When considering which outboard to buy for your three-metre tender, you have to ask these questions. Will the boat be used primarily at displacement or planing speeds? How much weight are you prepared to lug aboard your cruiser? And of course, how much are you prepared to pay?

With small tinnies or inflatables, you either operate them at displacement speeds or fit enough power to plane them. There's little point in fitting a three or 4hp outboard, as these will only wind out to inefficient semi-planing speeds, using a lot of fuel in the process.

Until this year, you were stuck with buying a two-stroke, as the four-stroke alternatives were relatively inefficient for their output and weighed considerably more than the two-stroke competition.

That's no longer the case after the release of Honda's new OHV BF2 and Tohatsu's OHV MFS5A, both of which are the most fuel-efficient motors in their respective classes.

Honda BF2
The new overhead valve BF2 replaces the long-running sidevalve BF2, which had lacklustre performance compared to the competition.

Sure, it carries over many of the features of the old model, but its new centrifugal clutch makes it an absolute delight to handle for kids and beginners alike.

It now performs more like a 2hp two-stroke and is slightly faster than the Yamaha 2C (for three years my favourite two) while returning 29% better fuel efficiency. And at Dead Slow Troll (DST) it is 361% more fuel efficient!

Once you're accustomed to rapidly throttling back the motor when it fires (to avoid engaging the clutch), operating the BF2 is a cinch. You just open the throttle and the clutch engages without any driveline 'snatch'. To stop, let go of the twist grip throttle, and the revs will drop and the prop stops turning. What could be simpler?

Evaluated over a two-month period, the loan motor normally started first pull, hot or cold. It would then warm quickly and refuses to miss a beat while trolling for extended periods. However, it should be stated that noise and vibration levels were considerably higher than its watercooled two-stroke competition.

A lift-off upper cowl simplifies servicing, which is recommended every 100 operating hours or six months (after the first 10 hours). As recommended by Honda MPE, we used a 5W30 Valvoline oil. You can check the level of oil by viewing through a sight glass on the port side.

Apart from its greater weight than two-stroke equivalents, the only other drawback of the BF2 is Honda's limited use of marine-grade materials. After 180 hours of saltwater leg/lower unit immersion, there was surface rusting in the tiller arm, lower cowl and lower unit areas due to the use of plated and galvanised bolts. Still, as time progresses, Honda will no doubt rectify these problems.

In summary, as the BF2 is so good in day-to-day operation, I can live with these faults Indeed, frankly I would find it very hard returning to a two-stroke two!

Tohatsu MFS5A
This motor is so good it's hard to believe that it's Tohatsu Corporation's first four-stroke outboard. Indeed, the MFS5A performs effortlessly from DST to WOT (Wide Open Throttle) and is relatively quiet for a single-cylinder four-stroke.

While this motor easily outperforms the Honda BF5, it still does not compete with 5hp two-strokes for WOT performance. The real benefits are at low to midrange speeds, where it's in a different class. Like the BF2, it's such an easy motor to live with, you'd have to think very hard about going two-stroke!

As you'll see in the performance tables, this motor is actually more fuel efficient at WOT than the BF2, but loses out at midrange speeds and in DST operation.

This is due to the fact that the Tohatsu has the power to plane a three-metre hull. The Honda BF2 can only achieve displacement speeds, and therefore is working much harder at WOT.

Because the carbie is mounted atop the powerhead, the Tohatsu occasionally suffers OEvapour lock' when restarted within half an hour of stopping, but this is easily cured by squeezing the fuel primer bulb. In all other aspects of operation, it's very user-friendly, and with features such as a dual-cable throttle system, it's much more sturdily engineered than its two-stroke opposition.

Servicing the Tohatsu is straightforward, with intervals recommended every 100 hours or six months after the first 20 hours.

Unlike many small four-strokes, a standard (though good quality) 20W50 automotive oil may be used. We found Valvoline XLD did a good job.

As the test period was only one week (the motor was needed for the 1998 boat show circuit) there was insufficient time to check saltwater corrosion resistance. But based on longer testing of Tohatsu products recently, there's no reason why the powerplant shouldn't stand up to the ravages of saltwater operation.

Conclusion
While I still prefer fuel-injected two-strokes (such as OMC's FICHT offerings) to four-strokes for offshore operation, I'm convinced that for tenders these four-strokes are the answer.

Sure, they're heavier and more expensive to buy and service than two-strokes, but once you've experienced their stable trolling, clean running and abundance of torque under heavy loads, there's no going back!