Ride Performance- CD25 vs CD22

bjidzik":1uez9x5c said:
We moved up from a 16' to a 25' Cruiser in October. What a difference in handling! We only have around 20 hours on the new boat so far.

Compared to the 16' & the 22' Cruisers we rode in, the 25' is much more comfortable in light wind & chop. I've also found the 25' is a bit easier to maneuver in the harbor.

What I'm still trying to figure out is the best tilt & trim settings to improve fuel economy. We have trim tabs, but no permatrim. I've contacted several folks about the best tilt & trim adjustments on the 25' cruiser for handling. General consensus was to tilt the motor all the way down to push the bow down and use trim tabs to adjust to plane. Anyone have other preferences?

Thanks :)
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It was eye-opening for us to put a fuel flow meter on Wild Blue. Using that, we are able to trim for the best fuel burn for a given speed/rpm. What has worked for us regarding trim: I generally adjust the tilt so that the prop is staying perpendicular to the water surface and adjust the trim tabs to give us the most comfortable ride. It's a "moving target"... when the water is flat (rare), I seem to get the best mileage with a bow up (slightly) trim. When the chop builds up, we will trim the bow down for a more comfortable ride. Then it's a matter of adjusting the rpm to get what I feel is the best balance of speed/comfort/fuel burn. Depending on conditions, we may get better fuel efficiency at 18 knots compared to 15. That range between 9 and 12 or 13 is generally our least efficient fuel burn, until we get around 20 knots.

The fuel flow meter really helps when running at speeds less than 9. Again depending on conditions, we generally see about 5-6 knots at 1800 RPM, burning just under 1 gallon per hour. Bump that up to 2000 RPM and our speed might go up a couple tenths of a knot, but the fuel burn goes to 1.4 gallons per hour. Doesn't sound like much difference until you look at it as a ratio: to gain less than 5% more speed, you are burning 40% more fuel.

When just bopping around or cruising in places like the Erie Canal and Trent-Severn Waterway, where much of that has a 10 mph or 10 kph speed limit, you are WAY better off to slow down to your most efficient speed and save a bunch of fuel and get more range.

Run it up to planing speeds, and there is that next "sweet spot", which on our boat seems to be in the 16-18 knot range. But that range is less significant in the ratio compared to slower speeds... perhaps 2.7 miles per gallon vs 2.5. Again, this varies with conditions. So, the performance charts can give you a starting place for estimated fuel burn, but in the "real world" of changing conditions... your mileage may vary. Really. :wink:

Hope that helps.

Best wishes,
Jim B.
 
bjidzik
I would suggest that the Permatrim will give you better response to the motor position. It is rare that you want the motor trimmed all of the way down, unless in really steep chop. Normally you want the motor trimmed slightly down, with the trim tabs slighly down when coming up on the plane. Then adjust the trim tabs us, and the engine to the point where the boat does not gain or loose speed as you trim the engine up or down. That will be the most economical running condition in most waters. (If you have flow meters it will confirm the most economical running position)

As for bad backs, the Cats take the prize for the best ride.
 
I'll have to look at fuel flow meter at some point. That said, we seem to get the best ride (depending on conditions) at about 12-15 knots +/-. When it gets rough, we slow down. The boat does pound more than other deeper V boats I'm familiar with back home, so it's a learn as you go issue. I generally adjust as Jim described and fine tune with the tabs. We don't have a Permatrim yet.

As far as bad backs go, I sympathize with you. Meredith had a blown L5/S1 due to a serious gymnastics injury she suffered as a teenager; I witnessed terrible, debilitating pain in her every day since we met back in 2000. She could never have been exposed to the pounding on a boat like she does now. About 4 yrs ago she underwent a total disc replacement as part of a national study to get a prototype approved for use in the U.S. She's been 100% pain free since and it has been a blessing in her life.
 
JamesTXSD":3567l8j3 said:
The fuel flow meter really helps when running at speeds less than 9. Again depending on conditions, we generally see about 5-6 knots at 1800 RPM, burning just under 1 gallon per hour. Bump that up to 2000 RPM and our speed might go up a couple tenths of a knot, but the fuel burn goes to 1.4 gallons per hour. Doesn't sound like much difference until you look at it as a ratio: to gain less than 5% more speed, you are burning 40% more fuel.
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That's the point where the boat is transitioning from displacement speed to planing speed. That intermediate point is the least efficient for any boat.
 
You CANNOT use the flow meter's instantaneous readout for anything more than comparing relative efficiencies. To determine real fuel economy, you must divide total miles traveled by gallons of fuel used, and do it over a number of tanks of gas. ]
 
Pat Anderson":2n4vzou3 said:
You CANNOT use the flow meter's instantaneous readout for anything more than comparing relative efficiencies. To determine real fuel economy, you must divide total miles traveled by gallons of fuel used, and do it over a number of tanks of gas. ]
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Comparing relative efficiencies is the point. And the fuel flow meter works well for that; certainly better than having no information. The meter also shows total fuel burned between fill ups... and it comes VERY close to actual. We still figure average mileage per tank by dividing the miles by the gallons when cruising. When we aren't cruising, we rarely top off the tank... no point in carrying around extra fuel. There is a fuel dock less than a mile from our house... and they charge the same price as the on-land gas stations!

Our speeds may vary greatly from tank to tank and hour to hour. Figuring average fuel burn by dividing the miles by the gallons won't tell you how to get the most range out of the remaining fuel you have. You can "guess it", but the fuel flow meter is just another tool. Prior to installing the meter, I figured 5 gallons per hour as an average. Your record keeping may be better than mine... I don't keep track of how many hours at 6 knots vs how many hours at 20; just total hours based on the hour meter... especially when you may go days on one tank.

I'm not saying one can't or shouldn't run without a fuel flow meter, but we've seen better efficiency since installing ours.

Best wishes,
Jim
 
Jim,

I agree on the fuel flow meter. It's does several things among which is experimenting with throttle and fuel flow based on weight and sea conditions. With my 22 and Honda 90 I could find the most efficient speed and attitude based on the weight and what we were running into. The difference I found was I increased overall economy by paying attention to what my instantaneous economy was over a short period of time. With the BF90D a small throttle change could make a lot of difference. It is kind of like playing with EGT in an airplane by leaning out the mixture.

This summer I get to go through the same experimental phase on the CD25 I just bought. I'll looking at props, trim tab settings, a Permatrim, and fuel consumption with initial impressions based on fuel flow and final decisions based on actual consumption. Since it is a Yamaha 150, the first thing I am adding is a Lowrance LMF400 guage connected to the engine's command link system so I can get fuel flow directly from the engine.
 
I will likely install a fuel flow device on "Katmai," since I found a Navman fuel flow meter on our previous boat so useful. With the Navman unit I got almost instantaneous readouts of the fuel usage. I could select an rpm then adjust motor trim followed by tweaking the trim tabs for the optimum condition. It worked extremely well although it didn't provide a direct readout of mpg or overall MPG for a tank of fuel, etc. ...and the Navman unit was about $120.

Now that I am back to having a Honda motor, there is another consideration. Honda sells a nifty (but very expensive) unit that appears to tell you Everything, including accumulated mpg; but it's a little over $600(!) plus a $120 wiring harness! Aside from the price, I wonder if the Honda unit (and I expect other modern units are similar...) provides direct readout of fuel flow, or does it "sample" the flow every 5/10/30 seconds and thus just give occasional sampling data.

My confusion comes from trying to figure-out a similar fuel consumption unit on our (Ford) truck. With the truck, getting an overall mpg for a tank of gas is silly. You can see what your momentary MPG is, but it only seems to provide the information when you push the magic button. Resetting the MPG option at fill-up, then run through a tank of gas, and the MPG information versus simple arithmetic provides significantly different answers. Trying to articulate this is difficult - but hopefully you see what I'm talking about.

Anyway, back to the issue at hand: Navman or the expensive Honda gizmo? My inclination is to just go with what I know (the Navman device) and save the extra money for Fuel.

Ideas?

Best,
Casey
 
A very interesting discussion ! In my professional life I work occasionally in the marine propulsion market though on a much different scale. It's fascinating to compare with this market sector and then our own boat.

The Yamaha system we bought with the CD23 was an expensive 'adder'. Fortunately the boat was already rigged when we started the purchase process because I do find it very useful. As an example, I switch tanks based on fuel used and not on time run.

I certainly get 'instantaneous' fuel consumption as well as gph, 'trip' fuel used, miles covered etc.. It also gives me the ability to adjust trolling rpm and a bunch of other stuff. I assume the instantaneous fuel consumption measurements are not samples at measured intervals. That would actually be more difficult than simply measuring flow/time. Bear in mind that when you move the throttle there is a lag until the new flow settles down and gets measured but usually this is only a second or two. Certainly you need much longer to let the vessel settle down as well so that you can judge the effects. In general a fuel flow meter is at least as accurate as the tank filling method unless one expects to dump that illegal overflow through the breather. None of us want that so we 'judge' when we are full. Measuring fuel flow is the easy part.

How are we all measuring miles covered? That is always the hard part since we want distance through the water. We certainly can't use the gps for that over the longer term because it really measures distance covered over the ground. It is, however, useful if we are thinking about a leg of a single journey and we want to know how much reserve fuel we have to reach the destination. A combination of time and speed toward waypoint (time to waypoint is usually shown) combined with gph will let us know if we are in trouble as long as we remember to check again when we change course.

Fishfinders and the integrated units usually use the paddlewheel on the back of the boat for DTW. Those are not usually too accurate. Have a look at the manual and see the capability to adjust the readings and you will see that there is a good deal of leeway possible here. For commercial measurement on time trials a sister (actually predecessor) system is still sometimes used whereby a log (torpedo looking trailing propeller) is streamed behind the vessel and its rotations measured. These units are tank tested for calibration. The readings are then used to cross check with other calculations. These can include an ultrasonic unit that measured air bubble flow past the hull. Too expensive for a CD :) .

Boating magazine did a test many years ago to answer this question and came up with what should be the obvious answer, the speedo. off the motor. It's using the classic pitot tube and then Bernouli's equation to convert pressure change into mph. (think aircraft). Are all the instruments calibrated in a lab. ? NO :roll: , but it's the best thing we have on a vessel our size. So, the integrated engine management systems that measure both fuel flow and speed from the pitot to give instantaneous mpg are the easiest way to judge efficient running.

I've spent way too much time writing this. I need to get my boat back in the water and stop worrying about 3.5 vs 3.7 mpg. That's 210 vs 222 miles on my combined 60 gal tanks. The fuel is going to be the cheapest thing I buy in that time. What about :beer ? And unless I'm going to duplicate the exact same runs in exactly the same conditions of tide, current, waves, temperature and wind combined with throttle position, weight and a whole bunch of variables I'm going to get a different range out of each tank.

Chimo
 
I agree- The fuel flow meter gives the information to help set up the best economy for the moment. But figuring out the most economical running speed and attitude is only effective based on the water and boat conditions as they exist at that moment.

Add passangers, gear or other variables, and the best economy speed may change. Not by a lot on these boats, but by some. I also agree that it isn't worth losing any sleep over the differnee between 3.5 and 3.7 mpg...

On the Yamaha boat- I would get the Yamaha gauge rather than the Lowrance. It plugs directly into the Command Link system and will be the most accurate. It can take speed date via NMEA 0183 from any source on board.

On the Honda boat- The Honda gauge will read data directly from the engine computer. More expensive, yes, but more accurate, easier to install and probably offers other functions besides just fuel burn.
 
Last time I posted this it was pretty much insinuated that I was full of BS. Here it goes anyway. My 26 with a 200 Honda gets 3.2 to 3.4 MPG in the ocean and 3.5 to 3.7 MPG in Puget Sound. From point to point (Olympia to Everett) using GPS and actual fuel burned it ran at 4.0 MPG. That was running nonstop without varying the throttle at optimum planing speed (28 to 30 MPH) which is the sweet spot according to the fuel flow meter. The fuel flow meter is Honda factory. When I'm just cruising (not using the kicker fishing), the fuel flow meter reads higher than the actual fuel consumed although not by much. The table is posted somewhere on this site. I didn't keep the numbers to be able to re post them. The meter does keep a running tally of fuel consumed and it is fairly accurate as long as I'm not using the kicker fishing. When I'm cruising the GPS mileage, Honda meter mileage, Honda fuel consumption meter reading, and the actual fill volumes at the pump are very close.
Forrest
 
I've got the Honda (smart gauge?) it gives gph, mpg, total burned, etc. It is wired into the cpu of the motor, which I think is a little more accurate and less problematic than a turbine wheel that is used by a lot of the other fuel meter manufactures. (I've owned both types). My current set-up uses the motors pitot tube for calculating fuel burn. My previous meters used the GPS. I've oftened wondered which would be more accurate for determining MPG, I would have guessed the GPS, but now Chimo's response has me wondering. :?
 
I would argue that the GPS is more accurate because it reflects the distance traveled.

The caveat is that your economy will be affected more by tide and current with the gps than with the pitot tube.

If you have current behind you, you will travel further via GPS with less fuel. Current against you, it will take more fuel.

Lets say your cruising speed is 15 mph. With a 2 mph current against you, you will only travel 13 miles via gps, even though the pito tube will show 15 mph. If the same 2 mph current is with you, than you will travel 17 miles at the same 15 mph. (I am not taking a ton of variable into account here to make the example simple).

So, if the question is- "What's the best rpm and attitude to travel the furthest per gallon of gas?" I would argue the GPS gives the best speed data- based on the conditions as they exist at that moment.

If the question is "How far can I go on the gas I have?" again, I think the GPS data is better, because it tells you how far you will actually travel towards the next port on the fuel remaining, or more importantly how much fuel will be needed to travel a distance based on the existing conditions.

The pitot tube will give the most accurate theoretical (or pure) data, because it eliminates the effect of current on the boat. My argument is that when figuring the fuel situation on board for any trip, I can't ignore the affect of current and tide.
 
Chimo, what kind of flow meter are you using? I wanted to get a Flowscan for our boat (Yamaha 80hp) but the folks at Flowscan said their units wouldn't give the info I was looking for.

Like many others here, I wanted to be able to watch the flow meter as trim was adjusted and try to dial in the most fuel effecient setting for the conditions. I was told that because the Yamahas have two fuel pumps, I would not get accurate data for that. The first fuel pump fills a tank on the engine, then another pump does the work from that small tank. I wouldn't be able to get a steady flow of fuel due to the first pump cycling to fill the engine tank. Bummer! What are you guys using with your Yamis'?

To get this thread back on track to the original question, when comparing the ride between the 22 and a friend's 25, I find the 25 can go much faster in the same conditions than our 22. This with a Suzi 150 and Permatrims and trim tabs. We went out for a run when the Permatrim was installed and it was pretty choppy and windy and the trim tabs weren't even used. There was no way I could have gone that fast in our 22.

Food for thought.

Thanks
Rick
 
I have had a 22 Classic, a 22 Cruiser and a 25. The 25 does ride much better in the chop than either 22. Tyboo was right, the thing that is more severe on the 25 is the pounding you will take falling out of a short steep wave. The 22 Classic will knock your filings out, the 25 is not that severe but it is worse than a 22 Cruiser.
When folks say they don't use the trim tabs I am sure they mean that they are set to neutral. With the tabs fully up the boat won't even get on plane. I put a permatrim on the 25 last year. I still need to trim the engine way down to get the best efficiency and can't say I see much change with it on. You do have to trim the engine a lot at speed with it on so as not to porpoise.
I know folks talk about MPG's near 3MPG but I have never come close to those numbers and I travel a lot alone with not much weight. I have a Navman fuel meter and use it constantly.
In my opinion the 25 is a more stable, roomy, comfortable boat and the best cruising boat. The 22 Cruiser is a better fishing boat and the 22 Classic is even a better fishing boat.

Fred
 
Rick,
I ran a Flowscan meter on a previous boat with a F150 yamaha. Worked fine and was very accurate. The only problem I found was sometimes the GPS and Fuel meter didn't want to communicate for MPG.

Fred,
I agree. On trips I figure 2.5 mpg. I've gotten upwards of 2.8 and on occassions have hit 3.0. But figuring all the trips I've made it pretty much averages out at 2.5 mpg.
 
Pretty much what I was going to say...I don't care about distance "through the water" whatever that means - the GPS gives me point to point distance, and I can determine my fuel ecomony over that actual distance, say from Bellingham to Nanaimo and back or whatever. I have current and wind of course that are going to affect fuel economy. But if I know on average over a long trip with favorable and unfavorable conditions that I am going to get 2.2 nmpg (which is pretty close to actual), I can plan my 1/3 going, 1/3 returning and 1/3 in reserve with reasonable accuracy.

I use my Navman to find how I am doing relative to other rpms and trim settings - you can clearly find the "sweet spots" with a fuel flow meter. But the instantaneous readings are always showing better economy than dividing miles traveled by gallons shows, even though the gallons used is reasonably accurate on mine, like it is on Jim's.

I am not touching a claim of 4 mpg, whether statute or nautical, on a Venture 26 with a 10 foot pole. I just would not plan whether I had enough fuel for a particular trip with an expectation of that kind of fuel economy. Of course there is always Vessel Assist I suppose.

I do know from much experience that the only time I do much better than 2 - 2.5 nmpg is at 5 - 6 knots, when I get between 4 and 5 nmpg. Unfortunately until I retire I seldom have the time for doing a lot of cruising at that speed, but I do look forward to slow cruising and good economy in a few years!


Matt Gurnsey":3c8e3jds said:
I would argue that the GPS is more accurate because it reflects the distance traveled.

The caveat is that your economy will be affected more by tide and current with the gps than with the pitot tube.

If you have current behind you, you will travel further via GPS with less fuel. Current against you, it will take more fuel.

Lets say your cruising speed is 15 mph. With a 2 mph current against you, you will only travel 13 miles via gps, even though the pito tube will show 15 mph. If the same 2 mph current is with you, than you will travel 17 miles at the same 15 mph. (I am not taking a ton of variable into account here to make the example simple).

So, if the question is- "What's the best rpm and attitude to travel the furthest per gallon of gas?" I would argue the GPS gives the best speed data- based on the conditions as they exist at that moment.

If the question is "How far can I go on the gas I have?" again, I think the GPS data is better, because it tells you how far you will actually travel towards the next port on the fuel remaining, or more importantly how much fuel will be needed to travel a distance based on the existing conditions.

The pitot tube will give the most accurate theoretical (or pure) data, because it eliminates the effect of current on the boat. My argument is that when figuring the fuel situation on board for any trip, I can't ignore the affect of current and tide.
Click to expand...
 
Pat,

I think the thing we always forget is that if you are doing 5Kts into a 5Kt tide then your mpg is ZERO. AND you will never get to your destination because you will run out of gas.
Turn around and you will get 10mpg.

That is why 2mpg at 15Kts is better all round because you will at least get there.

If we are going for the real economy then we have to get back to basics and pay much more attention to tides. The rest is semantics.

For our last 3 major trips, the bill for the dog Kennel was way bigger than the gas bill. Don't ask about food and anti-freeze :beer :beer

Merv
 
Pat you're right, I could never quite grasp that 4 MPG but that was what it was. Must have been an air lock in the tank because the fuel burped out the air vent while filling. I was busy trying to soak up the spill and was too embarrassed to try to put more in. The Honda gauges that day said a 3.5 to 3.6 MPG. I think perhaps that my vessel gets good fuel economy because my motor is running a little over half throttle at those speeds where the 135 and 150 are pretty much WOT at that speed. My fuel economy goes down in the 15 to 25 MPH range and down when above 35 MPH. I really don't see that much difference between the 25 and 26 hull. The Cape Cruisers were lighter than the C-Dory versions as a Cape Cruisers such as mine was about 35 to 36 hundred pounds. They were listed as 3800 pounds in the brochure but that was with all options including a radar arch. I will make you a deal though, this spring or summer I will come north and meet you at Everett. We can top off our tanks and head to Olympia. We'll travel at 25 to 30 MPH and the one with the worst fuel economy will buy the gas and chip in a C-note. Most people on this site says their 25's are in the 2.5MPG range. I know mine gets over three in the ocean cause that's primarily where I boat and my mileage is always over three there. It's rare that I can get to my sweet spot in the ocean.
Forrest
 
Thanks for the definitive info on fuel management units. I may have to go back in the "reconsideration" mode (not to mention saving my allowance for boat jewelry!).

Let's see - if the unit is around $650, plus $150 for the wiring harness, and another $150-$200 for installation ... and I can save ten cents per mile, I should break even in just under 10K boating miles! Cool!

Oops - error in Thinking. I already know what the most economical cruising speed is ... displacement mode. So I don't actually need the gauge at all! ...so look at all the money I just Saved!

Oops - another error in Thinking. My Dearly Beloved just pointed out that boat jewelry isn't inherently logical; so just Buy It. Is that a cool wife, or what? (...but Ultimately the cost of that gauge has just gone Way Up, given her consultancy fee..... Uh oh).

Best,
Casey
 
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