Tape Sealing [40]

An Alternative View

By Larry Gray

After a stack of phone calls questioning the sturdiness of the Pittarak, a fax fmally arrived with the source of the concern — an article titled “Barlings Beach training weekend” by David Winkworth.

It claimed that a Mirage was too lightly built, that a rear hatch cover came off causing the boat to sink and split, and that external joining should be applied in future on kayaks such as the Mirage, Greenlander and Pittarak.

Okay. Perhaps the Mirage was built too lightly for ocean kayaking. Mirage concentrate on flat-water racing events and design their boats around that concept. But for Mr Winkworth to further comment on the Pittarak’s joining technique is inappropriate and inaccurate. Pittarak does not have a seam splitting problem when built to standard specifications and rarely do we have defects.

For those who don’t know me, I am the Pittarak designer and a kayaker with a life-long dedication to our sport. I have trained Outward Bound sea instructors in Asia and helped developed the Australian sea-kayak award system. I spend a lot of time learning with Greenland people, who I consider the masters of our sport. My track record includes two Arctic expeditions — one in winter, one in summer — of more than 1000km each journey. I kayaked 4500 km up the east coast of Australia and through Torres Strait, crossed Bass Strait and did 2000km through PNG, plus various trips through England, Ireland, Indonesia and Tasmania.

I’m sure Dave IS dedicated to our sport. But to be honest, he doesn’t have the years of experience in a variety of sea conditions, nor the instructing mileage. Most of his experience relates to plastic kayaks and I do not believe he is qualified to comment on Pittarak, which has gained a reputation for handling the world’s toughest expeditions.

I know many sea kayaks are being built lightweight to win races — the Hawkesbury Classic, etc. — and they really don’t deserve the right to be called sea kayaks as they won’t handle average conditions. The ocean has the capacity to smash any kayak, even when perfectly joined. A good instructor teaches avoidance and how to spot danger zones but even that won’t save you in a lightweight racing kayak. Instructors shouldn’t take people into harsh conditions if their boats are light, especially if they are only beginners. I’ve never had these splitting problems when instructing.

The technical specifications for Fibreglass Laminates do not recommend an external tape to be applied to a mould-dried surface. It is considered a Band-aid approach. FGI tech engineers also said they had never such a method and it is not a good idea. Resins (marine) are designed to work so that when laid to a mould, the surface against the mould dries rock hard. The inside surface releases complex waxes, creating a tacky texture that allows what is known as a chemical bond to take place. This is the ideal time to apply an internal join, as the two wet surfaces cross-link.

Once the boat is released from the mould, the outside has dried completely. To then add an external tape is to apply a liquid to a solid (known as a mechanical join) and is far less effective. In fact, chemical companies won’t guarantee their product for maximum strength if this is done. Code for NSW waterways surveys specify internal joins only.

Sure, it has some strength value. But for every centimetre of non-chemical bonding externally attempted, three times the strength of that can be achieved if the same is applied internally at the correct time. To strengthen a join add a thicker laminate internally while the kayak is still “green”.

I spent time in the UK factory of Derek Hutchison, the famous kayak designer and writer. The factory owner, Dave Patric, has been manufacturing kayaks for 45 years. He taught me this technique for the fail-safe, internal overlap lamination. Pittarak uses this technique. All high quality sea kayaks worldwide are joined only on the inside, as are power boats, jet skis and surf skis. If I thought that externally joining the sea kayak would improve it, I would do it. It’s no trouble for me. I’d just instruct my laminators to do so and add $20 to the cost of the kayak.

Dave Winkworth goes on to recommend that if a manufacturer won’t apply external taping, to do it yourself or fmd someone who will. This is not good advice. I know that when an external taping lets go, a razor edge is exposed. If not repaired ASAP, sand falls between that edge and the kayak. The delaminated external join becomes more exposed and dangerous. The fine gel line, which usually fills in the join, may chip away a little in time but it is easily repaired and safe. This is the method recommended worldwide.

Dave Winkworth will be replying to this in the next issue with an article on how to tape seal.