Posts related, more or less, with ships design, construction, operation
Tuesday, December 10, 2013
Coaster ship Project "Gijón"
Comparative analysis with GetxoNaval program
The September 2013 issue of Ingeniería Naval journal has published an article from Aurelio Gutiérrez, Dr. Naval Architect, with the description of a desing coastal vessel prototype called "Gijón", for the short sea shipping trafic.
This article described in some detail the vessel specifications and published some interesting particulars from the point of view of naval architect, which are not very common in the journals, what suggested me the interest of comparing the published particulars with those obtained with my program "GetxoNaval" focused to ship preliminary dimensioning, that can be freely used on-line
by clicking here.
In this link you can look at the mentioned comparison that shows a good agreement between the results obtained with GetxoNaval and project characteristics published by Ingeniería Naval.
On last October 11th the ship "Jane EDT", designed for support of marine platforms, left La Naval's (Sestao, Spain) fitting-out quay, and run down the river for sea trials before delivery to her owner, the Cypriot group EDT.
In my blog post on 26/07/2013 I reported the launch of sister ship "EDT Hercules", whose delivery is foreseen in next spring and showed their main features that I will not repeat here, just to remember that both sister ships came from a renegotiation of their contract with CNN Group (Construcciones Navales del Norte) from that the owner got with the former Astilleros de Sevilla, that suspended its activity.
These vessels for EDT are the last two in the current portfolio of La Naval, which, according to my information, is awaiting confirmation for one or several new contracts currently under negotiation. I hope and wish that this will happen soon and I can continue reporting on the activities of this historic shipyard whom I'm bound to from unforgettable experiences and professionals memories after sharing so many years working in their facilities.
Following video shows the historic moment of this vessel passing under the "hanging Vizcaya bridge" and I emphasize historic because it was the first time a ship fitted with the famous "X bow" sailed under this bridge (I do not consider the trip in reverse direction she made a few months ago, way to her fitting-out in La Naval, because she wasn´t still a genuine and complete vessel).
Tuesday, September 17, 2013
Powering acc./ Holtrop and Menen
Holtrop & Mennen's ship powering method
Ship designers are familiar with the Holtrop & Mennen' method (H & M) to calculate the relationship between power and ship speed, used for years in the technical offices of shipyards and engineering sites. Due its great interest I programmed this method and have included it in GetxoNaval website as part of the calculation procedures used to perform preliminary design of a merchant ship.
The H&M method was developed by J.Holtrop & G.G.J.Mennen from MARIN "Maritime Research Institute" in Wageningen (Netherlands), based on the results of hundreds of tests with ship models and correlations with the data recorded in actual sea trials.
This method affords results considered satisfactory in 95% of cases, in the preliminary design stage, provided that the range of the variables is within the limits given in Ref.1, summarized in these figures:
Ship type
No. Froude máx.
Cp min-max
L/B min-max
B/T min-max
Tanker, Bulkcarrier
0,24
0,73-0,85
5,1-7,1
2,4-3,2
Coaster, Tug
0,38
0.55-0.65
3.9-6.3
2.1-3.0
Container C.
0.45
0.55-0.67
6.0-9.5
3.0-4.0
Carguero
0.30
0.56-0.75
5.3-8.0
2.4-4.0
Ro-ro
0.35
0.55-0.67
5.3-8.0
3.2-4.0
At this link to Getxo Naval site you access the main page and can choose between the Spanish and English versions of the H&M method. In addition to presenting the power-speed results in tabular form, a graph is displayed with delivered power curves in service and trial concitions, as shown herein.
Ref.1 An approximate power prediction method. J.Holtrop & G.G.J.Mennen - International shipbuilding Progress 1978 -
Sunday, August 18, 2013
Container vessels Capacity and Stability
Using GetxoNaval program
In my post of October 12, 2012 I enclosed a reference to an aproximate calculation of capacity of container vessels that now I have included in a larger program, called GetxoNaval, made-up of a set of calculations relating to main aspects to be considered during the preliminary design of a merchant ship, i.e. the dimensioning stage. But the revised module corresponding to container vessels is far more complete than the one displayed in said blog post. It now includes stability calculation, static and dynamic, with corresponding curves.
Clicking on next link you will enter in GetxoNaval program, that at this moment includes following modules:
Additional modules are expected to be added and all will be subject to continuous revision.
Friday, July 26, 2013
Launching of ship “EDT Hercules”
in La Naval from Sestao (Spain)
Ship type PSV for shipowner EDT from Cyprus
On 23th July “La Naval” from Sestao performed the launching of the ship
“EDT Hercules” for the Cyprian group EDT and her delivery will be made in
the next spring, although previously she will be preceded by the one of her
twin ship, presently in the fitting-out quay.
The launching was normal although with the rare arrangement of being
launched by the bow, due to the forms of the ship that are very fine at the stern which would make it difficult her
launching by this end as is normally made.
GetxoNaval
program objective is to allow making
quick, approximate calculations necessary to define the dimensions of a
merchant ship. This program can be used basically in two different ways:
To make an
estimation of the main ship dimensions based onits size, defined, for example, by deadweight, number of containers,
volumeof cargo spaces etc.
To make a
calculation of different particulars (deadweight, speed etc.) of a ship
whosemain dimensions are known,
eitherbecause they have been defined in
the previous point, or for being a known ship but one or several of her
capacities are unknown.
In my post of April 9, 2010, I presented a form to get a preliminary dimensioning of cargo ships once the user defined her type and a goal particular, deadweight, cargo volume or containers number, depending on the selected type. I have revised the form to be used and I present now its second edition.
On last 6th March the Dr. Naval Architect D. Juan José Alonso Verástegui issued a presentation of subject theme in the "Maritime Museum Ría de Bilbao", within the acts to celebrate its 10th anniversary.
A full account of his presentation, together with my comments, is to be found in my blog "Oteando desde Getxo", and a copy of his most important documents can be found hereafter.
In a previous post I included an approximate procedure to estimate the stability of cargo ships in the preliminary design stage, but a blog reader pointed out to me that it was not good enough for the special case of deck barges and pontoons , which are artefacts carrying all load above the deck. Due to this so special condition these floaters (they are not conventional ships) have received a different stability consideration in the IMO regulations and I have been preparing a specific procedure for estimation of their stability.
In the form that opens by clicking the following link, GetxoNaval ship dimensioning program is open and selecting the deck barges stability tag, the user is requested to input a few data of the barge / pontoon and he gets a suitable information about its stability in the specified loading condition. After the form a user guide is shown and a results interpretation.
WindFlip: A barge to transport and position wind turbines
Innovative System from WindFlip AS
Electric generation by wind turbines is increasing dramatically in Europe and other areas and placement of turbines at sea (offshore) is one of the booming posibilities due to the increased performance and environmental advantages that are got. However transport operations and placement of wind turbines at sea pose a significant cost and require the use of special vessels dedicated to these tasks.
Recently, new ideas are being released to solve or ease these problems and one of the most recent is the use of special barges, towed, low cost, as the type called WindFlip.
WindFlip is a simple barge which loads the complete wind turbine, is towed to its site at sea and there is ballasted and flipped by stern up to the vertical and then the turbine pedestal end is buried in its working position. WindFlip is unballasted then by injecting pressurized air in the tanks and proceeds returning to port. So simply said it seems easy, but I suppose it will be quite complicated, nevertheless it seems a bright idea and hopefully satisfactory.
This video briefly shows an outline of the operation, where nothing can be seen how to move the turbine from its location on shore up to its place on WindFlip, but I do not think it will be a big problem.
A typical WindFlip is about 100 m long and 30 m wide and such a barge could carry a complete wind turbine of 65 m and 15 MW power.
WindFlip uses an old idea, the pivotting ship type named FLIP (Floating Instrument Platform), to solve a new problem. The FLIP is as old as 1962 and was used by the United States navy as an ocean research platform, providing to the involved scientists a still and comfortable workstation, compared to that offered by a ship floating and moving among the waves. The Ship-Technology.com site describes and shows the ideas and reality of this ship.