5 Things you need to know about free fall lifeboats
Views: 210 Author: Site Editor Publish Time: 2022-11-22 Origin: Site
What is a Free Fall Lifeboat?
Free fall lifeboats are also fully enclosed lifeboats. It is usually stored on the inclined carriage at the tail of the ship. When in use, the safety device will firmly tie the person to the seat after entering the lifeboat, and then operate the release mechanism. The lifeboat slides on the inclined frame by gravity, falls freely into the water, and then floats out of the water. This type of motor lifeboat is used on cargo ships, oil tankers, etc., but not on passenger ships.
Free-fall lifeboats are rapidly becoming common life-saving equipment on seagoing vessels and installations. It represents a marked increase in safety compared to conventional lifeboat systems. Due to the apparent increase in safety, most maritime regulators have embraced the free-fall concept and have prepared design and certification standards for these lifeboats. The free fall provides the kinetic energy used to propel the lifeboat away from the vessel in distress during and after immersion. Even if the engine is not running, the lifeboat will stay out of danger.
What are the features of a free fall lifeboat?
The concept of a free-fall lifeboat was first proposed in 1897 and the first manned free-fall lifeboat was launched from the stern in 1977. The benefits of a free-fall lifeboat are obvious: during a rapid evacuation in an emergency, the lifeboat slides off the ramp on the vessel/installation and hits the water with a high positive forward motion, away from the vessel or installation. Passengers are safe and secure in the enclosed cabin, securely strapped into the anatomically shaped seats. The lifeboat system is robust enough to withstand high winds, high waves and extreme weather conditions.
The free-fall lifeboat has the advantage of rapid landing, which solves the problem of launching the boat at a speed of 5kn. The disadvantages are that the boat has a high storage height, takes up too much tail space, cannot be used as a rescue boat, and is expensive to manufacture.
For safety reasons, it is not acceptable to carry an inherently buoyant lifejacket during a free-fall launch, so all occupants of a free-fall lifeboat should be equipped with an approved inflatable lifejacket that can be worn during launch.
The lashing plate of a free-fall lifeboat
The lashing plate must not affect the normal free fall of the lifeboat, so when the lashing plate is installed normally, it is not tightly pressed against the lifeboat hull, but can be released easily when the lifeboat is hoisted by the davit. At present, there are two common types of lashing plates on the davits of free-fall lifeboats, namely the pressing plate type and the heavy hammer barb type.
Pressure plate type
There are two common types, one is set on the two slides of the davit, the device is composed of a pressure plate seat frame and ancillary components, the pressure plate is installed on the seat frame, and a return spring is provided, and one end of the pressure plate passes through a thin steel cable , turning pulley, pull ring, or connected to a hydrostatic pressure release device. When the pressure plate is tightened, the pressure plate is perpendicular to the end of the lifeboat. When the lifeboat is pressed tightly, when the steel cable is released, the pressure plate is automatically released by the action of the return spring. The other is arranged at the stern of the lifeboat, and the left and right pressure plates are directly connected by an elastic turnbuckle and a steel cable, and are loosened and tightened through the elastic turnbuckle.
Heavy hammer barb type
There is a heavy hammer type barb on the lower beam of the davit slideway, which is connected with a hydrostatic pressure release device through a thin steel cable, a steering pulley, an elastic turnbuckle, a pull ring, or a hydrostatic pressure release device. Tighten the barb of the heavy hammer to hook the bottom hook of the lifeboat. When the steel cable is released, the barb of the heavy hammer rotates under the action of its own weight to disengage the bottom hook of the boat.
The launching device of a free-fall lifeboat
When the free-fall lifeboat launching device is arranged on board, the distance from the lowest point of the lifeboat installed on it to the lightest-loaded water surface shall not exceed the approved height of the lifeboat for free fall. According to its position on the ship, the commonly used free-fall lifeboat launching devices can be divided into tail throwing type and side throwing type.
The tail-throwing free-fall device is located at the tail of the ship, and the lifeboat is stored on the slide of the landing device. The slideway is generally inclined to the stern by about 30°~35°, the bow of the lifeboat faces the stern, and the seats of the people in the boat all face the stern direction (that is, the bow direction), so that the people in the boat can withstand the impact of acceleration when they freely fall into the water.
After the lifeboat is released, it slides freely along the slideway relying on gravity, glides in the air according to a parabolic trajectory after detaching from the track, and then enters the water at an entry angle of about 50°~60°, glides underwater for a certain distance and then floats to the water surface. This kind of landing device can launch the boat quickly, which is beneficial for the boat to be launched when the speed of the ship is 5kn, and there is no difficulty that the two suspension ropes at the front and rear of the general davit must be decoupled synchronously in wind and waves.
The tail throwing free fall device is divided into electric drive and electro-hydraulic drive according to the drive mode. The electric free fall device is composed of a slideway, a door-shaped davit arm, a davit seat frame and an electric winch. The main method of launching the boat is to rely on the gravity of the boat to fall freely, and the secondary method is to use the boat rope to release the boat with the help of an electric winch. The recovery boat uses an electric winch to lift the boat from the water surface, and uses the door-shaped boom to recover the boat through the slideway to the position where the boat is stored.
Today, free-fall lifeboats are produced in several countries by many manufacturers. Materials used to make lifeboats include fiberglass, steel and aluminum. These lifeboats are being aggressively marketed and quickly gaining general acceptance. Currently, free-fall lifeboats are used on cargo ships, oil tankers, semi-submersible drilling platforms and fixed production platforms. The height of the free fall varies from about 6 meters on a small vessel to more than 30 meters on a drilling platform.
Ningbo new marine lifesaving equipment co.,ltd was founded in 1972, located in ningbo dong qian hu industrial zone. The company covers an area of 11,000 square meters and a building area of 8,000 square meters. We have more than 80 employees. It specializes in manufacturing rescue boat, fast rescue boat, totally enclosed lifeboat and free fall lifeboat and suitable boat davit, crane.
We have CCS, BV, ABS, RINA, IRS, RMRS.NK.EC and other classification societies certificates to provide high-quality marine lifesaving equipment, if you are looking for a reliable China Free Fall Lifeboat and Lauching Appliance manufacturer, we look forward to cooperating with you.