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I’ve seen some of these bows on seismic survey ships out the window where I live. I assumed the funky bow shape was due to them being ice breakers/science ship

I’ve seen some of these bows on seismic survey ships out the window where I live. I assumed the funky bow shape was due to them being ice breakers/science ships, but looking the ships back up they’re indeed examples of this X-BOW design. I wonder what the downsides are? The site does the classic thing of listing the advantages but not the opposite.

JonChesterfield 4y ago
The vertical component of the force exerted by the sea would be down instead of up. So I guess it's good if pushing the front of the boat down is OK. Sounds like go faster => sink to me, but as they seem to work I guess buoyancy overcomes it.
- upsidesinclude 4y ago
  The bow is only down as it pierces the oncoming wave in extreme seas. The important thing to consider about ship stability is that water on the deck of a ship is immediately inducing free surface effect and modifying the vessel buoyancy. The xbow design sheds the water and prevents free surface effect while reducing the impact of the bow on the wave. They don't pay me, but I wish they did...
upsidesinclude 4y ago
There are few downsides compared to traditional bows. Those that do exist relate to capacity. In large ships, the bow shape is really only providing any kind of input during extremely rough seas. All modern ships will have a bulbous bow beneath the waterline for efficiency in calm waters. The x-bow design adoption is seen, to-date, in vessels that will operate in heavy weather and rough seas. So, we see the xbow in OSV and MODU type vessels particularly in the northern latitudes.
mattlondon 4y ago
Yeah I wondered about lateral stability. I do not have a lot of experience of rough seas, but I did the crossing from the Antarctic peninsula to southern Argentina going through the drake passage and holy fuck it was rough, but not just up and down but also huge rolling left and right. It seems like a traditional bow and hull shape would resist rolling (more buoyancy the further over you go) but this design has less?

JonChesterfield 4y ago

The vertical component of the force exerted by the sea would be down instead of up. So I guess it's good if pushing the front of the boat down is OK. Sounds like go faster => sink to me, but as they seem to work I guess buoyancy overcomes it.

upsidesinclude 4y ago
The bow is only down as it pierces the oncoming wave in extreme seas. The important thing to consider about ship stability is that water on the deck of a ship is immediately inducing free surface effect and modifying the vessel buoyancy. The xbow design sheds the water and prevents free surface effect while reducing the impact of the bow on the wave. They don't pay me, but I wish they did...

upsidesinclude 4y ago

There are few downsides compared to traditional bows. Those that do exist relate to capacity. In large ships, the bow shape is really only providing any kind of input during extremely rough seas. All modern ships will have a bulbous bow beneath the waterline for efficiency in calm waters. The x-bow design adoption is seen, to-date, in vessels that will operate in heavy weather and rough seas. So, we see the xbow in OSV and MODU type vessels particularly in the northern latitudes.

mattlondon 4y ago

Yeah I wondered about lateral stability. I do not have a lot of experience of rough seas, but I did the crossing from the Antarctic peninsula to southern Argentina going through the drake passage and holy fuck it was rough, but not just up and down but also huge rolling left and right. It seems like a traditional bow and hull shape would resist rolling (more buoyancy the further over you go) but this design has less?