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Theodore Marine is a South Australian boatbuilder producing award-quality fishing trailerboats such as the Coastal 720 overnighter, writes Rick Huckstepp


The Theodore Coastal 720 is a boat that has been hovering around the edges of various marine awards for the past couple of years.

The manufacturer has been instrumental in claiming either finalist or runner-up in the trailerable section of the AMIF Boat of the Year Awards and continues to advance their R&D program to ensure they have a very smart and practical product to offer the Australian market.

Jim Theodore is a shipwright by trade and has extensive workshops on the Port River in South Australia, under the banner of Port River Marine. His business initially catered for large shipping manufacture and repair with a 70-tonne ship lift and large ramps into the river.

The Theodore 720 was initially fitted with a Volvo Penta 285hp diesel and subsequently outboards. We used one of the latter as a camera boat, fitted with a Mercury Verado 200hp.

With the advent of Yanmar's new 6BY 260hp engine into the market, Jim took the opportunity to bolt one in and claim a 168kg weight reduction in the boat in the process.

We got a run in one of these outfits but we picked a day that would have been better spent with the feet up watching cricket. We brought the rain gods with us to a city which had no rain for eight months and they showered down 40mm on the morning of the test. Thor the thunder god was there as well and while we sat in a small rain-free patch of St Vincent Gulf, the rain and lightning hammered and crashed around us for the morning.

The seas were running to 1.5m swell, barrelling up from the southeast, so there were plenty of bumps to put this rig through its paces.


The fit up of this new engine from Yanmar is very tidy indeed. It's tucked under the overhanging transom bulkhead and neatly sealed in with an engine box fitted with ample sound- proofing on its inside. The top of the engine box features twin cushions, which further diminish ambient noise into the cockpit, and a central grabrail between them makes this a practical installation.

We were a little disappointed we couldn't have a good look at the physical shape of these engines as, when we lifted the lid, we were met with a shrouded engine with the front and top covered in with separate shells. The new Yanmar utilises common rail injection technology and is electronically controlled, based on the same engine that is fitted to BMW's X5 4WD vehicles.

While neatly tucked away, access to the through-hull fittings and the pulleys behind the front shroud were made easy with ample room in front of the engine for arms and tools. Strainer, L-cocks, pumps and transducer were within easy reach. Also within serviceable reach is the float-switched bilge pump and another float switch for the water-level alarm in the bilge should the pump fail.

The engine box is fitted against the transom and the top is a large bait tank under a removable baitboard, featuring a sink and rodholders.

A vertical hatch on each side of the engine box accesses the cranking batteries and below this compartment, the bulkhead is slotted to drain deck water aft to the scuppers. The aperture for a large battery is really quite small, so quick and effortless access to ensure maintenance of the batteries in these compartments is a little difficult.

Sidepockets run forward to the seat modules, which are fixed to the cockpit liner. These modules have cushioned, stern-facing seats under which there is stowage space. The forward half of the module hosts the swivel seats which have fore and aft adjustment.

There are plenty of grabrails for both passenger and skipper at the dashboard and when seated, large footrests protrude from the bulkhead.

Inside the cabin, a V-berth will sleep two. The leg well is large and the forward cushion hides a portable toilet. The front bulkhead has a hatch that opens to reveal a Stress Free Anchor Winch. The wiring looms behind the helm are covered over by a neat fibreglass cover with a drop-down hatch for quick access to fuses.

Astern, a full-width swimout platform hosts an extendable ladder underneath and this overhangs the Bravo III duo-prop leg.

At the throttle, the Yanmar exhibits low noise into the cockpit. It utilises a mix of electronic and cable-driven shifting and throttle which is smooth under hand.

Holeshot is typical for diesel engines in that initial stages are slower than two-stroke outboards but once the engine gets to about 2200rpm the turbo cuts in and the Theodore is bolting, planing at about 2100rpm and 22kmh.

The following is the rpm per kmh results taken from the GPS recorded on the day and converted from knots: 1000rpm delivers 10.37kmh, 1500 equals 14.6, 2000 realises 18.5, 2500 produces 42.5, 3000 reels off 48.1, and 4000rpm tops out at 66.6kmh.


These hulls can handle chop and prefer more speed than less when traversing it. Manoeuvring with hard turns over the tops of waves and down in the gullies between, shows this boat to be very capable. At the helm, it is easy to manoeuvre and running from forward to hard astern pulls the boat up quickly and in line.

The boat is very responsive backing down in either direction port to starboard and this will be a dream for fighting fish. The high transom allows only minimal water over into the cockpit when backing down too, and is aided greatly by the marlin board creating a baffle.

The Theodore is not the cheapest boat in its size range and especially so if fitted with the diesel power option. To be sure, though, you will appreciate the fuel economy offered from this outfit if you do go in this direction. When you look closely at the overall finish and quality of fitout you will understand why the price tag.

If you are in a situation where you continually must contend with big and choppy seas, this boat will take your fancy and it deserves a test drive if you are looking at this level of the market for a new purchase.


Ambient noise for a diesel engine is low in the cockpit
Good ride in lousy sea conditions
Very smooth at the helm


Battery access hatches are small for large batteries and a revamp in the design here would be helpful