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Author Topic: Ships with "Blunt" Bows.  (Read 2346 times)

Tug Fanatic

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Ships with "Blunt" Bows.
« on: February 19, 2019, 03:13:50 PM »


Why am I seeing more ships with "blunt" bows? I have previously seen them on Great Lakes boats but they seem to be appearing more generally now.
It does not look like a good idea to me in terms of rough weather comfort.
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Taranis

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Re: Ships with "Blunt" Bows.
« Reply #1 on: February 19, 2019, 04:13:57 PM »

Significantly increases cargo space I presume
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Pirate

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Re: Ships with "Blunt" Bows.
« Reply #2 on: February 19, 2019, 04:54:13 PM »

www.marineinsight.com/naval-architecture/types-of-bow-designs-used-for-ships/

Quote from above reference;
These hull forms have the advantage of allowing maximum length waterline for ships of comparable sizes which means the highest possible hull speeds. Like the Axe Bow, these bows have less spray of water at entry and also have less pitching motions and slamming reduction is quite significant. This creates quite a comfortable experience for the crew. The fuel consumption is also reduced by a significant factor and this bow can operate quite efficiently in medium sized wave ranges mainly because of the larger part of the ship volume being above and upfront, directly impacted upon by the waves.

regards
  Pirate
 
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petermun

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Re: Ships with "Blunt" Bows.
« Reply #3 on: February 19, 2019, 05:41:01 PM »

This type of bow is referred to as `X bow.   Trials appear to confirm that this form performs better in rough seas.   Model hulls are available but a bit pricey, so my son is scratch building one from balsa and plasticard and it is looking good.  Pete
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Tug Fanatic

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Re: Ships with "Blunt" Bows.
« Reply #4 on: February 19, 2019, 06:55:26 PM »


Thanks, as usual, for the comments. I know that a lot of tank testing goes into any design but intuitively I would have thought a pointy bow cut through the water better.


So if this is better why are point bows the norm?
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Umi_Ryuzuki

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Re: Ships with "Blunt" Bows.
« Reply #5 on: February 19, 2019, 07:05:13 PM »

Quote
https://www.marineinsight.com/naval-architecture/types-of-bow-designs-used-for-ships/



That is NOT an Xbow,  from the article that Pirate linked, it is a parabolic, or cylindrical bow.
Typically found on Bulk carriers. We see them a lot here on the Columbia River, as they are moving
grain, or soda ash.
 
Significantly increases cargo space I presume

The photo below is an Xbow, patented by Ulstein. Definitly not like the bulk carrier from the original post.
 ;)
.

Tug Fanatic

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Re: Ships with "Blunt" Bows.
« Reply #6 on: February 19, 2019, 07:24:25 PM »




That is NOT an Xbow,  from the article that Pirate linked, it is a parabolic, or cylindrical bow.
Typically found on Bulk carriers. We see them a lot here on the Columbia River, as they are moving
grain, or soda ash.
 
The photo below is an Xbow, patented by Ulstein. Definitly not like the bulk carrier from the original post.
 ;)
.



So what is the advantage of the parabolic cylindrical bow? I can see that it might just have a greater capacity for a given length if lock length, or something similar, is important but for a sea going ship………….?.
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derekwarner

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Re: Ships with "Blunt" Bows.
« Reply #7 on: February 19, 2019, 08:01:35 PM »

The wheel turns every few 100 years.......built for comfort & not speed  %) .......... Derek
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Pirate

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Re: Ships with "Blunt" Bows.
« Reply #8 on: February 19, 2019, 08:06:51 PM »

 
I utterly agree that the remark quoted was not in direct reference to the given vessel but the comment is still valid. Those are the reasons for this shape hull also. If you would like further details on hull design, there are numerous highly detailed scientific reports and studied via google;

daim.idi.ntnu.no/masteroppgaver/007/7873/masteroppgave.pdf

link.springer.com/article/10.1007/s00773-016-0407-9

www.sciencedirect.com/science/article/pii/S2092678216305349

www.researchgate.net/publication/257760509_Estimation_of_added_resistance_for_large_blunt_ship_in_waves

core.ac.uk/download/pdf/81881926.pdf

I merely tried to find a simple quote that saved the studious reading. Read away, its jolly good stuff and has quite a influence on those wishing to design and build there own design vessel for rc.

Pirate
 
 
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Martin [Admin]

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Re: Ships with "Blunt" Bows.
« Reply #9 on: February 19, 2019, 08:24:03 PM »


 HMS Endeavour  (replica) as seen in Boston, 2002


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Martin [Admin]

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Re: Ships with "Blunt" Bows.
« Reply #10 on: February 19, 2019, 08:38:11 PM »

Why am I seeing more ships with "blunt" bows? I have previously seen them on Great Lakes boats but they seem to be appearing more generally now.
It does not look like a good idea to me in terms of rough weather comfort.

Just spent a few minutes looking up Bulk Jamaica.... not much on the internet that I can find.   {:-{
I was interested in the bow shape underwater.... 'bulb bow'?!

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Tug Fanatic

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Re: Ships with "Blunt" Bows.
« Reply #12 on: February 19, 2019, 09:41:57 PM »


I utterly agree that the remark quoted was not in direct reference to the given vessel but the comment is still valid. Those are the reasons for this shape hull also. If you would like further details on hull design, there are numerous highly detailed scientific reports and studied via google;

daim.idi.ntnu.no/masteroppgaver/007/7873/masteroppgave.pdf

link.springer.com/article/10.1007/s00773-016-0407-9

www.sciencedirect.com/science/article/pii/S2092678216305349

www.researchgate.net/publication/257760509_Estimation_of_added_resistance_for_large_blunt_ship_in_waves

core.ac.uk/download/pdf/81881926.pdf

I merely tried to find a simple quote that saved the studious reading. Read away, its jolly good stuff and has quite a influence on those wishing to design and build there own design vessel for rc.

Pirate




I have only read the last one & the maths will (greatly) tax me for a while longer but I love the term "blunt ships". Short waves seem to feature in the article. I haven't yet sussed what that means for long waves (deep ocean?).


It is hard to think of a Bantam tug as a cutting edge hull design 50 years later.!!  %)
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Martin [Admin]

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Re: Ships with "Blunt" Bows.
« Reply #13 on: February 20, 2019, 12:31:08 AM »


Yes bulb bow


Hmmm, that bow warning symbol only indicates 500mm,  most seem only to have a mild 'chin'...










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Martin [Admin]

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Re: Ships with "Blunt" Bows.
« Reply #14 on: February 20, 2019, 12:32:26 AM »

 
Are they"Chinamax"?


https://en.wikipedia.org/wiki/Chinamax


Chinamax vessels are one of the largest bulk carrier ships in the world and often classified under Very Large Ore Carriers (VLOC). Unlike other cargo carrying vessels which are measured in terms of their size, the Chinamax cargo ships are measured not just in terms of their size but also in terms of their length. These vessels were initially custom built to cater between the Chinese port facilities and the South American nation of Brazil, though presently the development of appropriate harbor facilities have ensured their applicability beyond these two regions. Also commonly famous as Valemax vessels, Chinamax ships have a Dead Weight Tonnage (DWT) of up to 4,00,000 tonnes and measure about 360 meters lengthwise with a breadth of about 65 meters and a draft of about 25 meters.





https://www.marineinsight.com/types-of-ships/the-ultimate-guide-to-ship-sizes/
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roycv

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Re: Ships with "Blunt" Bows.
« Reply #15 on: February 20, 2019, 01:13:50 AM »

Hi martin is there one zero too many there?Roy
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Re: Ships with "Blunt" Bows.
« Reply #16 on: February 20, 2019, 01:55:19 AM »

Hi martin is there one zero too many there?Roy

Who would have though a website could be unreliable?!   {-)

Chinamax ships are very large bulk carrier which can't be longer than 360m (1,180 ft), wider than 65 m (213 ft) and her draft can't be more than 24 m (79 ft). The deadweight tonnage of these vessels is 380,000–400,000 DWT.
 
http://maritime-connector.com/wiki/ship-sizes/
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derekwarner

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Re: Ships with "Blunt" Bows.
« Reply #17 on: February 20, 2019, 02:38:49 AM »

This is heading to ask more & more questions  %)


1. a Chinamax sized vessel as nominated could theoretically say 400,000 tones of cargo if it is a 400,000 DWT design
2. if it were a crude oil tanker she could carry 440,000 liters which would occupy 100% of her tank design space
3. if she was an iron ore carrier she would carry 400,000 tones of ore, however this would occupy only 1/5 the volume or approx the space 80,000 cubic meters, as Iron Ore ranges from 2.5 tonne to 5.1 tonne per cubic metre

4. So all of this means that a Chinamax Iron Ore vessel needs the volumetric design capacity up to 5 times that of a similar DWT vessel for Crude oil.................other wise the ore carrier would sink as she was loaded

5. a Chinamax Iron Ore vessel during loading would be possibly every 2nd hatch only....and to a height of ~~25% ....

6. naturally all such loading is via sophisticated computer control :police: .......if not the ore carrier would sink as she was loaded
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roycv

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Re: Ships with "Blunt" Bows.
« Reply #18 on: February 20, 2019, 04:36:06 AM »

Apparently the name Chinamax is superceeded by the name Valemax, Vale being the 2nd. largest mining company in the world who are slowly exporting a lot of Brazil to China in the form of iron ore and coal.  I suspect to the detriment of the environment as there have been associated landslides in Brazil.

It seems that India can now take these VLOC ships as they are also importing coal from Brazil.  Previously it came from Indonesia probably in small buckets.
Vale are said to be having 35 of these ships constructed.
It all goes well with the analysis of blunt nose ships referred to earlier in this thread and subsequent contributions. The points made in the thesis are sort of obvious but neatly brought together in this way for the likes of myself to read.  Much of the maths I skipped but the last part brings it all together.
Regards

Roy



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Tug Fanatic

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Re: Ships with "Blunt" Bows.
« Reply #19 on: February 20, 2019, 08:41:41 AM »

Apparently the name Chinamax is superceeded by the name Valemax, Vale being the 2nd. largest mining company in the world who are slowly exporting a lot of Brazil to China in the form of iron ore and coal.  ..................…..
Regards

Roy



The picture was taken in Santa Marta Columbia which also has very large coal exports although I am not sure that  Bulk Jamaica was actually being loaded with coal. Thought you might like to see how they unload the very long 22 wheel lorries that deliver the coal to the dock. There are lots of shiny new trucks but some of the older examples are just full of character. I am not sure how the suspension works but the axles on the trailer in the third pic look wonderfully out of line.


I don't think that Bulk Jamaica is anything max. It is has a deadweight of 63747t and is 199m x 32m.
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derekwarner

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Re: Ships with "Blunt" Bows.
« Reply #20 on: February 20, 2019, 09:51:41 AM »

Sorry.....my typo...  :embarrassed:


2. if it were a crude oil tanker she could carry 440,000 liters which would occupy 100% of her tank design space

should read

if it were a crude oil tanker she could carry 4,400,000 liters which would occupy 100% of her tank design space

[this still represents the same or original 400,000 DWT or tonnes @ say 0.9 kg/l]

Derek

PS...the largest vessel I worked on in the Port of Kembla was the BHP Iron Pacific @ 231,859 DWT.......she was big, but vessels of this size are either loaded or in ballast....so you never really get the real perspective of the mass

A snap below of her Maiden Voyage to Australia......then another when resold to Dutch ownership and sailed as the Berge Pacific

You will also see that during her discharge in [Europe?], hatches 2, 4, 5, 7 & 9 only are opened.....ie., being loaded in every second hatch etc 
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Re: Ships with "Blunt" Bows.
« Reply #21 on: February 20, 2019, 12:18:13 PM »

that every 2nd hatch may have to be due to having need somewhere to put the hatch whilst they load the hold then swap the 2nd, 4th etc onto the 1st, 3rd etc, the blunt question may have something to do with the submarine effect, the design of subs changed when the wave cutting design gave way to the more efficient whale shaped design as they moved from surface vessels to fully submerged. though I stand corrected.
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derekwarner

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Re: Ships with "Blunt" Bows.
« Reply #22 on: February 20, 2019, 02:59:31 PM »

Most bulk carrier design vessels from the 1960's onwards utilized split hatches opening 50/50 athwart ships....so not encompassing the next hatches


The Iron Pacific could have loaded into hatches 1,2,3,.......to 9 inclusive......but each would have been filled only to ~~ 12.5% of the volumetric space etc


This would naturally minimize induced stresses in the vessel hull at sea, however was calculated as unnecessary......as the downside of loading into each hold is the final trimming & mechanical cleanout of the hold by a 50 tonne D9 Bucket Dozer <*< which could take say an accumulated 24 hours per hold

Derek
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BrianB6

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Re: Ships with "Blunt" Bows.
« Reply #23 on: February 20, 2019, 11:18:48 PM »

Lots of problems loading iron ore
There are numerous web pages about it. http://www.bulkcarrierguide.com/iron-ore-liquefaction-cases.html is just one!

"Most dry cargo ship losses  mainly involved while carrying ores and, frequently, the practice of loading alternate holds. While this method has advantages such as making the ship less stiff and reducing loading, trimming, discharging and cleaning costs, it has the major disadvantage of imposing severe stresses on the hull in periods of heavy weather thus making her susceptible to structural damage."
p.s. They are still ugly ships. {:-{
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Tug Fanatic

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Re: Ships with "Blunt" Bows.
« Reply #24 on: February 21, 2019, 09:04:36 AM »




………………………………………….p.s. They are still ugly ships. {:-{



Actually I quite like them. Their sheer scale wins them brownie points and they look like proper ships.


I find very few modern ships attractive. Modern liners are tower blocks, modern warships slab sided (don't start me on the horror that is HMS Queen Elizabeth), container ships ugly when loaded but elegant when empty etc. A lot of freighters are just welded sheets with nasty corners etc. When I see something like Bulk Jamaica I think that it is nicely made with lots of design flourishes that I find appealing & which I am sure are functional.


Each to his own.
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