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Vessel Displacement and how it is measured
Displacement
Displacement is the weight of the vessel and all weights on board. The units most commonly used are metric tons. The concept that weight and displacement of a floating vessel are equal is called Archimedes Principle.
Displacement = weight of the vessel + all the stuff on the vessel
Lightweight Displacement = weight of the vessel
Deadweight = all the stuff on the vessel.
Deadweight, abbreviated dwt is the carrying capacity of individual ships and is used to compare ships as well as a nations entire merchant marine and loses at war.
Deadweight includes cargo, fuel, water, lube oil, stores, the crew. It might seem odd to refer to paying cargo as dead weight but the term deadweight implies that the ship itself is alive. A sailing ship in danger might jettison deadweight, paying or not – the origin of the concept of general average.
Displacement is measured in two ways
- By summing up all weights on board and adding them to the lightship weight. This is done by a program, basically a spreadsheet. The lightship weight is supplied by the builder. The chief engineer supplies the fuel, lube oil. The chief mate manages the ballast. The program computes drafts, in meters, displacement in metric tons and GM in meters.
- The vessel’s drafts. The two factors that determine draft are displacement and the density of the water. Drafts can be converted to displacement using a table provided by the builder.
Using some real numbers the PCTC pictured above:
Lightship weight is 16,108 mt.
Here are some typical weights that comprise deadweights
Cargo: 8520 mt – 5500 standard cars at 1.5 mt each
Fuel: 2000 mt (Max 3095)
Ballast: 4000 mt (max 9523 mt)
Fresh water: 400 mt (max 420 mt)
Diesel oil: 100 mt (max 190 mt)
crew and associated gear and equipment is 135 mt
Total Deadweight is this case is 15,155 mt
Lightship weight + deadweight= Displacement
Displacement = 16108 mt +15,155 mt =31,263 mt
A PCTC is at one end of the deadweight/lightweight ratio spectrum. At the other end are large tankers. For example from this site:
A VLCC is a is a ship with a deadweight of from 200,000 to 315,000 tons. The standard VLCC is about 300,000 tons which will allow is to carry about 2 million barrels of oil. The lightweight of such a ship will be around 42,000 tons.
K.C.
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Tagged Displacement, measured, Vessel
Revelling in luxury in Jumby Bay
Look on any official map issued by the Antigua Barbuda Tourism Authority and you will see it is called Long Island.
To well heeled travellers and the cognisant it is better known as Jumby Bay Island, home to one of the most palatial and luxurious resorts in the Caribbean. It is also a naturalist’s haven noted for its lush landscape, stately palm trees, protected nesting site for the endangered Hawksbill Sea Turtle and three superb beaches.
Nestled two miles off the coast of Antigua, set on a 300-acre private island, the resort run by Rosewood casts a spell of serene enchantment. It is the most perfect place to repair to after an exhausting week exploring superyachts available for charter.
The island has been claimed by royalty, possessed by smugglers, and in 1915, owned by an unusually free-spirited, pipe-smoking woman. Now it is a secluded and all-inclusive hideaway accessible only by private boat from the mainland or by superyacht.
The resort has just 40 beautifully refurbished rooms and suites, each suite an oasis of luxury embodying the island’s stylish good taste. The rest of the island has small collection of privately owned luxury villas and estates some available for rent through Jumby Bay.
We revelled in luxury in a Rosewood Estate Suite.
This gorgeous one-bedroom suite is huge, light, bright and airy with fabulous views across its own private infinity-edge pool to the Caribbean Sea.
A private courtyard, with pottery fountain and separate office, leads into the vaulted ceiling, spacious and comfortable living room. The huge and very comfortable bed in the master bedroom begs to be enjoyed for long luxurious lie-ins.
A dressing area and large bathroom with indoor shower lead off here and in to the garden in a secluded walled courtyard. This outdoor area includes a large rain shower and our favourite feature, a deep pedestal tub for wallowing under the stars.
With your own pool, big comfortable sun loungers, huge flat screen TV, iPod dock, fridge filled with drinks, a Nespresso coffee machine and in-room dinning you need never leave your private haven.
View full post on Super Yacht Blogger
Four New SuperYacht Marinas for Bermuda
Front Street, Hamilton
Bermuda is just twenty-one square miles of land set some 700 miles off the East Coast of the USA. It has been a quick place for yachts to stop, take fuel, fill up with fresh provisions and the crew to enjoy the occasional Dark ‘n Stormy drink.
In the short time we have been here in Bermuda researching for an article for SuperYacht Business, we can see things are changing. We have uncovered information about several new marina developments, which could, in years to come, change the way sailors view these Sommers Isles.
No less than four new dockage schemes for Superyachts have been drawn to our attention.
The first, the subject of our previous blog, is a new enhancement to the existing facilities at St Georges run by Captain Mark Soares of Bermuda Yacht Services.
The second we heard about is an ambitious plan conceived by the Corporation of Hamilton. They have grand plans that involve reclamation of land and a new marina and superyacht dock in the heart of the capital.
The scheme could breath new life into the once vibrant city’s waterfront where cruise liners used to dock. The new generation of huge passenger ships calling at Bermuda need the deeper water found off the West End of the island.
Their departure has not only left the docks seldom unused but has contributed to the slow decline of the shops on Front Street. Gone is Trimminghams that quintessentially Bermudan department store; gone are the horse drawn carriages; and gone are the policeman dressed in Bermuda shorts on point duty.
The city streets are comparatively quiet now that the click of the tourist camera has been transferred elsewhere. News that super yachts could soon take to the now desolate docks is going to be welcome news.
Visiting the West End and the dockyard at Somerset we learned they are also enthusiastic about welcoming large yachts. They too have a planned development that will see Superyachts being offered berths. A soon to be constructed dock will potentially have 15 spaces for yachts up to 70 metres.
After our conversations with local marina representatives had been reported in the Bermuda daily newspapers another group contacted us. They are planning a fourth SuperYacht marina. We will write more about Morgan’s Point Marina when we have visited the proposed site and met with the developers.
Stay tuned.
View full post on Super Yacht Blogger
Tagged Bermuda, Four, Marinas, Superyacht
Deadliest Sea – A review
-Captain Lloyd liked to keep the Coast Guard Cutter Munro upwind and at the ice edge during the fishing season in the Bering Sea.
-Peter Barry, who died when the fishing vessel Western Sea sank, was an Ivy League student.
- A pilot pushing a “Herc” to it’s limits is “flying the barber pole”.
- Running both the heater and the deicer on a Jayhawk helo requires two generators which reduces it’s range.
-The F/V Big Valley went down after leaving port early to avoid Charlie Madicott and the Coast Guard’s Alternate Compliance Program.
These were the kind of details that made Deadliest Sea: The Untold Story Behind the Greatest Rescue in Coast Guard History by Kalee Thompson a great read.
The book tells the story of the Coast Guard’s rescue of 42 crewmembers from the F/V Alaska Ranger. The book is mostly about the rescue itself, the role played by the Cutter Munro, the helo crews, it also tells the story of Ranger crew members.
I very much enjoyed Deadliest Sea – highly recommended.
K.C.
Alaska Ranger- shitty job shitty boat
Inside the Coast Guard’s Most Extreme Rescue Popular Mechanic article by author Kalee Thompson
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Scanner Review
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| Brother MFC-7360N Multipurpose printer/scanner |
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When I’m running coast-wise, it’s important to be able to get my various clerical chores done quickly so I can focus on more critical tasks. A key point is that it is more efficient and much quicker handling computer documents then paper ones. That means having a good scanner is important.
I’ve had several various scanners in my office over time but none as good as the Brother MFC printer/scanner. It prints fast, scans fast and the document feeder works much better then other models I’ve used. It also has software that is easy to use.
Imagine out the window I can see my green third mate is about to have a first encounter with the fishing fleet but I have a handful of paper to deal with. With this scanner I can shove the papers into the feeder, type in a file name, click the mouse button and then start a sprint out my office door. Before the ship closes a couple more ship lengths towards the nearest boat I’ll be on the bridge in time to show the new mate fishing vessel avoidance techniques and my documents will be safely on the hard drive.
K.C.
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