Advice & Info: Senator RH780 Widebody

For over a decade now Wayne McKinley’s team at Senator Boats in Napier has been turning out tough, no-nonsense hulls, which are fitted up and sold by Firmans Marine.

Two basic types of aluminium boat are made: large monohulls from 8.5 to over 10 metres, and pontoon-type boats ranging from 4.5 up to 7.8 metres.

The largest pontoon model, the RH 780 Widebody, is a scaled-up version of the highly successful RH 750. This scaling-up process has produced a hull with an overall length of 7.97m and an outside beam of 2.7m. This takes it into the over-width category (more than 2.5m wide), but that is not a big deal these days – a couple of flags and an over-width permit, and that is pretty much it. In return, you get a heap of extra space in the cockpit.

The Senator RH 780 Widebody was first launched at the 2006 Auckland Boat Show, where it won the Alloy Boat of the Show award. While I was in Hawkes Bay in early January this year I took the opportunity to go for a run in a 780 with Firmans Marine boss, Brian Firman, his son Adam and friends Richard and Sue. The fact that the snapper were running off Napier was entirely coincidental...  

Construction

The RH780 has 6mm bottom plates, 3mm pontoons and 3mm and 4mm topsides. Decks are 4mm chequerplate. The deadrise at the transom is 18°, with the bottom edge of the pontoon forming downturned chines.

Lengthwise, the hull is supported by four stringers, a flat plate across the keel vee, and the pontoon construction. Laterally there is a collision bulkhead forming the anchor well in the bows, and a second behind it; a bulkhead at the helm position; three underfloor sub-bulkheads forming the holds in the cockpit; and the transom structure.

There is a massive amount of reserve buoyancy in this hull, a feature I particularly like in pontoon designs. In this case there are five, separate, pressure-tested compartments: three in the pontoons, and two under the deck. Senator calculates the positive buoyancy (the buoyancy chambers’ area supports 2600kg, minus the rig weight of 1800kg) at 800kg, much of it high in the gunwales, which should ensure that the hull floats upright were it ever to be swamped. Hulls are built to survey standard.

Power and performance

Rated for 200-300hp, the RH 780 is recommended for 250hp. The test boat was fitted with one of Mercury’s massive Verado 250ph supercharged four-strokes, which crouched on the stern like a huge black beast ready to pounce. The gear ratio of Verados suits them to fine-pitch props, and the 250 was swinging a 15° Mirage. The ‘book’ top-end revs are given as 5800-6400rpm, and at full noise the test rig was producing 6000rpm and 37knots (68.5kph) with a load of fuel and five adults aboard. Comfortable cruise speed was around 4200rpm and 26 knots. Fuel carried is 300 litres in an underfloor tank.

Mercury appears to have done something special with the bottom end and crankcase configuration of the Verado. Brian Firman told me that the optimum engine-mounting height of Verados is two holes higher than any other breed of engine. The engine will trim out a long, long way without breaking out – almost to the point of looking ridiculous – and still holds on well in the corners. I believe that Mercury is in the process of adapting this bottom-end design to the Optimax range as well.

As we headed out of Ahuriri towards the Springs, we encountered the usual slop at the corner of the breakwater  and, further out, a metre or so of southerly roll. There was no wind to speak of in the morning, but by the time we headed back in early afternoon, a sea breeze was picking up.

Like its smaller brother the RH 750, the RH 780 travels well, landing smoothly when we came through the swells. When the pontoons lifted clear of the water on the plane and the hull was riding on its deep-V bottoms, it became a little more tender – something that trim tabs would sort. Overall, a good performer that should handle rough conditions with ease.

In a hardtop, spray is not a problem. Visibility from the helm was fair when seated and good when standing, through the three front panes of 6mm toughened glass. Side sliders are also toughened glass.

Teleflex hydraulic steering with a Mercury power-assist (fitted as standard) made steering easy – you could release the wheel and there was no payoff at all. The Mercury Smartcraft throttle and shift was, likewise, a pleasure to use.

Anchoring

It is an easy climb to the bow around the cabin sides, with non-skid panels, substantial bow rails and handgrips on the cabin roof. Should you need to freespool the Maxwell Freedom VC500 winch, you can get to it easily through the hatch in the cabin roof.

A permanently mounted anchor sits on the fairlead with the winch controls at the helm. If you need to get into the anchor-well to, say, sort out a chain tangle caused by travelling in heavy conditions, access is easy through the hatch in the forward bulkhead. An option is to install a warp counter, which will tell you how much anchor line you have let out – a useful device when anchoring mechanically.

Layout

The cabin sleeps two adults, and a berth infill would allow one more. A toilet is fitted under the centre berth. There is stowage space under the berths and extending back under the deck, where bung drainage connects it to under-deck holds. Two narrow side shelves offer further storage. The cabin entry is a wide one, easy to get in or out of, and can be closed and locked with a clever bi-fold door.

Out at the helm position is a full-width dash tray with a back lip, grabrail and marine carpet trim, which helps secure items and cut glare on the ‘screen. Use of multi-task units like the Mercury Smartcraft display and Furuno GP 7000F sounder/plotter, along with a Uniden Solara DSC VHF (all flush-mounted), makes for an uncluttered helm layout. A Fusion marine sound system is mounted overhead.

Seats are king and queen-style fixed bench seats. The helm seat has two stowage levels inside, and both rear-facing seats overhang, allowing space for a medium-sized chilly bin underneath. The passenger side seat is over-long and slides back on runners to reveal a galley unit underneath (a freshwater sink with a 20-litre tank and a two-burner gas cooker), a clever piece of design, making maximum use of space.

Three protected stowage nooks are built into the hardtop, and grabrails under the hardtop and around the edges give passengers something to hold onto.

Out in the huge cockpit (you could just about play basketball out there) are very long (approximately 3.8m) side shelves, each with two levels. The chequerplate decks drain back to a sump under the transom, where a 1500gph bilge pump is fitted. Two large under-deck holds are connected by bungs, with the rear one drained by a pipe under the fuel tank and directly out the transom. The bung is at the inner end, so the tank can be simply flooded or drained (with the hull on plane).

The gunwales are wide, flat topped and panelled with Deck Tread, making useful perches while at rest. Two batteries are housed in a locker in the transom wall – a starter and house with isolation switch – plus the hydraulic power steering system.

Substantial bollards are fitted at the bow, stern and mid-ships for full mooring. Over the transom are two large platforms with Deck Tread finish. The main boarding platform is on the port side with a step-through transom, two grab rails and fold-down ladder. Separate mounting plates for trim tabs and transducers are attached to the stern, removing the need to drill into the hull.

Fishability

The over-wide body of the 780 provides plenty of fishing space. On test day, five of us had rods out with no problems. The chequerplate decking allows good footing and there is reasonable toe room around the sides. High gunwales (760mm to the top) offer top-of-the-thigh support. Six through-gunwale rodholders are fitted, welded top and bottom through the pontoons so that they provide drainage without compromising the buoyancy chambers in the pontoons. Two further rodholders on the transom support a bait station.

A nine-position rocket launcher offers rod stowage on the hard top, where a cockpit spotlight is also mounted. The catch can be stored in the under-deck holds or in one of the large, after-market iceboxes available today.

Divers will find excellent boarding facilities, with a good-sized Deck Tread covered platform, fold-down ladder, two handrails and a step-through transom. Tank stowage can be in the lower side pockets or the under-deck holds.

The snapper fishing had been good off Napier, and we counted 25 boats fishing in the general area where we stopped in 35m just inside the Springs. Although it was late, about 10:30am by the time we had done the photo shoot and got to the spot, the fish slowly came on, and in a couple of hours we ended up with about a dozen snapper, some gurnard, a nice kingfish, and a bunch of kahawai, mackerel and ‘couta (the things I have to do for you guys...). The 780 was certainly easy to fish from, and it would not take much to set it up for gamefishing.

Trailering

The boat was carried on a DMW tandem-axle ‘Strongback’ trailer. This featured an impressive amount of extra gusseting and welded supports. Hydraulic override braking was fitted for both axles, but Sensa-brakes are normally fitted as standard.

The trailer was a cradle A-frame design with entry bay and 12 pairs of wobble rollers per side. Also fitted are galvanised rims, zinc-treated leaf springs, a dual-ratio manual winch, submersible lights, dual coupling and a wind-down jockey wheel. Firmans also supply 12-months’ registration and WOF, tie downs and over-width flags.

Tow weight for the rig is 2480kg.

All in all

A great workhorse with lots of working room, overnighting capacity, excellent reserve buoyancy and the safety inherent in pontoon construction. The RT 780 Widebody travels well and is definitely blue-water capable – an excellent platform for a hardcore fish and dive, or for commercial applications.