silverseal
New member
I have just been looking at a boat which is described as Non GRP - Foam Sandwich construction... Has the Brokerage got it wrong, as I thought the system involved GRP
<hr width=100% size=1>
<hr width=100% size=1>
Foam Sandwich construction
- Thread starter silverseal
- Start date
MLBURGE
New member
should be with grp - foam - grp unless they mean frp instead which could be epoxy and roving, carbonfibre or the like or praps they mean it's not just a grp layup and has the foam aswell as the grp.
<hr width=100% size=1>
<hr width=100% size=1>
Inselaffe
Member
Usually sandwich construction in boats is a relatively thick foam or balsa core sandwiched between two thin skins of fibre reinforced plastic.
however, some definitions might help clarify things a bit:
A Composite material is any material made of more than one part, eg glass in resin, or steel in concrete, or metal in metal (in two distinct phases, not mixed) etc
Most commonly known are Fibre Reinforced Plastics (FRP), i.e reinforcing fibres set in a plastic
When glass is the fibre its GRP (glass reinforced plastic)
When carbon CFRP (carbon fibre reinforced plastic)
The fibre reinforcements can be of different forms, two used mostly are CSM: lots of little chopped up strands in a mat (CSM = Chopped Strand Mat), and WR: bundles of strands (rovings) woven into a cloth (WR = Woven Roving)
Epoxy and Polyester Resins are both plastics
Any material where a fibre is reinforcing a plastic is an FRP. If its glass then its GRP.
sandwich construction is when any two outer skins separate an innner core. To make real use of this method the core should be light and able to withstand shear forces, and the bond between the skins and core are very important.
"advanced" or "exotic" composite materials are further wooley terms used just to emphasise the fact that expensive materials and manufacturing processes have been used.
However......
Problem is that in "normal speak" these definitions are often blured!
I think that often GRP is taken to mean CSM with polyester (from the original propriotory name?), not incorrect, but this isnt the only form of GRP (any Glass fibres, CSM or WR, in any Plastic, Polyester or Epoxy, is a GRP)
Also I think that FRP is often used to give the impression that some higher perfomance materials have been used (WR, Epoxy, Carbon, Kevlar). this isnt technically correct as any fibre in a plastic is a FRP by definition.
So I dont know what the broker means by "non GRP - Foam sandwich".
Literally it means that its a foam core sandwiched between two skins of something that isnt glass reinforced plastic.
the skins could be CFRP or Kevlar reinforced plastic, or even aluminium or wood but that doesnt seem likely to me.
I think that its probably a mis-term from the broker, but ask him what he means!
<hr width=100% size=1>
however, some definitions might help clarify things a bit:
A Composite material is any material made of more than one part, eg glass in resin, or steel in concrete, or metal in metal (in two distinct phases, not mixed) etc
Most commonly known are Fibre Reinforced Plastics (FRP), i.e reinforcing fibres set in a plastic
When glass is the fibre its GRP (glass reinforced plastic)
When carbon CFRP (carbon fibre reinforced plastic)
The fibre reinforcements can be of different forms, two used mostly are CSM: lots of little chopped up strands in a mat (CSM = Chopped Strand Mat), and WR: bundles of strands (rovings) woven into a cloth (WR = Woven Roving)
Epoxy and Polyester Resins are both plastics
Any material where a fibre is reinforcing a plastic is an FRP. If its glass then its GRP.
sandwich construction is when any two outer skins separate an innner core. To make real use of this method the core should be light and able to withstand shear forces, and the bond between the skins and core are very important.
"advanced" or "exotic" composite materials are further wooley terms used just to emphasise the fact that expensive materials and manufacturing processes have been used.
However......
Problem is that in "normal speak" these definitions are often blured!
I think that often GRP is taken to mean CSM with polyester (from the original propriotory name?), not incorrect, but this isnt the only form of GRP (any Glass fibres, CSM or WR, in any Plastic, Polyester or Epoxy, is a GRP)
Also I think that FRP is often used to give the impression that some higher perfomance materials have been used (WR, Epoxy, Carbon, Kevlar). this isnt technically correct as any fibre in a plastic is a FRP by definition.
So I dont know what the broker means by "non GRP - Foam sandwich".
Literally it means that its a foam core sandwiched between two skins of something that isnt glass reinforced plastic.
the skins could be CFRP or Kevlar reinforced plastic, or even aluminium or wood but that doesnt seem likely to me.
I think that its probably a mis-term from the broker, but ask him what he means!
<hr width=100% size=1>
snowleopard
Active member
as has already been said, the 'hard' part of the sandwich could be carbon/epoxy which would count as non-grp. i have also seen a sandwich of wood/kevlar/foam/wood all bound by epoxy. these structures are immensely strong & light. worth finding out more though strange the brokers should say what it isn't rather than what it is!
<hr width=100% size=1>
<hr width=100% size=1>