Composites?

[PeterCrisp]

Please ignore this if its a stupid question.

Have any ships that are under construction or in development made use of composite materials to keep weight down. I ask this as I assume weight in ships has the same effect as in vehicles (I.e less fuel efficiency and slower) so the extra cost of construction could be countered by the savings in fuel over the ships lifetime.
So other than cost what are the downsides to using composites?

 

[Grand Danois]

How about the Norwegian Skjold class? It's air cushioned at high speed, so weight saving should be an issue...

http://www.defense-update.com/products/s/skjold.htm

 

[AegisFC]

The Visby class is made of composites.

http://www.naval-technology.com/projects/visby/index.html

The hull material is a sandwich construction comprising a PVC core with a carbon fibre and vinyl laminate. The material provides high strength and rigidity, low weight, good shock resistance, low radar and magnetic signature.

I can't think of any large ship using mostly composites though. At one time a large part of the DD(X)/DDG-1000 superstructure was supposed to be composites but I'm not sure if that is the case any more.

 

[PeterCrisp]

This may be just me being brainwashed by films but doesn't building using composites make a ship less visible to sonar? I'm not sure how much use a stealth boat might be (given that unless they can make it invisible you can still see it and ships are not exactly fast) but maybe they might be a harder target for subs to find?

Again I'm sorry if that made no sense whatsoever.

 

[rjmaz1]

This may be just me being brainwashed by films but doesn't building using composites make a ship less visible to sonar?

You are spot on.

The Swedish Visby Corvette's website mentions that stealthiness of the composite design. Things like magnetic mines and radar cross section are reduced dramatically.

The Visby is the largest composite/fibreglass boat to be produced so far.

Regarding your original question regarding composites. Keeping weight down is not always a good thing. Sure speed will increase as the boat will now sit higher in the water, however during rough seas it may not handle as well.

So for instance the Australian Navy's armidale patrol boats from my limited research can withstand heavier sea state conditions than the much larger and expensive Visby corvette. The Visby can however travel much faster.

If you want a small and cheap boat that can withstand heavy ocean swells its going to be heavy and slow. If you want a small, fast boat its not going to be able to handle heavy ocean conditions.

The Visby Corvette is bloody awesome for Sweden. It wont see the open oceans so being able to survive in cyclone conditions is not important. Its speed and technology advantage make its great asset to the Swedes.

With the Australian Navy for instance it would be far from ideal.

 

[Systems Adict]

Mmmm....

Being king of stating the obvious, I thought I'd do just that. Here's Wiki's definition...


"Composite materials (or composites for short) are engineered materials, made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure."

http://en.wikipedia.org/wiki/Composite_material



So, Carbon fibre, Metal Alloys, GRP (Glass Reinforced Plastics), Fibre glass to the layman & certain types of Plywood can be considered "composite".

Add to this the Fact that these materials all can have inherent different properties regarding density, weight & the applications they can be used for, even though they may be very similar.


Another key fact that should also be noted wrt using these materials for constructing ship hulls is that although Carbon Fibre & Fibre Glass are quite similar, Carbon fibre has a tendency to ABSORB radar waves, while Glass Fibre tends to REFLECT it.


But most people will know some of this already ....


SA

 

[Feanor]

Quick question, the Stereguschiy which has some stealth characteristics (allegedly) does it not make major use of composites?

 

[Chrom]

Quick question, the Stereguschiy which has some stealth characteristics (allegedly) does it not make major use of composites?

Of course not. Composites are totally unsuitable for large hull shipbuilding. Although some parts above main hull could be made from composites - but generally it much too expensive and dont bring much benefit regarding stealth given usual big ship design and armament. Right shape is much more important here anyway.

 

[Gryphon]

Composite or Honeycomb?

Systems Adict rightly mentioned "composites" does not inherently mean a pure Carbon/Carbon/epoxy sheet. Composite panels also refer to Honeycomb sandwich panels where a lightweight honeycomb matrix is sandwiched between an inside and outside sheet.

Large Naval structures have and will continue to be fabricated from significant metallic honeycomb "composite" panels, which can consist of 2"-3" thick aluminum honeycombs with non-trivial (thick) stainless steel cover sheets. These are significant weight savers but not really 'Stealthy'.

I've bought panels from these guys before, excellent product - far stiffer than the weight suggests:
http://www.cattcousa.com/marine.htm