By: David Lockwood

If you found your 18-footer a bit cramped over summer, David Lockwood has found the boat for you

The 18-foot bowrider is synonymous with summer. Wherever you look on the waterways, it's a sure bet you will see families sitting shoulder to shoulder in this ubiquitous boat.
But an 18-footer can be quickly outgrown, and this is when Mariah's SX20 shines.
A high-volume, deep-sided boat, the 20-footer has more room for the growing family than the popular 18ft bowriders swarming the waterways.
The American boat builder's SX20 is five centimetres wider than the SX18. The 20ft also has a maximum 10-person or 771kg carrying capacity, instead of the SX18’s eight-person, 567kg capacity.
The maximum engine option on the SX20 is a V8 260hp petrol inboard, compared to a V6 190hp model on the SX18.
And, best of all, to cater for the bigger motor, it comes with a 144lt built-in fuel tank. This compares favourably to the modest 83lt fuel tank on Mariah’s 18-footer.
Not surprisingly, the SX20 has more freeboard than any 18ft bowrider on the market. This is important as far as unruly teenagers, who tend to gather in the bow away from parents, are concerned. And, when crossing a boat’s wake with the extra weight forward, the boat has a reduced risk of shipping water, too.
What's more, it comes with more storage space for summer water toys. With a V8 in its tail, this is very much the boat for pulling tubes, wakeboards and water skiers.
Turn up the stereo and throw the kids out the back while you remain comfortable in the deep bucket seats at the helm.

The SX20 looked quite smart riding atop a locally made dual-axle Sealink trailer. A lot of importers and dealers of American boats prefer local trailers, which seem to be stronger and better suited to our occasionally rough roads, ramps, and saltwater waterways.
Options on the test boat included pop-up deck cleats, a Clarion four-speaker marine stereo, digital depth sounder, snap in carpet, and a swim platform.
The latter item is a must-have on a summer savvy bowrider because it boosts outdoor living space and provides a place to don the wakeboard or skis. There’s also room on the platform to unfurl a towel.
All Mariah bowriders are available with an optional factory-made, polished-alloy wakeboarding tower, which provides a noticeably sportier profile. You can also order a back-to-back seating layout instead of the sports layout we had on the demo boat. But, if you do that, you’ll lose the full-width rear lounge.
Another option is a Silent Choice through-hull exhaust.
With the motor switched off, the 5.0lt engine appeared very serviceable, with lots of room around the block once the aft sunpad was raised.
Elsewhere, I noted all stainless steel deck fittings, which is preferable for a boat destined for the brine.
The stainless steel theme extended from the rub rail and navigation light to pop-up cleats, ski hook, fuel filler, engine vents, and the concealed swim ladder and its grabrail.
The struts supporting the five-piece safety glass windscreen are also stainless steel.

Seating extended from the adult-length bow seats to the twin helm seats, which had flip-up bolsters that let you sit higher to see over the screen.
There was no grabrail for the co-pilot or aft passengers, but this will be addressed for future boats, I'm told.
There was a beautiful, full-length lounge with sculptured headrests aft. Behind the lounge, the padded aft sunpad can accommodate two people.
There was more storage under the bow seats and the rear lounge, including two lined iceboxes.
There was a lined subfloor ski locker and shallow side pockets with drink holders, too.
The brushed metal-look dash inserts were home to a range of gauges; fuel, volts, speedo, tacho, engine oil, temperature and trim, with groovy stainless steel bezels.
There were also rocker switches with breakers instead of pesky fuses for the horn, bilge pump, stereo, lights, and accessories.
I thought the ergonomics at the helm were excellent, with a height-adjustable wheel, and a superior high-seated position on the bolster for close-quarters driving or putting the boat back on the trailer.

The hull is foam-filled GRP with a composite transom, stringers, and floor. The boat also has a full fibreglass liner with snap-in carpet that, once snapped out, makes for easy post-party cleanups.
The moderate-vee 19-degree planing hull is quite full in the bow, hence the buoyancy, with excellent stability at rest, thanks also to the boat's pronounced chines.
The wide body and moderate vee also helps to maintain efficient cruise speeds. There are three strakes per side to redirect water flow.
At 2500rpm, the inboard and Bravo One drive had the SX20 holding a wakeboarding speed of 22mph on the American speedo.
If trimmed out at 3000rpm, the boat gives a nice ski and family cruise speed of 31mph.
Everyday cruising was clocked at 3500rpm, with the speedo showing 38mph, but at 4000rpm and 45mph there was some engine noise.
I recorded a top speed of 58mph at 5100rpm into the wind, but I believe the speedo was reading 10 to 15 per cent too high.
Still, this is a fast boat that has terrific grip in turns and a lot of static appeal by way of its wide-bodied, accommodating interior.
I award bonus points for a dedicated anchor locker in the bow.

The local importer of American Mariah boats, Con Amvrazis, says he is a friend of one of the co-owners of Mariah boats, a badge that was relaunched two and a half years ago after the original owner closed its doors.
Now there are five dealers in five Australian states.
While you might save some brass by skipping the intermediate step with an 18-footer, you will save even more in the long run by cutting straight to the chase with this 20ft bowrider.

Good freeboard for staying dry
Built-in storage
Comfortable seating
Excellent helm ergonomics
An anchor locker
Top engine access
V8 pulling power

Styling graphics could be better
Walkthrough access to transom required stepping on upholstery
A lack of stainless steel grabs around the aft seating


Specifications: Mariah SX20

Price as tested: $57,990 with 5.0lt MPI 260hp MerCruiser on dual-axle Sealink trailer.
Options fitted: Covers, bimini top, pop-up cleats, sound system, safety gear, and more
Priced from: As above.

Length overall: 6.10m plus boarding platform
Beam: 2.50m
Deadrise: 19°
Weight: About 1270kg with base motor

Fuel capacity: 144lt
Water capacity: BYO bottled water

Make/model: MerCruiser 5.0lt MPI
Type: Inboard V8 four-stroke petrol motor.
Rated HP: 260hp at 5000rpm
Displacement: 5.0lt
Weight: About 385kg
Gearboxes: Bravo One sterndrive
Propellor: Alloy 21in

Blakes Marine,
1 Railway Road,
Mulgrave, NSW, 2756.
Phone: (02) 4577 6699

Originally published in TrailerBoat #203


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