What's New with Marinalife

Insider advice about avoiding pain at the pump

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World events over the last two years have created a record high interest in recreational boating, but unfortunately they also generated record high fuel prices. To help you understand exactly how various boats burn fuel differently and how to run your boat at its most efficient, we’re turning to Steve Zimmerman, founder of Zimmerman Marine, a highly respected boat yard and boat builder with six locations in the Mid-Atlantic and Southeast. 

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Steve is knowledgeable in all aspects of boat maintenance and design that affect fuel consumption. I had the opportunity to ask Steve recently to dispel commonly held misconceptions about fuel use in popular styles of recreational boats. 

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Bob: When boaters talk about fuel consumption, they mostly speak in terms of gallons per hour, not miles per gallon. What’s the difference?

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Steve: Many boaters focus solely on gallons per hour (GPH); however, in determining how much fuel you use to cover a given distance on your boat, we have to bring speed into the equation. For example, if someone asked which is more efficient, a boat burning 11 GPH or a boat burning 22 GPH? The answer is it’s impossible to say without calculating miles per gallon (MPG) 

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If the boat burning 11 GPH is traveling at 10 knots (nautical miles per hour), we divide 11 GPH by 10 knots to see it is getting 0.9 nautical miles per gallon (nMPG). If the boat burning 22 GPH is traveling at 22 knots, 22 divided by 22 equals 1.0 nMPG. So, in this example, we see that although the difference is minor, the boat burning double the gallons per hour achieves better mileage.

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Bob: If people are considering a new boat, are some designs more fuel efficient than others?

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Steve: All boat hulls require a certain amount of energy to move through water. The more easily they move through the water, the less energy is required. The primary factors that influence how easily the hull can be moved include hull shape, length, total weight and drag. Hull shapes are sorted into three basic categories: full displacement, semi-displacement and planing. To determine which offers the best fuel economy, we introduce the most important variable of all: speed.

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Bob: So, the faster a boat goes, the more fuel it burns?

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Steve: Usually that’s true, but not always. Different hull forms respond differently to the demand for speed. As speed increases, boats move through the water in three basic ways. At slow speeds the boat sits fully in the water, riding between a wave at the bow and a wave at the stern. Full displacement boats live in this zone. As soon as speed increases, fuel burn rises sharply. 

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Semi-displacement and planing hulls can apply more horsepower and begin to climb up onto the bow wave. In this phase the bow rides awkwardly high, and fuel economy plummets. By applying even more power, these hulls ride more on top of the water. The bow comes down, speed increases, and fuel burn levels off. All get better fuel economy at the slower speeds, but the penalty for higher speeds varies substantially between hull types.

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Bob: Can you explain how different hull types vary of fuel use?

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Steve: Yes, let’s look at the most common hull forms used in recreational boats:

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• FULL DISPLACEMENT
  Let’s look at some actual numbers from a full-displacement trawler in the 40- to 50-foot range. At a speed of 7.5 knots, if it’s using 3 GPH, that equals 2.5 nMPG?  If we push for a little more speed, the fuel burn changes, at 9 knots, burning 11 GPH, it’s down to 0.8 nMPG. Notice that by going just 1.5 knots slower, it’s using 300% less fuel. 
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• SEMI-DISPLACEMENT
  Now let’s look at a semi-displacement boat of similar size. If this boat is going 8.5 knots and using 3.4 GPH, it’s getting 2.2 nMPG.  If we increase to 10.5 knots, using 14.2 GPH, we’re down to 0.74 nMPG. Once again, going just 2 knots slower increases fuel economy 300%. If we push this boat into higher speeds though, the fuel burn differs significantly. At 15 knots, fuel use goes up dramatically to 23.5 GPH, and our efficiency is down to 0.64 nMPG. At 20 knots, using 35.0 GPH, we’re down to 0.57 nMPG. When more of the boat’s hull is on top of the water, the penalty for increases in speed diminishes dramatically and economy levels off. As speed increases, fuel economy will gradually decline in small increments. 
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• PLANNING
  Finally, let’s look at a boat designed for speed, a lightweight planing hull. When going slowly at 7.5 knots, burning 2.6 GPH, that equals 2.9 nMPG.  When we increase to 11.0 knots, burning 9.2 GPH, that lowers the fuel rate to 1.2 nMPG. At a top speed of 25.0 knots, burning 27.5 GPH, that gives only a small decrease in fuel burn to 0.9 nMPG.
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Notice that at the slow displacement speeds, a slight increase in speed causes a large decrease in fuel economy. But once the boat is out of the water at planing speeds, a significant increase in speed had a smaller effect on fuel consumption. 
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It should also be pointed out that weight matters, but it matters considerably less at displacement speeds. A full displacement trawler can pack on the cruising weight without much of a penalty. The other hull types won’t pay a penalty at lower speeds, but at higher speeds the additional weight will take its toll.
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Bob: Generally speaking, going slower saves fuel?
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Steve: For all cruising powerboats, when it comes to fuel economy, speed trumps all other factors—but only at slow speeds. At full-displacement speeds going a knot or two slower can double or triple your fuel economy. 
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Among the things that influence fuel economy on planing hulls are the condition and cleanliness of the props and rudders, alignment of shafts, health of bearings and a fouled bottom. Once you are on plane, increases in speed matter far less, but the importance of a clean underbody and running gear matters far more. Don’t be misled by GPH, taking the extra step to calculate MPG, which ultimately determines overall fuel use.

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Marina Updates

Oasis Marinas Expands across New England‍

The marina management company is pleased to announce its growth into New England with three Connecticut properties: Old Harbor Marina in Clinton, Mystic Point Marina in downtown Mystic and Glastonbury Marina (formerly Seaboard Marina) in Glastonbury.Since its founding on the East Coast in 2015, Oasis has spread out rapidly across the United States from the northern Great Lakes to southern Florida. The company is now stepping foot on the West Coast with plans to grow new team members and properties in the future. For updates, visit oasismarinas.com

Suntex Marinas Lands New Property in New York

‍Suntex Marinas, a premier marina owner and operator, is proud to announce its recent acquisition of Sunset Harbour in Long Island, NY. Situated along the South Shore, this 332-slip marina provides easy access to the lovely Great South Bay. Visit suntexmarinas.com‍

SWITLIK Life Rafts are Back for the Season

‍SWITLIK Life Rafts are back in stock, in every variety just in time for spring and summer boating. Short lead times are now offered on survival equipment, rafts and man overboard modules. For more than 100 years, this U.S.-based company has produced high quality safety equipment in Trenton, NJ. Visit switlik.com

‍Pursuit Boats Announces New Model

‍Since 1977, Pursuit Boats has produced high-end, yacht-quality fishing and cruising vessels across tons of locations. Magnificently appointed and highly anticipated with possibilities for every angler, the OS 445 is Pursuit's largest boat yet. Prepare to cruise in liveaboard luxury with this season's new model. Visit pursuitboats.com or marinalife.com/pursuit-concierge-club

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Marinalife Photo Contest

2022 Photo Contest Is Open for Submissions!

‍Marinalife is pleased to announce our third annual photo contest, where we welcome snapshots that capture moments of maritime merriment from photographers of all skill levels. For details, see page 16 or visit marinalife.com/2022PhotoContest

Upcoming Boat Shows

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Bay Bridge Boat Show

‍Stevensville, MD

‍April 21 - 24, 2022

‍Suncoast Boat Show

‍Sarasota, FL

‍April 22-24, 2022

‍Annapolis Spring Sailboat Show

‍Annapolis, MD

‍April 29 - May 1, 2022

MARINALIFE is pleased to announce this year's photography contest that showcases the joy of boating and good times on the water.

We welcome snapshots that capture moments of maritime merriment the freedom of getting back on the water after a long winter, a memorable boating experience with family and friends, a special seaside vacation, the thrill of water sports, an epic fishing trip where you reeled in a trophy catch, or the face of a pet who's too cute for words. Whatever floats your boat, we'd like to see it.

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Contest Details

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Who's Eligible: Everybody is invited from amateur shutterbugs to seasoned photographers to send your favorite shots of what you love most about the cruising lifestyle and high seas adventures.

Deadline: Spend the spring and summer taking great shots, then submit your favorite photos in the form below by Friday, September 9, 2022.

‍What to Submit: Limit of up to 3 photos per person, send high resolution images (300 dpi, 2 mb or 600 kb). Please include a brief description of the photo's location, the photographer's credit, and the contact info, email and phone.

‍Winners: Our staff will select the first, second and third place winners and runners up whose photographs will appear in upcoming issues of Marinalife. Prizes will be announced soon.

Please submit any questions to submissions@marinalife.com