Cut And Thrust
Installing a Bowthruster properly is crucial to achieving optimum efficiency, writes Rick HucksteppManoeuvrability in marinas, at docks, wharves, canals and the like is difficult enough at the best of times. But add a high flybridge and strong winds to the mix and you have a close-quarters navigational nightmare in the making.
While alloy can bend and fibreglass can flex and bounce back to a certain extent, plank hulls pop their boards and regurgitate their corking when an unwanted squeeze occurs. And there is only so much pressure a good set of fenders can withstand.
Thrusters are commonplace on many new boats, but they are still left as an option on many new purchases. Although sternthrusters are not so common, bowthrusters go a long way towards helping you avoid a collision in a tight situation.
The actual thrust determines the bowthruster’s effectiveness, rather than the output of the electric motor driving the propeller. According to bowthruster manufacturer Vetus’ catalogue, the following factors determine the effectiveness of any particular unit: the power of the electric motor; propeller shape, its dimensions and its revs per minute; and efficiency loss in the shape of the tunnel and its vents.
Maximum thrust is only obtained under optimum conditions and the following factors will prove to be a hindrance: low input voltage to the motor due to undercharged batteries; excessive voltage drop to the motor due to cables that are too long and or thin; insufficient battery capacity; length of tunnel; sieves, bars and grills over tunnel openings and their shape.
Four of the more common brands of bowthrusters are Max Power, Side-Power, Lewmar, and Vetus. While they have a variation of propeller setups, from one to two propellers, some have anywhere from three to six blades per propeller.
INSTALLATION
With thrusters of various powers available, it would take expert installation to achieve maximum efficiency and effectiveness.
All Marine Solutions, based at the Gold Coast Marine Precinct, specialises in marine pumps, sewage management, anchoring systems, and aftermarket bowthruster installation.
When we heard that another installation was about to take place, we headed south from Brisbane to learn firsthand how it’s done.
The boat receiving the bow treatment was a 46ft DeFever twin screw craft made in China.
The bowthruster being installed was a Vetus 125kgf (kilograms of force) sporting a six-blade single propeller, which the manufacturer claims runs quieter than other types of propellers.
All Marine Solutions can be contacted on (07) 5665 8166, or via email: laurie@ allmarinesolutions.com.au
Photos:
- The DeFever is prepared for bowthruster fitting at the Gold Coast Marine Precinct.
- A datum point is put on the hull and measurements are made to either side and up from the keel foot.
- Both sides of the hull are cut and the waste is then removed.
- With the holes drilled, other wiring and the air conditioning ducting is revealed.
- Once profiled, the hull is ready to paint and have anti-fouling re-applied.
- This is the inside of the hull under the under-bed storage section of the stateroom, before the tunnel holes were cut.
- Fingertip control at the helm.
Tags
Please see our Editorial Guidelines & Code of Ethics (including for more information about sponsored content and paid events). The information published on this website is of a general nature only and doesn’t consider your particular circumstances or needs.
