Andersen Stainless Winches: A Research Note

This is a research note — a deep look at the product and what we would assess, before hands-on testing. We do not publish ratings or ownership claims until we have used it ourselves, and every figure below is the maker's published specification, not our measurement.

Andersen's whole design thesis is metallurgical: keep the entire load path in stainless and bronze, cold-form the drum so it work-hardens, and grip the line with geometry rather than an abrasive surface. That buys corrosion immunity, a finish that survives years of salt, and a service interval a cruiser rarely worries about — at the cost of real mass the moment you compare it to a race-optimised aluminium primary. We have not run Andersen winches on our own Melges 40 programme, so what follows is an engineering read of the construction, the published numbers, and the specific things we would put under load before forming a verdict.

At a glance

Figures are Andersen/Ronstan published specifications. Metric conversions are approximate.

The construction, material by material

A winch is a torque-multiplying gearbox that has to survive salt, grit and cyclic shock load, and Andersen's answer is to specify each part for its job rather than mould most of the winch from one material.

The drum is grade 316L stainless, and the important detail is how it is made: Andersen cold-forms it in stages so the metal work-hardens as it takes final shape. Cold working raises the yield strength and surface hardness of austenitic stainless well above the annealed state, which is why the finished drum can run a comparatively thin wall and still resist the hoop and bending loads a loaded riding turn imposes. 316L (the low-carbon variant) is chosen because it resists sensitisation and chloride pitting better than 304 — the correct call for a component that lives wet in a marine environment.

The drive shaft is grade 329 duplex stainless, not austenitic. Duplex grades carry a mixed ferrite-austenite microstructure that roughly doubles yield strength over 316 while improving resistance to chloride stress-corrosion cracking. On the shaft — the one part carrying full input torque through the gear train — that combination of strength and crack resistance is exactly what you want, and it lets the shaft be sized without excess mass.

The pawls are cut from a cold-pressed 316 stainless profile and then machined. Pawls are the winch's fuse: they take the ratchet shock every time load comes on, and a broken pawl is the classic failure that lets a drum run backwards under a spinnaker load. Cold-pressing the profile before machining gives a harder, more consistent tooth than casting, and Andersen's claim of a "virtually unbreakable" pawl is the practical consequence.

The upper centre stem is aluminium bronze. This is the structural spine the bearings load into, and it is where the honest weight conversation begins: aluminium bronze is roughly three times stronger than aluminium and roughly three times heavier. Andersen uses the strength to run a stiff, low-torsion stem — and a stiffer stem means less flex under load and therefore a more efficient winch, because energy that would go into twisting the structure instead reaches the drum. But Ronstan's own material note is candid that the stem, not the drum, is where most of an Andersen winch's mass lives.

Around that spine sit stainless roller and ball bearings that carry the highest drum loads down to the centre stem. The roller bearings take radial drum load; the ball races handle the axial thrust that builds as sheet tension rises. Keeping the stack in stainless (rather than a caged composite) is consistent with the corrosion-immunity thesis and is part of why Andersen can quote a two-year service interval — there is less in the winch to corrode, gall or swell.

Power Rib: grip by geometry, not abrasion

Most aluminium winches get their bite from a hard, slightly rough drum surface — knurled, needle-peened or grit-anodised — which grips well but is, by design, abrasive to the sheet cover. Andersen inverts this. The Power Rib drum carries fine vertical ribs running up the barrel, with highly polished stainless flats between them. The ribs supply the circumferential grip that stops the turns slipping under load; the polished flats minimise vertical friction so the riding turns slide smoothly up the drum as it rotates, rather than juddering.

The engineering payoff is twofold. First, easing under load is cleaner: on an abrasive drum, feeding a loaded turn upward tends to shudder and chatter, whereas the polished flats let it climb. Second — and this matters on a Melges 40 running expensive high-modulus sheets — the geometry grips without chewing the cover. In Practical Sailor's multi-brand testing, Andersen's ribbed drums and Harken's smooth aluminium drums were singled out as the easiest on the line, while aggressively textured surfaces such as needle-peening were the hardest. On a boat that replaces cover-chafed sheets as a running cost, drum surface is a real-money variable, not a cosmetic one.

The self-tailing side follows the same logic. The stainless jaws self-adjust across the quoted 5/16–9/16 in (roughly 8–14 mm) range, and on the 40ST and larger the self-tailing arm rotates through a full 360 degrees so the tail can be led to whatever exit the cockpit demands. For a fully crewed grinding operation the self-tailer is secondary — you have hands on the tail — but the wide fixed grooves are genuinely easy to feed one-handed, which is what Practical Sailor noted, and it matters in a short-handed delivery or a peel gone wrong.

Reading the numbers

The published ratios tell a coherent story once you know what they mean. Power ratio is the gear ratio multiplied by the leverage of the winch handle, so it expresses how much the winch multiplies the grinder's input at a given handle length: the 46ST's 47.1:1 second speed means roughly 47 units of line tension for one unit of hand force, before friction losses. Andersen quotes 40.0:1 (40ST), 47.1:1 (46ST) and 52.5:1 (52ST) in second speed, with low-gear ratios of 8.9:1, 15.7:1 and 16.2:1 for grinding the last metres home under heavy load.

Where a spec sheet goes quiet is efficiency — how much of that input actually reaches the drum rather than being lost to bearing and gear friction. Two winches quoting the same 40:1 can differ significantly at the top of the load range, and that gap is precisely where the stainless roller-and-ball arrangement is meant to pay: a high power ratio only helps a grinder if the winch stays free-running when a genoa is loaded up in a breeze. That is not a number you can read; it is a thing you feel on the handle, and it is top of our test list.

The weight trade, stated honestly

This is where a race campaign has to be clear-eyed, and where the popular "stainless can be as light as aluminium" line does not survive contact with the numbers. Andersen's argument — stronger material permits thinner scantlings — is real and does close some of the gap. But for a size-40 primary, Ronstan's own published comparison puts the stainless Andersen 40ST at 10.8 lb against a Harken Radial aluminium 40 at 8.4 lb and a Ronstan Orbit aluminium 40 at 6.8 lb; a Harken Performa 40, the closer race analogue, is lighter still at about 3.8 kg. A Lewmar Evo aluminium 40 lands at 10.8 lb — level with the Andersen — while a Lewmar chromed-bronze Evo is 14.3 lb.

So the honest placement is: Andersen is clearly lighter than chromed bronze, roughly level with a heavy aluminium/bronze cruising winch, and meaningfully heavier than a weight-optimised aluminium race primary. On a Melges 40, where mass in the ends and above the waterline is scrutinised gram by gram, a two-to-three-kilogram penalty per primary is not trivial and has to be earned back in durability and finish. The mass, again, sits mostly in that aluminium-bronze stem — the price of the stiffness Andersen trades for efficiency.

Where it fits on the boat

Winches are the interface between crew and load on every sheet and halyard, so the choice is really a philosophy choice, and Andersen sits at one clear pole. Its case is strongest where a boat lives in the water in a warm, salty climate and is expected to look and work as-new across many seasons: the stainless does not pit, chalk or lose its anodising, and the long service interval is real. On a well-found cruiser-racer or a programme that values longevity and finish over the last kilogram, that is a genuinely coherent package, and Practical Sailor rating Andersen at the top of a six-brand field (against Harken, Lewmar, Antal and others) reflects build and grip that stand up.

For an outright grand-prix weight budget the calculation flips. The alternatives — Harken's Performa with its narrow composite self-tailing jaws tuned for stiff, small-diameter high-modulus line and an added ball-thrust race under peak load, or Lewmar's Evo — give up finish and corrosion margin to save weight, and on a boat measured to a rating box that saving is the whole game. Neither philosophy is wrong; they answer different questions. "Best in an independent test" and "right for our specific displacement and rating" are separate questions, and only the second is ours to answer.

If you are placing winches against clutches, cars and the rest of the running-rigging package, our winches comparison sets the field out side by side, and our note on deck-hardware servicing covers the maintenance argument a two-year interval is meant to win. Andersen's pitch is fundamentally a longevity-and-maintenance argument, so those two pieces are the natural context.

What we would assess

Before we would put a rating on Andersen winches, we would load-test the claims that a spec sheet cannot settle:

• Efficiency under peak load. Not the quoted power ratio, but how freely the roller-and-ball stack actually turns with a genoa loaded up in 20-plus knots — the point where a stiff winch quietly costs the grinders time.
• Power Rib on high-modulus sheet. Whether the ribs hold a modern Dyneema-cored sheet without slip and without shredding the cover, and how cleanly a loaded turn climbs the polished flats when easing under load.
• Self-tailing consistency. Whether the stainless jaws hold across the exact sheet diameters we run, given the jaws are tuned for a wide cruising range rather than one stiff race line.
• Service in practice. How quickly the winch strips, degreases and re-greases on the dock, and whether the two-year cruising interval survives a boat washed down after every session and repeatedly loaded to peak — we would expect to service far more often.
• Mass, weighed not quoted. The real, verified drum-and-stem mass of each size against a Harken Performa equivalent, so the durability gain is weighed against a number we have put on a scale ourselves.

The takeaway

Andersen has a genuinely coherent engineering identity: a cold-formed 316L drum, a 329 duplex shaft, cold-pressed 316 pawls and an aluminium-bronze stem, all wrapped around a Power Rib surface that grips by geometry instead of abrasion. The published power ratios (40.0:1 to 52.5:1 in second speed across the 40–52 range) are competitive, the corrosion story is real, and the two-year service interval is honestly earned by the sealed-stainless internals. The catch, stated plainly, is mass: this is a durability-and-finish winch, not a weight winch, and against a race-optimised aluminium primary it carries a real penalty concentrated in that bronze stem. Whether that trade lands for a Melges 40 specifically is exactly what we would test under load — and until we have run and weighed them ourselves, we will not put a score on it. Treat this as the engineering map of what Andersen is and what we would measure, not a verdict.