Fuel flow and economy - Marinaut 215

[C-Nile]

People,

Regardless of what anyone thinks, the cold hard fact is that I traveled 963 total miles and consumed only 210 gallons of gasoline. I assure you that I was not going hull speed for the majority of those miles. We generally travel between 14 and 23 MPH, except in slow-no-wake zones. Obviously, when we are in slow-no-wake areas, we are going 6 mph, but at slack, and at that speed, we get around 6 mpg as shown on the fuel flow meter. And on those 963 miles: this was measured by the tracks feature of our Raymarine, so not traveling in a straight line does not factor into this discussion. When you think about it, if I under reported mileage, that would be detrimental to favorable miles per gallon rates.

Our crusing grounds are rough. Long Island Sound usually has a good chop, and there are significant tidal flows in our area. These 963 miles were in varied conditions. But really -- does anyone think we bought a speedy cruiser to only go slowly?

I’m in agreement with Bob Austin that to hit 5 mpg on average is a stretch, but we can count on an average of 4.5 mpg (at a boat weight of 3,500 pounds) in varied conditions. It’s all about weight. If I lightened the amount of fuel in the tanks, reduced the amount of water in the bow, carried less gear, and with only me in the boat, I actually think that 5 mpg is possible. We came real close at 4.9 mpg after the last fill-up, and that was with two people in the boat with a full water tank and gas tanks at least 1/2 full. However, with 4 people in the boat, I don’t expect much more then 4.4 mpg, and if conditions were unfavorable, perhaps less then that.

Why are we getting such excellent mileage? In my opinion, the Honda BF115 is one of the most efficient outboard motors ever made. It’s a high torque, low rpm motor. As you all know, Honda makes very efficient engines, but Honda claims this model is 20 percent more efficient then its previous models. Another major factor is the Marinaut itself. She is a light boat for her size. She is not made with a chopper gun -- where you can get uneven distribution of the resin and fiberglass that can lead to higher overall weight. Rather, she is made with hand-laid fiberglass around a closed cell foam core. She is very light. As for hull shapes -- I’m going to stay away from that subject, because I’m not familiar with the hydrodynamics of efficient hull forms. Lastly, our boat is not undercoated. I don’t know the degree of the effect that undercoating has on hull efficiency, but subjectively at least, one would think it would have some affect.

On driving the boat, I agree with those that say that bad helmsmanship has a poor effect on fuel mileage. We're not taking the boat frequently on and off plane. We ride on top of the wave crests in following seas, and make subtle throttle movements -- not major ones. We frequently use our fuel flow meter to determine optimum motor speed settings. Whatever we're doing, it’s obviously working, and 963 miles using 210 gallons of fuel supports that claim.

Thanks,

Rich

[Will-C]

I guess that just about wraps it up. The Marinault 215 and the Honda BF 115 are the best boat and motor ever built. AMEN
D.D.

[C-Nile]

[Jake]

Rich,

I believe you have made some vary valid remarks backed up by hard facts as well as issuing some helpfull opinions/suggestions. Just looking at the design and knowing the weight difference, it would be hard not to think the 215 is going to get better fuel economy than a CD22 even with the same engine.

Jake

[C-Nile]

You know, Jake, I am not trying to convince people to purchase a Marinaut over a C-Dory based upon fuel economy. Honestly, Bob Austin is a boat designer, and he told me off-line that the design of the hull for the Marinaut is slightly less efficient then the C-Dory 22, but that the ride of the Marinaut is slightly better. Indeed, I used to have a CD 16 Crusier, and the ride was rough. If you look at the design of the bow of the CD 16 and the CD 22, it is more rounded. The Marinaut's bow is sharper, and really cuts through the water and travels faster when conditions are rough. Subjectively speaking, I think the main reasons for the excellent fuel economy on the Marinaut are:
1) Honda BF115 efficiency (high torque, low RPM, high technology)
2) shifting fuel weight from the stern to the saddle tanks, placing the water tank in the bow. This reduces drag at the stern
3) lighter overall weight
4) slippery hull that is not bottom coated ( so to compare the CD 22 and my Marinaut fairly, they both would need to be free of bottom coat.
5) using the fuel flow meter to determine optimum efficiency settings. I can't tell you how many times I subjectively think I'm running efficiently until I objectively look at the fuel flow and see how inefficiently I was traveling. Experienced boaters know that an engine, for example, could be running at 4,000 rpm and consuming 6 gallons per hour traveling along at 24 miles per hour, when a mere reduction to 3,500 rpm at 22 miles per hour could result in a drop in fuel flow to 4.8 gallons per hour. Was that extra 2 mph worth it if it is costing 5 more dollars more in fuel per hour? Conversely, one could be running at 3,000 rpm in poor conditions where one is in semi-displacement, and fuel consumption could be going through the roof. So several times per trip, I monitor fuel flow, which has yielded for me excellent results.

Rich

[rogerbum]

[20dauntless]

Here are some real world numbers from my trip to Alaska this summer. Honda BF90D, C-Dory 22 Cruiser, no bottom paint. Fairly heavy load most of the time. 1-3 people, food for a few weeks, big ice chest with up to 50 pounds of ice, up to 70 gallons of gas and 8 gallons of diesel, 6hp Tohatsu kicker, three group 24 batteries, dinghy, inflatable kayak, extra anchor and rode, and all sorts of other gear. And by the end, a somewhat dirty hull.

Anacortes to Ketchikan: 74.2 hours, 805.4 statute miles, 10.9 mph average speed , 219.3 gallons of gas, 3.67 miles per gallon

Cruising in SE Alaska: 279.9 hours, 1,978.5 statute miles, 7.1 mph average speed, 413.7 gallons of gas, 4.8 miles per gallon

I don't have the numbers for the return trip from Ketchikan to Anacortes yet because the boat hasn't been filled up with gas again, but from Ketchikan to Lund, BC they were: 108.4 hours, 740.7 statute miles, 6.8 mph average speed, 152.2 gallons of gas, 4.9 miles per gallon

Hopefully I've got all these numbers added, divided, and multiplied right...

Rich, what was your actual average speed during the last 963 miles? Just miles run divided by hours run. That would be helpful in comparing apples to apples. I've found that even if you cruise at 16 mph, the average including coming and going from marinas, anchoring, etc. is much lower.

[C-Nile]

Retriever,
Your are dead-on. My best estimate is 10.8 miles per hour, which ironically is very similar to your run for Anacortes to Ketchikan, but I'm getting 4.6 mpg -- not 3.7 mpg. It must be that your boat is heavier, and you were traveling in more harsh conditions. Even so, that is good mileage for big water, and it confirms, I think, the great efficiency of the CD 22.

My 10.8 mph YTD average number does not mean as much as one might think, particularly for which to draw conclusions. If I said I traveled 6 miles per hour for two hours, one might conclude that I might be getting 6 mpg or higher, and that would raise overall mileage levels to present a more favorable view. However, what if that 6 miles per hour was through 4 foot seas with wave periods of 2 seconds in which I was only getting 3.5 miles per gallon? This has happened to us. What I'm getting at is that an overall mileage figure is akin to taking an average of the averages. Next season, I'll take down precise engine hours for a certain period, and include fuel flow numbers and miles travelled for different legs of the trip. It's a lot of work, but it would be satisfying to see the numbers and share the results without taking an average of the averages.

To shed a little more light on my area and travel habits, our average trip is 45 miles. The waters we travel upon, while choppy, are well-protected. In ideal conditions, our trip would include a total of 2 miles departing and returning to our marina at 6 mph, slow-no-wake speeds to get to Long Island Sound. Travel 41 miles at approximately 20 mph at 3500 rpm on the Sound, with the tide and/or wind either running with me or against me (but we try to go out in favorable conditions and stay home when the winds are up.) Travel 2 miles at slow-no-wake to go into/leave a transient berth or anchorage.

When the seas are around 4 feet or higher, we either head home if it is a short distance or look for a safe harbor, and our speed is between 4 and 7 mph. We were heading past Orient lighthouse a few weeks ago, and I estimate wave height at 4.5 feet initially. A 42 foot sailboat turned back. We almost turned back, but the seas calmed to 3.5 feet or less, and we safely made it home. At 3 feet, we will travel anywhere between 7 and 15 mph, which is entirely dependant on the conditions relative to tide and wind. At 2 feet, we can usually go 10 to perhaps 20 mph, also dependant upon conditions. At 1 foot or less, we set optimum throttle settings to achieve 3500 rpm, which gives us anywhere between 18 and 24 mph. Obviously, if the speed dips to 18 mph, for example, I'll have to readjust throttle settings to get a more efficient rpm rate. Occassionally, I'll go 30 mph for a few minutes to get home quickly, but as you would expect, efficiency drops significantly. I never take it past 30 mph; in my opinion, that is too fast for a planing boat of our size. At 35 mph max speed, it feels like we are traveling on ice.

l don't want people to get the false impression that I'm overly focused on economy. On the contrary, I find it critical to know how many miles per gallon we experience in our area, and in varied conditions, so that we can determine a realistic range for our boat, which we set at 270 miles (assuming 60 gallons starting out.)

Rich

Rich

[My IRA]

Rich,

Thank you for posting your real world economy/performance numbers for your beautiful Marinaut.

I had the privilege of viewing your boat during it's construction phase and I can tell you that the Les Lampman Marinauts are built better than any other of the C-Dory family of boats that I have examined. The hulls are expertly crafted and the assembly work at EQ is completed as if each boat is to be Les's own personal craft.

I believe that your performance numbers are accurate and represent a documented average for a well equipped and moderately weighted Marinaut. My wife and I had the pleasure of sea trialing a Marinaut last September and we came away amazed at how well the boat handled and the unbelievable economy numbers posted on the Evinrude's gauge.

In short, the Marinaut performs much better than our 1992 22 Cruiser but then we only paid $29,000 for that boat new. I'm excited about the Marinaut and embrace it's superior design and performance.

[C-Nile]

Thank you for your kind comments, Jerry. Our experience with boats pales in comparison to yours, but we are very pleased with our boat. You are particularly right-on about Les. He and Kathy are a throw back to better times when a handshake meant something and people delivered on their promises. We have had the boat for one year now, and have spent over 31 nights on her. It's going to be hard putting her away for the season on October 15th; our season is too short in New England.

Rich

[Sea Wolf]

[Captains Cat]

Joe, I'm a little weary too. It's a nice boat and motor.

Charlie

[Captains Cat]

[potter water]

My comment was misunderstood. I was simply synthesizing general info on many different boats and motor configurations in the general class as the M and CD. I was only indicating that physics ultimately rules and probably puts all boats of the M and CD class pretty much neck and neck for fuel IF you could absolutely duplicate conditions, which of course, you can't. I made my comment as a GENERAL observation without the intent of putting down or boosting up any manufacturer.

I'm simply not interested enough in making the detailed and painstaking effort to figure out what MY MPG is as it will only be good on that day with that load with that power setting and that trim and at that density altitude and those water and current conditions. So, if I am within 25% of accurate for trip planning, I'll carry at least a third more fuel than that 25% uncertainty predicts. End of worrying about MPG.

I do like fuel flow though as a means of getting the best I can under those conditions of power setting, density altitude, load and water conditions.

I can say in general terms that the pleasure I get from my CD makes me very okay with my MPG. Which falls well within the 2.5 to 5 mpg others are getting depending on load and on or off plane. My MPG is probably going to be lower than most of the folks here because I hang out a 3500 to 7000 foot lakes most of the time, and on hot days at that. I'd rather be looking out at the water and the mountains and enjoying the movement over the water than fine tuning MPG, or arguing about it.

[Les Lampman]

Fifteen months ago I asked DaNerd (aka DaNag) if he would set up an "All Marinauts, All the time" sub-forum. The reason I asked him to do so was because I was fairly certain that the Marinaut boats would be discussed and I thought it was better that the discussions occur in a separate sub-forum rather than in the general forum. Why? Because it's a lot easier to ignore a sub-forum than it is interspersed posts within a larger forum. Therefore those not interested could easily avoid having to sift through posts about other than C-Dory branded boats if that is their desire.

If you care to look at the my join date over there to the left you'll see that I joined 30 Oct 2003, even before EQ became a C-Dory dealer (in fact I was also on the C-Dog site prior to shipping over). So you know I've long supported C-Dory boats and their owners. I've made a lot of great friends because of it. The point being that I did not ask DaNerd for a sub-forum so I could overwhelm the C-Brat site and the focus on C-Dory boats but rather because of the shared kinship between the C-Dory and Marinaut and because with one boat in the field (and four in production at this point) there's hardly enough critical mass to sustain a separate owners site.

I'm rather taken aback at the sniping going on in this thread. Rich has taken the time to report what he's observing with his boat so that others interested in the M215 will have some from-the-field information rather than relying on some slick sales dude spouting off. I can tell you that Rich's background lends itself to this sort of endeavor and he's just a bit on the picky side about data. I can also tell you that the Honda BF115 is a NMEA 2000 engine and the fuel burn is being reported right from the ECU to the Raymarine nav system for display at the helm. Speed is obviously coming from the GPS function of the nav system. Without resorting to measured fuel and radar guns I don't know how you get any better than that in real world (everyday) usage. The numbers that Rich is reporting are not the same as a light boat tested by a factory and then hyped up in their literature.

Rich is also not reporting his numbers in an effort to make the M215 "look better" than a C-Dory 22. After all this is the Marinaut sub-forum so the information is being posted in an appropriate place and we're being hosted by a site dedicated to C-Dory boats; it would be in poor taste to purposely denigrate the very boats that make having this sub-forum possible. I've asked all that post about the Marinaut to "stick to the facts m'am". The M215 is what it is, good or bad. There's no reason to hype it or trash it, it can stand on its own (or die for that matter) if honest and factual information is presented.

I can tell you why the M215 typically does better than the average CD22 and it shouldn't be surprising that it does given the years available to the designer to improve on an iconic design. In short, the CD22 as we know it today is stern heavy and oft times by a long way compared to optimum. It's a result of an earlier design having to suffer the aging process at a time when motive power is changing drastically. There is no way to take a hull design that was intended to carry about 375 pounds on the transom along with 36 gallons of fuel and a couple of (relatively) lightweight all purpose batteries and have it perform at its best with 500+ pounds on the transom along with 46 to 50 gallons of fuel and heavier batteries (often an AGM group 24 and 31). That would defy well known yacht design parameters along with physics. The typical modern CD22 is out of balance and the fuel economy suffers because of it. That doesn't lessen the fun one can have with the CD22 and it doesn't negate all of its good attributes, it does mean that it doesn't do as well as it could with a lot less weight in the tail end. I've personally run a CD22 with nothing but an E-TEC 90 on the transom and it performed as originally intended. I've no doubt that a CD22 powered with a lightweight engine (less than 400 pounds on the transom with a kicker) would do every bit as well as the M215. You can't take a hobbled CD22 and expect it to perform better than a much newer design that's specifically intended for heavier modern engines and that has the advantage of another 25+ years of experience behind it. If your 2012 vehicle can't boast being better than a 1987 version it's time for the design team to hang it up and go home.

The M215 was designed specifically for heavier 4-stroke outboards and the weight of the fuel was moved out of the transom (where it has the most affect on balance) and put forward to each side in saddle tanks. The balance, the waterline, and the shape of the M215 is completely different than a CD22 and for good reason given modern power plants and loads.

With 5 adults aboard, on a boat loaded with gear for a few days at a time cruising, and with full water and fuel aboard the Marinaut planes at 9 knots. It's totally balanced and able to take advantage of that happy state of affairs. When I did the testing for the Honda website (the Marinaut is on there under the BF115 section in their performance reports) time to plane was usually less than 3 seconds (and that was with a Honda observer on board and he was running the stop watch).

There are two other factors at play: the specific engine that Rich is running and the weight of the M215. Honda detuned the BF135/150 to come up with the BF115. It's a large displacement engine (for its horsepower) and because of that Honda put the peak torque of the engine down at 3,500 rpm. It also has the best specific fuel consumption of all the larger Honda engines (that's the amount of fuel required to produce one horsepower). The M215 hull can really take advantage of that and I'll be the first to admit that this is a totally serendipitous happening (meaning we didn't design for it, it just happened). The M215 runs very nicely at 3,500 rpm (18 to 19 knots), right where the engine is in a total "sweet spot". At that speed fuel burn is just over 4 GPH.

The M215 is light. All nine fiberglass pieces that make up the boat come to 1225 pounds. We add about 500 pounds in completing the boat to the same stage as a CD22 leaving the factory (fuel and water tanks in, rails on, interior in, windows in, etc...but no engine or customer rigging). Typically a completed M215 is about 300 pounds lighter than a C-Dory 22 completed to the same stage. That's equivalent to a couple of folks on board (well, at least a couple of light ones).

I still like the C-Dory 22 and I totally get why someone might choose it over a Marinaut 215. They're different boats (in spite of their shared heritage) and I would fully expect that one or the other would or could appeal to folks when choosing a boat for their own needs. My best friend of many years has a 1994 CD22 that he bought new and still has; I spent a lot of time on that boat (and still do) long before I had anything to do with C-Dory boats on a professional level. There's also another C-Dory 22 in my life right now that I plan to spend plenty of time aboard and fully enjoy. So if anyone thinks that I'm going to stand over here in the Marinaut section and throw rocks at the C-Dory section they're mistaken, and sadly so.

So quit picking on my doggone Marinaut! It's a boat, it floats, it's for fun, and it's just another choice of many. If offers another choice to folks looking for a trailerable "pocket cruiser" though it's by no means the "only choice" or even the "best choice" depending on what one wants.

And quit picking on Rich, we're supposed to be above that garbage here and I expect folks to comment and conduct themselves in that spirit. Snide remarks can be taken to the "that's life" section if you feel an overwhelming need to carp. Honest questions are of course encouraged and welcome but let's please leave it at questions and useful intercourse and leave the (semi) rude comments for other forums and places where it's more common and expected.

If you really think the numbers are BS hop a flight or drive to Connecticut and take a trip with Rich and Betty on the Betty Ann and decide for yourself whether or not the data is correct and the observations valid. Soon we'll have several other M215s on the water so if you're not within striking distance of Connecticut there should be a boat a bit closer.

I'm buried up to my eyeballs in production at the moment so I am sorry that I'm not here more often and participating (I hate that part of being busy). I'm sorry if some of this sounds like a rant but I have to speak the truth and say that I'm upset and angry about some of the crap being dished out in this thread for no other reason than someone has a keyboard in front of them.