Import substitution and shipbuilding

A couple of years ago, I was given the task of designing an outboard ladder for a ship. There are two of them on every large ship: right and left.

The steps of the ladder have a cunning semicircular shape so that you can stand on them at different angles of the ladder. The net is hung up so that fallen people and objects do not fall onto the pier or into the water.

The principle of operation of the ladder can be simply described as follows. When winding the rope on the winch drum 5, the flight of stairs 1 is pulled up to the cantilever part of the ladder-beam 4. As soon as the flight rests against the console, it begins to rotate relative to its pivot point of attachment, setting in motion the shaft 6 and the swivel platform 3. As a result this march of the ladder falls on the edge, i.e. to the "walking" position. Upon reaching the final vertical position, the limit switch is activated, which stops the winch.

Any such project begins with a study of the terms of reference, regulatory documentation and existing analogues. We will skip the first phase, since the TOR contained only requirements for the length of the ladder, the temperature range of operation, completeness and compliance with a number of industry standards.

As for the norms, they are set out in a single multi-volume document "Rules for the Classification and Construction of Sea-Going Vessels". Compliance with these rules is monitored by the Russian Maritime Register of Shipping, or in short RMRS. Having studied this multi-volume work, I wrote down on a piece of paper those points that relate to the outboard ladder and winch. Here are some of them:

Rules for the lifting devices of sea vessels

1.5.5.1 The winch drums shall be of such length that, as far as possible, a single-layer winding of the rope is ensured.
1.5.5.7 It is recommended that all drums that are out of the operator's field of vision during operation be equipped with devices that ensure the correct winding and laying of the cable on the drum.
1.5.6.6 Location of rope sheaves, pulleys and rope ends attached to metal structures shall prevent ropes from falling off drums and sheaves of pulleys, as well as exclude their friction against each other or against the metal structure.
9.3.4 With plain bearings, the pulleys of the blocks must be equipped with bushings made of antifriction materials (for example, bronze).

In the third phase of preparation for the design process, using the omnipotent Internet, I put together a folder with images of ladders. From the study of these images, the hair on the head began to move. A lot of offers to buy ladders were found on sites like Alibaba. For example:

• In hinges, the steel axle rubs against the steel lug
• There is no protection against the rope falling out of the block stream in the absence of tension
• The platform is made of solid sheet. When ice forms, its operation is not safe. It is better to use slatted flooring (although it is not very convenient if you are wearing heels)

Let's see another picture:

The fastening of the aluminum round post to the aluminum march is made with a galvanized bolt. There are two problems here:

• A steel bolt will quickly "break" a hole in aluminum to an ellipse and the structure will dangle
• Contact of zinc and aluminum causes electrochemical corrosion, especially in the presence of sea water at the contact point.

And what about the winches?

• Since the winch is located on the open deck next to the gangway, it is better to place the engine vertically upwards, rather than horizontally, to save space.
• The paint from the steel drum will quickly peel off and the corrosion process will begin. Responsible persons will be forced to regularly tint this disgrace with a brush.

Then it got even more interesting. Using personal contacts at some shipyards, I was able to see what they put on their current projects. Here at one plant I photographed the fastening of the fence post to the march:

The gaps are huge. The fence will dangle like a pig's tail. Sharp traumatic corners. But the plastic remote from the winch:

One fall on a steel deck on a frosty, windy day and it would shatter into pieces.

The winch on another ship was hidden in a heated insulated casing:

By itself, the solution with heated gearmotor is normal. This is due to the fact that a drive with an acceptable operating temperature below minus 40 degrees cannot be found. And for icebreakers, as a rule, minus 50 is indicated in the technical specifications. It is more economically feasible to buy and heat up a serial model of a geared motor than to order a special version from the manufacturer. But, as in any business, there are nuances:

• When the casing is closed, the laying of the rope is not controlled, which is contrary to the rules of the RMRS. There should be a rope handler here.
• The handle for manually releasing the brakes is visible, but the handle for manually rotating the motor shaft is not visible. GOST R ISO 7364-2009 “Deck mechanisms. Ladder winches» prescribes to equip all winches operating at low loads with a manual drive. That's just the concept of "light load" in the standard is not disclosed

Let's look at the ladder beam:

• There is no protection against falling out of the rope from the block. As soon as it sags, for example, when the ladder touches the pier, it will immediately jump out of the stream. With subsequent tension, a hall will appear on it and the entire rope will need to be changed
• It seems that something is wrong with the rope tracing. On the horizontal take-off roller, the rope bends down

Already on another ship we observe how the pulleys of the blocks stand on axles, re-sharpened from bolts. The likelihood that there is a bronze or polymer anti-friction bushing inside, as required by the rules of the RMRS, is minimal:

I managed to photograph the following ladders at the Blagoveshchensky bridge and on the Lieutenant Schmidt embankment (St. Petersburg).

In many places, the rope rubs against the metal structure:

And here is the fastening of the removable fence post to the platform:

About the flag clamps that fix the round racks, I will retell a wonderful story that a person who dealt with them told me. The latch flag always tends to turn vertically down under its own weight. Accordingly, when installing or removing the latch, there is a chance that the flag will turn down at the moment when it is inside the rack. As a result, the latch gets stuck and does not go in or out. The rack cannot be removed, the gangway cannot be removed, the ship cannot move away from the pier, the shipowner is losing money.

I won't surprise anyone with the next picture:

In the hinge, steel rubs against steel. The paint has already peeled off, despite the fact that after installation this place was already painted. This can be seen from the painted bolts.

Let's see the winch:

• The paint is peeling off the drum
• Ground wires won't last long

I didn’t sail on the icebreaker, but here is a photo from the Internet about cleaning the deck:

The layout of the winch is definitely not conducive to snow removal, the wires will be damaged very quickly with a shovel. Chinese nameplate from the winch:

Judging by the marking, the lower limit of the operating temperature range is minus 25 degrees. And the ship has the prefix "icebreaker".

I have not seen a system on any winch that prevents the complete unwinding of the rope from the winch (“fool protection”). That is, if you hold the button on the remote control, the ladder will fall lower and lower until the rope ends. After that, the rope termination will come off and the ladder will fly down (the rope termination itself cannot carry the load; the force is transmitted through the friction force that occurs between the drum shell and the first few turns of the rope).

Let me remind you that all these photos are from new or from ships under construction. This is new equipment, which should be created taking into account world experience and all modern trends in mechanical engineering and shipbuilding. And it all looks like homemade, assembled in garages. RMRS rules and common sense are not respected by most marine equipment suppliers.

I asked a question on this topic to a specialist from the purchasing department of one of the factories. To which I received an answer that all purchased ladders have a certificate from the RMRS of compliance with all necessary requirements. They are purchased, of course, through tender procedures at the lowest cost.

Then a similar question was asked to a specialist from the RMRS and he said that he personally did not sign certificates for these ladders and he would never have missed this.

The ladder that I designed, of course, was designed and manufactured taking into account all the aspects that I talked about:

• Stainless steel drum with single layer winding and wire guide;
• Stainless steel pulleys with rope fall protection;
• Plain bearings with anti-friction polymer bushings that do not require lubrication;
• Wires in silicone insulation and steel braid;
• Anti-vandal metal control panel;
• Removable hand drive handle on the winch with a protection system against turning on the power supply when the handle is not removed;
• Protection against full unwinding of the rope from the drum;

Show it in detail in this story, I can’t, because I will violate the exclusive rights of the customer to the design documentation developed by me. The ladder received the RMRS certificate, was shipped to the shipyard and has already been handed over to the end customer along with the vessel. But his price was not competitive and it is unlikely that he will be able to sell it to anyone else.

On this I will end the story so as not to offend customers, shipbuilders, competitors and representatives of the RMRS. You can draw your own conclusions about the state of affairs in shipbuilding.

Source: habr.com