Introduction

Here at Progressive Actuators we design and manufacture electric linear actuators for a variety of industrial applications, including marine vessels. Most commonly, electric marine linear actuators are fitted on boats where hatches, doors, panels, and covers require an automatic operation. In the following article, we will run through the solutions for critical system access if the installed marine power actuator stops operating correctly.

Types of Boat Hatches

Hatches are common fixtures on boats, typically powered by a marine linear actuator due to the force required to open them and for optimized convenience. Most sports and leisure boats are fitted with inboard or stern drive engines and typically have several covers and hatches over the engine, which will be utilised as both a soundproof cover and sundeck. Five or six hatches covering the engine compartment is not unusual.

Modern sport boat

Numerous Hatches are Present on Modern Sports Boats

Another solution for lifting hatches of lightweight or medium weight is mechanical nitrogen-filled gas struts. These require manual initiation and return, sometimes with the extra effort required on the part of the user if the struts are strong. However, these struts wear out and fail regularly over time and use, requiring more manual effort in order to fully open. Often, once they begin failing, the user can no longer prevent the hatch from closing due to the increased weight. This creates a safety concern due to a foot and hand trapping risk in the falling hatch.

Mechanical Nitrogen Filled Gas Strut

Mechanical Nitrogen Filled Gas Strut Example

These nitrogen-filled gas struts are traditionally specified in the design of a boat to save on initial component cost, however, the repercussion of customer complaints and warranty returns due to failed struts is a detriment to repeat customers; not to mention the possibility of liability in severe cases.

Engine Access Cover on a Modern Sports Boat

Typical Engine Access Cover on a Modern Sports Boat

Engine Access Hatches – Why Electric Is Best

Access to engine compartments tends to comprise of hatches with a heavier design due to soundproofing construction requirements, which requires more material than a standard storage hatch. Often engine compartments are large and require numerous access hatches for service and maintenance activities. A marine linear actuator is a prime choice for these hatches.

Engine Compartment Hatch Covers

Typical Engine Compartment Hatch Covers Closed

Key Benefits of Electric Linear Actuators in Marine Solutions

One advantage of our marine linear actuators is that they are much stronger than their nitrogen gas-filled counterpart, therefore a single marine linear actuator can replace a multitude of nitrogen-filled gas struts. Thus, a single hatch or cover may be designed.

Designing and installing a single-engine cover removes the requirement for additional:

  • Struts.
  • Hinges.
  • Fasteners.
  • Compartment separator panels.
  • Watertight seals.
  • Latches and locks.
  • Additional upholstery material.

An engine bay hatch or cover which will open and close by utilizing our marine linear actuators provides the following benefits:

  • No manual effort required.
  • Personal injury risk eliminated.
  • Smooth controlled operation reduces the potential for damage when closing heavier hatches.
  • Wireless control from a remote location.
  • Synchronised actuators reduce twisting stresses on hatches.
  • Larger and heavier hatches can be opened and closed.

Furthermore, smart remote controls allow the hatches to be controlled from a distance and removes the manual element of physically opening the hatch. However, what happens when power is lost, or the marine linear actuator stops working?

What Causes a Loss of Boat Engine Power?

Typically, boat engine power is lost when there is a reduction in the fuel supply to the cylinders. This can take the form of a restriction in the supply line system due to debris, or pipework failure. The fuel filter(s) may also be blocked or restricted, or a seal may have failed, causing air to be sucked into the system. Additionally, mechanical or electrical failure of the fuel pump(s) can reduce the quantity of fuel being received in the cylinders. Anyone of these conditions will cause loss of power, reduction in power at full throttle, or complete power loss of the engine entirely. If this situation occurs, getting access to the engine as soon as possible is the most important task, especially if you are drifting in open water.

What Causes a Marine Linear Actuator to Stop Working?

Similar to an automobile, a boat utilises an electrical charging system where a battery is charged by an alternator driven from a combustion engine. The 12-volt electric supply on the boat provides the energy for the marine power actuator’s motor to function normally. If there is a break in the supply voltage, the 12-volt marine linear actuator will stop operating.

Electrical component failure, battery charging problems, circuit breaker activation, blown fuses, failed relays, short-circuits and poor earthing could all prevent an electrical current from flowing to the boat’s marine linear actuators.

Engine Failure with Electrical Power Present

In this situation, we will be able to operate the boat’s actuators and gain access to the engine bay or engine control components for a limited time. However, the battery voltage will be decreasing as the boat’s electrical components are operated. Automatic bilge pumps, blowers, LCD screens, VHF radios, navigation, and internal lighting: all these components will gradually decrease the battery voltage to a level below that required to make a boat actuator operate.

Prompt repair of the engine is now required to keep the electrical systems operable. This may be achieved by activating all onboard hatches fitted with marine power actuators to the fully extended state. If the electrical supply were to be lost completely following this action, the hatches and doors would already be open for access.

Engine Failure with Electrical Power Not Present

In this instance, we have a potentially serious situation. A boat adrift with no engine power and no operable electrical system is the worst nightmare for most boat owners, on sea, lake, or river. With currents pushing the boat out of its intended position, no ability to avoid other vessels or obstacles, and with no navigation lighting, even the shore has the potential to damage the boat and injure passengers.

Even with no electrical power available, we must still be able to open hatches and doors to gain access to critical systems such as engine bays and control panels. In this scenario we have alternative access options available:

Quick Release System

Utilize a flexible Bowden Cable type system to manually pull and remove the clevis pin of the boat actuator from an exterior position, enabling the hatch to be manually opened.

Hand-Crank Custom Modification

A manual hand crank could be provided to allow the operation of the marine linear actuator in the event of electrical power loss. Depending on your application, this could be completely customizable. The handle would physically connect with the actuator and be manually rotated by an individual, extending the boat actuator.

Custom Support

Our engineers at Progressive Actuators can design marine linear actuator support that can be removed in emergencies, specific to your application. Although we have many supports and brackets for a variety of applications, there are still many more designs yet to be conceived, and our library of designs is constantly expanding.

Progressive Actuators – Our Best Suited Marine Actuators

Selecting the correct boat actuator for your application is an easy process. Consider the location and the angle of thrust that significantly affects the force required to open the hatch. Additionally, if the lift reaches the tipping point, you must use a “push and pull” version that allows for the opening and closing by the marine linear actuator.  Our 12-volt marine linear actuator motors incorporate an overload protection element as a thermal switch in their windings to shut the boat actuator motor off in case of overheating or overcurrent.

Push-Only Marine Power Actuator

If the purpose is to raise a hatch that is the sole access to the compartment, we would advise using a push-only model, to allow manual opening in the event of electric power loss.

Ball Screw Marine Linear Actuator

As an alternative to the ACME screw drive design of our standard models of marine linear actuators, a ball screw drive could be utilized. However, there are advantages and disadvantages of such a design. Ball screw drives have higher efficiency and performance ratings, and can operate at higher speeds, but they are more expensive to manufacture. They also require a braking system as the friction generated during operation is lower than ACME screw drive designs, making passive load-bearing more difficult to achieve.

Our high force PA-13 marine power actuator is capable of lifting 3000 pounds. Ideal for single-piece design of engine covers where weight is normally an issue for manual actuators.

High force PA-13 marine power actuator

PA-13 marine power actuator

Our waterproof PA-06 marine power actuator is capable of operating fully submerged. Ideal where space is restricted, or for raising sterndrive outdrives (drive legs), and even for raising swim platforms or water entry ladders.

Waterproof PA-06 marine power actuator

PA-06 marine power actuator

Conclusion

With known benefits for the use of electric linear actuators for boat hatches, automation of a range of physically effort-demanding tasks is on the rise. As demand for high quality and luxurious boats become more common, the requirement to replace physical effort with digital solutions is abundantly clear. For functionality, quality, safety, and cosmetic purposes, marine linear actuators should be utilized in new boat designs where possible, but you should be aware of how to mitigate their power loss in extreme cases.