BCS Trim Tabs
1956 - BCS s.r.l. is founded
2006 - Twin Disc Inc. acquires BCS s.r.l.
2007 - Incorporation of BCS s.r.l. in Twin Disc S.r.l.
Besides fifty years of experience and competence BCS has become a leading company in the production and worldwide distribution of high-quality marine equipment. The acquisition by Twin Disc Inc. – leader in several different areas such as marine and industrial, heavy-duty transmissions and the oil extraction industry – has consolidated its position on the market as a part of a multinational group. The merging of BCS, BCS Service, Twin Disc Technodrive, Twin Disc Propulsion has started, in Italy, the new Twin Disc S.r.l., a sound firm supported by the additional value of the sister-company Rolla SP Propellers.
Global “package”
Twin Disc S.r.l. offers boat builders and design engineers a complete “package” of products, from propulsion systems to gearboxes and transmissions up to control and steering systems, together with customized solutions and efficient technical support. A global customer service for the development and realization of the whole kinematics system. A dynamic team of engineers, technicians and professional people is devoted to support the customer in any step: from concept of the project to the planning, through prototype development and design definition, up to bench and fi eld testing, production, assembly, installation, and service also on board. Day by day, Twin Disc S.r.l. works alongside the customer.
The ability to acknowledge and anticipate market requests, the certifi ed reliability of products, the skilled service and the continuous research of technological innovation establish themselves in a unique worldwide system dedicated to the marine industry.
The trim tab systems are the result of over 40 years of experience and technological development: a continuous commitment in achieving higher performances, total control of stability in any condition, better maneuverability of the boat. The trim tab systems are available in different models covering a large application fi eld, from 8 to 25 mt (37’-110’) both for displacement and planning hulls.
Twin Disc - BCS line trim tabs: dynamic balance, moving stability.
INTRODUCTION
The trim tab systems have become a nearly “standard” system on every boat. They have a crucial importance in boat’s performance helping to make the control easier and safer, giving to the pleasure of ploughing the waves a really unique comfort.
A tab is actually a mobile extension of the hull connected to the lower end of the transom on both sides. This allows the boat balance to be improved in many different situations, thanks to this increased surface. Therefore, the trim tabs must be regarded as a mean to correct the boat balance when it is unbalanced.
Their working is based on the principle that the water flowing on the tab surface causes the boat’s stern to be “raised” as much as the tab is lowered. In many situations it is possible to take advantage of this principle:
- Getting on plane from a stand still: when the boat is at a stand still in the water the stern tends to drag down into the water making it difficult for the boat to take off and to get on plane (Fig. 1). When the tabs are deflected downward, the water force on their creates an upward pressure and helps the stern to raise, reducing the hull resistance (Fig. 2). Therefore, the larger the tab surface, the deflection angle and the boat speed are, the greater the lift will be and the faster the boat will get on plane.
The trim tab system improves the propulsion system performance: when the stern is too much dragged down into the water, the
propeller is actually too low a (ineffective angle Fig. 3). For the best performance the propeller should always be as parallel as possible to the water flow (Fig. 4).
- Safety: better boat balance improves the drive’s visibility, enlarging his fi eld of vision.
- Lateral control: because trim tabs are mounted on both sides of the boat’s stern and can be operated independently, it is possible to control any weight shift that can result in the vessel’s listing. By deflecting one tab more that the other it is actually possible to control this side-to-side movement (Fig. 5) and take the lower side to the right level (Fig. 6). Such a function is of crucial importance especially since smaller boats are more affected by a weight shift (or when crew members or guests are not well distributed on board).
- Plane control: little adjustments of the trim tabs while cruising assist the boat staying on plane while running at optimum speed as well as at lower speed. The fuel consumption is reduced with a noticeable saving in the boat operating costs.
- Smoother and drier rides: thanks to the tabs’ action the boat can get and keep a better position, more parallel to the water surface, allowing the bow to cut through the waves and reducing the pounding.
BENEFITS:
1) Performance improvement
- Stern lifting and better balance
- Faster getting on plane
- Better propeller efficiency
- Listing correction
- Decrease of yawing and wandering
2) Safety improvement
- Better and greater visibility
- Better maneuverability at low cruising speed
3) Efficiency improvement
- Better engine performance
- Reduced fuel consumption
- Staying on plane even at slower cruising speed
MAIN FEATURES OF STAINLESS STEEL TRIM TAB SYSTEMS
The stainless steel trim tab systems are available in a large variety of dimensions and can be combined with four hydraulic kits, satisfying many requirements and covering a wide application field. A large choice of accessories complete the system and help to make their use more efficient.
HINGE
It is the fixed part of the tab, which connects it to the transom. On all models the hinge already has holes for the connection to the hull.
TAB
All the tabs are in stainless steel for the highest corrosion resistance. All series MY3000, MY4000 and MY5000 are available in two tab types: the simple tab is made out of a single plate and is suitable for application on smaller boats or with lower loads; the reinforced tab, whose plate is provided with reinforcement in the same material directly fixed on it, which makes it stronger to better bear higher forces on the larger applications. Tabs of MY3000 series are provided with welded connection cylinder.
HYDRAULIC CYLINDER
The hydraulic cylinder is the real “power source” of the trim tab system. It is connected to tab and permits its defl ection. It is the cylinder itself that determines the different models and system confi gurations. Two different types of cylinder are available:
- series MY3000, that is single acting, i.e. it only pushes and the piston return is achieved by an internal spring, aided by the water pressure;
- series MY4000 and MY5000, that is double acting, i.e. the piston is hydraulically pushed out and pulled back again for a more powerful action.
Neither type of cylinders have external hoses as the oil fl ows internally through the cylinder’s base, which is directly fi xed to the transom. This feature is a guarantee of a longer life and better performance, as external hoses are more exposed to the fury of the elements, such as sun, water and the impact with foreign bodies. The piston rod is in stainless steel.
ZINC ANODE
It is made out of zinc and it has the function to protect the tabs against the galvanic currents that normally develop between metals of different nature. The anod is made out of a less noble metal than the tab: so as the corrosive action just applies to the anode, allowing the tab to remain undamaged. It is normally placed in the central part for the smallest tabs or in a doubled quantity on both sides of the tab for the largest ones.
WORKING PRINCIPLE
Working principle.
By pushing one of the buttons on the control panel, the electro-hydraulic power unit receives an electric impulse which starts the electric motor. In turn, the latter makes the hydraulic pump start; this sends an oil flow towards the side of the hydraulic cylinder corresponding to the desired movement (up or down).
Each button controls the movement of one tab. The trim tab system is completed with the installation of a trim tab angle indicator set, which helps to keep always the tab position and its adjustments under control.
The system.
A stainless steel cable with a protection hose is fixed to the lower end of the cylinder on each tab and, passing through the hull, it connects to a boxe containing the transmitter. At every cylinder movement the transmitter records its movement and sends it on to the angle indicator placed on the bridge dashboard, which shows the cylinder’s inclination angle in a scale going from -2° and +12°.
ELECTRONIC CONTROL PANEL
Compact design led technology with adjustable intensity for the new electronic control panel.
A handy and functional switch that use the built-in position sensors located inside the cylinders for the trim tab control and position detection.
It is provided with “auto-retract” system that guarantees an automatic retraction of the tabs when turning-off the engine: this protects the piston rod from both the corrosion and the encrustments that could damage the seals.
Its reduced dimensions allow a space optimization on the dashboard and facilitate a possible multi-station mounting. Water proof, with protection type IP65, it is not exposed to corrosions.
Supplied with harness wires in several lengths with fast lock connectors and without screws, it allows a fast and easy installation on system at 24 Vdc.
