300XXL SEAPRO PAIR

Description

This 300XXL SeaPro Pair is a matched pair of used Mercury SeaPro 300 hp outboards with 30 inch extra extra long shafts and Digital Throttle and Shift. SeaPro is Mercury’s commercial line, built for boats that work long hours. The pair is sold together, and we ship worldwide.

The original listing records the hours as around 1,887 and says warranty cover runs until April. Those details were not complete on the listing, so we confirm the hours of each engine, the model year, and the exact warranty end date in writing before you buy. For a pair of 300s, the asking price is a fraction of what two new engines would cost.

On this page:

• Why this pair
• Hours on a commercial engine
• Boats it suits
• Features
• Specifications
• Maintenance
• Alternatives
• Price and shipping
• FAQ

Why buy this 300XXL SeaPro Pair

Buying twins as a matched pair saves a lot of work. Both engines share the same shaft length, controls and set up, so rigging is straightforward and they run evenly together. SeaPro engines are calibrated for commercial use and validated for longer engine life than recreational engines, which is why patrol, charter, pilot and offshore work boats use them.

With DTS, the pair can be controlled smoothly, and on suitable boats you can use features such as single lever control and synchronised engine speeds. The 30 inch shaft suits tall transoms and deep engine brackets found on larger offshore hulls.

Hours on a commercial engine

Hours mean something different on a commercial outboard. A charter or patrol boat can put 500 hours or more on its engines every year, and SeaPro engines are built for exactly that. What matters most is the service record: regular oil and filter changes, water pump impellers, gear lube and anodes. Ask us for the service history and photos of both engines, and we’ll share what we have.

Be realistic too: at this level of use, you should budget for a thorough inspection and service by a Mercury technician when the engines are installed, and keep a close eye on wear items such as water pumps and thermostats.

Boats this 300XXL SeaPro Pair suits

• Offshore centre consoles with 30 inch transoms or brackets
• Commercial work boats and patrol boats
• Charter and dive boats
• Heavy RIBs
• Repowers of twin engine offshore boats

Check your boat’s rating for twin 300 hp engines and total engine weight before ordering.

On the water

With a pair of 300s on the back, a heavy offshore boat gets onto plane without fuss and holds a strong cruise in a sea. Twin engines also give you a way home if one ever has a problem.

300XXL SeaPro Pair features

• Matched pair of used Mercury SeaPro 300 hp outboards
• 30 inch (XXL) shafts
• Digital Throttle and Shift
• Commercial SeaPro calibration
• Power trim and tilt
• SmartCraft compatible
• Warranty cover as listed, dates confirmed before sale

300XXL SeaPro Pair specifications

For the manufacturer’s own overview of the range, see Mercury’s SeaPro commercial outboards page. Mercury updates details between model years, so if one spec really matters to your purchase, ask us and we’ll confirm it on the exact unit we ship.

Maintaining the 300XXL SeaPro Pair

First step: have both engines serviced when installed: oil and filters, fuel filters, gear lube, water pumps and anodes.

Oil: change on hours, which comes around quickly on a working boat.

Cooling: flush both engines after every salt day.

Records: keep a service log for each engine.

If you’re newer to boating, the US Coast Guard boating safety site is worth a read. It’s written for US boaters, but the advice on kill cords, life jackets, fuel handling and navigation rules applies wherever you are in the world.

Choosing the right shaft length

Shaft length has to match your transom. Mercury uses L for 20 inches, XL for 25 inches and XXL for 30 inches. Measure straight down the centre of the transom, from the top where the engine bracket sits to the bottom of the hull. Most single engine bass and bay boats use 20 or 25 inches; most offshore centre consoles with twin or triple engines use 25 or 30 inches. Too short and the prop ventilates and the water intakes run dry; too long and you add drag and lose speed.

If you are replacing an engine, the old one’s model code usually tells you what you need. If you are not sure the 300XXL SeaPro Pair is the right length for your boat, send us the transom measurement and the boat model and we’ll check it.

Running twins and counter rotation

A lot of boats in this power range run two engines side by side. When they do, one engine normally turns its propeller the standard way (right hand) and the other turns it the opposite way (left hand, or counter rotation). That cancels out the steering torque you would feel with two props spinning the same way, so the boat tracks straight and handles evenly at every speed.

Mercury marks counter rotation engines with a C in the model code, so a CXL is a 25 inch shaft counter rotation engine, and an XL is the matching standard rotation engine. If you are building a twin rig with the 300XXL SeaPro Pair, pair it with its opposite rotation twin, and match shaft length, controls and colour. We can supply matched pairs and help with the rigging list.

Digital Throttle and Shift, explained

Digital Throttle and Shift, or DTS, replaces the old push-pull cables between the helm and the engine with electrical signals. When you move the lever, the 300XXL SeaPro Pair gets a digital command and the engine’s own actuators do the work. The result is shifting that feels smooth and light every time, with no clunk into gear and no stiff lever after a season of salt spray.

DTS also opens the door to the useful SmartCraft features: one lever control of twin engines, docking and trolling modes, synchronised engine speeds and, on suitable boats, joystick piloting. The trade-off is that DTS needs matching DTS controls and wiring at the helm. If you are replacing a mechanical rig, budget for the new control box and harnesses, or ask us to quote the full package.

SmartCraft and engine information

The 300XXL SeaPro Pair is compatible with Mercury SmartCraft, the digital network that lets the engine talk to gauges and displays at the helm. With a SmartCraft gauge or a compatible multifunction display, you can see fuel flow, fuel economy, range, engine temperature, oil pressure, trim angle and battery voltage, and get warnings in plain language rather than a mystery beep.

That information is useful day to day, and it is even more useful for spotting a small problem before it becomes an expensive one. Mercury technicians can also read the engine’s stored data when it is serviced, which makes diagnosis quicker and more accurate.

What rigging an engine this size involves

A 300XXL SeaPro Pair is not a bolt-on-and-go motor. Rigging normally includes mounting and bolting the engine to the transom or a jack plate, connecting controls, fitting a steering system rated for the power, installing gauges or a SmartCraft display, wiring the battery with properly sized cables, connecting the fuel system with a water separating filter, and choosing and fitting a propeller. On twin installs, the two engines also need a tie bar and matched set-up.

Most buyers have a local marine technician do the installation, and we recommend that. We’re happy to put together the parts list for your boat, or to supply the engine alone if your installer is sourcing the rest.

Getting the propeller right

The propeller is the part of your 300XXL SeaPro Pair that actually turns engine power into movement, and the right one makes a big difference. The goal is simple: with your boat loaded the way you normally use it, the engine should reach the top of its recommended full throttle rpm range. If it can’t get there, the prop pitch is too high and the engine is labouring. If it goes past the top of the range, the pitch is too low and the engine is over revving.

As a rough guide, each inch of pitch changes full throttle rpm by around 150 to 200 rpm. Heavier loads and bigger boats usually want less pitch. Lighter, faster boats can take more. If you mainly carry heavy loads or tow, a lower pitch prop helps. If you run light and want top speed, a higher pitch may suit. Tell us about your boat and how you use it, and we’ll help you choose.

Offshore running and fuel planning

Big outboards are built to run for hours at cruise, often far from shore. With a 300XXL SeaPro Pair, good planning matters as much as horsepower. Know your boat’s fuel burn at cruise, keep a reserve of at least a third of your tank, and check the weather and sea state before heading out. A fuel flow gauge takes the guesswork out of range.

Carry a spare fuel filter, a spare prop and hardware, a basic tool kit and a way to call for help. On twin engine boats, practise running on one engine so you know how the boat behaves if you ever have to.

Repowering with a 300XXL SeaPro Pair

Many of these engines go onto boats that already have a hull someone loves and an engine that has had its day. A repower can give an older boat a new lease of life: better fuel economy, quieter running, easier starting and modern electronics. Before you order, check the boat’s capacity plate for maximum horsepower and engine weight, measure the transom for shaft length, and look at the condition of the transom itself. A soft transom has to be fixed first.

You may also need new controls, harnesses, gauges and steering to match the new engine. We can help work out the full list so you know the total cost before you commit.

What electronic fuel injection means for you

The 300XXL SeaPro Pair uses electronic fuel injection, or EFI, instead of a carburetor. In plain terms, a small computer measures things like air temperature and engine load and injects exactly the right amount of fuel every time. You don’t need to fiddle with a choke. It starts easily whether it’s a frosty morning or a hot afternoon, it idles smoothly, and it responds cleanly when you open the throttle.

EFI is also less fussy about sitting. Carburetors have tiny jets and a fuel bowl that gum up when old fuel evaporates inside them. A sealed injection system is much more tolerant, although fresh fuel is still the best policy. And because the fuel is metered precisely, EFI motors tend to be more economical, which means more time on the water per tank.

Mercury’s small EFI engines can even start and run without a battery on manual start models: the pull of the cord generates enough power for the fuel injection system to fire. That’s a clever bit of engineering, and it means you get the benefits of EFI without having to carry a battery if you don’t want to.

Using your motor in saltwater

The 300XXL SeaPro Pair is rated for saltwater use, and Mercury builds its outboards with corrosion resistance in mind. Still, salt is hard on any engine, and a few habits make a big difference to how long your motor lasts.

• Flush the cooling system with fresh water after every saltwater trip, using a flushing attachment or muffs as the owner’s manual describes.
• Rinse the outside of the motor with fresh water, and wipe it down.
• Check the sacrificial anodes regularly and replace them when they’re about half worn. They protect the metal parts of your motor from corrosion.
• Tilt the motor out of the water when the boat is moored, if possible.
• Spray exposed metal parts under the cowl with a corrosion inhibitor from time to time.

Owners who follow those simple steps routinely get many years of service from their motors, even in hard saltwater use.

Using your motor through the seasons

In spring, check the oil, fit fresh fuel, look over the fuel line and connectors for cracks, and run the engine on a flushing attachment or in a test tank before the first real trip. Look for a strong cooling stream and a smooth idle.

Through summer, the main jobs are fresh fuel, regular oil checks and rinsing after saltwater use. Keep an eye on the propeller for dings. A damaged prop costs you speed and fuel, and can cause vibration.

In autumn, before the boat is laid up, do the full storage routine: flush, change the oil and gear lube, deal with the fuel system as the owner’s manual describes, grease the moving parts and store the 300XXL SeaPro Pair somewhere dry. Twenty minutes in autumn saves hours of frustration in spring.

Why fuel care matters so much

If there’s one thing that decides whether an outboard starts first time or leaves you pulling and swearing at the ramp, it’s fuel. Modern petrol, especially with ethanol blended in, starts to break down within weeks. It absorbs moisture, separates and leaves gummy deposits that block the tiny passages in fuel systems.

For your 300XXL SeaPro Pair, the rules are simple. Buy fresh fuel from a busy station. Don’t store it for months in a can. Keep the tank vent closed when the boat isn’t in use. Use a fuel stabiliser if the boat will sit for more than a few weeks. And before any long lay up, deal with the fuel system as the owner’s manual describes, rather than leaving old fuel inside the engine. It’s a few minutes of effort that saves a lot of cost and frustration.

Why buy from us

We deal in outboard motors every day, and we would rather give you a straight answer than make a quick sale. If you are not sure the 300XXL SeaPro Pair is the right motor for your boat, message us with the make, model and length of the boat, how you use it and where you boat. We will tell you honestly whether it is a good match or whether something else would suit you better.

Every motor is packed carefully for the journey, and we keep you updated from dispatch to delivery with tracking. We ship worldwide, and we are happy to explain in advance what to expect with import duties and local taxes in your country, so there are no surprises when it arrives.

After you buy, we are still here. If you have questions about setup, break in or maintenance, just ask.

A quick checklist before every trip

It sounds obvious, but most days that go wrong on the water start with something small that got missed at the dock. Before you head out with your 300XXL SeaPro Pair, run through this in your head:

• Enough fresh fuel for the trip, plus a sensible margin
• Engine oil checked and at the right level
• Motor mounted securely and everything tight
• Kill cord clipped to you, not left on the tiller or dash
• Cooling telltale spraying water once the engine is running
• Life jackets, a way to call for help, and a small spares kit aboard

It takes a minute or two. It is also the habit that separates relaxed boat owners from the ones waiting for a tow.

Alternatives to the 300XXL SeaPro Pair

New 300s: the Mercury 300HP XL Four Stroke, the Mercury Verado 300HP XXL and the Mercury Verado 300HP CXXL.

See the main Mercury outboard motors category and the full outboard shop.

300XXL SeaPro Pair for sale: price and worldwide shipping

The current price of the 300XXL SeaPro Pair is shown at the top of this page. You can add it to your cart and check out straight away, or if you’d rather talk to a person first, send us a message through our contact page and we’ll come back to you with a full delivered price to your country.

What you get

• 300XXL SeaPro Pair: two used Mercury SeaPro 300 hp engines
• Warranty cover as listed
• Any service records that came with the engines

Ask us for photos, serial numbers, hours and service details for both engines before you buy.

Shipping worldwide

We ship to buyers all over the world. Every motor is packed securely for the journey and sent by courier, freight or sea depending on its size and where you are, with tracking from dispatch to delivery. Import duty and local taxes depend on your country, and we’re happy to explain what to expect before you pay so there are no surprises.

Buying with confidence

Have a read of our refund and return policy, see what other boat owners have said on our customer reviews page, and find out more about who we are on the about page.

300XXL SeaPro Pair FAQ

Is the 300XXL SeaPro Pair sold as two engines?

Yes, a matched pair, sold together.

Are they new or used?

Used. We confirm hours for each engine before sale.

What shaft length?

30 inches (XXL).

Do you ship worldwide?

Yes. Contact us for a delivered freight quote.

Order your 300XXL SeaPro Pair

A matched pair of commercial 300s at a used price. Add the 300XXL SeaPro Pair to your cart now, or send us a question first. You can also compare it with the rest of our outboard motors for sale.