Do you know the advantages of free fall lifeboats?
Views: 236 Author: Site Editor Publish Time: 2022-12-19 Origin: Site
Advantages of free fall lifeboats
1. Automatic release in case of emergency
The free-fall lifeboat release device is equipped with a boat pressing device on the slideway. One end of the boat pressing device is connected to the hydrostatic pressure release device through a chain and a breakable rope, and the other end is pressed against the side of the lifeboat (both left and right sides have).
The role of the boat pressure device is to prevent the lifeboat from derailing or being damaged due to shaking and shaking under severe sea conditions.
Once the ship is in distress, when the seawater immersion depth of the hydrostatic pressure release device reaches 2~4m, the action will be triggered, and then the easy-to-break rope connected to the chain of the pressing device will be cut off, so that the pressing device will be under the action of its own rotation force after losing the external pulling force deflected.
At this time, the pressure boat plate will change from the pressing state perpendicular to the slideway to the release state parallel to the slideway, thereby releasing the restriction on the lifeboat.
Afterwards, the lifeboat will slowly float up under the action of buoyancy. In the process, although the hook of the boat has not been disengaged, the chain link hanging on the horn-shaped fixed stake at its far end will slowly rise as the lifeboat floats up.
And finally break away from the fixed pile, so that the lifeboat floats out of the sea freely. Afterwards, the pressure boat device will release the compression on both sides of the lifeboat under the action of its own turning force, so that the lifeboat will automatically float under the action of buoyancy.
For the traditional gravity lifeboat, in order to prevent the lifeboat from falling out or falling overboard under the action of external force; at the same time, the lifeboat suspended on the davit also needs to use fixed ropes to limit its swing, so when releasing the gravity lifeboat, it was necessary to manually open the carabiner or safety pin and then release the anchor line.
Such structural features make it difficult for gravity lifeboats to be automatically released in emergency situations.
However, after the ship loses stability and/or strength, the capsizing may be instantaneous, and the crew often has no time to release the lifeboat. Based on this alone, the free-fall lifeboat has a huge advantage that the traditional gravity lifeboat cannot match.
2. The release speed is faster
Free-fall lifeboats are generally equipped with two ways of unhooking:
1. Conventional uncoupling: Turn the switch of the manual pump clockwise to close the hydraulic valve; then manipulate the handle of the manual pump and move it back and forth about 8 times at a range of about 45° to complete the decoupling.
2. Emergency uncoupling: When the hydraulic system of the manual pump fails, turn the emergency uncoupling hand wheel clockwise to complete the uncoupling directly by mechanical push.
Regardless of whether it is a conventional unhook or an emergency unhook, the core working principle is the same, that is, the external force (hydraulic/mechanical push) is used to continuously push the piston forward, thereby pushing the stop rod at one end of the hook to make it rotate and finally with the hook. The boat hook is disengaged.
The boat hook will fall naturally without the support of the stop rod, and the other end will rise accordingly, and then disengage from the chain ring hanging on the horn-shaped fixed pile, and the lifeboat is thus completely unhooked.
The traditional gravity-type lifeboats arranged on both sides have many steps in the release procedure. From preparing to launch the boat to raising the boat outboard and then completing decoupling, the whole process takes more than 5 minutes or even longer. It may be affected by the sudden change of attitude of the mother ship during the lowering process.
However, for free-fall lifeboats, there are few preparation steps for launching and a small workload. Whether it is conventional unhooking or emergency unhooking, the entire unhooking process only takes a few seconds or more than ten seconds!
When every second counts, compared with the traditional gravity lifeboat, the time efficiency advantage of the free-fall lifeboat is very obvious.
3. The release process is less affected by the ship
Less affected by ship speed
The Convention stipulates that for cargo ships of 20,000 gross tonnage and above, the lifeboats shall be capable of landing when the ship advances at a speed of 5 kn in calm waters.
But in fact, for the gravity lifeboat, because most of the release process is in the state of steel wire suspension, it is still quite difficult to safely launch the boat when the main ship is at a speed of 5kn. There is a life accident. But for the free-fall lifeboat, because there is no wire connection between the release process and the main ship, the speed of the main ship has little effect on it.
There is no problem of decoupling and out of synchronization
Although the decoupling device of the gravity lifeboat has realized synchronous disengagement in design, when actually abandoning the ship, the sea conditions are often bad.
When the gravity lifeboat lands on the sea surface, affected by the waves, the degree of tightness of the front and rear davit hooks is different, and the stress is also different. In this case, it is often impossible to realize synchronous decoupling.
Once the decoupling is not synchronized, it may cause the lifeboat to fall into a passive or even dangerous situation such as being towed and suspended. The free-fall lifeboat has only one hook, so there is no problem of unsynchronized decoupling at all.
The descent process is less affected by the host ship's heel, trim, burning, etc.
The traditional gravity lifeboat is always very close to its main ship during the release process, which makes it vulnerable to fire, explosion and the movement of the mother ship, and may collide with the main ship during the shaking process. The descent process is full of variables and risk.
In addition, once the main ship has a large heel, the gravity lifeboat on the high side will not be released, and the gravity lifeboat on the low side will be far away from the mother ship after being swung out, making it difficult for the crew to board the boat. It means that the lifeboats on both sides cannot be put into use!
However, for the free-fall lifeboat, because it is installed on the slideway, it can still be released normally when the main ship has a huge heel, and its descending direction is opposite to the main ship's heading, and it can quickly escape the influence of the main ship once released area, away from danger.
If you want to learn more about free fall lifeboats, check out the following articles:
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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.