The Flybridge Motor Cruiser
The flybridge cruiser is a lot of boat to handle, but proves a rightly popular design once mastered
Made by some of our world-famous yards and a few specialist sports fishing builders, the flybridge cruiser is an Aussie icon. Nowadays most are fast, semi-displacement models but the bluewater sailor may prefer displacement trawler designs for frugality and offshore seakeeping.
Flybridge Motor Cruiser Design
Hull shape determines the performance but the design of the towering flybridge is a major factor that naval architects pay attention to. In semi-displacement designs, most common is the deep-Vee and warped-Vee hull shapes. The Vee gives linear stability and wave protection, while the warped, flatter aft section with various levels of slope (deadrise angle) affect how the boat planes, lateral stability and its fuel efficiency. Bow shape determines the performance in various conditions. Typically, the fast, semi-displacement has cutaway bow while the heavy vessels have a fuller bow — the latter can be more prone to broaching in a running sea. The sleeker the lines, the less drag, but the downside is reduced volume inside. A sleeker profile also sits much easier at anchor, rather than blunt shaped forward sections. In displacement hulls a streamlined topside profile isn’t so critical given the lower speeds. However, at speed and offshore for instance, a badly designed flybridge rolls the vessel, so is uncomfortable for longer passage-making.
Flybridge Motor Cruiser Characteristics
Typically characterised by wide beam and a square-sterned hull, the modern flybridge cruiser usually has two powerful engines. While older displacement ones may have a wide variety of power plants — often single engine and some even have offset propellers, which makes going astern challenging.
Two engines are generally used on the modern flybridge motor cruiser, and modern ones often come with thruster in the bow, and some have one aft as well. Coordinating them via blackbox technology and joystick is commonly done in later models. Twin, separate systems also offer a level of redundancy.
The helm position is also important. Offshore, the swaying flybridge can be uncomfortable, so a second lower is good, or a simple autopilot control can suffice in open waters.
Transmissions affects how the vessel handles, with traditional straight-shafts often found on old sports fishers fairly challenging in slow manoeuvres. Sail drives and the latest pod drives with joystick handling is the ultimate in ease, but of course the height of complexity to maintain. Transmissions greatly affect overall performance, with long fine-angled shaft drives giving an efficient trim angle for the planing hull, as opposed jackshafts, sail drives or pod drives.
Handling a Flybridge Cruiser
Twin engine, widely separated, aids the novice steerer and the views from the flybridge console gives good sight-lines for slow handling. Most of the comments below applies to nimble, semi-displacement power boats.
Windage, created by the high topsides and vast flybridges, means that scenarios can become complicated and fraught in tight marina spaces. Using the natural elements is essential where possible — the wind and the tide — to help handle the vessel.
At speed, the planing motor cruiser is thrilling. Key controls are the trim to manage stability, speed, and fuel consumption. Automatic tabs allow the skipper to focus on the steering in key moments such as high speed turns and the heeling angle of the hull.
Slow speed handling is generally controlled by using both throttles to control the direction. The wider apart the propellers, the more pronounced the effect. Also, turning the vessel in its own length is easily done by fore and aft movements of the throttles. However, as mentioned, flybridge windage can create leeway. The same principle applies when going astern, with judicious use of both levers to maintain way, and corrections with the thrusters if fitted.
Going astern, or if you are in marlin hunting mode backing-up, is an essential part of flybridge motor cruiser handling, often required when berthing, setting an anchor or simply getting out of some spot of bother. Backing into marina berths is a common manoeuvre and preparation is essential, taking account of all the elements — wind, tide, and your boat’s characteristics. Twin engined boats make this an easy manoeuvre. The initial approach can be straight back or to approach at 90-degrees and pivot.
Ideally reverse into the wind, so you have control and pivot the boat around the piling as you finalise your approach. From downwind, at a 90-degree angle to your berth, go astern, then with one engine engaged in forward and one in reverse, you are going to pivot the boat around that piling slowly. More complicated scenarios occur for single engined vessels that may have prop-walk (a bias towards moving one way in reverse) or vessels with deep hulls and offset propellers.
Single engines also make it difficult when the wind is side-on to stop the bow from falling away (blowing downwind) because the pivot point of the boat is around the engine, where it ‘weather cocks’. But, working as a single-handed charter skipper, I’ve often used weather cocking to approach a mooring in stormy weather by reversing the vessel against the wind so that I can easily pick up the mooring from the stern of the boat without the bow falling away.
Oncoming seas is what the deep-Vee hull is for, ideally trimmed down so that the forepart of the hull takes the impact. Speed should match conditions with slower speeds in medium sized waves. Whereas larger oncoming seas require more control of the ascent and descent — speeding up then slowing down to avoid crash landing. Short chop can create slamming, so moderating speed minimises the impact. Heavy seas may require fore-reaching which is slowly going forward at a slight angle to the growing waves.
Running with the seas uses the volume from the wide, square stern to maintain buoyancy in moderate conditions but this changes in larger waves. If boatspeed does not match the wave speed, the main danger is broaching. Often done by a sea going faster than the vessel and pushing it sideways to the oncoming wave. Going beyond the hull speed can lead to losing control and broaching or even pitch-poling, yet slowing down can lead to being pooped. Experience and nimble throttle control is required in these challenging scenarios. Using the tabs to keep the bow up and avoid dipping into the wave ahead, as well as staying on the back of the leading wave, are some common techniques.
Beam seas can often be challenging given the relatively high centre of weight and the pendulum effect on a towering flybridge. Correcting the heeling is done by putting the windward trim tab deeper than the leeward. Slowing down or even facing or running from the larger seas are techniques used. Look ahead at the seas, so you can decide on your plan of action, and beware of that rogue wave.
Cruising on a flybridge motor cruiser is a popular pastime in places such as the shoaling waters of Australia’s east coast where coral dangers require a high vantage point to steer from. Places like the Gold Coast and behind the islands of northern Queensland are popular territory. Approach coral with the sun behind and wear good, polarised sunnies.