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Ethanol as Fuel for
Recreational Boats
www.mercurymarine.com
ENGS 190/ENGG 290 Final Report
Sponsor: Professor Charles Wyman
Group Members:
Erik Dambach, Adam Han, Brian Henthorn
www.dartmouth.edu/~ethanolboat
8 March 2004
Presentation Outline
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Need Statement and Background
Engine Choice and Modifications
Specifications and Testing
Marketability
Conclusions
Acknowledgements
Ethanol as Fuel
for Recreational Boats
Need Statement
Due to the potential for environmental
contamination by gasoline in recreational
boating, fuel ethanol is a potential solution
to reduce pollution associated with
recreational boating.
Ethanol as Fuel
for Recreational Boats
Why Ethanol?
• Recreational boating with gasoline as a fuel is a
major source of pollution for both water and air
• Ethanol, unlike gasoline, is biodegradable and
low in toxicity
• Ethanol is comprised of much fewer chemicals
than gasoline
• As an additive, the use of ethanol as a fuel has
the ability to allow for cleaner combustion and to
lower air emissions
• Ethanol is a renewable source of energy
Ethanol as Fuel
for Recreational Boats
State of the Art
• The use of ethanol as a fuel has mainly
been focused on the automotive industry
• There are limited studies of ‘alternative
fuels’ in boating applications
• Fuel ethanol has never been researched
for recreational boating
• Ethanol was investigated along with other
‘alternatives’ in use to strengthen fuel
choice
Ethanol as Fuel
for Recreational Boats
Alternative Fuels
for Gasoline Marine Engines
Ethanol as Fuel
for Recreational Boats
California Case Study
• US fuel prices and
regulations vary by region
• Toughest emission
regulations in country
• High price of gasoline
• Supportive of alternative
fuel technology
• Phase-out of MTBE 
replaced with EtOH
• 2nd most registered
number of boats in US
• Discourages the use of
carbureted two-strokes
Ethanol as Fuel
for Recreational Boats
California Case Study
Projected Price Range* for Ethanol
Sale in California at Marinas
Production Cost
$1.020
Price Incentive
$0.050
Transportation/handling costs
$0.146 ─ $0.187
Excise Tax Rate
$0.090
Mark-up
$0.350
Projected California Price Range
$1.656 ─ $1.697
Gasoline Equivalent Price Range
$1.441 ─ $2.562
*Price per gallon of ethanol
Ethanol as Fuel
for Recreational Boats
Engine Overview
• 2000 Mercury 5 hp
Four-Stroke Outboard
• Four-stroke for
smaller needs
(<90hp)
• Necessary
Modifications
– Materials Compatibility
– A/F ratio
– Cold-start
Ethanol as Fuel
for Recreational Boats
Materials Compatibility
• Rubber Tubing, O-Rings
– Soaked in EtOH
– Tubing replaced with
Viton B
– O-rings replace with Butyl
Dupont Dow Elastomers Chemical Resistance Guide
Ethanol as Fuel
for Recreational Boats
Replacement of Rubber
in Fuel System
Tubing
Fuel
pump
o-ring
Drainage
screw
o-ring
Intake
manifold
o-ring
Ethanol as Fuel
for Recreational Boats
Materials Compatibility
• Rubber Tubing, O-Rings
– Soaked in EtOH
– Tubing replaced with
Viton B
– O-rings replace with Butyl
• Fuel Filter
– Soak in EtOH
– Not needed to be replaced
• Metal Corrosion
– Determine primary metal in
Fuel System using EDS on
SEM
Dupont Dow Elastomers Chemical Resistance Guide
Ethanol as Fuel
for Recreational Boats
Energy-dispersive X-Ray
Spectroscopy (EDS)
Main Jet - Brass
Ethanol as Fuel
for Recreational Boats
Fuel Pump – Aluminum
Carburetor
Source: Mercury Service
Manual, 4/5/6HP 4-Stroke
Ethanol as Fuel
for Recreational Boats
Carburetor Modifications
• Enlarge Main Jet inner diameter by 20-40%
– (.033”, .036”,.039”)
Main Nozzle
Ethanol as Fuel
for Recreational Boats
Main Jet
Cold-start Solutions
Cold Start Method
Effectiveness
Environ.
Portability Availability Fuel Cost Retrofit Cost (single start) Repeatability Impact Ease of Use TOTAL TOTAL weighted
Gasoline
Propane
Natural Gas
Hydrogen Gas
Diethyl Ether (EtOH)
Diethyl Ether (Starting Fluid)
Electric Heater (outlet)
Electric Heater (battery)
Ethanol as Fuel
for Recreational Boats
5
6
7
1
1
4
8
1
5
6
7
1
1
4
8
3
3
4
2
0
0
1
0
0
4
5
6
8
7
1
2
3
4
4
4
1
2
2
7
7
1
1
1
1
1
1
1
7
8
7
4
3
5
5
1
1
4
5
6
7
7
1
1
1
34
38
37
22
24
19
28
23
77
88
94
66
68
39
74
66
Other Important Modifications
• Ignition Timing
– Advance ignition timing for EtOH
– Unfortunately, not possible with Mercury
outboard engine
• Compression Ratio
– Increase (8.5:1~11:1)
– Extremely expensive
– Can only be drastically altered at production
stage
Ethanol as Fuel
for Recreational Boats
Target Specifications
Area
Quantification
Justification
Test
NOx + HC emissions
1770.8 PPM
2008 CARB Exhaust
Emissions Standard
Snap-on MT3505 Emissions
Analyzer at Vermont
Technical College
CO emissions
0.85% (reduction by 10%)
The reduction is acceptable or
ethanol to be preferred
over gasoline.
Same as above
Horsepower
5 hp (100% of running on
gasoline)
Maximum power output of
gasoline engine
Torque, RPM, horsepower
relationship
Efficiency
At least 0.0140 gal/hr-hp (at
least 66.7% of gasoline)
Energy content ratio of
gasoline to ethanol
Run known volume of fuel
until engine stopped
Cold-start
Must start above 30°F
Minimum starting
temperature of gasoline
engine
Start at cold temperature
Weight
< 62.7 lbs. (110% of original
engine weight)
According to Fairlee Marine
Scale
$250 (25% of engine value
maximum)
Alternative Fuel Data Center
vehicle cost analysis
Economic analysis
Environmental
Performance
Economics
Overall cost to retrofit
(excluding labor)
Ethanol as Fuel
for Recreational Boats
Testing Methodology
Ethanol as Fuel
for Recreational Boats
Testing Methodology
Ethanol as Fuel
for Recreational Boats
Testing Setup
• Preparation for testing
– Construct test stand
– Break in engine
• Fuel Used
– Gasoline: Shell 87 Octane
Unleaded
– Ethanol: Ethanol with
Natural Gasoline
Denaturant (2-5%)
• Testing Facilities
– Emissions testing at
Vermont Technical College
– Thayer School Ice Lab
– Thayer School Loading
Dock
Ethanol as Fuel
for Recreational Boats
Emissions Testing
• Snap-on MT3505
Emissions Analyzer
• Emissions Analyzed
–
–
–
–
Hydrocarbons
NOx
CO
CO2
• Tested at each throttle
range (idle, mid, full)
• Tested at each jet size
(.028”, .033”, .036”, .039”)
Ethanol as Fuel
for Recreational Boats
Emissions Testing Results
• Full and Midthrottle testing
Hydrocarbon and NOx Emissions
• EtOH had
dramatic
reductions in
emissions at
.033” jet size
Ethanol as Fuel
for Recreational Boats
PPM
– Idle is
independent of
main jet size
4500
4000
3500
3000
2500
2000
1500
1000
500
0
3825
2481
1953
Full Throttle
Mid Throttle
819.5
241.25
Gas
89.5
314.25
403
EtOH (.033) EtOH (.036) EtOH (.039)
Fuel (Jet diameter in inches)
Emissions Testing Results
• CO emissions
– Increase using
EtOH
– Lower CO2 values
• .033” jet similar to
gas emissions
Ethanol as Fuel
for Recreational Boats
14.00%
12.00%
%
• Engine not
optimized for EtOH
combustion
CO and CO2 Emissions
10.00%
Full Throttle CO%
8.00%
Full Throttle CO2%
6.00%
Mid Throttle CO%
4.00%
Mid Throttle CO2%
2.00%
0.00%
Gas
EtOH
(.033)
EtOH
(.036)
EtOH
(.039)
Fuel (Jet diameter in inches)
Power Testing
• Power Calculated
using:
Maximum Power Output
hp  5252
torque( ft  lb ) 
RPM
– .033” jet
– .036” jet
Ethanol as Fuel
for Recreational Boats
5
4.9
hp
• Torque = 4.22ft-lb
at full throttle
running on
gasoline
• ~5 horsepower
5.1
4.8
4.7
4.6
4.5
Gasoline
EtOH - 0.028" diam. jet
EtOH - 0.033" diam. jet
Fuel and Jet Size
EtOH - 0.036" diam. jet
EtOH - 0.039" diam. jet
Fuel efficiency testing
• Put in known amount
of fuel (500 mL)
• Run until the engine
stopped
– Record run duration
time
• Measure amount of
remaining fuel
Ethanol as Fuel
for Recreational Boats
Fuel Efficiency with Power
• Divide fuel efficiency
by power output
• .036” jet size
Full-Throttle Efficiency with Power
0.25
0.203
0.2
• .028” jet size
(original optimized
for gasoline)
– Did not sustain
combustion of EtOH
Ethanol as Fuel
for Recreational Boats
0.142
0.15
0.134
gal/hr-hp
– closest to gasoline
efficiency
0.122
0.1
0.093
0.05
0
Gasoline
EtOH - 0.028" diam. jet
EtOH - 0.033" diam. jet
Fuel and Jet Size
EtOH - 0.036" diam. jet
EtOH - 0.039" diam. jet
Cold-start Testing
• Gasoline Benchmark
– Location: Cold room in ice lab,
– Engine temperature monitored
with Fluke IR Thermometer
– Cold room initially at 20°F
– Warm cold room and engine
gradually
• Results
– Below 30°F, engine did not
start
– At 30°F, engine started with
much difficulty, requiring 15
pulls of recoil starter rope
Ethanol as Fuel
for Recreational Boats
• EtOH Testing
– Location: Loading dock
– Minimized difference between
• Results
– Engine would not start at 30°F
without cold-start assist
– Ether-assist achieved ignition
in four applications (pull of
starter rope couple with ether
spray into carburetor)
– EtOH engine with cold-start
achieved ignition quicker than
gasoline-powered engine
Determination of Optimal Jet Size
Jet Diameter (in.)
Emissions
Efficiency
Power
Total
0% (0.028)
4
4
4
12
20% (0.033)
1
2
1
4
30% (0.036)
2
1
1
4
40% (0.039)
3
3
3
9
• .033” and .036” jet sizes determined
optimal air-fuel ratio
– .033” preferred due to reduced emissions,
slightly reduced efficiency
Ethanol as Fuel
for Recreational Boats
Engine Economic Analysis
• Actual modification
cost relatively minor
– Rubber replacements
relatively inexpensive
• Labor costs
significant, but within
specification
• EtOH fuel costs for
60gal/yr increase
from $101 to $141
compared to gasoline
Ethanol as Fuel
for Recreational Boats
Modification
Cost without Labor
Cost
with
Labor
Tubing
$25.00
$25.00
O-ring
$9.06
$9.06
$0.00
$45.00
$0.00
$0.00
$0.00
$60.00
Labor
Jet Size
Labor
TOTAL
$34.06
$139.06
Target vs. Actual Specifications
Area
Target Specification
Actual Specification
NOx + HC emissions
<1770.8 PPM
819.5 PPM
CO emissions
<0.85% (reduction by 10%)
1.03%
Horsepower
>5 hp (100% of running on
gasoline – no compression
ratio change)
5.06 hp
Efficiency
At least 0.140 gal/hr-hp (at
least 66.7% of gasoline)
0.142 gal/hr-hp
Cold-start
Must start above 30°F
Started above 30°F
Weight
< 62.7 lbs. (110% of original
engine weight)
57 lbs.
<$250 (25% of engine value
maximum)
$34.06
% Deviation from
Specification (if does not
satisfy)
Environmental
21.2%
Performance
Economics
Overall cost to retrofit
(excluding labor)
Ethanol as Fuel
for Recreational Boats
1.4%
Engine Marketability
“The buying public always looks towards mainstream
success for their purchasing decision. If a product has
had success and proven to perform at or near that of a
gasoline powered engine, they will most certainly
consider it. “
-Randy Stratton, The Stratton Group
Although there are a lot of environmentally-conscious
people, they are often unwilling to pay anything extra.
-Chris Virgo, mechanic at North Tahoe Marina
Ethanol as Fuel
for Recreational Boats
Timeline for ENGS 190
TASKS
Environmental
Background Research
Investigate fate and transport for gasoline and ethanol
Investigate effects of gasoline and ethanol in lakes
Investigate regulations
Economic Case Study
Background Research
Determine most applicable location
Investigate infrastructure for introducing fuel ethanol
Investigate cost associated with infrastructure
Determine retail cost of ethanol on lakes
Technical
Background Research
Determination of engine type for modification
Investigate adaptation of engines for ethanol
Investigate cold start technologies
Evaluate literature research
Search for and secure an engine
Written Proposal
Oral Proposal
Written Progress Report
Oral Progress Report
Ethanol as Fuel
for Recreational Boats
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Timeline for ENGG 290
TASKS
Pre-testing procedure and preparation
Design retrofit for engine
Benchmark testing for gasoline
Materials acquisition for retrofit
Construct prototype for ethanol
Test ethanol prototype for performance
Test ethanol prototype for emissions
Cost analysis of retrofitted engine
Investigate marketability of engine
Investigate implementation of engine
Implementation report via website
Oral Progress Report
Written Final Report
Oral Final Report
Ethanol as Fuel
for Recreational Boats
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Project Conclusions
• Ethanol was found to out-perform gasoline
environmentally for water and air pollution in recreational
boating applications
• Ethanol as a fuel has high potential given the
infrastructure, fuel cost, and environmental policy trends
• A four-stroke outboard engine was successfully modified
to run on ethanol fuel
• Testing of the engine running on ethanol showed similar
performance in terms of power, varied for emissions, and
decreased fuel efficiency
• Website: www.dartmouth.edu/~ethanolboat
Ethanol as Fuel
for Recreational Boats
Recommendations
• Obtain dynamometer for engines of low hp to
strengthen existing data
• Determine optimal jet size between 20% and
30%
• Alter compression ratio/timing to further optimize
the engine at manufacturer level
• Research effects of ethanol materials and
potential long-term replacements to increase
longevity of engine
• Use findings to further ethanol-fueled engine
research
Ethanol as Fuel
for Recreational Boats
Acknowledgements
At Thayer School:
Prof. Charles Wyman
Prof. John Collier
Prof. Robert Graves
Doug Fraser
Gary Durkee
Thayer School Instrument Rm
Thayer School Machine Shop
Paula Berg
Prof. Benoit Cushman-Roisin
Prof. Horst Richter
Joan Levy
Cathy Follensbee
William Cote
Bin Yang
Daniel Iliescu
Daniel Cullen
Ethanol as Fuel
for Recreational Boats
Outside sources:
Fairlee Marine
Betsy Dorries and Steve Belitsos at Vermont
Technical College
Roberta Nichols
Terry Jaffoni and Jackie Fee of Cargill
Michael O'Keefe and Professor Phil Malte at
University of Washington
Don Mathey at Donlee Pump Company
California Air Resources Board
Environmental Protection Agency (especially
Stout Alan)
Edward Nelson at Wisconsin Department of
Natural Resources
Tom Durbin at University of California Riverside
Warren H. Hunt of the Aluminum Association
Garland Lewis at Tohatsu
John Cruger-Hansen
Jeff Schloss at University of New Hampshire
Jack Hull at Rainbow Rubber Extrusions
Jay Kidwell at The Carburetor Shop, Inc. and
Mile High Performance
Bones Gate Fraternity
Zeta Psi Fraternity