“Fibreglass” it’s just a posh way of saying fibreglass
I apologize to readers from the US “Fiberglass” it’s just a posh way of saying fiberglass
Well, that’s not exactly true!!!!!!
Fibreglass used to be called GRP (glass reinforced plastic), but more recently fibres such as carbon, aramid, uhmwpe (ultra high molecular weight polyethylene), and pp (polypropylene) have been used to assist glass or to replace it, so the G bit became F, also polyester resins were the bulk of resins used, now vinyl esters and epoxies are reasonably common. Also, plastic sounds a bit, well, PLASTIC so the P went from P for plastic to “P” for POLYMER.
Fibre Reinforced Polymer (FRP) now tell me that doesn’t sound stronger, lighter, and indeed faster!!!!
That’s FRP, how about the “composite” part!
I’m sure you all know what a composite is;
“Two or more materials with significantly different properties, put together to produce a material with improved characteristics”
A good example of a composite is cement which is a composite of silica, calcium, aluminium and iron, add some aggregate and it gets stronger, add some steel reinforcing rods and you can build a bridge out of it.
But what about Fibreglass??
With an FRP composite it usually comprises of (but not limited to) three main elements;
Gelcoat Provides the cosmetic finish and protects the laminate
Fibre Provides the strength, distributes the applied loading
Resin Matrix Holds the fibres in column
Ok, So what’s the “not limited to” bit??
As with the concrete, you can add stuff into the middle of an FRP composite to make it lighter, stronger, and stiffer. This is the core material, the principle of a cored FRP laminate (again the oldies may know it as a sandwich laminate, good ol’ Earl of Sandwich) is the same as an “I-Beam”.
By splitting and separating the laminate skins either side of a lightweight core material the stiffness and strength can be greatly increased. For example, a test sample using an aramid paper honeycomb (having the lowest density of the core materials) and doubling the overall thickness whilst maintaining the same laminate thickness the stiffness of the panel is increased 7 times and the strength increased by 3.5 times with a 3% increase in weight. Increase the overall panel thickness (t) x 4, the stiffness is increased by 37 times, it is 9.25 times stronger and just a 6% increase in weight (thanks Hexcell Composites for the figures).
So, rounding up
An FRP composite boat is a boat made from a combination of structural fibres held in column and protected by a resin matrix. Its hull shell (planking) will be either a solid laminate or will have a core material, often core materials will be limited to the topsides or above the waterline.
Secondary stiffening will be a subject of another post 😊