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Kresli Marko - One of the best experts on this subject based on the ideXlab platform.

  • ANCHORAGE OF RO-RO AND PASSENGER SHIPS
    2020
    Co-Authors: Kresli Marko
    Abstract:

    V diplomski nalogi se lotevam obravnave sidranja RO-RO in potniških ladij ter proučujem sestavne dele sidrnega sistema in načine sidranje samih RO-RO in potniških ladij. Sidranje je namenjeno ohranjanju položaja ladje na določeni poziciji izven pristanišča, brez pomoči pogona in uporabe krmila. Pri sidranju RO-RO in potniških ladij je treba paziti na čvrstost sidra, saj ladje z velikimi stranskimi površinami nadvodja delujejo na veter kot jadro, kar pomeni, da imajo nanje veter in vremenski pogoji zelo velik vpliv. Za sidranje ladij se uporablja sidrni sistem, katerega glavni element je sidro. Pomožni elementi sidrnega sistema so: sidrna veriga, sidrni vitel, skladišče sidrne verige, vodilo in sklopka. Tehnike, ki se uporabljajo pri sidranju, so z enim ali dvema sidroma. Pri sidranju se ladja postavi v veter, odvrže eno ali dve sidri in se z vetrom spusti. Ko je spuščena zadostna količina verige, se veriga zategne in ladja zaustavi. Če sidro ne drži, je treba postopek sidranja ponoviti. RO-RO ladje se po navadi ne sidrajo, saj so linijske ladje in imajo večinoma zagotovljen takojšnji privez v pristanišču. Lahko pa sidro uporabljajo kot dodatek pri vezanju s krmo na pomol, kar imenujemo mediteranski privez. Tudi potniške ladje se le redko sidrajo, saj se običajno natančno držijo urnika in imajo v pristanišču zagotovljen privez. Sidrajo se le, če so prevelike za pristanišče oziroma križarijo na območju, kjer ni zagotovljenih privezov za takšne ladje in morajo sidrati pred pristaniščem ter izkrcavati potnike s tako imenovanimi tenderji, pomožnimi čolni. Ko smo na sidru, se straža ne prekine, ampak se nadaljuje. V tem procesu je izjemno pomembno nenehno preverjanje pozicije, opazovanje okolice in ladij v bližini ter poslušanje radijske zveze. Ladja na sidru mora biti pravilno označena, saj s tem opozarja druge ladje na svojo pozicijo. Dnevna oznaka je izobešena črna krogla na premčnem jamboru, nočna oznaka pa bela luč na istem mestu, torej na premčnem jamboru, vidna iz vseh strani. Zelo zanimivo se mi je zdelo mnenje kapitana RO-RO ladje, gospoda Roka Šusterja, ki pravi: »RO-RO ladje ne sidrajo. Sidro imajo le še za okras.« V tej nalogi sem raziskoval, ali to drži, pri čemer sem odgovore poskušal najti v teoretičnih delih in člankih ter v pogovoru z izkušenimi sogovorniki, predavatelji, mentorji in pomorščaki.In this undergraduate thesis I wrote about anchoring of RO-RO and passenger ships, the components of the anchoring system and ways how to anchor the ship. The anchorage is meant to hold the ship in one position, outside of a port, without using the ships engine or ruder. By anchoring of the RO-RO and passenger ships we need to be careful that the anchor holds, because these ships have large freeboard which performs as a sail and wind and weather have a large effect on it. For anchorage of the ship is used an anchorage system, for which the main part is an anchor. Auxiliary elements of anchorage system are: anchor Chain, anchor winch, Chain Locker, hawse pipe and stopper. Technics of anchorage are with one or two anchors. While anchoring the ship turns into the wind, drops one or two anchors and rolls down the wind. When there is enough anchor Chain dropped, we tide up the stopper and stop the ship. If the anchor does not hold, we need to do the entire manoeuvre once again. RO-RO vessels normally do not anchor, because they are liner ships and always have a place in the port. RO-RO ships can use their anchor in the port as a supplement to the mooring with the stern to the pier. This is called the Mediterranean mooring. Passenger ships also do not anchor a lot because they are on time and have a free pier space in the port. They are anchoring only if they are too big to be docked in the port or if they are cruising in areas where there are no docking facilities for such ships and they need to anchor outside of the port, so they can drop off passengers via tender boats. When we are on anchor the bridge watch is still going. We need to check our position all the time, we need to look out and look for neighbour vessels and listen to the radio stations. The ship on anchor needs to be correctly marked so other vessels can see that we are on anchor. The daily marker is a black sphere on the bow mast and the night marker is a white light, that can be seen from all sides, on the same place. I find the fact that I’ve heard from RO-RO ship captain Rok Šušter very interesting. He said, that »RO-RO ship does not anchor. They have the anchor just for decoration.”

Gong Shao-jun - One of the best experts on this subject based on the ideXlab platform.

  • Calculation of Minimum Water Depth to Brake the Anchor Chain during Anchoring
    Navigation of China, 2009
    Co-Authors: Gong Shao-jun
    Abstract:

    Accurate calculation of the minimum sea water depth for dropping anchor has been a top concern of ocean-going vessel's captains.The mass of the anchor Chain out of Chain Locker is constantly changing in dropping process,so anchor Chain is an ever-changing mass system.It is difficult to calculate accurately the minimum water depth for anchor gear to be braked effectively in weight dropping mode by Newton classical mechanical law.Michaelis-Menten equation is introduced,with which it is relatively easy to give a comparatively reliable computed results of the minimum water depth for anchor-casting.

Jeričević Luka - One of the best experts on this subject based on the ideXlab platform.

  • Anchors of Ships and Anchoring Maneuver
    University of Split. Faculty of Maritime Studies. Department of nautical studies., 2018
    Co-Authors: Jeričević Luka
    Abstract:

    Sidro je naprava, izrađena od metala, koja se obara s broda, odnosno drugog plovnog objekta, na morsko dno kako bi ostao na jednom mjestu, odnosno kako ga vjetar i struje ne bi pomicale. Sidro je vezano za brod željeznim lancem ili užetom. Sidreni uređaj obično se sastoji od dva glavna sidra smještena u sidrenim ždrijelima, sidrenih lanaca, sidrenog zapora, sidrenog vitla i lančanika. Za obaranje i izvlačenje sidra danas se najčešće koriste električna vitla. Manevar sidrenja je postupak, kojim se brod obarajući jedno ili dva sidra, održava na željenoj poziciji u luci ili sidrištu zbog promjenjivog djelovanja struje, valova i vjetra.Anchor is a device, made of metal, which runs from a ship or another floating object to the sea floor to prevent the craft from drifting due to wind or current. The anchor is linked to a ship by an iron Chain or rope. The anchor device usually consists of two main anchors located in hawse pipes, anchor Chains, anchor stoppers, windlass and Chain Locker. For letting go and heaving anchors, electric windlasses are most commonly used today. Anchoring maneuver is a process by which a boat is, letting go one or two anchors, held at the desired position in the harbor or anchorage due to the variable current, wave and wind action

Reidar Grindheim - One of the best experts on this subject based on the ideXlab platform.

  • Movable Chain Jacks and Winches, Case Study of Petrobras' P58/P62 and Eni's Goliat FPSOs
    All Days, 2013
    Co-Authors: Reidar Grindheim
    Abstract:

    Abstract Recently, Aker Solutions delivered a movable Chain jack system to Petrobras's P58/P62 FPSOs and a movable windlass system to ENI's Goliat FPSO. This paper highlights the main differences between the two systems and when it is beneficial to employ movable systems. There are many parameters to consider in determining which system to use - also a traditional system involving a single winch or Chain jack per mooring line may in many cases be preferred. The movable Chain jack concept is designed to operate multiple mooring lines within the same cluster. A single Chain jack is lifted by a skidding gantry and moved to the next mooring line and so forth. Installation and messenger Chains are moved using a large sliding Chain Locker allowing for later offloading of the surplus Chain. The movable windlass system is also designed to operate multiple mooring lines within the same cluster. However, in this case the winch is rotary and can operate via electric or hydraulic power. One of the main considerations is to move the windlass and keep the mooring lines intact without cutting them. Introduction The primary purpose of an offshore mooring system is to maintain a floating unit on station within specified tolerances. These tolerances are often based on offset limits determined from the configuration of the riser system. The mooring system provides restoring forces that act against environmental forces (wind, waves and currents) that are trying to move the unit off station. Most mooring systems for offshore application are spread moored or single point moored (including turret systems). Spread mooring is the conventional mooring approach and is widely used for both drilling and production units. Spread mooring keeps the unit in position at an optimal heading but does not allow weathervaning. Single point mooring (internal/external turrets) is used primarily for ship-shaped vessels allowing the vessel to weathervane. However, a spread moored system can also be applied to ship-shaped vessels and we see many of this type off the coast of West Africa and Brazil. Traditionally, on-vessel mooring equipment has consisted of individual winches, fairleads and Chain stoppers located at each mooring line. The mooring lines can be Chain, wire rope, fiber rope or a combination. This paper discusses movable Chain jacks and winches recently supplied for spread mooring systems on both ship-shaped and cylindrical- shaped FPSOs. 1. Traditional Spread-Moored Platform Designs Position moored production and drilling units come in various shapes and sizes. Traditionally, we have seen semisubmersible, spar and ship-shaped units. All these units have applied winch or Chain jack systems. Figure 1 shows typical designs that have been in use for several decades.

Donald J. Wudtke - One of the best experts on this subject based on the ideXlab platform.

  • Mooring Chain Handling & Tensioning System for FPSO
    All Days, 2011
    Co-Authors: Donald J. Wudtke
    Abstract:

    Abstract A mooring Chain handling and tensioning system has been developed as an alternatative to the other on-vessel mooring equipment for the FPSO (Floating Production Storage Offloading) type vessels. The mooring Chain handler is intended for use on any vessel that is anchored with a pre-laid spread mooring system. A comparable vertical windlass type mooring system and a Chain jack type mooring system are also reviewed. The mooring Chain handler can accommodate any deck location, requires only one Chain Locker and can accommodate all turndown sheaves. A vertical windlass compromises the location of the single windlass to accommodate the additional Chain Lockers and locations of the turndown sheaves Chain jacks are limited by the intermittent pull and also require additional vertical shaft guide sheaves. The mooring Chain handler does not require additional guide sheaves and has uninterrupted power-in power-out unlimited variable speed. The mooring Chain handling & tensioning system requires only two (2) Chain handlers and four (4) moveable turndown sheaves to handle up to twenty (20) mooring lines per vessel. As a result, the initial investment, maintenance, and installation costs are substantially reduced and the operation, safety, and reliability significantly improved. Introduction The mooring Chain handler, located on the centerline of the vessel, can rotate in a horizontal plane about the center of a single Chain Locker allowing it to line up with the individual turndown sheave locations. This makes it practical to safely handle multiple mooring Chains with a single piece of equipment. The integral messenger wire winch, located directly behind the Chain, guides the Chain to the front of the mooring Chain handler reducing the need for handling equipment such as cranes, davits, winches, etc. The platform Chain and messenger line is connected and disconnected at the front of the mooring Chain handler eliminating the need for a special windlass wildcat normally used to pass the wire rope messenger line, connector, and platform Chain. Mooring Chain Handler The mooring Chain handler (Fig. A1) is a horizontal shaft type wildcat mounted in a frame that rotates on a circular foundation. The wildcat is centered directly above the Chain pipe. The mooring Chain handler can be rotated about the center of the Chain pipe to lead the Chain in any direction. The wildcat maintains the same degree of Chain wrap for any horizontal orientation. The messenger line winch (Fig. A2) is located above and behind the modified wildcat. The wire rope lead is always in line with the mooring Chain lead. The Chain handler is designed for 20% of the Chain breaking strength. The winch drum is sized to handle the required length of wire rope messenger line.