BALANCING EVERY MOVE WITH PRECISION
Both fin and gyro stabilisers work to dampen sea forces acting on your vessel’s hull. These movements are referred to as “degrees of freedom” and include pitch, roll, yaw, heave, surge and sway.
These days, stabiliser technology has come a long way since the agricultural outrigger or “flopper stopper” days of the prawn trawlers, which are obviously tried and true because they still feature onboard trawlers in both New Zealand and Australia. They are a very agricultural method and work with long boom arms on both sides of the vessel with a heavy fish or triangle plate on the end of a chain. Think of the movie Perfect Storm, where poor George Clooney had to shimmy out on the boom to cut one off so it didn’t destroy his trawler’s wheelhouse.
Even my father, a commercial fisherman from New Zealand’s port of Houhora, first discovered the flopper stopper back in the ‘80s on a trip to Queensland. He brought the idea home, and we made them from memory using some 44-gallon drum lids and scrap jungle gym materials from the school next door – at least, he did tell me they were scrap. After a couple of disastrous near-tipping false starts and once we refined the round lids into triangles and got the length of the chain correct, everyone in the port started to install them, and a new, comfortable era of fishing began.
These basic stabilisers work on the resistance of the plate hauling through the water as the vessel rolls and dampen the rolling effect. But they do not work on the pitch, yaw, heave, surge and sway due to their simplistic design.
These days, we have two main types of stabilisers, gyros and fins, which are designed to reduce the effects of the sea on the stability of your vessel, both while at anchor and underway. The purpose of this article is to let you, the boat owner, decide which system is best for you based on the size, projected usage and cruising grounds of your vessel. I asked industry representatives, who each understandably have their own barrow/brand to push, and each delivered convincing arguments for their products.
Firstly, let’s shoot the elephant in the room, size does matter, so if you have or intend to get a trailer boat, you can’t trailer with fins, and a small gyro is for you. But read on as I have taken the mystic out of three types of gyro boxes.
I started my journey of discovery by talking to Humphree stabiliser dealer in Auckland, Wayne Patten, asking how they work and when they were developed.
“The fins can rotate 360 degrees using servo motors which run off DC current, so a generator is not required (depending on onboard charging systems and battery bank), and they adjust left and right
to counteract the roll and pitch of the vessel. The system detects a motion in one direction and paddles in the opposite direction to make the boat stay level,” Wayne said.
“But it is worth noting only the stabiliser fins also work in conjunction with the Interceptors to keep the vessel’s ride level when underway, which the same can’t be said for gyros. And we are achieving a high percentage of roll reduction at low speeds and excellent results the higher the speed.
“The development of the fin stabilisation has been a little bit later in the piece than the gyro stabiliser markets, and the fins were first being developed 10 or so years ago. As you know, boat building companies are putting them in their bigger vessels now, and initially, they had a restricted size for the fins up to one metre, but now they go from 1.3 to 1.5 square metres. They are very light and made of carbon fibre and designed to fill with water which is where the weight and push comes from once submerged.
“Where they bolt up to the Servo, there’s a zinc anode, so every couple of years, you’re supposed to pull those off, replace the anodes and put new bolts back in and re-torque them. The fins rotate right through 360 degrees so they can paddle backwards at zero speed to keep weight on the anchor and prevent the vessel walking forward over the anchor. But, when you put them in anchor mode, you’re supposed to acknowledge that you’re aware of the surroundings, and if anyone’s in the water, be aware that the paddles are moving, so stay clear of them.”
Wayne says the Humphrees are for 50-to-165-foot vessels, with larger vessels, requiring a second set in which they interface perfectly together. “Most cases require the input of a designer or naval architect to work out, among other things, the LCG of the vessel, which is the longitudinal centre gravity of the vessel.”
With long phrases like “longitudinal centre gravity” entering the rhetoric it was time to take an Aspirin, wrap up the conversation with Wayne and pick up the phone to Pier Gambacorti (PG) from Quick Gyro.
“The Quick Gyro is really the new kid on the block. The unique patented vertically spinning mass design means we are the only brand that spins the mass like a motorcycle tyre as opposed to the traditional horizontal spinning mass designs.
“Quick also has adaptive precession. That means that the computer constantly monitors the velocity and the angle of roll of your boat and adapts the precession angle to deliver the maximum amount of anti-roll torque at precisely the right time.
“It’s like active suspension in your car. If you’re at the supermarket and you’re driving at 8 kilometres an hour, your car is riding high, and the suspension is soft. But, on the other hand, you start doing 110 kilometres an hour on the freeway, the car, unbeknownst to you, drops its ride height and stiffens the suspension because as you go around a high-speed corner, you don’t want soft suspension.
“Now, there is no way in God’s given universe that passive precession can match adaptive precession. It’s like, as I said, active suspension in your car, and passive old school shock absorbers in your car. What gives you a better ride?
“Seven years ago, an Italian engineer called Roberto Chiesa said he couldn’t understand why the older brands were spinning the mass horizontally, like an LP record. He found that there was a series of problems when you spin the mass horizontally. Firstly, you only have one bearing underneath doing all the work, and everything else is just along for the ride.
“He said that forces you to use the lightest possible mass, and in terms of physics that means this light mass needs to spin very fast to generate the anti-roll torque required to stabilise your boat. That fast spin speed generates high friction and heat on the bottom bearing, and that bearing therefore needs water cooling.
“The second problem with spinning the disc horizontally, like a record, is not only does it try to stop the boat from rocking port to starboard, but the vertical ‘rocking’ precession movement can also put downward pressure on the bow and restrict the bow from riding over waves. That is not ideal because you want boats to ride over waves in rough seas.”
Roberto decided that the solution was to turn the mass 90 degrees and spin it vertically. This is the basis of the patent.
This is what I’m getting to, the difference between the Quick gyro and everything else on the market. When you were a kid riding your bicycle, if the wheels were turning, the bike wanted to stay upright. If the wheels stopped turning, the bike would fall over
to one side, so you had to put your foot on the ground to stay upright. Our patented vertically spinning design means the gyro keeps the boat upright. The same simple principle applies here.
The additional advantages of the vertically spinning mass is that you no longer have just one bearing underneath doing all the work. It has two bearings, one on the left and one on the right of the spinning mass, sharing the weight of the mass. This means they don’t work as hard and can therefore be air-cooled. That eliminates all the complex systems of a water-cooled gyro that require expensive yearly servicing.
In summary, the difference between our product and the rest of the gyros on the market is the innovative patented vertically spinning mass design. This, combined with adaptive precision, means a 30 per cent smaller gyro, which has a simpler air-cooled system, whilst delivering market-leading anti-roll performance in any sea state.
“Quick gyros really are smaller, simpler and smarter technology.”
But PG represents only one of the three methods of gyro stabilisation so to dig a little deeper I talked to Chris Thompson from Twin Disc Pacific, the APAC distributor for Seakeeper to see what his point of difference was.
“Back when gyros were first designed and implemented, they were massive, around 100 plus tonnes designed and put into cruise liners and ships. They were huge and heavy and cumbersome. As boats became more modern, they just didn’t have the space for them anymore. It was more about putting larger numbers of passengers on ships than fitting gyros, so gyros sort of sat on the sidelines.
“The two guys behind Seakeeper wanted to bring that sort of technology back to fishing boats and smaller boats. The first one hit the water in 2007 and that was the M7000, the 7000 denotes the amount of Newton metre seconds of angular momentum and that’s a measure of torque over time. That’s the important number when you’re measuring gyroscopic force, it’s kind of like horsepower for gyros.
“So, Newton metre seconds is the sort of universally accepted way of measuring gyroscopic force and that’s how much torque it can produce per second. Since 2007 we’ve now got about 26,000 Seakeeper gyros in operation throughout the world, which is a long way ahead of any other manufacturer and makes Seakeeper far and away the market leader in terms of gyro technology.
“The unique proposition of what we have brought to gyros is the fact that they’re vacuum sealed, so it’s an enclosed sphere that we spin the flywheel inside. That’s taken down to a vacuum and then backfilled with helium. The reason we do that is to be able to spin the gyro faster because there’s no air resistance and if you can spin a gyro faster, then you can reduce weight to achieve the same performance. That’s what makes Seakeeper lighter than if you look at the other brands in the market and achieves more angle momentum for the size.”
Talking about the smaller size boats which can be fitted with a Seakeeper, Chris has a great yarn.
“We’ve got a customer in Queensland who is in his 80s, and he’s got a little 15-and- a-half foot Haines Signature, and the gyro would be worth more than the boat. He’s owned this boat for 30 years, he loves the thing, he goes fishing five days a week, and his knees have all but given up. To enable him to go fishing on pretty much any day in any conditions, he went and put a $35,000 gyro in his 30-year-old boat.
“We custom-fitted it down the back of the boat with a box on top of it for his bait board and a battery system in it, and off he went. He runs his gyro, sits there, fishes for whiting, and goes out for a couple of hours every day so that that gyro doesn’t need a genset to work.
“The Seakeeper 1,2,3 & 4 will run off DC power and then anything from the 4.5 and up runs on AC power. So just to break that down for you, the Seakeeper 4.5 you would put on a vessel around that 45foot mark. So anything up until about 45 feet we can work just using lithium batteries and then anything from 45-feet upwards is more than likely going to have a genset.
“A big point of difference with Seakeeper is power consumption, and it’s a big thing that’s really commonly missed. Because we spin in a vacuum, so there’s no air resistance. Yes, we consume a fair bit of power in that first half an hour of spool up, but once the unit’s spooled up, because there’s no resistance inside that sphere and we’re spinning at 8000 RPM or more, it takes very little power to continue spinning the flywheel.”
“Using a single gyro, at the moment, we can go up to about 130-feet or about 100 tonnes from the aforementioned 15.5-foot. Past that, the sky’s the limit in terms of how many gyros you want to add, and yes, we’ve fitted big boats. We’ve got navy frigates that are 500 tonnes and 200-plus feet and 500-plus tonne ships running multiple gyros which don’t need to talk to each other because each individual gyro is actively controlled. Our gyros work like spinning tops, always trying to reduce roll and keep the boat upright.”
WHAT ABOUT LARGER BOATS?
“Using a single gyro we can go up to about 130-feet or about 100 tonnes from the aforementioned 15.5-foot. Past that, the sky’s the limit in terms of how many gyros you want to add, and yes, we’ve fitted big boats. We’ve got navy frigates that are 500 tonnes and 200-plus feet and 500-plus tonne ships running multiple gyros, which don’t need to talk to each other because each individual gyro is actively controlled. Our gyros work like spinning tops, always trying to reduce roll and keep the boat upright.”
Last but certainly not least I spoke to Dean Ryder from Motor Yacht Service Centre and agent for TOHMEI, which is now Anti- Rolling-Gyro (ARG).
“Back in the day Mitsubishi Heavy Industries in Japan developed gyros for the International Space Station. They have an aerospace division, and they build rockets, missiles, planes…all sorts of things. So, they’re a very high-tech company, and in 2000, they developed the first commercially available pleasure boat gyro. Shortly after that, they were locked in a commercial agreement with a specific boat builder for a significant period. This boat builder had access to the product, but the rest of the world didn’t, and by the time that agreement was finished, there were other competitors in the marketplace.”
Dean says the ARG gyro is self-contained, without complicated hydraulics or sea-water cooling. “Fundamentally, it’s an air- cooled spinning flywheel, with long-life bearings that sits in a gimbal. Because the ARG doesn’t have hydraulic rams to limit the precession travel, it will achieve 180 degrees of angle, essentially meaning it will work in larger and longer waves, compared to ram driven equivalents. There’s nothing to go wrong, we don’t take the covers off. And we’ve been selling these things for 15 years, and we haven’t actually had a failure yet. So, in the pleasure boat market they’re extremely reliable. And with very low running costs and good performance.”
What size vessels do you cater for?
“It seems our competitors are a bit quicker off the mark into that small boat market and we’ve been concentrating on the bigger pleasure boats in the 40 – 90ft range. But now we do all models all the way down to big trailer boats, as we have gyros now that run off batteries through an inverter internally to power the units. So, there’s a full range of product.”
CONCLUSION
As stated at the beginning of this yarn, we would lay out all the facts for folks to draw their own conclusions. And the points to look out for when making your mind up as to what product suits your usage are:
- Power usage: Do you need to drive your stabiliser with a generator, what are the associated fuel costs versus benefits of the product.
- Usability: Are you a weekend warrior, a long-range cruiser, a mud skipper or a combination of all three.
- Facts: Look at test analysis and comparative test and be careful you are looking at the same yard stick of measurement.
- Size: What is the size of your vessel, and what piece of stabiliser kit is best for your needs?
- Maintenance: What is your maintenance schedule going to cost you per cruising mile.
- Gyro and fins co-existing on the same boat: For years, both in the gyro and stabiliser camps have said both won’t work together and are, in fact, counterintuitive to each other. But the camps are starting to warm to the fact that if a vessel has both systems, they can be used together, not just as a redundancy if one or other fail. It appears, reading between the lines, that a true groundswell of opinion in favour of both systems on larger vessels is happening. And there seems to be a lot more development in the space and into the future that will ensure both methods of stabilisation can work in harmony.
