Sunday, May 15, 2022

New Bow Shapes ("backslash" and "just a bow) and Ducted Props

I've recently noted cruse ships that have what I think of as a "backslash" bow.

Ocean Explorer:
Port of Johnstown via Dennis DeBruler

Viking Octantis:
Bobby Dzz via Dennis DeBruler
[It is going over the East Main Street Tunnel under the Welland Canal.]

Carl Burkett commented on his photo: "With her patented Ulstein inverted X-BOW, OCEAN EXPLORER will cleave the waves in such a way that internal noise and vibration is reduced and the hull's shape reduces slamming against the vessel with little spray on its deck."

I had concluded that the comfort of the passengers is more important than efficiently cutting through the water. But the following taught me that this design is more efficient as well.
David Schauer posted
Vlieborg departed Duluth this evening after loading beet pulp (animal feed) at the Gavilon elevator in Superior. The small ocean vessel with a unique bow is headed to Northern Ireland. 5/14/2022
MN C-Patch: Here is some information on the Vlieborg and its unusual bow design - a design gaining popularity, along with its unique propeller configuration.
James Burroughs: MN C-Patch She is an Ice Class also, pretty cool stuff.

Eric Saed commented on David's post
I keep hoping her fleetmate, the Egbert Wagenborg, makes a trip into the Lakes because it bears a strong likeness to what a modern day classic-pilot-house-forward Laker would look like.

I was going to title these notes "Backslash Bows," but then I came across this ship that I think of as "just a bow."
NL Maritime & Seafarers posted three photos with the comment: "Ramform Atlas & sister ship Ramform Titan have been in Newfoundland waters over the last number of years. And the Ramform Titan arrived in Bay Bulls yesterday to start the 2022 season.  These vessels are designed with 70-meter [260'] beam (wide) and 24 reals [reels] for a capacity of up to 22 streamers designed for Seismic surveys for oil and gas.  They are a class of amazing ships, the widest in the works."
Roxane Bay Photography shared
Mike Sutherland: 7:29 YouTube (This video is juat about the construction, not what it does.)



Their website assumes you already know what these ships do and that you are interested in hiring a ship for your oil company. But I did finally find some overview photos of it in operation. In the middle of gthe photo below, we can see it towing six sounders (pictured further below). The sounders periodically make a big bang. The 22 streamers that are also pulled through the water have lots of microphones to record when the "bang" has reflected off rock below and returned. You can barely see the parallel ripples in the ocean made by the streamers.

This is a diagram of how the sounders and streamers are deployed. 

This view of Ramform Atlas shows why they need a wide ship, but they don't need a long ship. 
"Three variable pitch propellers provide 1.8 Megawatts [2400hp] of power, more than sufficient to tow her enormous spread of multisensor recording equipment. The propulsion system permits full operations with just two propellers, and just one of the fully-separated, dual engine rooms."

This 70m (260') beam ship is big enough to hold a basketball court and...
3:01 video @  2:36 like interior spaces.
3:01 video @ 1:47

This is what one of the sounders looks like. I wonder what the sequence of "big bangs" do to marine life. Hopefully they start a survey with some small bangs and then increase the volume so that the marine life that can move understand that they had better get out of the area for a while.

6 photos posted by NL Maritime & Seafarers of the Ramform Titan crew accommodations. And Jamie Kehoe added several more photos as comments.
Ida Gavlas shared

Ducted Propellers

The comment above by MN C-Patch says that the Vlieborg has a "unique propeller configuration." The ship's web site explains: "Nb. 407 and 408 are equipped with a main engine delivering 3000 kW to a ducted propeller. The first ship in this series, Nb. 406 M.V. ‘Vikingbank’ was delivered with a 4000 kW engine with an open propeller." I don't think of a ducted propeller as unique. They have been used for a while on towboats. In fact, a USACE towboat with ducted props has been retired to a museum in Vicksburg, MS. But then it occurred to me that scaling this up to the size of an ocean-going ship could be unique. I was surprised by how much it reduces the horsepower needs of the ships.
Dennis DeBruler

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