What's All This About Electric Outboards?

2021 was an interesting year for electric outboards. In the spring Mercury announced that they will launch a new line in 2023. Then Yamaha debuted their HARMO electric outdrives at the IBEX (International BoatBuilders’ Exhibition) in September. A couple of relatively unknown companies also showed prototypes of high-power electric outboards. Now that General Motors has decided to pursue electric boat building (“GM Acquires 25 Percent Stake in Pure Watercraft to Accelerate All-Electric Boating,” 11-22-2021), it’s time to get serious about electric outboards…

(Pure Watercraft photo)

Advances in high-efficiency motors and lithium-ion battery technology are slowly finding their way into electric-powered boats. Since we normally think in terms of “horsepower,” maybe it’s also time to recalibrate how we think about an electric outboard’s power. How do you measure horsepower, anyway? (OK. One horsepower is equal to 550 pounds of force to move at a speed of 1 foot per second; or if you’re on a boat, 65 lbs of drag at 5 knots…). Electrical power is easy to accurately measure -- voltage times current, or watts. Torqeedo rates their 3-kW motors as equivalent to 6-hp gas outboards; and their 10-kW motors to 20-hp outboards. So if you really can’t make the switch, take the peak power of an electric outboard in kilowatts, and then double it to get a (very) rough idea of the equivalent horsepower. In the end, however, whether it's a gas or electric outboard, the thrust exerted by the propeller -- in pounds of force -- is what actually gets (and keeps) the boat moving. That’s the number we’re really looking for; and it’s obvious that it depends on more than “power.”

Besides Mercury’s and Yamaha’s plans to produce electric outboards, as noted above, we can reasonably anticipate that other established manufacturers like Honda and Tohatsu will soon include electric outboards in their lineups, and possibly transition to fully-electric at some point. A couple of long-shots worth watching announced their plans at the 2021 IBEX show. Rhode Island-based Flux Marine (www.fluxmarine.com) will introduce 15, 40, and 70 hp electric outboards in 2022. And Vision Marine (www.visionmarinetechnologies.com), a Canadian company that is now listed on the NASDAQ, claims they will begin delivering “the world’s most powerful outboard” – their 180-hp eMotion – to OEMs. [Coincidentally, Evinrude, which was owned by Quebec-based BRP (Bombardier Recreational Products), branded their high-efficiency, high-output gas outboards “E-TEC.” And BRP exited the outboard business in 2020.]

But Pure Watercraft (www.purewatercraft.com), a Seattle-based tech start-up, might be the closest to actual production. Back in 2010, after the Great Recession, Pure Watercraft got venture capital to develop and manufacture a 25-kW electric outboard and integrated battery pack. They used the playbook from Tesla Motors, starting with a clean sheet design, developing their own PMAC (permanent magnet alternating current) motor and gearbox, and building a bunch of not-for-sale prototypes from components and systems they produced in-house. The Wye Island (MD) Electric Boat Challenge is a 24-mile circuit that has been run every year since 2001; and in 2017 Pure Watercraft finished the course in just over an hour, setting the course record – still unbroken – with one of their prototypes (see “Wye Island Challenge – An Epic Marathon” in their website blog). At the end of 2021 GM invested $150M in the company, apparently as part of its plan to diversify beyond automotive applications.

Each of these start-ups listed above began taking reservations at the end of 2021 for their as-yet-unreleased outboards. The $64 question now is, Who will deliver the goods? But I think the biggest unknowns are how exactly GM will leverage their investment in Pure Watercraft; and if other automotive manufacturers will pursue similar deals of their own. We can anticipate that lower-cost, higher-performance lithium-ion battery technology will continue to benefit from the economies of scale that automotive manufacturers and suppliers bring to the table.

www.businesswire.com/news/home/20210928005812/en/Yamaha%E2%80%99s-HARMO%C2%AE-Electric-Outboard-System-Makes-U.S.-Debut-at-IBEX

www.soundingsonline.com/news/mercury-announces-plans-for-electric-outboards

More Small Boat Power

My latest article in Small Craft Advisor No. 132 (Nov/Dec 2021) is out. Lots of information of the current status of the drop-in lithium iron phosphate batteries that you can use to replace a lead-acid battery. Why it might be useful, and why it might not be worth it the cost.

Small Boat Power

My article on adding electric power on your small boat is now published in Small Craft Advisor, Sep/Oct 2021, No. 131. I used a couple of low-cost sealed lead-acid batteries -- and a small solar module for on-water charging -- to power my GPS/depth gauge, run a fan during humid nights at anchor, and charge my other stuff.

My column in the next SCA issue will continue this thread with a discussion of "drop-in" lithium-ion-iron-phosphate batteries that can upgrade and even simplify the system.

Recycling a Racing Dinghy -- Part 1

A few years ago I acquired a little Penguin dinghy for teaching. My boat has a fiberglass hull and an aluminum mast, but the Penguin was designed almost a century ago, and most of the Penguins were/are fabricated using plywood and have wooden masts. Although Philip L. Rhodes originally drew the 11-½ foot dinghy’s lines for a design competition (it lost), the Penguin’s story actually begins five years later, in 1938, with a request by a group of Potomac River dinghy sailors for a small, car-toppable racing boat that could be easily constructed by amateur boatbuilders. Rhodes already was a well-known naval architect and would design many of the first-generation fiberglass dinghies produced by O’Day (the Sprite, Widgeon, and Mariner) as well as Dyer’s Dink and Dhow, among many other boats. For his Chesapeake Bay clients, Rhodes supplied plans for a stable single-chine catboat that could be constructed using low-cost boatbuilding materials -- waterproof plywood and resorcinol glue -- which, at that time, were considered “state-of-the-art.”

(from the Penguin Class photo gallery)

While the process of laminating thin layers of wood -- plywood -- was actually invented in the mid-1800s, it was not until the early 20th century that high-speed rotary lathes were designed that could produce the thin veneers needed for large-scale plywood manufacturing, which developed around the fir and spruce forests of northern California, Oregon and Washington. Propelled by the rapidly growing automobile industry, by 1929 there were more than 17 plywood mills on the West Coast. And when new waterproof glues were introduced in 1934, plywood became an interesting new construction material for boatbuilding and for many other exterior applications (from the APA History). Rhodes now took advantage of large-area sheets of waterproof plywood to produce plans for a single-chine dinghy constructed using “developed panels” that were attached to a relatively light-weight internal framework. The technique is used extensively by Phil Bolger, Jim Michalak, and many other designers to produce easy-to-build small boats. And the bible on epoxy and boat building, “Gougeon Brothers on Boat Construction” (5th Edition, 2005), has a detailed description of “compounded plywood” design (Chapter 25). But Rhodes was probably the earliest designer to take advantage of waterproof plywood to simplify small boat construction.

The Potomac River sailors built a dozen of Rhodes’ plywood dinghies to test the design. And Hull No. 1 was displayed for many years at the Chesapeake Bay Maritime Museum in St. Michaels, MD. When plans were published in Yachting magazine in 1940, interest in the Penguin surged, and racing fleets were established on both coasts and around the Great Lakes. Although competition paused during WWII, by 1955 there were more than 100 Penguin fleets. And according to Chris Museler, more than 9,700 Penguins have been built.

With a plumb bow, hard chines, high sides, and 72 square feet of sail, the two-person Penguin dinghies are dry, stable boats. Right from the beginning they were campaigned through the fall and winter seasons, and the Penguin excelled at frostbite racing until tippier and wetter Lasers eliminated the need to find a crew willing to freeze and dry suits replaced wool sweaters and oilskins. The Penguin’s Portsmouth Number rating (D-PN) is 111.5 -- not fast, but not too shabby, either. For comparison, the lateen-rigged Sunfish is rated at 99.6 (lower is faster), and the Laser -- which is quite a bit faster and much higher-strung -- is rated at 91.1. Today there are only a few surviving Penguin fleets, and class racing is centered on the Chesapeake Bay, very close to where it all started (see the International Penguin Class Dinghy Association (IPCDA) website, www.penguinclass.com).

Now it turns out that I’ve got one of the last Penguins built (hull number 9744), a fiberglass boat that was constructed by Lightwave Yachts (aka Innovator?) in Florida in 1995. It’s a “self-rescuing” design, with integral flotation chambers between the hull and the deck; and it has a light, tapered aluminum mast. The only wood on it appears to be in the gunwale cores.

It had been listed for sale on the Penguin class website, but apparently there was no interest from racing skippers who apparently prefer the traditional wooden hulls, which do not carry a 20-pound weight penalty. I found my Penguin for sale on Craigslist and bought a clean boat with top-of-the-line hardware, a roadworthy galvanized trailer, and a crisp North “training” sail. Since I’m not interested in competition anymore, my annual summer boat project is focused on incorporating changes that would transform a classic racing dinghy, typically sailed with a crew of two, more sailor-friendly and capable of being safely managed single-handed. And in the bargain keep an obsolete and unwanted hull (and sail) with lots of useful remaining life out of the landfill.

Comparing the Force 5, Laser, and Sunfish

The Force 5 dinghy was designed by Fred Scott and Jack Evens in 1972, around the same time that Bruce Kirby and Ian Bruce designed and developed the Laser. At one point both boats competed for the same sailors who grew up racing the Sunfish, with it's iconic and simple -- but effective -- lateen rig. With its roots as a home-built boat constructed from plywood, the Sunfish is hard-chined, with high initial stability, and it can plane under the right wind conditions with a skilled sailor. The Laser and Force 5 were designed from the ground up to be molded from fiberglass. Their chines are rounded, their bows are much sharper, and their stability is much more dynamic and sensitive to crew weight. Both of these next-generation, cat-rigged dinghies are capable of planing and of sailing faster than the Sunfish. 

When Kirby introduced his Laser at the New York Boat Show in 1970 there was a groundswell of interest -- and more than 100 orders. But without the means to manufacture the Laser in volume, Kirby licensed the rights to established builders in three separate geographic regions -- Europe, North America, and rest of world. Although he imposed "one design" restrictions along with the licenses, Laser variations proliferated, mainly in Europe. In contrast, the Force 5 was designed and produced by AMF, who dominated the bowling equipment market after World War II. Over a couple of decades of growth, AMF diversified by acquiring a raft of recreational product companies like Harley-Davidson motorcycles, Head skis, and Ben Hogan golf clubs. In 1969 AMF acquired the Alcort sailboat company, which had been founded in 1947 by Al Bryan and Cort Heyniger to produce the original Sailfish sailboard, and which introduced their blockbuster fiberglass Sunfish dinghy in 1960. Under AMF, the Alcort subsidiary produced a series of recreational sailboats. Some were hits -- the Apollo sloop (also designed by Kirby), Minifish (a smaller, cheaper version of the Sunfish), Puffer (from Scott), Sunbird (Scott and Evans), and the Zuma. Other AMF designs became historical footnotes -- the Hilu (a proa), the Tiga (windsurfer), and the Trac catamaran.

AMF, like many other companies that had gone on acquisition sprees during the 1960s and 70s, began to break up and sell off their subsidiaries during the high-inflation 1980s. According to the Sunfish class history, AMF's small boats were spun off into a reconstituted "Alcort Inc" in 1986. And two years later in 1988, Pearson Yachts, which itself had been split off from the Grumman conglomerate (still famous for their aluminum canoes and rowboats), bought Alcort -- and O'Day and Cal Boats (aka, Jensen Marine). Separately Pearson also acquired the rights to produce the Laser from Vanguard, the original manufacturer licensed in North America. But in 1991, rocked by an economic recession and the impact of a 10% luxury tax on boat purchases, Pearson declared bankruptcy. SunfishLaser Inc ("SLI") was then created (under Peter Johnstone, son of Bob Johnstone, the founder of J Boats, and with significant funding from North Sails -- the authorized Laser sail supplier) to produce AMF's best selling products, the Sunfish, the Laser, and the Zuma. 

Since the Laser and the Force 5 were so similar in size and performance, SLI in effect killed the Force 5 in order to focus all commercial and racing attention on the Laser, which, based on its Portsmouth ratings, is the faster of the two. The Laser also became an Olympic class boat in 1996, and more than 200,000 boats have now been built. SLI sold the Force 5 design rights to Weeks Boat Yard (in 1994) who continued to produce boats that improved upon the AMF design. Altogether, maybe 15,000 Force 5's have been built, a stark contrast to the order of magnitude greater number of Lasers produced since it's introduction in 1971. But it turns out that Alcort's first racing dinghy -- the Sunfish -- is still the production champ; more than 300,000 Sunfish were built as of 2001, it's 50th anniversary. This year, 2021, is the Laser's 50th anniversary; and with current worldwide production at less than 2,000 boats a year, there's little chance that the Laser will ever surpass the Sunfish as the production king of racing dinghies.

Here are some comparative specifications for the Force 5 and the Laser, as compared to the Sunfish...from SailboatData.com

Sunfish

Length, overall, 13'-9"

Length, waterline, 13 feet

Beam, 4'-1"

Weight, 120 pounds

Sail area, 75 square feet

D-PN Rating, 99.6

Displacement/Length ratio (prismatic shape): 26.2

SA/Displacement ratio (power to weight): 47.0 

Brewer comfort ratio: 2.31

Capsize screening ratio: 3.23

Force 5

Length, overall, 13'-10"

Length, waterline, 13'-2"

Beam, 4'-10"

Weight, 145 pounds

Sail Area, 91 square feet

D-PN Rating, 95.4 (lower is faster)

Displacement/length ratio: 27.3 (lower is better)

SA/Displacement ratio: 54.0 (higher is better)

Comfort ratio: 1.98 (higher is more comfortable; racing boats are less than 20)

Capsize screening ratio: 3.72 (higher is more stable)

Laser

Length, overall, 13'-9"

Length, waterline, 12'-6"

Beam, 4'-7"

Weight, 130 pounds

Sail Area, 76 square feet

D-PN Rating, 91.1

Displacement/Length ratio (prismatic shape): 26.4 (better than Force 5)

SA/Displacement ratio: 47.4 (lower "power/weight" than Force 5)

Brewer comfort ratio: 2.01 (about the same as Force 5)

Capsize screening ratio: 3.60 (less stable than Force 5)

All of these dinghies have unstayed aluminum masts. As mentioned above, the Sunfish has a lateen rig. The mast is 2-1/4 inches in diameter and is only 10 feet long, while the gaff and boom spars, 1-1/2 inches in diameter, are both 14 feet long -- a big disadvantage when transporting the boat. The Force 5 and the Laser were both designed as sloop-rigged cats with sleeved sails. The Laser mast is 20'-2" in length. The Force 5 mast is 21 feet long. Both the Force 5 and the Laser have multi-part aluminum masts. The Laser is in two parts; the base is 9'-5" and the top section is 10'-11" long. The Force 5 mast comes in three parts, and the longest section is 9'-10" long. The base section for both masts is 2-1/2 inches in diameter, so a Laser rig will fit into a Force 5 mast step, and vice versa. I have found, through experience, that it's important to have the boat on the ground before you try to step the mast (with sail) on either the Laser or the Force 5. The boom for both rigs is 9 feet long; the outhaul on the Force 5 is internal, whereas the Laser uses lower-cost external lines and blocks. Since all the spar components are shorter than the boats, it is much easier to transport a Force 5 or a Laser than a Sunfish.

The sail dimensions, from the Sailrite (www.sailrite.com) database, are as follows. For the Laser: luff = 16.5 feet; foot = 9 feet; leech = 18.32 feet. For the Force 5: luff = 17.75 feet; foot = 8.62 feet; leech = 19.27 feet. As mentioned above, the Force 5 sail has 20% more area (15 SF) more area than the Laser (76 SF).

The mast "bury" on both the Laser and the Force 5 is 14 inches. On the Force 5 the boom height above the deck is 19 inches. The boom height on the Laser and the boom height of a Laser rig on a Force 5 hull (the latter verified by actual measurement) is about 23 inches, or 4 inches higher than the Force 5 boom.

The original Force 5 from AMF was built with four clam cleats on the foredeck to handle the cunningham and downhaul lines. The Laser has deck-mounted cam cleats that are typically used during racing for the downhaul and the outhaul (no cunningham). Both boats have their sheet rachet blocks located mid-boat, just aft of the daggerboard trunk. The Force 5 has a traveler attached to a thwart across the cockpit. The original Force 5 is set up for boom-end sheeting with a fixed traveler line across the aft deck, while later versions have two blocks in the middle of the boom for the sheet directly above a multipart rachet block. The Laser uses boom-end sheeting and has a simple tensioning adjuster for the traveler line (an advancement over the simple fixed traveler used on the Sunfish).

The foils on AMF's Force 5 are constructed of solid mahagony. Based on the class rules, the daggerboard's maximum chord is at 36% of it's width (3-3/4 inches of the 11.75 to 12 inches width limit). The rudder surfaces are flat and parallel except it can be profiled within 1-1/4 inches of the trailing edge. The Laser foils are composite construction. The class rules do not specify the foil cross-section, but a measured daggerboard's maximum chord is at 1/3 of it's width (11 cm over 33 cm, or 13 inches, in width). The shape of the Laser's daggerboard and its rudder is much more streamlined NACA profiles (probably NACA 0010 and 0012). Both boats have kick-up rudders; the Force 5 rudder is "spring-loaded" and does not work very well, so it does not need a downhaul. The Laser's rudder blade does have a downhaul line. 

One of the biggest design differences between the two hull designs is that, due to its large footwell, the Force 5 can comfortably accommodate a crew of two even though it was designed for single-handed sailing, whereas the Laser cannot. I suspect that the Force 5 is more comfortable to sail even if you are sailing it single-handed. Lasers "wear out" when the deck becomes "spongy" -- especially prevalent on Lasers sailed by heavier skippers. The Force 5 is designed and built, by comparison, much stiffer than the Laser and should not have that particular issue. Look for holes and flex in the bottom rather than soft decks.

Because the Laser is still being built and it remains a popular teaching boat, as well as an Olympic class boat, it's easy to find literally any part, and new "class legal" sails are readily available. You can also find "practice" sails for just a few hundred dollars (www.intensitysails.com). But if you need rare parts such as a mast or boom for a Force 5, your best bet might be to find another Force 5 and cannibalize it (older boats sell for under $500). You can get a "zipper luff" sail ("class legal" and $635 in 2010, the date on their parts list) from Weeks Boat Yard, if they are still in business when you call. But a "practice" sail from Intensity Sails is less than $200.

References

Force 5 History, http://www.force5sailboats.com/history.htm

"The Pearson Era," https://goodoldboat.com/the-pearson-era/

Force 5 zipper-luff sail, http://www.force5sailboats.com/zipper_rig.htm

"The story of the former Olympian who designed the world's more beloved boat," Popular Science, 2019,  https://www.popsci.com/bruce-kirby-laser-sailboat/

Laser Class, https://www.laserinternational.org/