Top 5 fuel-saving tips for boaters

Up until the last few years we’ve had a good run of low fuel prices in Australia, but between high inflation and a weak exchange rate, the cost of topping up a boat, let alone a car, has soared.

What makes it worse is that a boat uses way more fuel than a car, so the amount of fuel a  day on the water burns can be the difference between having to eat steak or sausages for dinner.

But there are some tricks you can try to get more out of your engine for less fuel burn. Some are easier than others, but it can save you from having to pass the hat around at the end of a day out on the water.

Here is what we’d recommend.

It sounds simple, but ensuring your boat’s engine is in tip-top shape is key to eking out those longer-term fuel savings.

Boats fall out of tune with use, and also with disuse. Therefore, if you’re using your boat a lot, or not very much, it’s important to keep things in their optimum operating window.

The tip is to service your boat at least once a year, or if you’re using it more often, every 100 hours – depending on the size of your boat, about the equivalent of driving around 3000km in a car.

Even of the fuel saving is only 0.1 litres an hour of engine runtime, the cost saving is beer in the fridge and bait in the icebox that you wouldn’t have had before.

The efficiency of the hull beneath your boat is key to ensuring that you’re getting the best fuel efficiency you can from the running surface.

Hulls induce a lot of drag, even at planing speeds when the boat is operating at its optimum efficiency. Scrapes, dings, dirt and even scratched paint can all affect how efficiently the running surface cuts through the water.

Optimising the hull so that it is as smooth and imperfection-free as possible will ensure you also get the least drag while moving through the water.

This can be as simple as polishing the hull to give it a smooth, shiny finish, filling any scratches in the paint or gel coat, or removing anything that alters the flow of water across the hull’s surface.

You can steer a sailboat that has lost its rudder by dragging a rope in the water, so the effect of having the running surface on one side of the boat different to the other can have a significant effect on its performance.

One of the easiest ways to gain efficiency is to use a different-sized propeller for your boat.

Most boat owners run what they brung, using the same propeller fitted to the boat as was fitted when they bought it. 

However, the prop that suited the boat when there was only you onboard, but now you’re doing lots of family trips is likely to be less-suited to your current needs.

Much like you need to change down a gear in a car when going up a steep hill, you should drop the propeller’s pitch to bring the engine’s rev range closer to its optimal running speed.

Adding people or accessories to a boat such as extra batteries or ice boxes full of drinks is like making the hill a bit steeper for a car, so gearing down the engine via a less aggressive prop may reap big benefits.

Modern outboard engines are pretty fuel efficient, so many boat owners can get away with being a bit lazy at the helm and not tune the boat to the conditions.

The easiest way to tune a boat is via the engine’s or stern leg’s tilt, or trim. This adjusts the angle of the propeller to the water.

Have the trim in too far and the boat will plough through the water with its nose down. Trim out too far, and the boat will bounce up and down, an act known as porpoising. Trim just right and you’ll be able to balance the boat perfectly.

You’ll know when you’re trimmed right. Tilt the engine out until you hear the engine increase its revs slightly, and the boat is sitting happily in the water. However, if you’re turning, you may need to trim back down slightly so the propellor doesn’t suck air in from above it and cavitate.

There are other ways to trim up, such as physically moving weight around the boat or using trim tabs that push the boat up on the water.

Monitoring the fuel gauge is key, so try and match revs and trim to a litres-an-hour fuel burn number you know will get the most out of your tank.

It sounds so simple, but replacing your engine can be one of the easiest ways – but not necessarily the cheapest – to cut down on fuel use.

Each time an engine maker brings out a new powerplant, chances are one of the benefits is that it brings fuel savings.

If you’re running a bigger boat, hybrid engines that mate an oil-burning diesel with an electric motor combine the best of both worlds.

However, for outboard-engined users, hybrid doesn’t really cut it yet. 

The other option is to ditch the fossil-fuelled drive for an electric one. It’s early days yet for the technology so you need to be something of an early adopter with deep pockets to go down this route.

At the moment, it’s also largely confined to smaller outboard engines, with the battery technology not yet quite there to get the range needed for electric motors to compete directly with outboard engines.

That’s not to say it won’t happen; just look at how much the electric car world has developed in the last decade and you can only imagine the same thing will eventually happen for boats.