Review: Mercury 3.3 hp outboard motor

By: Andrew Norton

Presented by
  • Trade-A-Boat

The portable 3.3 hp Mercury outboard motor is one gutsy little engine.

Review: Mercury 3.3 hp outboard motor
The Mercury 3.3 hp outboard motor is cheap to run, easy to maintain, and unlikely to cause many problems.


Originally published in TrailerBoat #288, October / November 2012.

Wow, it’s been almost 20 years since I borrowed a portable  Mercury 3.3 hp outboard for evaluation on my 1978 De Havilland John 10 punt. That was back when there was hardly any grey in my hair, and I was more than a little fitter than I am now.



It was Christmas Day in ’92 when my then-partner Susan and I were putting up a local creek on NSW’s Lake Macquarie. We’d reached the navigable end when the heavens opened. There we were, two drowned rats munching cake and thinking that it was a long way back to the boatshed.

But the trusty portable 3.3 hp Mercury outboard didn’t miss a beat and we trolled downstream, with just the occasional puff of oil smoke to keep us company. My tiller arm was getting a workout from the transmitted vibration — "Who needs to go to a gym?", I thought to myself — but in all fairness, the Mercury 3.3 was never designed for extended trolling periods.

We kept that Mercury for some time, putting all around the southern end of Lake Macquarie and enjoying the pleasures of simple boating. And when we borrowed the Mercury Mariner 3.3 hp version several years later, we experienced those same pleasures all over again.



Made in Japan, the Mercury 3.3 outboard motor develops 3.4hp at 5000rpm from its 74.6cc, loop-charged, single-cylinder powerhead, with a wide open throttle rpm range of 4500-5500. The Mercury 3.3 hp outboard fuel mixture of normal 50:1 premix means the engine’s single piston ring would last very well, and the fixed ignition timing works well above a two-thirds throttle opening.

The Mercury 3.3 engine’s OEDA zero-star emissions rating does mean it’s pretty dirty, but considering the small amount of fuel it uses, that might not be such a consideration.

The deep 2.15:1 gear ratio improves thrust efficiency at displacement speeds using the standard 5.7in pitch plastic weedless prop. The Mercury 3.3 hp outboard weight of 13kg (dry weight) is made even more attractive by the addition of a large carry handle. There are four trim positions, a full-tilt locking knob and a reasonably large 1.4L fuel tank that gravity feeds to the single-jet carbie.

Given the upper cowl completely unclips from the lower, with a separate spark-plug hatch fitted, maintaining the 3.3 is nice and easy.

Mercury recommends servicing the 3.3 hp every 100 hours, or annually after the first service at 20 hours. The recreational-usage warranty is for five years, provided the engine is maintained by an authorised Mercury service centre.



With a clutch that eliminates the joy of crashing into other boats when the engine fires up, starting the Mercury 3.3 two-stroke could be called ridiculously easy. The engine does shake around while warming up in neutral, but once forward gear is engaged the vibration transfers to your tiller arm, saving your precious boating investment.

Without a thermostat, the engine runs cold when trolling. But if you do want to troll, buy the four-stroke Merc 3.5 instead, which has thermostat-controlled cooling and a twist-grip throttle. It also weighs almost 50 per cent more than the Mercury 3.3.

Since ignition timing is especially advanced, the engine shakes around a fair bit at less than two-thirds throttle, so you need firmly fixed teeth. However, when you are in the upper rpm range, even dentures can survive the onslaught.

Operating the Mercury 3.3 hp outboard becomes almost pleasant as you plug along, taking ages to get anywhere. This never worried Susan and I, however, because we would simply motor out from our boatshed and drop anchor for fishing. And because Susan was a vegetarian and I hate cleaning fish, we’d usually end up having an omelette when we got home.

After a total of 50 hours of salt-water leg / lower unit immersion on both engines, no corrosion was apparent anywhere apart from some slight surface rust on the propshaft. Both engines appeared in showroom condition thanks to Mercury Marine’s high-quality paint finish.



As of October 2012, the Mercury 3.3 hp outboard had a price of $979 RRP. A spare plastic propeller had a price of about $80.



Almost 20-years on, the Mercury 3.3 is still readily available because it’s a simple little engine that’s cheap to buy and to run. Annual servicing will likely set you back around $90, but one dealer told me owners often keep their 3.3 Mercury outboards for a few years and buy a new one without ever servicing the original. That’s really a shame, because with a little TLC there’s no reason the 3.3 won’t provide many years of boating pleasure.

Thanks to Mercury Marine in Dandenong, Vic (03 9791 5822), for the two review outboards used in this story.



Fitted to John 10 punt with two adults, total 225kg.

1.6kts (3kmh)

1430rpm (trolling)


6.0kts (11.1kmh)

4000rpm (cruise)


6.9kts (12.8kmh)

5070rpm (WOT)


Note: Data based on a loop of cruising with 10 per cent WOT and 40 per cent trolling, averaging 4kts (7.5kmh), 0.8L/h or 1.7 hours per tank.




Tohatsu M3.5B

Yamaha 3A







Dry weight



Warranty (yrs)



OEDA stars




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Originally published in TrailerBoat #288, October / November 2012. Why not subscribe today?


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