G'day Marcus,

You're best off using the silicone Gear Aid option which you can find here.

G'day Alex,

We've recommend the standard waterproof Seam Grip for repairing canvas tent or swag seams.
The seam sealant you've commented on is ideal for polyurethane tent floors, etc

G'day Jarno,

The Sealer will need around 4 hours of curing time depending on the application.

G'day Aaron,

We've given the suppliers a buzz, and done a quick run around the office to see how much other people have used, and the consensus is around 2 tubes.

Its abit hard to say specifically as we dont stock the Vango tents and cant check out the seams for ourselves, but some of the people here have seam sealed their 2 person dome style hikers with 1 tube.  Give the Vango has that extra vestible, we'd go for a second tube.

You really dont need much at all, just apply a super thin layer and you should be right.