JBS 5.2 Centre Cabin

Considering the JBS Marine workshop is virtually in the author's backyard, this boat test was conducted far from home - McLoughlins Beach in fact, in southern Victoria.

The weather on the testday was dodgy to say the least. Local anglers in vessels up to 7.0m sat at the ramp telling tall stories, waiting for the possibility of a break in the gloomy skies and wind that was whipping the sparse treetops.

A couple of diehards in a Quintrex 600 Offshore returned sheepishly. They had been out on daytrips for the past two days and conditions on the bar and offshore had been pretty rough, but the prevailing conditions on the testday were worse. Obviously they had stuck their bow into the tumultuous churning seaway, but had decided against another day of pounding.

While others at the ramp opted for home duties, we launched to see for ourselves.

The waterway behind the beach at McLoughlins is shallow and smooth even on the roughest of days. It does get deeper closer to the bar, displaying typical conditions for a southern seaway. Shallow water, sand and waves rolled in continuously. As well as the waves rolling in from a rough Bass Strait, the 20kt southeasterly wind generated a big chop which ran at an angle against the swell, turning the seaway into a mishmash of foam and filthy water.

With three people aboard we headed for the bar. The testboat, a JBS 5.2 Centre Cab, was fitted with a 90hp Johnson two-stroke motor with a 17-inch propeller. In smooth water it attained a top speed of 59kmh at 5300rpm. Easing back the throttle to 3700rpm the boat settled into its 'comfort zone' while maintaining a cruise speed of 37kmh. Many boats of this size with comparative power would not find that comfort zone until around 4000-4300rpm. This result is good news for those who wish to stay on the well-worn path of two-stroke propulsion. An additional 500rpm at that point of throttle setting on a carbed two-stroke motor can make a big difference to fuel expenditure.

Fitted with mechanical steering the boat was relatively easy on the helm and with the outboard trimmed down, felt very responsive. Nudging into the bar entrance the hull proved itself to be very dry indeed. Pushing our way further into the slop the waves lashing the bow and forequarters were reflected off the contoured forefoot and laid flat.

STICK LIKE GLUE...
Well into the bar entrance the swell was 1.5-2m and very close together. Hard turns on the tops of waves and navigating along the backs of the swell gave an impression that this boat was glued to the water. It did not list dramatically, rather it maintained an upright attitude even when sliding off the front and backs of the swell. With its nose trimmed down, there was no evidence of broaching.

In these conditions we pushed it into the swell at up to 25kmh and ran with it at over 40kmh. Some spray came over the top of the screen, but in fairness, we were pushing the envelope harder than normal and the safety-conscious boater would not have tackled such conditions. Going head-on to big lumps of approaching water, the JBS would pull up quickly but without the telltale slamming and banging of the hull against a sheer wave.

After half-an-hour in the 'washing machine' the JBS hull passed the litmus test. It behaved in the water similar to a vessel twice its weight. For a short beamy hull, the usual hard slamming into big chop was noticeably absent.

Back in the sheltered water, and viewed from McLoughlins jetty on a run past, the contoured forefoot and pronounced chines of the JBS hull could clearly be seen doing their job.

BRAINWAVE...
This hull is the brainchild of Cliff Joshua, who has been in the boatbuilding game for over 40 years. Still on the good side of 70 years old, his initial boatbuilding experience involved timber hulls, building similar shapes on the forefeet of planked vessels. This hull is laid up, its forefoot section consisting of contoured straps of aluminium plate, which are welded together to give the boat a sharp entry. Then it flares in a gentle curve outwards till it reaches the forward chines. The result is the soft and dry ride we experienced through chop. Some of the water that is rolled off the flared forefoot finds its way under the chines further aft. This aerated water under the outer edges of the hull may well account for the low RPM while still maintaining a good cruise speed as the hull slips along broken water. We noticed no cavitation during the test.

Aft of this hand-contoured forefoot the hull flows into a deadrise of 14° that supports a 2.5m beam.

The outboard sits on a full-width floating pod with mounting boards either side, which protrude slightly aft. On the starboard mounting board an auxiliary motor bracket forms part of the back edge.

The transom bulkhead sports a livebait well on the port side and a high-mounted baitboard centrally located on top. It sits directly over the enginewell so that bait scraps fall clear of the cockpit.

The JBS has a relatively high freeboard for a boat of its size. This is evident on the water but also when climbing over the transom bulkhead from the mounting board. Having said that, and taking into account that these hulls may be customised at the point of manufacture, placing the livebait well on the same side as the auxiliary engine mount and manufacturing a short door in the transom for the vertically challenged would be an advantage.

Inside the cockpit a supported full-width shelf holds a battery and oil reservoir. These items are on both sides of the imposing enginewell. While that shelf looks low to the floor, feet clad in running shoes will fit under comfortably.

Running from the shelf forward on both sides are short sidepockets that meet a step leading to the walkway around the cabin. A high handrail lends support while walking around the cabin in bumpy conditions. The width of the walkway allows for 'foot over foot' walking rather than shuffling to gain access to the bow.

At the bow the walkway is slightly wider, providing comfortable access to a large anchor well. The bulkhead separating the well from the walkway has a standard bollard and a polypropylene bowroller that sits in an aluminium yoke. The roof of the cabin is deeply recessed at this point, providing an ideal position for lounging, bottom fishing or just hanging on when pulling the pick in rough weather. No-one could slide off to the side from this safe position. Effective handrails run along both sides of this recess from windscreen level to the front of the seat position.

The handrail from the aft position at the start of the walkway runs right to the bow where it drops down to the deck. Each side of that rail termination has a rear-mounted gusset made from alloy tube.

From the aft section of the cab walls, an aluminium-tube targa runs up and over to the opposite gunwale. It has a freestanding bimini top attached, and on the testboat a set of clears ran from its forward strut down to the tinted aluminium-framed perspex windscreen. This targa proved to be quite strong when out in the bar entrance with two passengers totaling 170kg using it for stability with minimal movement.

Back inside the cockpit, the floor is fully carpeted and flat from the transom to the cabin where it is raised slightly.

Midships, the standard 150lt fueltank is installed underfloor and an optional 50lt freshwater tank may be installed forward of that. A killtank is now standard and is aft of the fueltank in current models.

A large hatch centrally located in the floor of the cabin provides storage for spare ropes, lifejackets, etc. There are no standard V-berths or standard seating supplied with this hull. These options may be fitted at manufacture or at a later date. Optional seats on the testboat were a 'high box', with padded tops and storage within.

The cabin is quite roomy. The lack of V-berths allows for more comfortable camping (if you wanted to carry your own swags) and allows the cabin to offer a large, dry storage area.

A sidepocket at the steering station supports the engine controls. A matching sidepocket for the passenger is on the port-side cabin wall.

Hull bottom thickness on this vessel is 4mm with 3mm sides. These thicknesses can be increased to 5mm and 4mm respectively, at an additional cost of $500.

The JBS 5.2 Centre Cab presents as a cost-effective way to get into a boat capable of handling a rough sea. It is strong, has good freeboard and behaves correctly in uninviting condtions.

Its estimated weight on a single-axle trailer of 1100kg allows it to be towed behind a six-cylinder family car or wagon. This fact alone enhances its attractiveness to those demanding a little extra from a 5.2m boat than the average production-line rig offers for a similar price.