World maritime day

 IMO celebrates World Maritime Day 

25 of September 2014

Today September 25th, IMO: International Maritime Organization  celebrates the World Maritime Day, designated by the United Nations to focus global attention to the safety of navigation and protection of the marine environment. 

This year theme of the World Day has been the implementation of international conventions issued by the IMO, noting that after the long work meetings and discussions by the working committees, after the approval of the relevant agreements, after the IMO promulgation of the formal agreements, it is necessary that the participating countries implement the adoption in their territories, by adapting and providing the necessary facilities and conducting training activities for the staff concerned and an effective compliance control. 

In the IMO website, the following video of the speech by IMO Secretary-General, Mr. Koji Sekimizu  during this day celebration, is shown

"EDT Hercules" leaves the shipyard

"La Naval" from Sestao (Spain) last ship 

Time elapses very quickly, more than we usually realize. Yesterday we saw the departure of "La Naval" shipyard's last ship, built there and named "EDT Hercules", and she is the last because there is no one behind to build ... until they get new contracts. This situation is similar to that which occurred about 8 years ago, when this historic shipyard, "La Naval", changed ownership from public Izar to private Construcciones Naval del Norte (CNN).

By that date, October 2006, the LNG gas carrier "Bilbao Knutsen" was launched,  and I put in my other blog a brief post on the launching, with a beautiful night photograph taken by my daughter Natalia. She was the last Izar ship but it was not the last "La Naval" ship, that continued building many ships, some very important.

Ship’s motions at sea

A vessel under sea has two types of movements:

• Desired, to move the ship from one point to another and get she achieves the objectives for which  was built
•  Unwanted, occurring mainly as a result of the waves and wind on the ship and causing trouble, inconvenience and danger to the vessel, persons and cargo, so they try to minimize them.

In this post I will only refer to the second type of movements, motions, relating to ships sailing on the surface.

The ship motion in a 3D space is made up, like any other solid, of the motion of its center of gravity and the movement or rotation around that point. The six possible motions, summarised in the following table, consist of three translations and three rotations, which refer respectively to the trajectory of the center of gravity and the rotations  around the main axes through it. Names are given in Spanish and English languages​​.

Reference axis	Translations	Turns r/ ref. axis
Longitudinal x	surge (avance)	roll (balance ó rolido)
Transversal y	sway (deriva)	pitch (cabeceo)
Vertical z	heave (arfada)	yaw (guiñada)

In the following drawing the three axes are shown, for which the movements of translation and rotation relate.

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.

"EDT Jane" goes to sea

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).

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 -