Stabilizer Series 2: MagnusMaster aboard the new Helmsman 46 Pilothouse
Mastering the Magnus Effect
Our ongoing Best4Boats stabilizer series led me to Port Ludlow, Washington for a ride aboard the newly splashed hull number one Helmsman 46 Pilothouse trawler. The Helmsman was equipped during commissioning with a unique stabilization system designed and built by the manufacturer DMS in Holland. This system is very different from the gyros and fin stabilizers most of us are familiar with and I was anxious to find out if and how it works, hopefully without having to dust off my old physics textbook.
The MagnusMaster—unlike traditional fin, gyroscopic, or stern actuator models—is a hull mounted rotor stabilization system that taps into the Magnus Effect to counteract boat motion in seas while underway. If the Magnus Effect sounds familiar, perhaps you are a baseball fan. The physics phenomenon occurs when a spinning object moves through a fluid or gas (air) that results in a lifting force of the object. The Magnus Effect is what made Sandy Koufax’s deadly curveballs possible. The spinning ball curves in flight due to the difference in air pressure on its sides as it moves.
Testing the system
The sun was out, and the seas were calm with a 5-knot breeze as we cast off the dock lines with the owner Robert Chanpong and Helmsman Trawlers build manager Van Helker. Curse my good fortune with nice weather on these stabilizer demos, pretty much the only scenario where foul seas would be desirable in my estimation. My interest in the yacht’s MasterMagnus system was initially peaked when Chanpong and I met at the CSR Marine yard in Ballard where the rotors were being installed during commissioning. Has he been pleased with the MagnusMaster system so far?
“I am very happy with them,” reported Chanpong. He described the maiden voyage from Seattle to Port Ludlow under moderate two- to three-foot following seas and 10- to 15-knot winds. The day would’ve been a bit bouncy if not for the twin MagnusMaster rotors. “We negated that roll almost immediately and it was very comfortable after that.”
Helker, a former NOAA marine research deck officer, summarized the technical nitty gritty that checked out with my own research. The all-electric MagnusMaster system is comprised of at least one hull mounted rotor. A single rotor is reportedly adequate for boats up to 20 tons while a dual system is recommended for heavier vessels. The 45,000-lbs. Helmsman 46 [light load spec] packed twins. Vessels approaching 100 tons would require four and in theory one could keep adding rotors beyond.
“The MagnusMaster uses a spinning carbon fiber rotor externally mounted to the hull to generate force,” explained Helker. “That force is transferred into the hull to stabilize a vessel from rolling. This force generated is a result of the Magnus Effect… The MagnusMaster rotor spins at speeds of up to 1000 RPM and can reverse the direction of spin nearly instantaneously.”
When not engaged, the MagnusMaster rotor folds to be streamlined with the hull—not flush, but within the turbulent boundary of the boat to produce minimal drag. We deployed our twin rotors with the push of a button. A nifty electric display at the helm shows the operator a live diagram of the rotors extending from the hull. The vibe is a bit like in Star Wars: A New Hope when Luke Skywalker locks his “S foils in attack position” on his X-wing starfighter. Deploying or retracted the rotors takes about 12 seconds and they are ready for action within seconds. It is worth noting that gyro stabilizers often require substantial warmup time to spool up properly before they are ready.
Also unlike a gyro system, the MagnusMaster is an underway stabilizer that, like a wing, requires air or liquid flow to generate force. As the vessel moves forward, the carbon fiber rotor spins almost like a rolling pin through the water. As the water current flows over and under the rotor, which is perpendicular to the hull, the Magnus Effect kicks in. This makes the MagnusMaster most effective between approximate speeds of 4 and 12 knots, ideal for trawlers like the Helmsman.
The rotors are paired with sophisticated software with multiple motion readings per second. The technology automatically calculates and commands the rotor RPM and direction of spin to counteract incoming forces from seas. Clockwise spin creates a downward force, counterclockwise creates an upward one.
“For cruisers with boats that operate at speeds below 12 knots, we believe that the MagnusMaster presents the best option for stabilization,” said Helker. Notably Helmsman Trawlers is offering the MagnusMaster stabilization option for their new builds—a first for the company that until recently didn’t engage with stabilization systems much. Retrofits are also increasing in popularity. Their smaller Helmsman Trawler 38E and 43 models only require a single rotor. From owner reports, Helker said there is only about .2 or .3 knots of speed lost when the system is deployed.
Also importantly, the MagnusMaster is all-electric. A 240VAC and 24VDC power supply is required. “On many US installations a dedicated 240VAC inverter tied to a battery bank provides the 240VAC power and a simple DC converter steps up 12 volt to 24-volt power,” explained Helker. “The average power consumption is low (about 700 watts per stabilizer when fully deployed) so a generator is not required to power the stabilizers.”
Forced Roll Demo
Fortunately for those of us who want to experience the MagnusMaster in action on a calm day, the system has a forced roll feature. With dual rotors engaged, Chanpong brings us up to forward idle of 650 RPMs resulting in about 4.5 knots of speed—enough for the MasterMagnus to be effective.
“I’m going to hold the forced roll button down and you’ll notice that we go back and forth with greater and greater amplitude,” said Helker, letting ‘er rip. Indeed, the Helmsman 46 starts rolling as if we were taking on considerable seas abeam. “As soon as I take my finger off, those stabilizers will go back to stabilizing, so you’ll be able to feel how quickly those are stabilizing the boat.”
He does and, after a few initial seconds, the boat is completely still again. Quite impressive, but let’s see this thing in action at a higher forward speed, a la, greater Magnus Effect for the forced roll. We initiate the same forced roll and stabilize exercise at 1,000 RPM (about 6 knots) and again at 1,400 RPM (cruising speed, around 8 knots). One really feels the additional juice behind the lifting rotors that the additional speed gives. The forced rolls created washing machine conditions at these RPMs. Pots clattered in the galley and objects threatened to fly off tables. A pilothouse door we forgot to secure slammed wide open then shut with a bang.
Every time Helker took his finger off the button, the entire yacht went dead still in a matter of seconds. It was hard for me to imagine what a more successful demo would look like, although I would like to see it work the other way, stopping us from rolling in actual seas.
“The demo is very impressive, I would say, the thing that really creates confidence,” said Chanpong with a grin. He opted for the MasterMagnus system after a similar demonstration on Lake Union in Seattle.
In Summary
All in all, I found the MasterMagnus on the Helmsman 46 Pilothouse very impressive for this application. But the system is definitely designed for specific situations, i.e. non-planing power boats going between about 4 to 12 knots. A gyro stabilization system does not require forward momentum to be effective. For those who need relief at idle, when trolling, or in rollie anchorages, gyros are known to work well at zero or near zero speeds.
One feature that most may regard as a perk is that the MagnusMaster is a completely electric system—no hydraulics.
“The stabilizers are all electric, which is I think one of the biggest selling points,” said Helker, citing ease of maintenance and availability of electricians.
The MagnusMaster does require through hull installation, similar to fin stabilizers, but have a modest footprint within the actual vessel. Pretty much any 20” x 20” patch of hull along the port or starboard should do. Gyros are housed in self-contained onboard units.
“That [the small onboard footprint of MagnusMaster rotors] is a benefit both for new builds but also retrofits if you wanted to squeeze one into an existing boat. There hasn’t been a boat yet we haven’t been able to find a spot for them,” said Helker. Having those big pieces of metal underwater also makes following best anti-electrolysis practices important—be it an installed anode or making sure the rotors are properly bonded to the vessel’s system.
A final consideration would be that the deployed MagnusMaster rotors underscore the need for vessel operators to practice situational awareness. You’ll want to make sure those arms are stowed before coming into dock or give that big log a little extra space to avoid it clipping the fancy tech. The software does some of this managing for you by automatically disengaging the rotors when the engine is in neutral.
Zooming out, it’s telling that DMS Holland also makes gyrostabilizers and modified fin-style stabilizers. Perhaps the real question for boaters intrigued by stabilization isn’t what physics method is inherently superior, but rather what’s the best fit for one’s particular vessel. For the Helmsman 46 Pilothouse I hopped onto, the MagnusMaster seemed like an excellent match. Stay tuned for the next installment of the Best4Boats Stabilizer Series.
