SONIC 386 STS

Powerboat Magazine / April 1999

Holding All the Cards

Sonic USA's 386 STS combines the hot-rod performance and creature comforts that poker-run enthusiasts need.

Anyone who enters a poker run wants to be out in front, if only for a short burst, just to say he has the fastest boat in the fleet. But so often, the "fastest boats are little more than one-dimensional racing hulls with big power. They can run plenty fast, but they're not particularly comfortable for passengers.

The folks at Sonic USA figured its 386 STS would make a good poker-run model with a pair of MerCruiser HP900SCs that gave the 38'6" boat with the 8'6" beam a 100.8 mph top end. The Hollywood, Fla.-based manufacturer also added comfort items such as air conditioning and a television, video-cassette player and CD stereo that made the boat a pleasure to spend time on once the crew was finished with the poker run.

Owners will have to ante up if they want to play with the HP900SCs and required MerCruiser Hi-Performance Dry-ump Six drives that raised the price by $135,000. The other options came to $30,540 and helped put the retail on our 386 STS Poker Run edition of $379,040. The base 386 STS with a pair of MerCruiser HP500s sports a sticker of $204,000.

PERFORMANCE

Sticking with a tried-and-true V-bottom design, Sonic founder and designer J. Ross went with a 25-degree deep V that sported a pair of strakes and a flat chine. The inner strakes terminated under the cockpit, while the outer strakes stopped at the transom notch, which was about 6" deep.

After dialing in the boat, Sonic decided on 1.49:1 gears in the Dry-Sump Six drives turning Mercury Racing 17 x 31 four-blade cleaver propellers. We ran the twin 850-hp blown powerplants to a max rpm of 6100 rpm, which translated into 100.8 mph on Stalker radar. Our lead test driver theorized that the billet speedo mount and water pickup on the transom and two brass clamshell-style scoops bolted to the bottom to feed the inter-coolers provided enough drag to slow the boat by a few miles per hour. Still, a cruising speed of 61 mph at 3500 was more than respectable given the conventional bottom design and the as-tested weight of 10,500 pounds. From there the 386 STS moved out to 70 at 4000 rpm, 77 at 4500, 88 at 5000 and 96 at 5500.

While 25 mph in five seconds and a time to plane of 6.1 seconds weren't all that impressive for the power (and there was significant bow rise coming up), the 386 STS caught up in a hurry as we gave it a little more time. It doubled its speed to 50 mph in 10 seconds and poured on the power, hitting 68 in 15 and 79 in 20.

Mid-range acceleration tests were also enjoyable as the boat needed only 5.3 seconds to run from 30 to 50 mph and 5.5 to hit 60 mph from 40. Tracking at low (30 to 40 mph) and mid (70 to 80 mph) speeds also drew praise, but at the top end, the boat was a little unsettled, riding high on the V. Fortunately, the 386 STS was sensitive to trim. Tucking in the tabs and drives a tad settled the ride to a smooth 85 mph.

In open-ocean tests, the 386 STS felt strong, pancaking Gulf of Mexico waves that it took head-on, following and quartering. We did notice that with the big motors, transmissions and drives, the boat felt a little tail heavy, but a little bit of negative tab kept it running smooth and level. The 386 STS Poker Run edition also drew raves for its handling in slalom turns at 30, 40 and 50 mph and in wide arcing circles at cruising and higher speeds.

WORKMANSHIP

A designated poker run model needs a hot look that will stand out in a sea of stripes and checkered flags. To guarantee that his would get noticed, Ross took the 386 STS to Graphic EFX, one of the premier custom graphics designers in the game. Not only were the purple and yellow hues eye-catching, they were expertly applied.

The aggressive finish was protected by multiple coats of clear and by an extruded plastic rubrail that exhibited minor waves in an otherwise strong installation. Equally strong was Sonic's three-piece construction method. The 386 STS was essentially built from the hull, a cabin liner that included the bases for the berth, lounges and the head, and the deck that included the molded cockpit components.

Each piece of the boat was molded with Divinycell foam coring, vinylester resin and biaxial fiberglass. Once all three pieces were bonded together, Sonic filled the open cavities with foam. Deck hardware on our test model consisted of navigation lights, six cleats and water and fuel fills. Because it took the bench seat with it and opened to nearly vertical, the engine hatch offered walk-through access to the motors. The HP900SCs, which sported CMI Big Tub headers with pneumatic mufflers, were installed on MerCruiser offshore mounts thru-bolted to 3/8" aluminum L-angles thru-bolted to the stringers with appropriate backing hardware.

Huber transmissions were in-line between the engines and drives, which were installed with heavy-duty transom assemblies. Each engine and intercooler picked up cooling water through Gil strainers. For flushing the engines with freshwater while the boat is in the water, there were two spigots connected to remote hoses plumbed into the raw-water intake lines with "T" fittings.

Just above the heavy-duty transom assemblies for the drives were remote overflow tanks of the transmission. Mayfair billet brackets provided a solid installation for the Fram fuel filters, while the batteries were in black aluminum boxes on each side of the outside stringers. The Kohler 800 generator was easy to get to at the front of the compartment.

INTERIOR

Usually, having the bench seat raise with the engine hatch means losing bench-seat stowage. Sonic's solution of molding in small boxes below the seat and offering gunwale cutouts should please owners and mechanics alike.

The bench seat provided space for four passengers who sat deep in the boat, and the top of the engine hatch was a single-piece sunlounge. That was a plus--usually supercharged motors require the hatch (and sunlounge) to be modified. Deep freeboard made it possible for the 386 STS to have supercharge power and an uninterrupted sunlounge.

There was a small swim platform aft with a grab handle just ahead, but the only way to reboard this boat after a swim would be to climb the drives. Putting nonskid on top of the cavitation plates to provide better footing when reboarding would be a good idea. Stepping in from the docks was much easier thanks to steps molded in just ahead of the bench seat.

Our driver and co-pilot enjoyed the bolsters with power dropouts. Alongside the port bolster were gunwale trays with sliding hatches, while the dash just ahead contained a pair of cup holders above a draining cooler and a VHF radio.

Across the way, the Gaffrig white-faced gauges and Danforth compass were set up in three tiers behind a clear acrylic shield. Up top with a Lowrance 3500 depth sounder were twin tachometers, a speedo and Mercury Racing mechanical trim indicators. The middle row featured instruments for oil temperature and pressure and blower boost, while the bottom contained those for fuel pressure, water temperature and pressure for the engine and intercooler, fuel level and volts.

Always a good setup, the shifts and throttles were separated on each side of the steering wheel, and the throttles were equipped with thumb trim for the drives. Sometimes, traditional is the easy way to go. Such was the case with the nonskid side walkways on the 386 STS that led to the bow.

We entered the cabin area via a sliding door held open by a snap-down strap. The aft section of the cabin had more than 6' of headroom. That made for good space in the head compartment, which had a porcelain toilet and a sink faucet that pulled out for use as a showerhead.

Directly across, the galley featured a refrigerator in the base, another sink and a microwave oven, plus minimal stowage. Ahead at the back of the lounge area, the entertainment center contained a television, video-cassette player and stereo. We found stowage in the cabin beneath the seats in the horseshoe-shaped lounge, in a hanging locker that was partially obstructed by the television and in a spacious molded tub in the base of the V-berth.

There should be plenty of space for a crowd of card players in the lounge, while the long V-berth would accommodate at least two adults quite comfortably. With the air conditioning and the overhead hatches, owners should have a choice between natural and artificial ventilation.

OVERALL

Amenities such as air conditioning are rare on 100-mph poker run boats. The 386 STS Poker Run should appear to buyers with an ideal combination of strong performance and creature comforts.

STANDARD EQUIPMENT Twin batteries with switches, twin bilge blowers, freshwater flush, electric engine hatch, K-Planes, power steering, race-engine mounts, full instrumentation mechanical trim indicators, twin racing bolsters, compass, six cleats, deck hatches, cockpit rails, new lights, stereo, V-berth, electric head, shower, sink, galley with sink, stowage, pressure water, glass rack, refrigerator.

OPTIONS ON TEST BOAT Upgrade to MerCruiser Hi-Performance 500SCs and Dry-Sump Six drives ($135,000), custom paint ($95,00), 4kw generator ($7,900), air conditioning ($4,950), hydraulic steering ($4,700), switchable mufflers ($4,400), entertainment center with TV/VCR ($1,990), stereo upgrade with CD changer ($1,500), U-shaped rear seat ($1,500), power bolsters ($1,300), microwave ($975), VHF radio ($875), transom shower ($450).

ENGINES & PROPELLERS Model MerCruiser Hi-Performance Series 900SC Cylinder type V-8 Cubic inch displacement 540 c.i. Lower unit gear ratio 1.49:1 Max. prop horsepower @ rpm 850 at 6000

POWERBOAT TEST RESULTS

TOP SPEED AT RPM Speedometer 103 mph Stalker Radar 100.8 mph at 6100

PLANING Time to plane 6.1 seconds Min. planing speed 18 mph

SOUND LEVEL 105 dBA (open)

FUEL ECONOMY At 45 mph N/A At 55 mph N/A At 65 mph N/A At

WOT N/A FUEL CAPACITY 200 gallons

Test conducted at Sarasota, Fla.