Building Sandy Ferguson’s Mac50 ply/glass kayak.

Built and reviewed by Steve Dorrington

 

Figure 1 Mac 50 on the beach with two other plastic kayaks

The Mac50 is the second ply kayak I’ve built. The first was a Pygmy Golden Eye, which I built from plans back in 1996/97. The Golden Eye was a multichine design from John Lockwood and one of only two Pygmy Kayaks offered in plans form. I never did fit a rudder to it and ended up selling it to buy a small dinghy.

This was a mistake because last year I yearned for a kayak again and had to start from scratch. I’d paddled the Pygmy enough to know that I preferred a different design this time around. Something that had a little more rocker so that it was easier to turn and a lower sheer and volume for less windage. Wellington harbour has been known to get a little windy occasionally. While building the Golden Eye earlier I had found Sandy Ferguson’s name on the wavelength-paddling site. We had exchanged emails about suitable ply and once I’d made the decision to build another boat I called Sandy again and purchased plans for the Mac50.

The Mac50 differs from the Golden Eye in several ways. Its hard chined, has a curved deck, sheer clamps and deck beams. The Golden Eye had no sheer clamps or beams, the deck being stitched to the sides. It had a peaked deck and was glassed inside and out. The Mac50 went together a lot faster than the Golden Eye. This time I made the hull from 4mm marine glued Hoop Pine. This was a mistake as while the timber thickness of the ply were equal one of the sheets had voids at one end which weren’t visible at the edge. The deck is 4mm BS1088 Maranti. I elected not to glass the hull but to tape and glass the lower seams only inside and out. I didn’t enjoy sanding the epoxy last time but there was just as much time in fairing and finishing the hull that I’d glass any other boats I build in future. I also glassed the inside of the cockpit this time for wear and all other surfaces were epoxy saturated. The deck was glued, clamped and screwed to the shear and as I wanted a varnished deck the edges were not taped and glassed.

Figure 2 Mac 50 showing the deck beams, sheer clamps and bulkheads

The epoxy I used on both kayaks is from CRC ADOS. This was called Ancris Resamax and you can now buy it from CRC in Auckland (0800 367 349) ~$100 (trade price) for 5 litres (4:1 mix). You can get summer and winter hardeners for it but I've only used the summer hardener. CRC also have a range of fairing and glue powders, which I used, but when I ran out of glue powder I reverted to Epiglass HD120 glue power that was available locally.

To mix small amounts of resin to make glue I use a plastic kitchen measuring spoon set $3.50 from Woolworths. To brush the resin on I used small disposable 38mm brushes that I purchased from M10 for $2.10 ea. The bristles need to be shortened to stiffen the brush up but using them saves cleaning up afterwards.

I used a large ¼ round router bit on the deck/hull joins and the cockpit combing, top and bottom. This gives a smooth, professional and tidy looking appearance to the topsides. It certainly saved any planing and filing of these edges.

One trick that I did use was after glassing a join I’d apply a strip of polyester lining material on top of the tape/epoxy, smoothing it by hand with disposable gloves so that all the air bubbles were removed. Once set the polyester lining was ripped from the epoxy leaving a reasonably smooth surface to finish.

Figure 3 Mac50 showing polyester fabric applied to keel tape

Sandy’s plans leave ample opportunity to customise the Mac50 to your own design but I decided to build it stock. After all he has built and paddled far more ply kayaks than I have. Because the patterns are on paper I transferred them to the ply using a scriber, small brads and a long strip of thin fair timber to pencil in the lines. I then roughly cut two pieces from the sheet, bolted them together, (good faces to the outside) before cutting them both out. These were then joined on the floor with butt blocks and glue after aligning them using a string and the panel datums.

Figure 4 Mac 50 deck on, hatches and cockpit cut out

If you had feet larger than size 10 (UK) I’d add another 25mm height to the sides. Long legs would also necessitate moving the front bulkhead 100mm or so forward and the rear hatch opening could be smaller.

The hatch covers are two pieces of 4mm ply. The cutout from the hatch opening and a piece 25mm larger than the opening, were glued together by strapping them with ratchet strops to the deck of the kayak. Thin spacers and plastic protected the deck. Worked a treat!

The hatch rubber is ¼ round EDPM glued to the deck with nothing on the hatch cover yet. I spent a long time trying to sort out suitable hatch clamps. As for the Pygmy I used straps double screwed to the sheer clamps and plastic snap buckles. This time though I cut a strap tensioner from a 125x45x4mm piece of ply. This tensioner has two slots at one end and is threaded onto one end of the strap. Moving the tensioner through 180 degrees (over centre) opens or closes the hatch by tensioning the strap. I use a strap clip to hold the tensioner closed. It doesn't take up any internal hatch space and costs next to nothing!

Figure 5 Mac50 ready to go

So what did it cost?

~NZ$900, including the seat and rudder. It would have cost nearly the same using epoxy sheathing. $60 more and it could have been from BS1088 Gaboon which is much lighter! Final price is less than ½ the cost of a new plastic sea kayak, a lot more fun than buying one and a sure fire conversation starter on the water.

How long did it take?

Started in January 2003. Finished at the end of April 2003. Four months from start to finish. I didn’t keep a record of the time but spent a lot of time hunting for the right bits. I also wasted a lot of time workshop paddling and waiting for epoxy, paint and varnish to dry.

Final size

LOA 5.1m

LWL 4.8m

Beam 0.61m

Weight 25kg

Sources of materials

Ply City Timber

Sheer clamps 20x20mm Pine. City Timber

Deck Beams Laminated Cedar (scrap)

Epoxy ADOS Epoxy 4:1

Cloth Almac Cars

Polyester material Spotlight

Rudder /pedals Fergs Rock & Kayaks Quality Kayaks kit $255

Paint/Varnish Barton Marine Epiglass single pot polyurethane

Deck Fittings Barton Marine

Hatch rubber Rubber Bits (EDPM)

Hatch straps/clips YKK (NZ) Ltd

Gloves NZ Safety

 

Things I will do differently next time

1 Paddle during summer; build kayaks at other times of the year!

2 Only use BS1088 Ply.

3 Epoxy/sheath the outside of the hull. Just as much work as not doing it and more robust long term.

 

Mac 50 Update
6 June 2003

Additions since launching

After the initial launch and paddle around Wellington harbour serious thought was applied to a seat back. In the end I borrowed Nick Schade’s Guillemot design and built the seatback from scrap ply, suspending it using 1” webbing and leftover bungee cord. It now has a 5mm foam rubber facing glued to it. Rubber Bits supplied the 25mm closed cell foam for the seat bottom that, on Pete Notman’s suggestion, I sculpted with an angle grinder to a bum shape. Rubber Bits also supplied the 5mm foam glued to the underside of the deck and 10mm foam glued to the cockpit side cheek plates. I’ve discovered Ados F2 now comes in a spay can. No brushes or mess and simply brilliant to use!!

Total price for foam, F2, strap & clip $43

I’ve had four trips on Wellington harbour in the Mac50 now. Two calm ones on the inner harbour, one off Island Bay paddling out past Taputeranga Island down to Owhiro Bay and back in a 1-2 metre swell and last weekend in 25–30 km/hr North Easterly winds from Worser Bay up past Scorching Bay to Mahunga Bay surfing back in ½ metre waves.

What’s it paddle like?

The Mac50 handles very easily. I’m a novice paddler who’s done the basic paddling course at the local pool. My only other experience was a five day trip down the Wanganui river, a day trip around the outer islands in the Bay of Islands, and a couple of short trips in the Pygmy. I found with the rudder up the Mac50 is extremely manoeuvrable and turns easily with a sweep stroke and bit of lean. When the rudder is down the boat tracks straight and is less susceptible to paddle strokes affecting the course. I was surprised at how stable the kayak feels even with more V in the hull than Pete’s S&G Guillemot. I expected more initial instability but was pleasantly surprised at how immediately comfortable it was. The Mac tracks well and doesn’t bounce or slap on small wind generated waves. Pete commented that it appears to cut through the chop really well. It’s also not affected by cross winds to any great degree.

I’m really happy with the design and the resulting boat. It’s everything I had hoped for when I started looking to build another boat and perhaps not surprisingly I can’t wait for the next adventure.

More information on the Mac50 can be found here

If you have any questions about the Mac50 e-mail Steve here:- Steve Dorrington