made the breakwater entrance at Leland around 1:45 p.m., the wind was nearly calm.

No sooner had we made CONTINUOUSWAVE fast to the new floating docks about 2 p.m., the wind switched to southwest and piped up to 20 to 25-knots, holding flags out straight and snapping. It blew like that all afternoon, and by 4 p.m. there were white caps as far as you could see. You can see the flag in the picture below, and it was in the marina, behind the sea wall. The big flag on the marina 50-foot tall flag pole was really out straight. This experience reaffirmed my belief that late afternoon in the summer on the Great Lakes is generally the worst wind and wave conditions. It is much better to leave early and miss that 4 p.m. wind peak.

You can also see the new Leland marina office and bath house, which just opened. Its facilities are nicer than most yacht clubs I have visited. We enjoyed watching the Stanley Cup Finals GAME 6 in high-definition television from the boater's lounge on Wednesday evening.

Tom W Clark posted 06-14-2010 03:00 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
There are two things that really stand out to me about this motor.

- The range of RPM where fuel economy is optimized is very broad. 2.7 MPG can be achieved anywhere in the 3450 - 4500 RPM range.

- The idle speed fuel economy is amazing. I am accustomed to idling one of my two motors (and almost never both at the same time) absolutely as little as possible because it is such a smokey waste of gas.

In Jim's case he achieved significantly greater trip average fuel economy that the optimal cruising speed fuel economy.

It is usually the case that cruise speed fuel economy is brought down when slow speed operations are included in the calculations.

Peter posted 06-14-2010 09:39 PM ET (US)     Profile for Peter  Send Email to Peter     
The broad range of cruising RPM where fuel economy is optimized is pretty typical of a DFI 2-stroke. I see the same broad range (3500 to 4500 RPM) where fuel economy is optimized with the Evinrude 225 Fichts on my Whaler 27 WD.

Idle speed fuel economy on my Whaler 27 with both motors running in gear is 6.3 MPG at 3.8 MPH. On one motor in gear, it rises to 10 MPG at 3 MPH. Not bad for almost 30 feet of boat with a 10 foot beam.

jimh posted 06-14-2010 09:45 PM ET (US)     Profile for jimh  Send Email to jimh     
The outstanding fuel economy of these modern motors when at idle speeds has opened up a whole new realm of boating, what I call the Boston Whaler as a Trawler mode. If you are not in a hurry to get somewhere, and you just want to enjoy a day on the water underway, with a modern motor you can putt along at 5 to 6-MPH and get terrific fuel economy, about 8 to 10-MPG. You can make a passage in your Boston Whaler and not burn 10-gallons per hour, but instead burn less than one gallon per hour. It almost makes me want to invest in an autopilot. I could sit back and enjoy the ride while the boat steers itself.
Peter posted 06-15-2010 07:34 AM ET (US)     Profile for Peter  Send Email to Peter     
The superior low speed fuel economy of the Evinrude DFI 2-stroke is a result of the stratified charging mode. This is the mode where the injector injects a blob of atomized fuel into the cylinder near the sparkplug and the blob is surrounded by air in the cylinder. In contrast, in the homogeneous mode, the entire cylinder has a homogeneous mixture of fuel and air. In the stratified charge, virtually none of the fuel injected escapes through the exhaust port.

The Yamaha HPDI DFI 2-stroke does not yield similar results because it does not use stratified charging. It operates exclusively in the homogeneous mode so its less efficient at low engine speeds.

themclos posted 06-15-2010 10:56 AM ET (US)     Profile for themclos  Send Email to themclos     
The Mercury Optimax also provides excellent fuel economy at idle and low speeds.

Dan

Peter posted 06-15-2010 11:37 AM ET (US)     Profile for Peter  Send Email to Peter     
The Optimax also uses stratified charging at low engine speeds.
jimh posted 06-15-2010 08:06 PM ET (US)     Profile for jimh  Send Email to jimh     
When operating a boat in rough seas, the engine will face a wide variety of load, and, as a result, at a constant throttle setting the classic two-cycle engine speed will vary over a wide range of RPM. When the loading is light, the engine will increase in speed, and when the load increases, the engine will decrease in speed. In order to maintain the boat at a constant speed, the operator has to continually adjust the engine throttle setting to maintain the engine speed at a constant speed. In some cases, the throttle will require constant attention to keep the boat at the desired speed. If the throttle is left unattended, the boat speeds up in some conditions and bogs down in other conditions.

With a modern outboard motor where the engine speed is controlled by an engine control module with computer processing, the need to constantly adjust the throttle to maintain an engine at a particular speed is greatly reduced, to the point where it becomes almost unnecessary to closely monitor. This past week I was running my boat with Evinrude E-TEC engine into rather rough seas. The E-TEC maintains an almost constant engine speed at a particular throttle setting. The engine does not race up in speed as the boat comes over a wave and runs down the back, nor does the engine speed drop drastically as the boat climbs a wave front. Under the control of the engine management module (or EMM), the E-TEC maintains a nearly constant engine speed at a particular throttle setting. This greatly reduces the need for throttle adjustment from the operator in order to maintain the boat speed at the desired pace. In running upwind into waves, I was able to leave the throttle setting constant, which produced the desired boat speed, and give my full attention to driving the boat. This is another significant benefit of the modern outboard engine over traditional two-cycle engines where there was no real computer control. Having run both carburetor and simple electronic fuel injection engines (such the Mercury EFI series) in many situations with large waves, I can say that the modern engine, such as the Evinrude E-TEC, gives the helmsman a great relief from the burden of constant throttle manipulation. For anyone who has not run their boat with modern, computer-controlled engines in high seas, you cannot believe how much a modern engine can contribute to your driving pleasure.

jimh posted 06-15-2010 08:15 PM ET (US)     Profile for jimh  Send Email to jimh     
The constant engine speed characteristic of the Evinrude E-TEC in varying load conditions also seems to help the propeller perform. With the engine reluctant to race higher in speed when load conditions decrease, the propeller does not have as much tendency to ventilate or lose grip. I think the E-TEC helps the propeller perform better than it might with a conventional two-cycle or four-cycle engine which did not have a computer running tight control on engine speed at a particular throttle setting.
Peter posted 06-16-2010 07:29 AM ET (US)     Profile for Peter  Send Email to Peter     
As all Vee hull boats run in choppy conditions, they tend to rock somewhat side to side, back and forth about the keel. On a single engine powered boat, the propeller is aligned with the keel and so the rocking about the keel does not substantially change the running depth of the propeller. In contrast, on a twin engine powered boat, the propellers are not aligned with the keel and as the boat rocks about the keel, one motor's propeller will be caused to run deeper in the water and the other motor's propeller will be caused to run shallower. In my experience, even with the similarly tight computer controlled engine speed of my Evinrude 225 Fichts, these motors can race up in RPM at least 250 to 500 RPM if the load on the propeller is reduced substantially because the propeller is temporarily running in shallow water. Some might describe this as the propeller is "breaking loose."

I frequently observed the "breaking loose" or blow out with virtually all of the three blade propellers that I tested on my Whaler 27 WD when the boat was not running port to starboard level. The 4-blade propellers, in particular the Revolution 4 propeller, did not exhibit this characteristic most of the time.

You could probably simulate this on a single engine boat by trimming the motor up to the point where the propeller loses grip. My guess is that you would see the RPM's fluctuate by several hundered RPM.

Also, while divorced from propeller performance, one difference between a computer controlled DFI 2-stroke and a carbureted 2-stroke is engine speed control under no load conditions. While I do not know whether an E-TEC has a tendency to "run away" under no load conditions, if the throttle of an Evinrude 225 Ficht is advanced in neutral, no load conditions to be held at about 1500 RPM, within about 30 seconds to 1 minute later, the RPM will have a tendency to run away. I believe this could be caused by fuel vapor recirculation into the air box. This phenomenon does not happen with my carburated outboards.

jimh posted 06-19-2010 12:19 PM ET (US)     Profile for jimh  Send Email to jimh     
This most recent five-night trip on the boat also established a new trend in our boating: we used more fuel in the truck hauling the boat up north than we used in the boat running around for five days once we got there.

The round trip highway towing distance for this trip was about 500-miles. My truck gets about 10 to 11-MPG when towing. The truck burned about 45 to 50-gallons of gasoline on this vacation.

The boat burned 42.75-gallons over the five days. I don't have an exact figure for the distance (as I forgot to note the LOG value at the start of the trip), but a reasonable estimate is 143.6-miles (based on my accurate record of the distance from Leland back to Elmwood, then doubled). This puts the trip average fuel economy at 3.37-MPG. As I have noted before, with our old two-cycle V6 motor with carburetors, we were lucky to average 1.8-MPG for a week-long trip in varying sea conditions. This means the new motor improved the MPG by 1.57-MPG, which is an improvement of 87-percent.

For boat gasoline we burned the fuel in the tank that was added last fall when the boat was winterized. For a bit of safety margin, we added 10-gallons of non-ethanol mid-grade fuel from the fuel dock, for which we paid a princely $3.90-per-gallon.

If we had used our old motor on this trip, we would have burned more fuel, approximately 146.3-miles/1.8-miles-gallon = 81.3-gallons, or 38.6-gallons more than we did with the E-TEC. If that extra fuel had been replenished at the $3.90-gallon price, we would have spent an additional $150 on fuel for the trip.

fourdfish posted 06-20-2010 10:08 AM ET (US)     Profile for fourdfish  Send Email to fourdfish     
As I know Jim is not a fisherman and does not troll for long periods of time as I do, I'm sure he does not realize that
his gph at idle is about .33 gal/per hour! My mechanic set my idle lower than normal because of trolling. My engine, although about five years older still idles at 450rpms and gets better than that super fuel sipping burn.
Still runs great and saves big bucks with the fuel prices
way up there. Jim, You gotta love it!
jimh posted 06-20-2010 04:53 PM ET (US)     Profile for jimh  Send Email to jimh     
My 2010 E-TEC 225-HP engine burns about 0.2 to 0.3 gallons-per-hour at idle or trolling speeds.(See data in a table of performance above.) But thanks for mentioning the excellent fuel flow at idle speeds.

I have also written about the paradox of great fuel economy at idle speeds. The overall fuel economy is weighted by the amount of fuel consumed, not by the time. You could troll at idle 95-percent of the time, but if you only burned 5-percent of the fuel at that speed it only influences the overall fuel economy by 5-percent weighting.

On the other hand, at a fuel flow of only 0.2-GPH, it takes five hours to burn a gallon of fuel. You can have a lot more time underway on one gallon of fuel at that rate than you can at wide-open, where the engine burns a gallon of fuel in less than three minutes.

jimh posted 06-21-2010 10:02 AM ET (US)     Profile for jimh  Send Email to jimh     
In the example I gave above, the time needed for a 225-HP E-TEC to consume one gallon of fuel varies from three minutes to 300 minutes. This 100:1 ratio in fuel flow is, in itself, quite amazing. I do not think most internal combustion engines--certainly not an older classic two-cycle engine--can be throttled down so low that they only burn 1/100th as much fuel at idle as they do at maximum throttle.
jimh posted 06-24-2010 12:22 AM ET (US)     Profile for jimh  Send Email to jimh     
As mentioned above, we burned just under 43-gallons of fuel on the five day cruise with the E-TEC. Oil consumption was about 0.8-gallons. I don't have an exact figure; I am just estimating from how much oil it took to refill the reservoir. These rough figures put the gasoline:oil ratio at 43:0.8 or around 54:1. This seems reasonable. I still have the engine set for the standard oil flow rate, which is approximately 50:1.
peteinsf posted 06-13-2015 10:54 AM ET (US)     Profile for peteinsf    
Did you keep the Mercury MIRAGEplus as your primary prop?
jimh posted 06-15-2015 08:16 AM ET (US)     Profile for jimh  Send Email to jimh     
PETE--In the almost six years since I wrote this article, I have been using the Mercury MIRAGEplus propeller as the primary propeller. Although it was not the best propeller in the test data above, it had one big advantage over the other propellers: I already owned it. There was no additional cost to acquire it, whereas the other choices would have been rather expensive, in comparison, to purchase.

I have come to the opinion, after testing many propellers, that my boat is presently set up with a decent propeller. Unless there is a miracle in propeller development--which does not cost a fortune to buy--I am content with the propeller I have now.

jimh posted 06-15-2015 08:19 AM ET (US)     Profile for jimh  Send Email to jimh     
For a test of a fourth propeller, a TURBO Offshore II Series three-blade, see

http://continuouswave.com/ubb/Forum4/HTML/008194.html

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