Comparative Fuel Economy?

[FlyMeAway]

Long time lurker, first time poster 🙂

I've been looking at both Ranger Tugs and Cutwater boats since selling my sailboat a few years back (and, to be honest, since before I sold my sailboat). I'm now getting serious about buying a boat and starting to compare options.

Is there a place where I can find cruising speed, WOT speed, and fuel economy / consumption at each for the diesel Ranger and Cutwater models? The OB models helpfully have fuel economy charts on their product pages, but diesel not so much. I'm comparing the entire range, and consumption/speed is an important consideration in my decision. I've searched and searched the forums and the web but haven't found what I'm looking for.

Happy to share back with this community when I'm done compiling in one place!

Thanks!

 

[serpa4]

I also sold a 40' sailing catamaran to get a gas guzzler.
I have really narrowed down my search to the CW30/435hp, but still searching and comparing.
Seems the C30 fuel consumption varies a lot.
I've test drove a 2020 435hp with 4 adults, packed, and 160 gall fuel with AC/Gen combo. Cruise 20.2kts at 15-16 gallons per hour. Not bad!
I just drove a 2015 C30 also with 435hp, 5 adults, 150 gallons diesel, AC/Gen combo. It had low hours, 78 or so. It did WOT at 3600 RPM, 22.1 gallons / hours at 21 kts. Really bad economy. The 2015 was WOT and the 2020 was at cruise with room to spare!
I'd like to cruise at 17-20kts with WOT a little better for outrunning weather if required. The Ranger R31 as a 320hp 4 cylinder vice the C30 with a 6 cylinder 435 hp. The ranger wont cruise at 17kts.
One thing I noticed was the manufacture weight on ALL these Ranger and Cutwaters are vastly vastly under rated, by thousands of pounds.
I turned down the 2015 due to about 1 statue mile per gallon. I'd gladly buy my friend's 2020 at 1.65 mpg! But cannot afford a 2020.

FYI, on the Cutwater 302 with twin 200hp gas yamahas are advertised as about 1.3 mpg x 300 gallons! However, a read a post and about 100% of the owners report a very solid and consistent .9mpg.
I'd rather do a C30 for 288 miles on 180 diesel than 270 miles on a C302 on 300 gallons of expensive gas. In marinas, Bahamas, Caribbean, diesel is always cheaper and often much cheaper than gas.

 

[knotflying]

I would say that honing in on what boat you want and the size should be your starting point. Then see if you can live with the fuel consumption. We have an R-27 classic and fuel is not the most expensive cost on the list. Eating out, groceries and liquor are number one. Fuel comes in at number three. You, being a former sailor, would probably not be looking for speed while cruising, hence going slower. A planing hull won't be as efficient fuel wise if you want to go slow. Living space, comfort and amenities, IMO, would take priority over fuel flow. As we all know owning a boat is an expense.

 

[pleeson]

The fuel economy on all these boats is pretty much a direct function of the speed you intend on travelling on your typical cruising day. If you are going to be happy just chugging along as per your sailing history then just buy the boat you like best for all the other practical reasons, because almost any boat is economical at slow speeds. Our Cutwater 28 - 260 hp diesel only burns 0.4 - 0.5 gal per hour at 5 knots! However, we bought the boat for all its other cruising attributes. We happen to enjoy just being out on the water in nature, and the journey is as good as the destination to us so yes, we spend the majority of our time at 5 - 6 knots. It's quiet and peaceful, and we can make coffee any time we want. However, if there is a tidal rapid to catch at slack, the available throttle is certainly nice to have, as it is if the weather is deteriorating and we are still some miles from a preferred anchorage.

 

[Chimo]

PM me an email address and I will send you some RT25SC numbers carefully compiled by another TugNut

 

[Cutwater28GG]

I reliably get 1.8NMPG on a D4260 Cutwater 28 at a speed of 18 knots.
You have to get entirely off plane down to 6 knots before fuel economy improvements make sense. 12 knots is still 1.8 NMPG - you are just getting there slower.

 

[Dubs]

On the 2018 R31 with the D4-300 we get close to 3.0 NMPG at hull speed and 1.4 NMPG cruising at 14-16 knots at 85-90% of WOT. Previous tug was 2015 R27 with D3-200 which got closer to 2.0 semi planing.

 

[FlyMeAway]

Thanks all! I have to say, I love the assumption that since I'm a former sailor I want to go slow 🙂

Sailing is about the journey -- power boating is about the destination. If I wanted to keep going 7 knots, I'd buy another big sailboat (you get much more room for the money!) and just run the diesel more often than raising the sails.

I'm switching to power to get places faster, so I have time to get to a destination *and* enjoy it (turns out my family likes the destination more than the journey too, sad to say). Fuel economy matters more because I want to know what I'm getting into, I can afford it unless its truly terrible (like 0.2nmi/gal) but I don't like surprises!

 

[pleeson]

Okay then. A fully loaded Cutwater 28 D4 260 with everything for two weeks marina free offers a consistent 1.6 to 1.8 NMPG on the plane at any speed between 14 and about 22 knots. Speeds outside that window mean worse fuel economy until you get well below planing speed and push less water. I don't care about the extra room in a sailboat, I want to live where I can see what's going on outside all the time, and not have to be outside while I'm doing it!

 

[FlyMeAway]

I want to live where I can see what's going on outside all the time, and not have to be outside while I'm doing it!

This is great. And another reason why my family prefers power to sail — being able to spend the journey indoors, in the heat. Me, I see pros and cons both ways, but I think the way you put it is perfect.

 

[BB marine]

Okay then. A fully loaded Cutwater 28 D4 260 with everything for two weeks marina free offers a consistent 1.6 to 1.8 NMPG on the plane at any speed between 14 and about 22 knots. Speeds outside that window mean worse fuel economy until you get well below planing speed and push less water. I don't care about the extra room in a sailboat, I want to live where I can see what's going on outside all the time, and not have to be outside while I'm doing it!

I wish I could get that with C26 D3. 12kts loaded for a trip gives me 1.4 nmpg 3380 rpm ,3600 rpm 1.4 nmpg 13.5 kts, 3750rpm 15kts 1.4 nmpg, 18kts wot 4100 rpm 1.4 nmpg . Drop down to 8 kts 3 nmpg drop down to 7 kts 3.8 nmpg. The extra displacement of the D4 and torque out shines the D3 . C28 is 2000lbs more 40 hp more and 5 kts faster. C26 never really planes throws a big wake and pushes a lot of water. It will definitely get you from point A to point B without an issue. Knock on wood!!!

 

[Megalina]

Numbers from a C32CB - Loaded for a cruise in the Apostle Islands of Lake Superior, best we can make is about 0.9 mpg - but that is at 38mph! The boat has an inverted economy curve - efficiency drops terribly from 38 mph down to about 10 mph. Maybe 0.7 to 0.8 mpg if half loaded with fuel. Have gone through various prop configurations and even negative trim wedges to get lift under the hull. At any safe cruising speed (say 25 to 30 mph or so) the boat either slows or speeds up on its own. There is a problem with the stepped hull design... but it is not efficient as promised. Other outboards with heavier boats produce 100% better numbers... Diesel boats seem to have a better hull/engine match.

 

[Cutwater28GG]

That's fascinating data Megalina.
it sounds as if the C32 is still struggling to get up on plane; almost reads to me like there isnt enough torque. Im curious how heavy you had the boat loaded for the trip; its very very easy to overweight these boats

 

[serpa4]

Numbers from a C32CB - Loaded for a cruise in the Apostle Islands of Lake Superior, best we can make is about 0.9 mpg - but that is at 38mph! The boat has an inverted economy curve - efficiency drops terribly from 38 mph down to about 10 mph. Maybe 0.7 to 0.8 mpg if half loaded with fuel. Have gone through various prop configurations and even negative trim wedges to get lift under the hull. At any safe cruising speed (say 25 to 30 mph or so) the boat either slows or speeds up on its own. There is a problem with the stepped hull design... but it is not efficient as promised. Other outboards with heavier boats produce 100% better numbers... Diesel boats seem to have a better hull/engine match.

I've read a lot on the C302 and that 0.9 is very common with the outboards. I've looked at a lot of the CW302 competition and they very often get better MPG or significantly better for bigger and heavier boats. The C302 is very poor in MPG department. It would be nice to have dual engines for way off shore, but unfortunately, diesel is the only boat that has the range for a 30' boat which is affordable for those who rack up miles/hours.
C302: 270 gallons (90%) x .9 = 243 miles range. Vastly less than rated of about 1.39 mpg.
C30: 162 gallons (90%) x 1.5 = 243 miles range. Vastly less than rated of about 1.7 or 1.8 mpg.
But at the end of the day, at least in the Bahamas, gas is about $3.92 x 270 = $1058 for 243 miles.
Bahamas diesel: $3.39 x 162 = $549 for 243 miles.
In the US Key West: $3.80 for 90 octane gas = $1026 and $2.70 diesel = $437.
Being retired, $400-$500 saving per tank of fuel is a significant. At the rated 1.39mpg I'd do a C302. But not at .9 mpg.

 

[Megalina]

Thanks for comments. I think Cutwater 28GG hit the nail on the head - so to speak. There is not enough torque from the motors to push the boat up into an efficient speed unless you are going wide open. Prop experts commented on this - need bigger diameter props to get the prop slip to a manageable level. Interesting that a quote by Boston Whaler's designer says they avoid stepped hulls for these reasons - hard to hit the sweet spot for all boaters. Great for running a CC offshore fast for fishing, but for a family cruiser not the hull that should be used. I would say all of my tests are at a reasonable weight for two people headed out on a day cruise... will be heavier with a full 300 gallons of fuel!

 

[dazedgonebye]

Hello All,
New here, don't have a boat yet. I'm still in the decision-making phase and in no real hurry.
Whatever I get, I plan to put a good deal of hours in and fuel economy is a big part of the picture. I contacted Ranger today for info.
What I was given, I've posted below.
What I'm really looking for though is the most efficient speed for each boat I'm interested in. Right now that would be:
R-27 old style diesel
R-27 OB
R29
Cutwater C28

Any input at all would be appreciated.

https://photos.google.com/photo/AF1QipNkezdtrDnXtLzFBWu4-rnA8sYSExfDXYbvRva9
https://photos.google.com/photo/AF1QipOgh_77r4D6a2Ov4Be27qEtcfuVcyh5DVeEqbTM

 

[Bruce Moore]

Bumping delayed post.

 

[Submariner]

Hello All,
New here, don't have a boat yet. I'm still in the decision-making phase and in no real hurry.
Whatever I get, I plan to put a good deal of hours in and fuel economy is a big part of the picture. I contacted Ranger today for info.
What I was given, I've posted below.
What I'm really looking for though is the most efficient speed for each boat I'm interested in. Right now that would be:
R-27 old style diesel
R-27 OB
R29
Cutwater C28

Any input at all would be appreciated.

https://photos.google.com/photo/AF1QipNkezdtrDnXtLzFBWu4-rnA8sYSExfDXYbvRva9
https://photos.google.com/photo/AF1QipOgh_77r4D6a2Ov4Be27qEtcfuVcyh5DVeEqbTM

For the R27-OB with the Yamaha F300:
We can slow boat at 6.8kts, 2.8nmpg, 2.5gph at 1700rpm. The slower we slow boat, the better the fuel economy would go (seen as high as 4nmpg)

If we slow boat on the 9.9kicker, we get approx
1gph at 4.8kts at 7/8th throttle.

On the main engine, at cruising, 4500rpm, 25.5kts, 15.6gph and 1.6nmpg.

WOT is 35kts. 5600 rpm, 27gph, 1.3nmpg. Get there fast and spend more time enjoying the destination.

At 10kts I see 1.9nmpg, which is close to what I can obtain doing 25 kts.

Faster than 10kts and slower then 22 kts, is pretty much how to burn fuel fast and get not much for it. (Inefficient).

On plane, depending on conditions of wind and current, I see 4200-4700 rpm, between 22 and 28 kts.

At 150 hours on the engine, traveled 1,526nm, 968 gallons of gas consumed, we averaged 1.57nmpg (1.8mpg) over this summer.

Hope this helps.


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[Alpina]

Thanks all! I have to say, I love the assumption that since I'm a former sailor I want to go slow 🙂

Sailing is about the journey -- power boating is about the destination. If I wanted to keep going 7 knots, I'd buy another big sailboat (you get much more room for the money!) and just run the diesel more often than raising the sails.

I'm switching to power to get places faster, so I have time to get to a destination *and* enjoy it (turns out my family likes the destination more than the journey too, sad to say). Fuel economy matters more because I want to know what I'm getting into, I can afford it unless its truly terrible (like 0.2nmi/gal) but I don't like surprises!

At planning speeds (~13 knots and above) the nmpg don’t vary much. Very surprising for me coming from a very different shaped hull power boat. I see between 1.4-1.6 nmpg which is influenced more by how many people/fuel/waste/water I have on board than the speed itself. Below planning speeds, I see anywhere from 10 nmpg (barely above idle), to 3 nmpg which is just before I’d push the boat to planing speeds. Just before planing I get under two so I either will slow down or speed up.

I have a 2019 Ranger R29 CB with a Volvo D4-300 diesel.


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