Efficient Powerboats vs Efficient Sailboats (Running Cost Comparison)

[alohaboat]

I am new on this Board and ran across this interesting thread.

I have owned full displacement sailing boats and full displacement power boats. I don't think one is better than the other, they are similar, but different concepts. I like them both, so I have no axe to grind.

Boat designer, George Buehler (George Buehler Yacht Design Home Page) makes an argument that a full displacement power boat is less expensive to maintain and operate than a sailboat in his "The Troller Yacht Book." I don't know if he is right or wrong, it is just another opinion. I think more depends on the philosophy of the owner/operator than the boat itself.

I would like to provide some information about what a very efficient trawler yacht can do. I have owned a Willard 40 Pilothouse trawler for the last 5 years. I have cruised her from the San Juan Islands all the way down to Mexico so I have a pretty good understanding of her capabilities.

The Willard 40 is a full displacement, fully ballasted (7,000 pounds), canoe stern power boat. This is nothing more than a sailboat hull that was designed about 40 years ago by boat designer Hale Field (now deceased). I am powered by a single 120 hp John Deere 4 cyl. turbo diesel. I carry 700 gallons of fuel.

These are my performance specifications. I burn 1.5 gph at 7.5 knots (my normal cruising speed). I get 5 nmpg. My range at 7.5 knots is therefore about 3,000 nm with an additional 15% fuel reserve. If I slow down, I can increase my range by 10% to 20%. Because I purchase fuel in large quantities (which isn't very often), I get a break on the price per gallon. I change my oil and filters every 300 hours as recommended by John Deere. Well maintained John Deere engines generally run in excess of 10,000 hours before they need any kind of rebuild. I believe that the Willard hull is more efficient than the Krogen or Nordhavn hulls. I am getting much better performance than what those owners are experiencing. I think my cost to operate and maintain is comparable or less than most power boat and perhaps sailboats too. I don't want to start any arguments, this is just my personal experience.

I am cruising Mexico this year and plan to cross over to the South Pacific in 2008. I will cross from Puerto Vallarta to the Tuamotus where I will refuel. Then I will island hop around Polynesia where I lived in Tonga for two years a long time ago.

[Brent Swain]

I've been cruising 11 months a year since I was 26 years old, and working one , something which would be impossible in a power boat. A winter in the south pacific cost me less than a similar sized power boats fuel bill for a couple of weeks.

[GordMay]

In his landmark publication, “Voyaging Under Power”, Robert P. Beebe also contends that the costs of passagemaking can be similar under power or sail.

[Brent Swain]

********. A used mainsail that I bought for $100 and a genoa I bought for $350 took me to Mexico and back , 9 trips to the Charlottes and back and two trips to Tonga and back . Try power a 31 ft power boat that far( 25,000 miles) on $450 worth of diesel.
Brent

[alohaboat]

Originally Posted by Louis Riel

A used mainsail that I bought for $100 and a genoa I bought for $350 took me to Mexico and back , 9 trips to the Charlottes and back and two trips to Tonga and back . Try power a 31 ft power boat that far( 25,000 miles) on $450 worth of diesel.

I don't disagree with you Brent. I said, "I think more depends on the philosophy of the owner/operator than the boat itself."

What did you think of Tonga? Must have liked it since you went back a second time.

[cat man do]

I'll agree Brent, that on a small mono the numbers could well be different,

But if you read from the start of the thread it was relating to a 50ft performance cat, with about $60,000 worth of rig, sails, winches and deck gear, compared to a similar vessel with just the motor's, and the $$$ to spend on diesel.

Dave

[alohaboat]

Here is what Steve Dashew says when he compares his new, power "Unsailboat" with his previous sailboat, Beowulf:

"Surprisingly we've found that operating costs are a lot less. True, we've got diesel and lube oil to purchase. But the running cost per mile is about sixty percent of what was necessary with Beowulf when maintaining her sails and rig are considered (using diesel at US$2.50/gallon as an average cost)."

[cat man do]

Certainly work's on the big boat's, I think, but on something under 35 ft if trying to do over 1000 nm hop's in one go, I would have to say that I would go back to sail.

Dave

[Lynx]

Size and speed and destination is a lot to consider. Motor sailors is an option. A lot to consider and not a really simple question.

My Mac 26M is powered by a Mercury 50hp Bigfoot with a 14" prop. At Full speed (16 mph) I get from 3.5 to 4 mpg. At 5 mph I get from 12 to 15 mpg.

A smaller boat will get you better gas milage. Long distance cruising, Sails is better due to lack of gas stations. However, short hops of 20 miles and needing to charge the batteries, well.......

[Amgine]

You need to consider the complete costs of cruise. Which includes wear and tear on the rigging, bottom paint, and food.

So, for example, a cruise to Mexico from Seattle in a sailboat at 100 miles per day versus a motor vessel getting at 7 kt (150 miles per day) is going to have 3/2 crew costs. A motorboat bucking the current on the way back, though, may end up taking as much time or more than the sail boat going out, up, and over the Pacific high.

The bigger the vessel, the more size would work against the sailboat as the rig costs and wear/tear increase geometrically (but, at the same time, the speed advantage of the displacement motor vessel decreases.) Contrariwise, the fuel costs for a larger motor vessel increase more lineally, but additional speed costs increase geometrically (the mass of the wave increases geometrically, and thus the cost for minor speed improvements are equally equally increased.)

Where the break-even point is, the point where a motor vessel becomes cheaper than the sailboat, will probably not even consider the cost per mile though. It will be in the price pound of initially buying the boat, and its rate of depreciation. An old, classic sailboat might compare very favourably with a brand-new chromy bayliner, while an older heavy tug-style cruiser might come out ahead of a modern high-tech cruising catamaran, in the strict cost comparisons, no matter the size of the engines or masts.

Try finding a mid sized off-the-shelf power boat with a configuration like Dashew's Un-sailboat. Don't forget that he gets a big benifit from the very long waterline and very narrow (relatively) beam. That sort of power boat doesn't exist in the under 45' range.
The BEST fuel consumption figure I've seen in mid-sized power is 4 mpg. Most are 2 to 3 mpg. Comparable sail will get 6 to 8. That's double to triple the economy for AVAILABLE mid size craft.
Build your own is a totally different set of rules.

[alohaboat]

Originally Posted by xort

Try finding a mid sized off-the-shelf power boat with a configuration like Dashew's Un-sailboat. That sort of power boat doesn't exist in the under 45' range.
The BEST fuel consumption figure I've seen in mid-sized power is 4 mpg. Most are 2 to 3 mpg.

I don't want to start an argument but I do get right at 5 nmpg at around 7.25 knots in my bone stock Willard 40 trawler with 36 ft LWL. I have 5 years of experience and several thousand miles, most of it off shore, so pretty good supporting data. If I slow to 6 knots, I get more than 6 nmpg. I run a single, 4 cyl. John Deere turbo diesel.

The Diesel Ducks are also racking up some pretty impressive statistics. A Diesel Duck 44 just completed a circumnavigation running a 55 hp Kubota engine.

[Capct]

It mostly depends on "how " you run your power.If you are talking about gas inboards
My 35 year old small block v8's , 318 twins get pretty much the same efficiencies now as they did new ...which is to say they are gas sucking pigs
I can gobble the gas at an incredible rate if I wanna do 38 knots or I can conserve by running at 8 knots...
Works out for me to around 250-300 nm per tank [using both engines]

[cat man do]

How goes it Capct

How big are your tank's for that sort of range?

And 318's, are they the 318 Fireball engines that were in the Chrysler cars ?

Make's my 65 hp x 2 Cummins seem a bit small.



Dave

[Capct]

Originally Posted by cat man do

How goes it Capct

How big are your tank's for that sort of range?

And 318's, are they the 318 Fireball engines that were in the Chrysler cars ?

Make's my 65 hp x 2 Cummins seem a bit small.



Dave

Hey Cat
200 US Gallons -twin SS 100 gallon tanks with crossfeed so they drain evenly.
I guess I should have put in weather/current/tide/ parameters in my original comment.So I will now...that would be 300NM with the current and the wind behind my back.
That literally will drop 100% to 150 NM if I am bucking the currents around here and going into the wind.So it would be fair to say there are other factors that
increase or decrease fuel efficiency.

They are Marine 318's made by Chrysler in 1972.Small block V8's that generate around 225 HP at 2800 RPM on the curve and they will generate as much as 310HP each at 4000rpm.
I never run them that hot though.

Twin Four barrel Carter carbs
Direct shaft driven Borg Warner trannys 1.5/1

They are the ones pictured in my Avatar.They are as you can see in fantastic condition but they are not what you would call fuel efficient.
Unless they run at 8-10 knots.