New 'foam' core material?

A.K.

Sorry, but this is incorrect. HMS Sheffield was an all steel vessel. No aluminium.
Another urban myth I'm affraid.

In 1982 a defence white paper also concluded, that was no evidence that aluminium contributed to the loss of any vessel during the Falklands War.

For commerical vessels, fuel tanks are also, generally, not allowed in Engine rooms, unless made of steel. In pleasure/luxury market, you can do as you please though...

 

From Wikipedia:
The sinking of the Sheffield is sometimes blamed on a superstructure made wholly or partially from aluminium, the melting point and ignition temperature of which are significantly lower than those of steel. However, this is incorrect as the Sheffield's superstructure was made entirely of steel.[10] The confusion is related to the US and British Navies abandoning aluminium after several fires in the 1970s involving ships that had aluminium superstructures.

 

Yep, steel it was.

From Wikipedia:

 

It looks like this is being marketed for military use as blast insulation. No worries of delamination from the cast pieces as the foam and shell are cast simultaneously. I mast made this way would be bomb proof......literally.

 

Good to know. The story is still going aroud the net and I remember it from news media reports at the time. Incorrect information is always enthusiastically reported and reluctantly if ever retracted or corrected. You can always trust what you read in the newspapers, right?

 

In the mid 70s, in the Med, the U.S. guided missile cruiser Belknap was involved in a collision with the carrier John F. Kennedy. I think she accidentally turned across the carrier's bow. The entire aluminum superstructure burned/melted down to the steel deck. This probably doesn't have a lot of relevance to aluminum foam as a core material but does illustrate the ability of aluminum to burn even without a missile strike to start it off.

 

Chris, I complain of nothing: I'm concerned, it's different. I do not see the utility of using a foam made with a material well known for its flamability and synergy with hydrocarbures. So I'll say for the third time: why to take the risk when you have systems already working and not having this eventual risk??? So keep alu foam where it belongs; "dry" uses, far from any hydrocarbures or anything able to make a very hot fire.

Engine room is the best place to start a fire; oil, fuel, hydraulic fluids and electricity at high amps and low voltage with ventilation system that look like excellent chimneys. Better to have an automatic extinguisher in a yacht, I won't enter in all the precautions to take, specially with gas. There is good litterature about that.

It seems that not a lot of people in this forum have seen a true fire, except the heat of their barbecues...
Those who had to fight a fire know too well the difficulty to extinguish one, and paradoxically it's a harder task on a boat when you are in the middle of the sea with billions of cubic meters of water.

 

Should I worry about the aluminum block on my car's engine? Ignition temperatures exceed 2000 deg inside that thing.

 

Oh man...good joke. You made my day.

 

No, your aluminum engine has either cylinder liners made of steel, or a coating on the cylinder walls. Plus your cylinders are surrounded by jackets of cooling water to dissipate heat, as in almost all engines. Air cooled engines have fins on their heads to dissapate heat. Fins on their heads? Uh, that sounds kind of funny, like fans at a Jimmy Buffet concert.

 

The heat necessary to cause aluminum to go explosive with the contact of water as the catalyst is so high that fears over its use in pleasure craft are unwarranted. Unless you have a habit of storing molten aluminum on board

 

This is also an urban myth. There is no record of aluminium used in naval ship building to have ever 'burnt'. The RN Board of Enquiry reports are available to the public and they go out of their way to counter this rumour. Any combustion that can be contrived in particular circumstances, certainly doesn't happen at anything like as low as it's melting point, otherwise you couldn't weld it, cast it or even recycle it. The whole 'aluminium burns' story was due to press speculation and uninformed comment.

The problem with aluminium in warships is its reduction in mechanical strength at the sort of temperatures where damage control is still possible. Steel ships can 'survive' more intense fires without being structurally compromised.

 

The Belknapp after the fire:

 

From the official report synopsis.

 

"The entire aluminum superstructure burned/melted down to the steel deck." My bad. Al burns at 6920 F. If you have a fire that hot on board your boat I guess you have other things to worry about.