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Auckland's new tug


vic008

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That's about 128,000 Chihuahuas! ?

 

New tugs have to have a pullboard around the 50-60 tons for the M line of box boats and the big awful cruise ships.

To get that sort of pullboard id say as a guess your need some where around 4,000kws or around 5,200 +- Clydesdale's

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V16 Cats of 2,900 hp per side bollard pull of 68 tonnes ahead and 71 tonnes astern. Two four bladed 2.4metre azimuthing shrouded props or ASD's as they are called.

Free running maximum speed of 12.4knots, not bad for a 23 metre waterline.

It would equate to a sh*t load of elephant sh*t!

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So of they are a fully rotational Propulsion Unit, I wonder why the difference in ahead and aft pull measurements. OK, so I could understand Hull having an influence, but I would have expected the Pull figures to be the other way around.

Can Mr Rigger, our resident Tauranga Tug Man tell us what causes this ??

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Not that you can believe anything 100% off the TV

They said it motored from China and it burns $1000/hr

5000nm @ 10kts = 500hrs or $500,000 but still cheaper than building it here.

Sounds a lot but there are a lot of assumptions in that equation

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What kind of fuel is it burning for a start? I suppose it would be Diesel, but it could be a heavier cheaper Fuel oil as well, and the $1000/hr would also depend on TV's figures of, is that our NZ pump price? or the actual cost of fuel the Tug uses and what the Port pays for it? and is that at Cruising or Full Pull and blah blah blah. It's almost as meaningless as saying the Pull of Seven Elephants. Like who would know how much that was and I would have said that wasn't much. I find it hard to believe 7 Elephants could pull 60tonne. It's also like when Americans say, it's as high as a 30 story building. Well how high is that?? Why not just say, it's 300ft or what ever the heck it is.

 

Wheels, could it be that the props are mounted at one end of the tug, so the hull has different effect depending onahead or astern?
It was that thought in my mind as to why I said I would have thought the figure the other way around. Maybe it's because the Prop is in clear water and in forward, the Hull is impeding the Flow. Or is that what you meant anyway? I figured it would be a reasonably flat hull so it can go sideways and every which way easily.
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-Fuel -Diesel,

-L/hr burn between 450-550 at max load per engine - Cannot remember exact figure.

-Engines are Cat 3516C ~ 2100kW D rating

-Azimuth units are Rolls Royce US 255 units with props of 2.6m diameter.

-LoA = 24.47m

-Displacement = 490tonne

 

BP according to spec sheet as viewed (but might have got more on test) 63tonnes pull over the bow, 69tonnes over the stern. The difference is caused by the prop wash when pulling over the bow impinging on the hull. see picture.

 

Service speed ~12.5kn.

Side stepping speed ~ 2.5kn (Waipapa ~4kn)

I figured it would be a reasonably flat hull so it can go sideways and every which way easily.
Not as well as the Waipapa class(~4kn) or the Blackadder (6-7kn side ways)

 

The 2411 is a good design - there are now 5 of the design in NZ.

damen 2411.jpg

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wo that's some pullboard! $1000 an hr that's prob at full flank. The

Emma Mersk burns around Ten cubes an hour or 166ltrs a minute at service speed. During the trials at full rpm halfway through a turn it peaked at just under 500ltrs a minute....Yikes!!

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Wow, so it has a really deep Hull/Keel on it. I was expecting it to be really flat.

BP according to spec sheet as viewed (but might have got more on test) 63tonnes pull over the bow, 69tonnes over the stern. The difference is caused by the prop wash when pulling over the bow impinging on the hull. see picture.

Arrr, that makes more sense.

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This one is different to the concept of the Waipapa class in that it has a large skeg probably designed more for escort work than the Robert Allan designs such as Waipapa which have no skeg. This makes the W class boats more nimble and also means that the W class will go sideways quicker. I don't think you will ever see the seventy tonners doing donuts like the W boats do.

Differences in forward and reverse pull are purely caused by interaction of the hull ie astern the props are working in clean solid water. The original specs have changed several times over the course of the planning of the project and modifications made to ensure the tug turned in 70 tonnes as opposed to the original draft of 65-68 tonnes bollard pull.

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This one is different to the concept of the Waipapa class in that it has a large skeg probably designed more for escort work than the Robert Allan designs such as Waipapa which have no skeg. This makes the W class boats more nimble and also means that the W class will go sideways quicker. I don't think you will ever see the seventy tonners doing donuts like the W boats do.

Differences in forward and reverse pull are purely caused by interaction of the hull ie astern the props are working in clean solid water. The original specs have changed several times over the course of the planning of the project and modifications made to ensure the tug turned in 70 tonnes as opposed to the original draft of 65-68 tonnes bollard pull.

 

Waipapa is from a different designer - http://www.agmcilwain.com/Design%20Gallery.htm

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Displacement = 490tonne

 

:think: :think: :think:

 

Good News so that being less than 500 tonnes, we do knot have to give way to her if she is underway and in the main shipping channel.

 

Different as soon as she has a line onboard a ship I guess.

 

Thanks for the drawing and Info :thumbup: :thumbup:

 

NO. I won't be responsible for 100+ x small

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Displacement = 490tonne

 

:think: :think: :think:

 

Good News so that being less than 500 tonnes, we do knot have to give way to her if she is underway and in the main shipping channel.

 

Different as soon as she has a line onboard a ship I guess.:

 

Don't confuse displacement tonnes with gross tonnage which the collision rules are based on, in this case gross is probably still under 500 tonnes. On ships there can be thousands of tonnes difference. gross tonnage has nothing to do with weight or displacement of the vessel, to simplify an explanation it is purely a volumetric measure of the inside volume of the hull.

My advice is don't get too close as the thrust of these units can be used to their advantage and your disadvantage big time.

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Displacement = 490tonne

 

:think: :think: :think:

 

Good News so that being less than 500 tonnes, we do knot have to give way to her if she is underway and in the main shipping channel.

 

Different as soon as she has a line onboard a ship I guess.:

 

Don't confuse displacement tonnes with gross tonnage which the collision rules are based on, in this case gross is probably still under 500 tonnes. On ships there can be thousands of tonnes difference. gross tonnage has nothing to do with weight or displacement of the vessel, to simplify an explanation it is purely a volumetric measure of the inside volume of the hull.

My advice is don't get too close as the thrust of these units can be used to their advantage and your disadvantage big time.

 

IT might be able to find the article that Dave did on the Waipapa a few years back, I think he commented on the prop wash - the Waipapa and Waka put out about 3-4tonnes of thrust per unit at idle.

 

GT

 

http://www.damenchangde.com/EnProductShow.asp?ID=166

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