WHAT IS GELCOAT?
Adding a layer of gelcoat to the mold is the very first step performed when building a composite boat.
Gelcoat does 3- positive things:
i) Gelocoat provides a smooth glossy exterior & provides colour choice
ii) Gelcoat covers the Fibreglass, Kevlar or Carbon cloth to provide an additional exterior layer of durability & impact resistance.
iii) Gelcoats main purpose is its slippery smooth surface as it better enables a boat to be removed from the mold upon completion. Think of it like spraying Pam into a frying pan – so the eggs slide out easier!
Ironically, most people think that glossy finish was painted last… when gelcoat is actually the very first step taken in building a composite boat.
Note: As technology has continued to evolve manufacturers began making ‘Clearcoat’ or ‘No-gel’ boats. These boats are made by spraying a ultra-thin layer of vinylester resin into the mold. Boats made this way are lighter but they lack the abrasion resistance & colour choice that the additional layer of gelcoat provides.
WHAT IS A HAND LAY-UP?
A hand lay-up is the least technical method of reliving excess resin when building a composite boat. Excess resin is removed using a hand tool without the help of an automated pressure process like vacuum-bagging or dry-infusion.
WHAT IS VACUUM-BAGGING?
Originally aerospace technology, vacuum-bagging is similar to a wet hand lay-up, except a bag is put round the boat & mold. The air is then retracted from the bag. This presses the material mix together under pressure, which in turn pushes excess resin out. This pressure process maximizes a boats cloth to resin ratio, which in turn builds a stronger and lighter boat.
Note: Remember resin is simply a binder, thus excess resin provides little positive function except to add weight.
WHAT IS DRY-INFUSION?
Dry-Infusion is similar to vacuum-bagging except the boat is laid up ‘dry’ – meaning without resin. A hose is run from a resin container up and through the hull of the mold. The air is then retracted from the bag until zero gravity is achieved, this enables the resin wick up into the boats cloth ~ like water creeps into a paper towel.
Dry-infusions manufacturing advantage is similar to vacuum-bagging but its more refined and less labour is required!
Note: Increasingly companies are incorporating both a ‘male & female mold’, which spoon together to relive excess resin as the very best pressure boat building process.
CAN YOU EXPLAIN THE DIFFERENT TYPES OF RESINS?
Sure, resin is ‘the glue’ which holds all the boats building materials together. Put simply, “the better the resin… da better da boat!” There are 3- main types of resins used today:
Is the least expensive resin. Its offers less flex than other resins so it breaks down quicker. Polyester resin and is normally used in standard fiberglass boat construction and shockingly is used in many supposedly high-end craft.
Vinylester resin offers a good compromise of price vs. strength characteristics. Premium weight fiberglass, moderate weight Kevlar and even some ultralight Kevlar boats are made using vinylester or blend of vinylester & epoxy resins. Vinylester & epoxy resins flex better than polyester resins, which in turn help lengthen the life span of your craft!
Epoxy is the most expensive of the resins and its often a whopping 10- times more expensive than polyester resin. Epoxy is also the strongest of the three resins. Further, its the most difficult resin to work with and it slows the build process as epoxy resin made boats must sit in a heated mold to cure after production.
Note: One of the best questions potential boat buyers can ask… but seldom do is – what kind of resin is used to build the boats they’re comparing? Remember you can’t see or feel the difference between Polyester, Vinylester & Epoxy resin… but they’re sure as heck is a Difference in Quality!
HULL CORES VS. FLEX RIBS?
Rib or Flex Ribs:
Ribs are used as hull stiffeners and to minimize weight. This technique provides moderate flex between ribs and non-flex points underneath the ribs. This process actually maximizes a canoes rip n’ tear points or flex vs. non-flex points as the hull travels over an object – like an underwater object.
A diamond shaped dense foam core is pulled to the boats hull using a wet vacuum bagging or dry infusion pressure process, while also sucking excess resin out. Unlike ribs, a hull core material EQUALLY disperses stress throughout the entire length of the boat – an obvious advantage over older rib technology.
FACTORS THAT EFFECT WEIGHT
The Boat Building Process:
Last time I checked people aren’t perfect… heck just ask my wife Christine- she’ll confirm that I’m deeply flawed. Seriously though, this means that ‘hand laid boats can’t be perfect’ either. Accordingly, hand-laid canoes often vary up to 6 lbs as some spots receive more or less resin than others. Whereas vacuum-bag or dry-infusion made boats are precisely controlled by an automated process, thus weights seldom fluctuate more than a couple of pounds.
Gelcoat Colour Choice:
A bright colours vividness is largely achieved by adding more gelcoat, thus darker colours tend to weigh more than lighter colours – and yellow is the heaviest colour of all… who knew!
Wood trim gunnels add a substantial amount of weight to a canoe (ash: 6 lbs & Cherry 4 lbs). Also remember individual wood weights fluctuate naturally. Heck anybody who ever bought & carried a bunch of 2 x 4’s knows you get vastly different weights.
Integrity Challenged Manufactures:
Any manufacturer can make an honest mistake, however sadly to gain market share via increased sales, ethically challenged manufacturers purposely understate weights by as much as 20%… so buyer beware!
Note: The H2O Canoe Co. is the ONLY Co. we know of that individually weighs each finished boat. They then install an aluminum plate, which includes both the crafts serial number AND the canoes ‘actual weight‘ to the stern on the starboard side… pretty cool eh!
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