CD22' 90hp or 2 40hp motors for fuel efficiency?

[nesibus]

Can anyone tell me if you get the same range on a tank with the different setups?

And maybe a difference in drive out cost?

[nesibus]

I was reading online about the twin 40hp motors...

"Twin Honda 40 Hp Four Stroke - Fuel consumption, is for both motors"


It says they get about 5mpg....does that mean each motor gets 5mpg...or is that together?

Does each motor require 1 gallon to go 5 miles at cruise speed...so 2 gallons total to go 5 miles?

Or do the motors together only require 1 total gallon to go 5 miles, so technically each motor only uses half a gallon during the 5 miles?[/u]

[Sneaks]

Check with El and Bill on the Halcyon with twin 40's. They cruised to Alaska a couple of years ago with Chris, Rana Verde, single 75 and if memory serves me they mentioned the overall fuel consumption of both boats on that LONG cruise was almost exactly the same

Don

[jlastofka]

5 mpg would be great mileage for a boat if you're talking about some kind of cruising speed and not just barely moving along. It would be the total fuel for both 40 hp motors together. It would also be statute miles instead of nautical, and it would be at the "good mileage cruise speed", whatever that turns out to be.

Usually you'll see great mileage at really slow speeds, like a couple miles per hour. Then a dropoff as you speed up, followed by an improvement after you just get on plane, followed by a steady dropoff until you get toward top end, where you'll start using lots of fuel to go just a little faster.

Something like that. Your optimum bang for the buck speed is probably somewhere above planing speed, but well below top speed. I'm in the process of installing a Floscan setup and will be able to do some real optimizing after it's in. Trim tabs, motor trim, moving weight around the boat, waxing the antenna, whatever it takes....

A diesel sailboat will motor along at something approaching 10 mpg. A power trawler will get maybe 3 mpg or so. A big sportfisher maybe 1 mpg at reasonable speeds and maybe 4 gallons per mile (!) if you put the hammer down.

5 mpg is a good number for a fairly efficient small power boat.

On a gas engine you can divide the hp by 10 and get a good approximation of the maximum fuel burn rate, as in 40 hp over 10 is 4 so you could burn 4 gal per hour. At a good cruise setting you'd probably use 50% of that or so. Now you're looking at 2 gal per hour. Two engines means 4 gal per hour, so you'd get 5 mpg at 20 mph.

With a diesel you could reduce fuel consumption by around 40% perhaps. You need to keep the diesel a long time to have the fuel savings pay the engine cost difference, though.

Jeff

[westward]

Greetings! Here are my personal conclusions after much research/agonizing on engine choice recently: The fuel economy for twin motors should be about the same as for a single 90 and you should choose your configuration based on your personal usage/preferences and budget rather than any expectation of better economy. Twin 40 or 50 Honda's show slightly better numbers than single (carb) engines, but most of the new 90's are fuel injected and will use less fuel. The 40-50HP engines that are fuel injected are, taken together, way too heavy for the transom of the CD22 in my opinion. So are some of the new 90's when installed together with a kicker. Twins cost more initially than a single 90, but the delta largely disappears if you add the cost of a new kicker. Those who want a kicker mainly as a backup will have as a backup a motor that is seldom started/run, probably is using older fuel, may not be on the same maintenance schedule as the main, will not move/control the boat very well in rough water, and will need to be started in an emergency situation as opposed to a 40 already down and running. For a fisherman, the kicker is easier to control and shut off from the cockpit and can troll slower. Twins have a lower profile/CG and arguably nicer form factor. One could purchase a single initially then add the kicker later as $ allowed, whereas twins obviously need to be installed up front. The twins add manuverability and lateral trim ability (especially with Permatrims installed) and give much better low end throttle response due to more prop biting the water. The single has less drag and should therefore do better at the top end. One could conceive of flotsam or grounding knocking out both props of twins, where the kicker rides up out of the water and would be available as a backup. Les stated that the tune-up cost for a single 90 and kicker happens to be exactly the same as the tune-up cost for twin 40's. My personal choices are: for single engines the E-Tec 90 and for twins the Honda 40 or 50. We opted to go with Honda twin 40's. The Honda 90VTEC will be very attractive when they get the bugs ironed out, which I have no doubt they will. When we used to make a rough crossing in our old boat (single 70 and 15HP kicker) I would always start up the kicker and warm it up a bit before casting off, so it would fire right up if needed emergently. All of my personal motor failures have been propeller related. I have read, though, that by far most marine engine failures are fuel related, followed by electrical problems. Hope this helps the discussion in some way. Mike.

[C-Gypsy]

Another consideration will be how & where you may be using your boat. Think about the future, these things last forever.

I liked the idea of twin 40's or 45's when I purchased my C-Dory, but my dad is 71 years old and likes to fish the state parks in PA. I like to keep dad happy.

Some PA state parks have 10 horsepower limits. So my C-Dory has a Honda 90 and a Honda 9.9 kicker. I figure I have all the bases covered for MY situation, but yours may be different.

I confess I love watching a boat with "twin screws" dock. I admire them for their manueverability.

Sometimes there are considerations more personal & important than fuel consumption & performance.

When you look at albums on this site remember that each of us may have left personal circumstances influence our decisions.

Perhaps not the technical answer you were hoping for, but life is not that technical. Just complicated!

Al

[jlastofka]

Regarding:

"I confess I love watching a boat with "twin screws" dock. I admire them for their manueverability." from C-Gypsy

I see you have a 90 and a 9.9. I've run my 90 and 9.9 at the same time and the boat maneuvers just like the twin engine boats I've watched at the harbor. Spins in it's own length or slides forward or backward at the same time as I please. REALLY easy to control with twin throttle/shift levers, which I have because both engines are Hondas and use the same controls, even though they're different sizes. The 9.9 is the geared-down, high-thrust model with a big prop, which makes it act similar to the 90 at or near idle speeds when playing around like this.

It was an unexpected bonus when I tried it. I thought it might work, but not too well, because the engines are close together. I was wrong. It works great! Probably because it's a small, light boat with little draft.

I don't start both engines every time I come to a dock, but if I'm approaching a really tight spot or strange conditions some day, you can bet I'll have it idling, just in case. The kicker is power tilt and electric start, so it's a no-brainer to fire it up. Having the steering linked and using a twin throttle control makes it pretty darn easy to fool with.

I REALLY wanted the factory swim step and easy access for SCUBA, so the main/kicker combination was very attractive to me. I decided to give up twin engine maneuvering in favor of that. Imagine my delight when the "twin engine" trick worked anyway.

There's no ONE answer. You gotta figure out what works for you. It helps to have owned and/or driven a few boats. You're not likely to get it right the first time. (Even if you do, you'll change your mind later........)

I see the majority of people here in SoCal run a single outboard these days and not worry about backup. That's how reliable they've become. I wanted a kicker just in case.

Jeff

[C-Gypsy]

You have inside controls for BOTH motors?

Can you start both of them & shut them both down from inside?

I may be asking a LOT more questions of you.

I want to be able to have FULL control of BOTH motors from inside & yet still have a helm in the cockpit for the kicker.

Is that too complicated to be practical?

[RJD Wannabe]

for me as mainly into fishing, having a small kicker for trolling at hi mpg and still hi end maneuverability via 2 engines is huge. BUT, real twins seem to tilt back less into the cockpit, so an icechest, fishbox, etc will be less intrusive into that area.

Since used will be my direction, best deal will probably win as both set ups have their advantages.

[SEA3PO]

I have twin 40 Yamaha's.....on my 22' cruiser... and my mileage varies...from a low of 4mpg when I am heavy loaded or running hard, to a high of 4.5 mpg when I am running at 14-18 mph... comfortable cruise...with a normal load.... I think that is pretty good fuel economy, I am quite happy with it... I really like the twins.... I have had one die in a bad spot....and was able to control the boat while I attended the dead motor... (usually a fuel like disconnected)... I like that.

Joel
SEA3PO

[smittypaddler]

Na Waqa has twin Honda 40's, mainly because I thought it would be safer; lose one engine, you still have a backup. But others with a lot more experience have told me that most engine problems are because of contaminations in the gas tank, which of course would affect both engines. I've been very, very careful, and have only lost a prop blade once. But with the Piranha props I can change out a single blade in less than fifteen minutes, though a heavy swell would make it more difficult.

It seems to me that maintenance costs for two engines has to be higher. It was a real shocker when I got service in the Florida Keys at 200 hours engine time and the bill was over $800! The expense of course was double because I had two engines. I'd guess a larger single engine might be more than $400 for the big 200-hour service, but surely not double?

It is nice to be able to rotate the boat in its own length, but I can do that almost as well on one engine, by alternate shifts forward/reverse and rapid spins of the helm. I usually have one engine in neutral anyway, or shut off, when docking, because I find fiddling with two throttles adds to my confusion. Dealing with only one throttle seems to make it a little easier for me to avoid panic.

I don't know where they get those figures for gas mileage at C-Dory. I kept careful track of my mileage over the 7,000 miles of the Great Loop, and my overall average was 3.75 mpg. My best day was only 4.25 mpg. I usually went as fast as the waves would let me, though most of my day averages were around 15 mph due to wind and waves. At WOT I can do 28 mph. The only way I can get better mileage is to run on one engine at a time, at hull speed, which is about 6.5 mph (1.39Xsqrt(lwl)); that gives me about 7 mpg.

If I had it to do over, I'd still get the Hondas, because they've been so reliable, but twin 50s instead of 40s. I don't really need the extra 20 horsepower; the twin 40s pull a waterskier just fine. But sometimes I'd like to have a little extra oomph.

[teflonmom]

I am not going to get into the single /twin debate. I can however tell you about our fuel use on our recent 575 mi trip on the NYS Canals.

Our 22 is powered with a 90 HP Honda with carbs(05) We tend to have a heavy boat. My wife likes to keep the food lockers well stocked, then we eat out more than we planned.

Our fuel use was about 2.3 gal per hour. Our speed was varied as some parts of the system allow speeds up to 45 MPH. The normal; 10 MPH canal speed limit is not very good for our boat,3300 RPM. If we increase the RPMs to 4000 we make about 14 MPH and it feels a lot better.

We keep records of our mileage with our chart plotter and comparing that with fuel use we got over 4.3 MPG This trip I was careful to shut down the motor while waiting for locks and during locking.

We are going for another 10 day trip on the canal starting from Geneva and as far west as Brockport. We are leaving the cat at home and taking our son Brian with us. I am also taking a folding bile for the first time. My son is taking his fancy road bike so he will be way too fast for me, but at least I will get some exercise.

Fred, Pat and Mr. Grey (the swimming cat)

PS Mr. Grey went to the Vets Kitty Condo. I hope he likes it.

[jlastofka]

My combination is a VTEC 90 and Hi-Thrust 9.9 (make sure you don't get the High Thurst 9.9 or your economy will suffer) (just kidding).

Anyway, both engines are electric start and power tilt/trim. I have a standard Honda twin throttle quadrant, but two small separate starter key pads. (The idiot lights on the keypads are a little different for the two engines.) It all fits next to the helm in the usual position. Both electric trim controls are on the left throttle, which is the main engine throttle lever. You just leave the right lever alone most of the time.

The steering cylinder is on the main engine and there's a quick disconnect rod that couples the kicker to it so they both steer together. You can tilt and start either engine from the helm. I normally run with the kicker up and the main down. I can have them both down also. If I were to run with the kicker down and raise the main, my steering angle would be somewhat limited. (If the power tilt fails on either engine, there's a release screw that will lower them, so I can't get trapped with the main up and not be able to steer.) Running with the kicker, leaving the main down makes it steer better. Big rudder back there.

There's a friction lock on the kicker steering so I could release the link bar and lock the kicker from turning, although I haven't needed to do that. Because of the hydraulic steering, a person could add a second steering station in the cockpit. It's done often on larger boats. I guess I could also just remove the steering link and clamp on a tiller gizmo to the kicker....

I think I'd be out of luck for running the throttle from the cockpit, though. I don't expect that to bother me. Maybe later?? (It would be pretty easy to have a remote switch in the cockpit to just kill the kicker if that's what you want for dealing with a fish or something. You could wire a switch in series with the little emergency kill switch on the console. It would be just like pulling the little lanyard on the kill switch. Click, dead engine. Or tie a long string to the lanyard.....)

At the moment, the only thing I'd like to add to my setup is a remote power tilt switch for the kicker back at the stern. The big engine has one built in, but to tilt the kicker I need to climb into the boat and use the control on the throttle lever. It's handy when you're rinsing the engines after hauling out.

By the way, I don't know if the other new engines do this, but on these two Hondas you don't run the engine while flushing. You just plug a garden hose into the engine and let water flow through for 10 minutes. Water flows out of several places and you have a Honda water fountain decorating your driveway for a while. They specifically tell you to NOT run the engines. You could also clamp on the earmuff gizmos if you did want to run them, but why?

The fuel injected main starts so quickly you can hardly hear it crank. The carbureted kicker has an auto-enrichment feature so you just crank it and it starts and runs itself, almost like a fuel injected engine, but you can hear it fluctuating a little bit as it warms itself up for a few moments. There's no tach or hour meter on the kicker. Yet.

The kicker will run the boat up to near hull speed. About 6.0 or so. A single from a twin setup would run it a bit faster, but not much. (Actually, with big seas or wind it might do better than the kicker, so there's an advantage, although the Hi-Thrust version pushes pretty hard at low speed, so I'm not too sure there's much difference.) If you assume that an engine would fail every 2000 hours let's guess, you'd average about 2000 hours before you dropped from main speed to kicker speed. With a twin setup, you'd average 1000 hours before you dropped speed ranges (two times the probability of an engine incident). That's assuming engine failures. In reality, there's bad fuel, log strikes, groundings, whatever. With a log strike or grounding, having the kicker stored "up" means it's protected from these disasters, so there's an advantage that way.

The kicker has a quick connect fuel fitting on the front, so you could have a small extra tank with different fuel on hand, as an option. A good choice for a kicker is one of the Hi-Thrust models, geared down for a larger prop and lower boat speed. You get more pushing force that way at low speeds, and a kicker is never going to make the boat go fast anyway, so there's no point having a prop and gear ratio made for pushing a little fishing skiff at speed.

This all makes sense to me, but I can understand that others have different preferences, too. So many considerations and speculations to mull over, eh?

I don't talk much, but I type a LOT. Any more questions, fire away....

Jeff

[tpbrady]

Jeff,

What prop are you running on your 90 and any idea of its performance/fuel economy? My current favorite is a four blade Solas 15P. WOT is 6100 RPM at 31 mph. Working on a new favorite now.

Tom

[jlastofka]

I've only tested it a little at WOT. I got 31 mph (27 knots) GPS on fairly smooth water with no wind or current. I forget the RPM, but I want to say something like 5300. Mine has the stock Honda 13.5 x 15 three blade. The boat was light that day. Only 29 hours so far. No good mileage testing yet. Only trips have been in pretty good chop with some load in the boat. Got around 3 mpg I guess. Lots of throttle jockeying and trim tabs down for smoother wave penetration. Speeds of 13 to 17 knots.

I'm waiting for Lake Powell to do some better testing. Plus I'm trying to get my Floscan hooked up, in addition to other things. I shouldn't be here typing, but it's dark out and I kind of shut down at night....

Jeff