Wednesday, March 18, 2009

S&G Night Heron – Fibreglassing the Outside

Quick notes from here on as the exterior was considerably easier than the interior.

I bias cut the fibrglass for the exterior to get it to drape better. The epoxy application was much simpler than inside although I did find a few areas that ended up a bit on the dry side. Main reason for this was I ended up working into the evenings and the lighting was awful. This also resulted in a couple of unnecessary floating bubbles and drips – but all easily fixed. So much easier after having done the interior first.

One tip (I think) was to fibreglass across the sheer line; that is, when I fibreglassed the deck, I went to about an inch beyond the deck-hull join, and likewise when I fibreglassed the hull, so that the join between deck and hull was secured with interior tape and a doubling of the exterior glass.

I doubled the glass on the exterior hull from the sheer line to the keel so that under my body I ended up with 4 layers of 200g (6oz) fibreglass.

Having read about the difficulties of making a lightweight boat I spent a lot of time checking the weight as I progressed. One very useful thing here (especially to avoid wastage) was a cheap digital scale. I bought this from a supermarket for $16 and used it to successfully mix epoxy down to 1g hardener and 5g epoxy. I recorded the weight of each batch of epoxy and I weighed the boat after each major application so I could clearly see the increase from 12kg prior to exterior glassing to 19kg after the fill coats were complete.

I found the fill coats a little painful. I seemed to never quite get the right amount on. I’d put a coat on, sand some off, then try again; many times over. What was particularly irritating here was that to avoid excessive exposure to the epoxy while curing I would make myself wait a few days before any sanding. The time just seemed to drag!

If I was doing it again I’d make two changes.

Firstly, I’d use a slow hardener and warm epoxy/conditions. I found that on a few of my (autumn) evenings the temperature had dropped to maybe 15C and the epoxy had thickened and would spread easily. You want it to spread really easily so a really hot day with a slow hardener would be a better combination.

Secondly, I’d use a random orbital sander more extensively. I spent far too much time continuing on with hand sanding when I should have just used the ROS. The pads clog up quick but crikey it does a hell of a job!

S&G Night Heron – Varnishing and Outfitting

I was initially unsure what to use for the final coat: varnish or polyurethane. The documentation on the net seemed a little confusing. In the end I’ve gone with a varnish from Altex. Not sure if this was the best choice, I suspect it’s more expensive than the equivalent products I could have just bought at Mitre 10 or Placemakers. Nevermind.

The can said 6 to 10 coats. I think I’ve run up 7 on the top and 6 on the bottom. Hard to remember!

I used the ROS with 180 grit pads and this seems to produce a good surface. I’ve still got a fair 250mls left so I’ll put that on sometime in winter.

I enjoyed this part much more than the epoxy. No special safety gear required and it could be done at an enjoyable pace.

I put the kayak in the garage – there was some dust but it pails into insignificance when viewed from a few feet. Runs were definitely a problem. Sponge applicators helped but invariably I’d come back the next day and find a few runs that had formed.

For the outfitting I’ve kept to a bare minimum, at least for the moment. I used window weather stripping for the hatches – seems a bit leaky but I’m sure I’ll be able to tune it better.

I used plastic foot pegs; very light but they also seem a bit flimsy. In retrospect I’d go aluminium.

The back rest provided in the Night Heron plans seems quite effective without any padding. In fact, I spent $80 on closed cell foam and so far haven’t put any in yet, but it doesn’t seem to be especially uncomfortable so I’m in no great rush to finish it.

For the spray deck I ended up, after a few false starts, with getting one made by someone (Gabi) in Nelson. You can get hold of them on TradeMe and I’d recommend the product. Other options include Rasdex and BackOfBeyond.

And the final result? Well, here I am on the inaugural launch in the Waikanae River at the Otaihanga domain. Beautiful spot; you can head out at high tide down the 2kms to the river mouth, play in the sea, then come back with the salt water washed off in the river.DSC03342


In the end I guess I spent 10 hours / week from the middle of November 2008 until the first week of March this year. So that’s about 160 hours. The cost is approximately $1000. It’s easy to spend more if you don’t hunt around for good prices on ply, fibreglass, epoxy and varnish.

And performance? Well, I’m very familiar with the plastic sea kayaks that you can hire. My Night Heron is faster, feels more manoeuvrable (and it doesn’t have a rudder) and it’s much lighter. So all in all – I LOVE IT!