Sunday, December 28, 2014

Preliminary ship dimensioning

Preliminary cargo ship dimensioning
in conceptual design stage

In following form you can do a preliminary estimation of cargo ships main particulars, based on a statistical analysis of actual ships, based on a unique objective goal, f.e deadweight. This set of dimensions can serve as a basis for a systematic investigation in order to get ship particulars that comply with the basic goal (as deadweight) and others as speed, cargo volumen, tonnage etc.

Ckick on following URL to get access to the dimensioning form

Thursday, September 25, 2014

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

Thursday, February 20, 2014

"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.

Sunday, January 12, 2014

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
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.

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 in this direction

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.

Monday, October 28, 2013

"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).

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 typeNo. Froude máx.Cp min-maxL/B min-maxB/T min-max
Tanker, Bulkcarrier0,240,73-0,855,1-7,12,4-3,2
Coaster, Tug0,380.55-0.653.9-6.32.1-3.0
Container C.0.450.55-0.676.0-9.53.0-4.0
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:

  1. Tonnage
  2. Cruising ships
  3. Stability cargo ship
  4. Stability deck barge
  5. Stability container carrier
  6. Hull forms (coefficients)
  7. Freeboard
  8. Maneouverability
  9. Lightship weight
  10. Predimensioning
  11. Powering
  12. Cargo & tanks capacities
  13. Help

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.

Tuesday, July 9, 2013

Dimensioning a merchant ship
 With the program GetxoNaval

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 on  its size, defined, for example, by deadweight, number of containers, volume  of cargo spaces etc.
  • To make a calculation of different particulars (deadweight, speed etc.) of a ship whose  main dimensions are known, either  because they have been defined in the previous point, or for being a known ship but one or several of her capacities are unknown.

Clicking  following link you can access to the program GetxoNaval  hosted  in Google-Sites.

Wednesday, March 20, 2013

Preliminary dimensioning
Cargo ships

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.

To use this procedure click on following 


Monday, March 11, 2013

Training Sail Vessels of Bilbao River
Speech from Juan José Alonso Verástegui

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.

Friday, March 8, 2013

Stability of deck barges and pontoons

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 real 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, 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.

Sunday, February 17, 2013

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 site describes and shows the ideas and reality of this ship.

Friday, October 12, 2012

Container vessels capacity

In the form that follows the cellular container vessel dimensions are input and her 20 ft TEUS capacity is estimated
This 2nd. edition fixing some errors and adding drawing of Containers in holds

Click to begin calculation

(updated on 21 Feb 2012)

Thursday, August 9, 2012

"La Naval" shipyard of Sestao(Spain) launches the "Joseph Platou"
 "Fall-Pipe" type vessel for Jan de Nul

On August 3, 2012 "La Naval" shipyard, in Sestao (Spain), of the CNN group (Construcciones Navales del Norte =  Northen Shipbuilding) proceeded to launch this vessel for the Belgian shipowner Jan de Nul, a regular customer of this shipyard which has already delivered a twinship, "Simon Stevin", and several suction dredges, including the two largest in the world, in its class, "Cristobal Colón" and "Leiv Eiriksson". About these ships I already included posts  stressing their notability and the "La Naval" capacity to build such a high technology ships and competing worldwide with major shipbuilders .

The shipyard invited me to attend this launching, that I thanked especially in these times of shipbuilding drought , as evidenced by the absence of a keel laying after this launch, as was to be the norm in old good times when shipyards laid the keel of following ship waiting her turn in the queue of orders. I have news, unconfirmed, that "La Naval" will finish the construction of two medium-sized vessels begun in the late Seville shipyard, what will lead to an easing of shipyard situation in the absence of "serious" contracts, matched to its proven category and capacity. I hope that the "tax lease" system  resolves soon, after many months of stand-by, without which the shipyards in this country would have many difficulties to survive.

In this post about the "Simon Stevin", first ship of this series, I summarized the main features of this vessel whose dimensions are

 Overall length (m)     191,50
 Breadth (m)       40,00
 Depth (m)       13,20
 Draught loaded (m)         8,50
 Deadweight (tonnes)     32.500
 Speed (knots)       15,50
  Crew        70
 Azimuthal propellers  4 x 4.500 Kw
  Retractable propellers  2 x 2.000 Kw
 Electric generators  5 x 3.300 Kw

Delivery of "Joseph Platou" is scheduled for early next year.

I wish I had taken pictures and video of the launching from the other side of the river, but as I saw it from the guests platform visibility was very poor and I include here some photos of the event only as a recollection, nothing to be with quality.

Ship launching seen from the visitors platform

Wednesday, July 4, 2012

Which sails quicker the rowing boat "trainera" or "trainerilla" ?

The great mathematics magazine + Plus Magazine, in its May 2012 issue published an article entitled "Outer space: Canoeing and kayaking", authored by John D. Barrow, which raises the question of whether these boats run more or less when they double the crew, which we do not know in advance because if the propulsive power is doubled so does the displacement and therefore the hydrodynamic resistance.

+ Plus presents simple and reasonable equations to estimate the variation of this resistance and determine from it the necessary power increase, which compares with the increased power provided by the additional rowers. He gets a theoretical conclusion that  a double crew boat increases its speed by 8 to 10%, what matches well with the actual data recorded in kayacs and canoes races. This conclusion appears consistent with the intuitive impression we have that larger similar boats are faster than smaller ones. 

Saturday, March 10, 2012

A new site about Naval Architecture

A new website about Naval Architecture

In the February issue of the Spanish journal Ingeniería Naval (Naval Architecture) they report the creation of a new website entitled "Revista del Sector Marítimo. Ingeniería Naval" (Journal of the Maritime Sector. Naval Architecture), whose stated aims are to "... encourage news update daily and flexibly, enabling readers to easily find news of interest through tags that allow you to select all news related to a topic."

This website is in this URL "Ingeniería Naval"

The journal editorial keeps saying they have tried that the new website be accessible from the largest possible number of devices in addition to PCs, such as tablets, already in operation, and smartphones, which will be soon.

Index of sections of the website is this
  • Home
  • Information
  • Maritime news
  • Maritime energies
  • Magazines
  • Subscription
  • Reports
  • Ships
  • Applications
  • Sitemap
The preceeding items are subdivided, in some cases, into lower levels and in particular, subscribers have access to the full contents of the journal "Ingeniería Naval" (Naval Architecture), on all its numbers since 2004 when the digital version was created, that is also handed over annually on a CD.

The inclusion of RSS allows you to add news to feeds readers and share them on social networks like Facebook and Twitter and to connect to the video channel of Naval Architects at Youtube.

I think that this site is very well presented with large and handy information and although it is currently a complement to "Ingeniería Naval" paper magazine edition, I think, is my opinion, that it will not be long until they retire the latter from the market, because, contrary to the opinion of some friends of mine, I think that although currently books and publications coexist in digital and paper formats, the very next generations will know the latter only in museums.

My congratulations to the AINE President, José Esteban Pérez Garcia and to the Journal Director, Belén García de Pablos, together with all their team, for the creation and promotion of this new publishing media, which I hope will help to reactivate the decayed shipbuilding situation in our country.

Monday, February 27, 2012

First and last aircraft carriers

First and last aircraft carriers

The first one

By chance I found an online article (Ref.1) about the first aircraft carrier in naval history, i.e. the first ship on which an aircraft landed and took off. It was the cruiser Pennsylvania, of the U.S. Navy, and the first landing on its provisional flight deck occurred on January 18, 1911, in San Francisco, California, by a biplane aircraft Curtiss, piloted by Eugene B. Ely , a U.S. professional civil pilot.

Tuesday, February 21, 2012

Volumes calculation in preliminary ship design

Volumes calculation
in preliminary cargo ship design

In following form, main dimensions of a cargo ship can be input in order to get  an approximate  calculation of her cargo spaces and ballast  tanks . User instructions are shown  at the end.

Volumes Calculation

Cargo ships

Length between pp (m)
Breadth B (m)
Depth to Upper deck (m)
Draft summer T (m)
Block Coefficient at T draft
Propulsion engine(s) power (Kw) 
Propulsion engine(s) RPM
Engine & Pump rooms length (m) *
Fore peak tank length (m) *
After peak tank length (m) *
Fore deep tank length (m) *
After deep tank length (m) *
Double bottom height (m) *
Double hull breadth (m) *
Hopper wing tank breadth (m) *(from double hull)
Hatch ways total length (m) *
Hatch ways average breadth (m) * *
Cargo volume experience coefficient *

Spaces     Volume(m3) 
Ship type
Cargo space
Fore peak  
After peak 
Fore deep tank 
After deep tank 
D. Bottom + D. Hull + H. & W. tanks