Ferretti 800 vs Princess Y85 — and how shipyards play with prices

Your neighbour in the marina may have paid up to €25,000 more for his bow thruster than you did — and his thruster does exactly the same job as yours. He probably doesn't even know it. In this article I explain why electric bow thrusters are not worse than hydraulic ones, how shipyards hide the real costs, and what actually matters when you buy a 70–90 ft yacht.

I work as a yacht broker, and on almost every viewing I hear the same line: “electric thrusters are a compromise, hydraulic is better.” That single sentence costs my clients real money, and it rests on a misunderstanding. So I decided to take it apart — using two real yachts almost everyone knows: the Ferretti Yachts 800 with an electric thruster, and the Princess Y85 with a hydraulic one.

Both are 80-foot flagships. The Ferretti 800 is 24.5 metres long and weighs 76 tonnes. The Princess Y85 is nearly 26 metres and 78 tonnes. Base prices are close — both in the €5–6 million range. They do exactly the same job: pushing roughly 75 tonnes of water sideways in a marina. So why do they have completely different thrusters? The answer, as you'll see, has nothing to do with quality. It's a matter of yacht architecture and money.

Let's start with the number nobody says out loud at the negotiating table. Imagine a hypothetical scenario: you walk up to a Princess Y85 dealer and say — I don't want any stabilization, no gyro, no fins, but I do want a hydraulic bow thruster, because I've heard it's better. How much is that? The shipyard would have to cost it honestly — and here's how it works out:

The difference is brutal. A hydraulic thruster with all its infrastructure runs €35,000–45,000. An electric thruster with batteries and cabling — €18,000–22,000. Twice as cheap. And this is where it gets interesting.

The shipyard really does not want to give you that hydraulic quote openly. Because if it told you straight — “pay €25,000 extra for hydraulic instead of electric” — it would shoot itself in the foot. Any informed buyer would stop and ask: why should I pay €25,000 more for a thruster when the electric one does the same thing? And they would be right — that is the single best question you can ask when buying an 80-foot boat. Sales would drop, and the shipyard's image would suffer.

So shipyards don't confront the buyer with that choice head-on. They do it more cleverly: they hide the cost of the hydraulics inside the cost of the stabilizers. A hydraulic thruster only appears in the offer when the client is buying hydraulic fin stabilizers anyway. At that point the hydraulics for the thruster cost next to nothing — because the whole infrastructure (pump, piping, pressurised oil) already exists. The client never even notices buying it. And if the client chooses a gyro, or no stabilization at all, they get an electric thruster for €18,000–22,000. Doing exactly the same job.

First, one thing buyers often forget: stabilization on both yachts — the Princess Y85 and the Ferretti 800 — is an OPTION, not standard equipment. Most buyers choose it, of course, because without stabilization an 80-foot boat in a swell is unpleasant even for an old sea dog. But it's a formal decision made when signing the contract — and it's serious money:

–    Sleipner fin stabilizers on the Princess Y85 — the fins that deploy from the hull, hydraulic — cost in the order of €100,000–150,000.

–    Mitsubishi ARG gyro stabilizers on the Ferretti 800 — a similar order of magnitude, €80,000–120,000.

Whatever the type, a premium configuration costs real money. Now watch how the thruster type follows logically from that one decision. There are exactly four possible scenarios:

And here's the heart of it, the part you won't find in any brochure: in three out of four scenarios the client gets an electric thruster. Only in one — a hydraulic one.

Why is that proof? Because if a hydraulic thruster were objectively better than an electric one, shipyards would run hydraulics every time — into every yacht, regardless of stabilization. But they don't. Because it isn't worth it, and because an electric thruster on a 24-metre boat does exactly the same job when it's properly engineered. The shipyard picks the thruster type that fits the rest of the yacht. It's not a quality decision — it's an engineering decision.

So the next time you hear “electric thrusters are a compromise,” it should make you think rather than convince you. It's not a compromise. It's the logical choice for a specific yacht architecture, made by engineers who know exactly what they're doing.

Whatever thruster you have, your yacht weighs 76 tonnes. And the laws of physics apply to both types identically. You press the joystick. The motor — electric or hydraulic — instantly drives the propeller in the tunnel. The propeller pushes water sideways, and a lateral force vector is created. But the bow doesn't move yet, because 76 tonnes of mass has enormous inertia and the water resists. The boat needs 3, sometimes 4 seconds before it moves at all.

And here's the surprise for many helmsmen: whether you hold the button for five seconds or a full minute, you still have a physical maximum of lateral acceleration — and that is a function of thruster power, not holding time. The boat does not turn faster the longer you hold. After the first 3 seconds it reaches its maximum rate of rotation, and you can't squeeze any more out of it. Ferretti and Princess — identical physics, identical inertia, identical water resistance, the same bow behaviour.

Cavitation — the thing almost nobody in the industry explains

Cavitation in the thruster tunnel is a purely hydrodynamic problem. Not electric, not hydraulic — hydrodynamic. It depends on what happens to the propeller and the water, not the motor behind it. During long, continuous thruster use the propeller starts to suck air from the free water surface through the tunnel opening. After a dozen or so seconds it's churning a water-air mixture, and thrust drops by 30, sometimes 40 percent. It gets loud, and the yacht turns slower than it would with short bursts.

Short bursts are not “a protocol for electric thrusters because electric overheats.” Short bursts are the physically best way to manoeuvre with any thruster, because only they exploit the yacht's inertia and avoid cavitation. The correct technique looks like this:

–    Short bursts — one to three seconds each. Then you release the button.

–     Let the mass of the yacht carry the turn through on momentum. Watch where the bow goes.

–     Another 3-second burst, another pause, another observation. And so on to the end of the manoeuvre.

The benefits are real and measurable. Short bursts generate no cavitation. They fully use the yacht's inertia, which you have available for free. They minimise wear. They are quiet — no roar in the saloon. And they give you time to observe: you see how the bow reacts and correct with the power of the next burst. This applies to both thruster types. It's not an electric rule — it's a hydrodynamic rule.

One nuance where hydraulics genuinely wins

There is one situation where hydraulics has a real edge: when you must continuously oppose a steady, large force. For example, you're mooring beam-on to a quay in a 25-knot crosswind and for 30 seconds you have to hold the bow so it doesn't get blown off. Electric used in bursts has 5-second gaps between bursts in which the wind pushes you back. Hydraulics delivers steady, uninterrupted force — and wins there.

But note: on the Ferretti 800 with the proportional SEP210 PRO thruster you can hold the bow by touching the button at five percent power in a steady press. That's not even 50 amps — the motor doesn't heat up. It works; the technique is just slightly different.

The thruster manufacturer Side-Power, model SEP210, states that the maximum continuous single press of the button is 2.5 to 3 minutes. After that time a thermal bimetal cuts the power and waits for the motor to cool. It's very important to understand this correctly:

Both systems are mechanical, so things do occasionally break. It's worth knowing what to expect.

The electric thruster in average use needs its carbon brushes replaced every 3 to 5 years — that's a wear part. A service replacement costs €600–1,200. The second typical wear item is the solenoids, the contacts linking the battery to the motor — also replaceable, similar prices.

The hydraulic thruster after 5–7 years needs a seal inspection, an oil change and a valve check — a cost in the order of €3,000–8,000. Less often, but heavier.

Statistically, the failure rate of both technologies is similar and low. I'll be honest, as a broker: I've probably seen more burned-out electric thrusters than hydraulic failures. But 90 percent of those burned-out electrics were helmsman error — someone held the button down for a minute, two minutes. Burned windings, a repair cost of €10,000–15,000, two weeks out of the water. Hydraulics is more forgiving of that kind of mistake. But if you're a competent helmsman, both technologies will last for years without trouble.

If the thruster type doesn't matter, what does? One thing: kgf — kilogram-force. It's the only metric that genuinely counts when sizing a thruster to a yacht. Not kilowatts, not horsepower — the kilograms of lateral force the thruster generates on static water.

Why? Because kilowatts only tell you how much current or oil the thruster draws. You can have a 10 kW thruster with a badly designed tunnel that delivers a feeble 100 kgf — and an 8 kW thruster that delivers 200 kgf. The second one turns your yacht twice as well using less energy. Engineers at Sleipner, Vetus and Quick have formulas that account for windage area — the side surface of the hull above the water. The taller the superstructure and the longer the yacht, the greater the crosswind force, and the stronger the thruster you need. Rough figures:

–    60-foot yacht with a moderate profile — 100 to 150 kgf.

–    80-foot yacht with a heavy wind profile — 240 to 300 kgf.

–    100-foot yacht — 350 to 500 kgf.

And here's the absolute key: 240 kgf in an electric thruster delivers exactly the same yacht-turning force as 240 kgf in a hydraulic thruster. The unit is physical, independent of the drive type. The bow reacts identically. There is no such thing as “stronger electric” and “weaker hydraulic” — there is only a thruster correctly or incorrectly sized to a specific yacht.

–    1.  Electric bow thrusters are not worse than hydraulic ones. They are optimised differently and do exactly the same job, provided they have the right thrust in kgf.

–    2.  The choice between electric and hydraulic is an architectural decision by the shipyard, not a quality ranking. Princess picks hydraulic because it already has hydraulic stabilizers. Ferretti picks electric because it has a gyro.

–    3.  The operating technique is identical for both types: short 3-second bursts, pause, observe. The laws of physics — the inertia of 76 tonnes and tunnel cavitation — are the same.

–    4.  Electric has the S2 cycle (a maximum of about 3 minutes of continuous holding); hydraulic has no such limit. But with correct technique you will never approach it in either technology.

–    5.  When buying, look at kgf, not kilowatts. For an 80 ft yacht aim for 240–300 kgf. Anything else, regardless of drive type, is just marketing.

I also covered this topic in detail on my YouTube channel — with animations and visualizations of both yachts:

▶  Episode on bow thrusters:  youtu.be/dQp8ddeghIw

▶  Live stream (Q&A):  youtube.com/live/LJ7WqKJPxTE

About the author

Tomek  Wrzesiński — yacht broker at W Yachts. I show yachts from the angle you won't hear in the sales lounge: hard data, real prices, real engineering decisions. No sponsored narratives, no shipyard allegiance, always on the buyer's side. If you're planning to buy a yacht in the 70–90 ft class and would like my help with the process — we work in Monaco, Cannes and Warsaw. Reach out through the W Yachts channel.