Duffy Motor Overhaul
Brushes, bearings, couplers, and shaft seals. When a Duffy motor starts to hum, drag, or pull more current than it used to, an overhaul is usually cheaper than a replacement — and lasts longer than you'd expect.
A Duffy drive motor is a simple, tough thing, and that is exactly why it gets ignored until it stops. Brushes wear down, bearings dry out, the coupler between motor and shaft goes slack, and the stuffing box starts to weep. None of those is expensive on its own. Left alone together, they take the motor with them.
What's included
- Current draw, temperature, and insulation resistance measured under real load
- Motor removed, stripped to the housing, and inspected against spec
- Brush replacement, with the commutator turned true and undercut
- Bearing replacement and an honest assessment of the windings
- Shaft coupler, cutlass bearing, and stuffing box serviced
- Shaft alignment set with dial gauges on reinstall
- Controller and throttle tested against the rebuilt motor
- Sea trial before the boat goes back on your slip
Signs it's time
Current draw climbing
The boat is slower than it was and the bank drains faster for the same run. People almost always blame the batteries first. If a new bank didn't fix it, the motor is where to look next.
Noise and vibration
A growl that rises with speed is usually bearings. A rhythmic knock that comes and goes is usually alignment or a tired coupler. Neither gets better, and both are cheap now and expensive later.
Water in the bilge after a run
A stuffing box is meant to drip a little at speed and not at all at rest. If yours is filling the bilge on a Sunday afternoon, it needs repacking — and it's worth doing while the shaft is out anyway.
Overhaul or replace?
An overhaul runs roughly a third to a half the price of a new motor, and it drops straight back onto the existing mounts and wiring. We only recommend replacement when the windings are cooked or the housing has corroded through — and when we do, we'll put the motor on the bench and show you why.
Other boats
We also take on inboard and outboard work on other harbor boats up to about 30 feet, gas or diesel, from diagnosis through to sea trial. Duffys are most of what we do, but they're not all of it.
Motor stopped dead? Don't keep cycling it. A motor that has drawn stall current once will do considerably more damage the second time. Leave it alone and call us.
Typical pricing
| Work | Price |
|---|---|
| Diagnostic and load test | $165 |
| Brush and bearing service | $580–860 |
| Full motor overhaul, Duffy 16–22 | $1,250–2,100 |
| Motor replacement, installed | $3,400–5,200 |
| Shaft, coupler and stuffing box service | $340–620 |
| Inboard / outboard work, other boats | $125 / hr + parts |
The diagnostic fee is credited against the overhaul if you go ahead. Overhauls carry a 12-month warranty on parts and labour.
How it works
Four steps, no surprises on the invoice
Test
Current draw, temperature, and insulation resistance measured under real load, before anything comes apart.
Pull & strip
The motor comes out, gets stripped to the housing, and every component is measured against spec rather than eyeballed.
Rebuild
Brushes, bearings, seals, and coupler replaced, and the commutator turned true and undercut.
Align & trial
Reinstalled, shaft alignment set with dial gauges, then a sea trial before you get the boat back.
Common questions
Motor Overhaul, answered
How long will it take?
Five to ten working days for a full overhaul. Your boat can stay in its slip until the day we pull the motor, so you lose one weekend rather than three.
Can you do it at my slip?
Diagnosis, yes — that's a dockside visit. The overhaul itself is a shop job: it needs a bench, a press, and a lathe for the commutator.
Is it worth overhauling an older boat's motor?
Usually, yes. A well-maintained Duffy drive motor will outlast the hull it's bolted into. Unless the windings are gone, an overhaul buys you another decade for a fraction of replacement cost.
Do you rewind motors?
We assess the windings and manage the rewind through a specialist we've used for years. You get one invoice and one point of contact rather than being handed off.
Will a new battery bank fix my slow boat?
Sometimes. That's why we load test the bank and measure motor draw in the same visit — it's the only way to know which one you're actually paying to fix.
Ready when you are
Tell us your boat and your harbor, and we'll come back with a free written estimate — usually within one business day.