Folding propeller · 2 / 3 / 4-blade
Under sail it disappears. Under power it means it.
The Varifold folds its blades to a streamlined dart — the lowest drag a propeller can have — then opens instantly with real bite in forward and reverse. For racers and performance cruisers from 20 to 750 hp.
Why owners fit one
The Varifold case, in four points
Lowest possible sailing drag
Blades fold flat together behind the hub — and unlike some folders, Varifolds don't rotate when sailing, even at higher speeds. In light air that's worth up to a knot over a fixed prop.
Blade design from serious naval architecture
Proper helical pitch distribution, deliberate pitch reduction at the tips to kill cavitation, high-skew cambered blade forms to soften pressure pulses against the hull. Some folding props have one of these features — none puts the whole package together across a full range.
Opens astern, reliably
Varifolds open when you go astern — hydrodynamics as well as inertia drive the blades out, with rubber bump stops soaking up the opening impact. Thrust astern is greater than other folders by design.
2 to 4 blades, 20–750 hp
From club racers to a Baltic 147: shaft and saildrive fits, machined from nickel-aluminium-bronze on Bruntons' own CNC plant — the same machines that cut propellers for naval and commercial vessels — and chosen as standard equipment by Swan, Baltic, Wally, Oyster and Moody.
| Model | Blades | Diameters | Engines | Signature |
|---|---|---|---|---|
| VF70 · VF70SD | 2 | 305–432 mm (12–17″) | to 50 hp | Blades fold fully together; substantial blade area for smooth running |
| VF108 · VF108SD | 3 | 406–635 mm (16–25″) | to 350 hp | High-skew cambered blades, pitch reduction at the tip |
| VF120 · VF120SD | 4 | 457–635 mm (18–25″) | high-power | For big saildrives and shafts — including the new SD15 saildrive unit |
| VF160 | 4 | 660–813 mm (26–32″) | — | Large-yacht blade area, smooth at full power |
| VF230 | 4 | 914–1,143 mm (36–45″) | to 750 hp | The largest folding propellers made |
2021 brochure figures — exact sizing engineered per boat. Want lighter still? Bruntons machined the first four-blade titanium folding propeller ever made, for a Baltic 115 Custom — 40–50 kg lighter than the bronze equivalent with no loss of strength or performance.
The technical drawing
The folding geometry, working
Toggle between driving and sailing to watch the blades swing on their hinge pins — and click the numbered parts for the engineering that separates a Varifold from a bargain folder.
Interactive technical drawing · BA-VF-01
Varifold — the folding geometry
Hub — taper or saildrive spline
Machined nickel-aluminium-bronze, cut on the same CNC plant as Bruntons' naval and commercial propellers. Shaft and saildrive versions across VF70–VF230.
The measured record
Owner-logged results, plotted
Real boats, real logs — each chart carries its measurement badge and data table.
Holding speed in a seaway — 132 ft cat, before and after
MeasuredThe strongest single Varifold result on file: two extra knots held, punching into 20 knots of wind and a three-quarter-metre head sea.
| Condition | Previous feathering | Varifold 4-blade |
|---|---|---|
| Flat water @1,800 rpm | 9 kn | 10+ kn |
| 20 kn wind · ¾ m head sea | 6.5 kn | 8–8.5 kn held |
The Varifold envelope — diameter coverage by model
Measured305 mm club racers to the 1,143 mm VF230 — the largest folding propellers made. A titanium 4-blade (Baltic 115) trims 40–50 kg more.
| Model | Blades | Diameters | Rating |
|---|---|---|---|
| VF70 | 2 | 305–432 mm | to 50 hp |
| VF108 | 3 | 406–635 mm | to 350 hp |
| VF120 | 4 | 457–635 mm | high-power |
| VF160 | 4 | 660–813 mm | — |
| VF230 | 4 | 914–1143 mm | to 750 hp |
“Perfect.”
“The 3 blade Varifold is matched very well to motor output… no vibration whatsoever… the first time on any of our three boats!”
“Cavitation noise is much reduced and we're about half a knot faster at the top end — exactly as Bruntons predicted.”
Designer Germán Frers is “very fond” of the four-blade and normally recommends it on his designs; Southern Wind specified Varifold for its 94-footer's Yanmar package.
Questions owners ask
How much drag does a folded Varifold actually save?
A fixed 3-blade propeller drags like a bucket — published testing puts it at roughly 20 times the drag of a folded prop, worth up to a knot under sail on many boats. Folded, the Varifold presents essentially a streamlined bullet behind the hub.
Do folding props reverse badly?
Cheap ones can. Varifolds open when you go astern — the design uses hydrodynamic force as well as inertia to throw the blades out reliably in either direction, with rubber bump stops absorbing the opening impact. Astern thrust is greater than other folders by design, which is the main thing separating a Varifold from the reputation of older folding props.
2, 3 or 4 blades — which do I want?
Two blades for the lowest possible drag on race boats; three for the all-round performance-cruiser balance; four where blade area or smoothness matters (bigger boats, higher power). It's application-specific — the Builder scores it from your inputs.
Varifold or Autoprop?
Sail more than ~80–90% of your hours and count tenths of a knot? Varifold. Cruise, motor-sail and want fuel savings and low-rev cruising? Autoprop. We make both, so you'll get the honest answer for your usage — see the comparison page for the full trade.
Racing this season?
Tell us the boat, the engine and how hard you race — we'll spec the blade count and size, and admit it honestly if an Autoprop suits your programme better.