The Low Down on Hull
Materials
For those who are wondering how to buy a boat, there are a lot of choices, but
basically sail or power. Once that basic decision is made, then there is the question of hull material.
Most boats today are made of fibreglass (GRP or glass reinforced polyester). GRP has many advantages, but there
are disadvantages too. Here, we are going to look at the wide choice of hull materials available, with the major
advantages/disadvantages of each.
Fibreglass (Basic/Traditional)
This is the most common production material. Older boats used very heavy ‘layups’ – thicknesses.
For: GRP has a good strength to weight ratio, low maintenance requirement, is cheap to build in high volume, and
has moderate repair complexity – minor repairs are easily dealt with by the average handyman.
Against: Older compounds can be subject to osmosis (which can be cured), and bleaching (‘chalking’) in strong UV,
though modern compounds are less susceptible to this.
Ideal for: All round uses – fishing boats, sailing boats, dinghies, trawlers, even minesweepers!
Composite (Exotic)
Sometimes known as exotics, they may use Kevlar or carbon fibre reinforcement, with an epoxy base.
For: High strength to weight ratio.
Against: Expensive to build, expensive and technically complex to repair.
Ideal for: Racing and high performance craft, big budgets.
Composite (GRP on balsa core)
This is a popular construction for one-offs, using sheets of balsa wood (usually end grain on) for
stiffness and coated with polyester/epoxy resin and gelcoat.
For: Good Strength to weight ratio.
Against: Not easy to repair. If water gets to the balsa core then serious problems can result. Some traditional GRP
boats have balsa cored decks (I owned a Jeanneau Sun Fizz 40' with such a deck). Check around the deck fitting for
water ingress. Small deck problems can be easily fixed by cutting back, drying and injecting epoxy. However, if you
can do the work, or know a friendly yard, then you could get a good deal - or a load of problems, depending on
whether your glass is half full or half empty..
I'm not a lover of Bruce Roberts designs, but there is a very racy looking yacht moored nearby, and she is GRP
on a balsa core.
Ideal for: Home build, one off designs. Continued...
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