Still topping.

Epoxy screed

Epoxy screed

It is funny how I cannot give up being anxious over this hull bottom. If I were to sit with a psychiatrist I am sure they would diagnose some sort of obsession mixed with fear of completion. I am rationalising it by arguing the boat will never be upside down again…

Hopefully.

I expect the last thing you want to be going is working on it lying on your back, cursing the past when it was all at an arms length, waist level.

The other thing I am wrestling with is those little wicked creatures that sit on your shoulder and whisper in your ear, suggesting this or that.

My particular creatures come from the sail boat racing world, where speed is everything. The creatures are echoing my old racing friends criticising my choice of boat, questioning the rig….will it go to wind…blah blah blah.

I distinctly remember how impressed my friends were at a crew spending the morning before a race, wet sanding the boat for that extra speed. How dull. I recall discussions of re-fairing a hull for the next season (further cringing). I do not know why this bothers me.

So it is fair-ish. As you can see in the photo, I have screeded it. I used a builders trowel and epoxy thickened with micro-baloons to a fluffy-sloppy consistency. You will notice the wood showing in places, suggesting I have done some degree of levelling.
It still looks lumpy to my eye.

I asked Sensai Ayliffe for his opinion, and he gave me the “…but grass hopper, are you happy?” line. Exasperating.

He did suggest I lob off the forefoot and replace it with an epoxy-made sacrificial one. Which to my reasoning seems much easier than studying the fairness issue. So I bolted after this distraction.

Mould for sacrificial forefoot

Mould for sacrificial forefoot

Bow details

Bow details – how cool!

Posted in Epoxy, NIS, norwalk island sharpie, Robert Ayliffe | 9 Comments

Bottom topped.

Is work/life balance a thing to chase? Is just the energy spent chasing it, or feeling like you should be doing something wrong, destructive?

I am starting to think you can burn yourself out just worrying about the balance.

If your’re lucky, you will like your job and this makes spending time at work easier. I do enjoy mine, and it is rewarding. This year Kate has moved from focussing on her design business, to helping me redesign mine. She is a mighty talent, and I’ve never felt better about where it is going. However, on this boat build blog, this is starting to sound like an excuse.

The Sharpie has been a little neglected. I’ve made some pleasing progress. But it does mean the boat is not ready to turn over. Most of the past months have been fixing my unfair bottom.

Last weekend I afixed the third layer of 6mm ply just in time for some international travel. It felt so good leaving having reached a big marker like that.Last layer on, looking aft

I thought it would be helpful to detail the process of putting these strips on the bottom because there are some subtle shortcuts that I had learned by the last plank. I hope these help you, dear reader:

  1. Rip up your planks to 200mm wide in advance. Don’t be precious with the cuts, just make them as parallel as possible.
  2. Use weights to lay out each plank on the boat and mark off where it needs to be cut.
  3. Note any spiling that is needed. This does not have to be perfect. I had to narrow the planks at the end by upwards on 6mm. I did this by marking what I thought needed to come off the plank ready for planing.
  4. Rough cut it to length with a small hand-held circular saw.
  5. Plane off the excess at the ends to spile the planks . I use a Stanley rebate plane with guide fitted, it can fair long cuts and trim for spiling the very quickly whilst keeping the edge square.
  6. Refit the plank and check the spiling. It does not have to fit perfectly, a fit within a three millimeters is acceptable in my book and has been confirmed by Robert Ayliffe. If needed, mark for further spiling and plane off some more.
  7. Whilst the plank is back on confirming its fit, trace where it sits on the hull so you know where apply the glue to. Leave a weight on each end and number them in a way the orientation on the hull is clear.
  8. Trim up the next piece. You will need lots of weights. The further you can glue up in one session, the less cleaning up there is. If found I could do four to six at a time.
  9. Once the strips are cut and spiled, stack them in order.
  10. Starting at the fist plank, give both surfaces a light spray of water, then spread out the Purbond with a spreader, I found a 100mm wide works well. You will note the purbond goes whitish and begins foaming, you want to be clamping before it really takes off, so you can’t spread more than a full plank
  11. I think the most effective clamping is screws with plywood washers. The plywood washers need to be covered in brown packing tape to keep it removable. You will need a screw every 150-200mm. Even with the screws the pressure from the foaming purbond can distort things. So stagger the screws and put others in where needed. The critical areas are where the planks meet, so I overlap the washer from the next plank to the previous to help the mating.
  12. You will need to do some clean up as you go, as with any glue, it’s harder when it’s harder.
  13. Once you’ve gone as far as you can, keep cleaning up. The Purbond will keep oozing.
  14. When it’s set, remove the screws and clean up. If you have enough screws, you can just remove those on the leading edge and cleanup the squeeze out so you can continue gluing. A sharp chisel followed with a sander does well cleaning up.
  15. So there you are, after all that, all I have left to do before turning over is trimming up and rounding the chines, cutting in the centreboard slot…and…probably some serious sanding final fairing and the ‘glassing and then more sanding, then painting and then………..something else I’m sure.

Last layer on, looking forward

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It’s not fair!

If you have young children you’ll recognise the other meaning of this exclamation. Actually it’s not an exclamation here, I did expect to have to fair this hull, but I didn’t expect to have to do it so soon…

I think I failed when shaping the chine logs, not nearly enough attention to them, plus that first layer of 6mm ply can sag. Thus after the second layer lamination, I saw troughs that need filling before the last layer lands.

uggg

uggg

The process involves using epoxy thickened with ‘micro balloons’, they are fine balls that will sand easily but have a good compression strength (See BoteCote Pacific). You first wet the area with normal epoxy, then trowel the thickened epoxy on with a toothed scraper. I chose one with an 8mm tooth. The mix has to be just right, too dry and it is ‘flaky’ and too wet and the peaks sag. Too hot a day and you have no time to work, too cold and it will sag.

The tools.

The tools.

The toothed pattern left halves the sanding effort.

After you make your boat’s bottom super ‘groovy’, you hit it with a sanding board, aptly called a “torture board”. You get tortured and board all at once. If the board is long enough and you are careful, you will reshape the hull to perfection. The grooves are then roughed with a wire brush and filled in with more of the same thickened epoxy. A final sand brings the magic.

Torture and board

Torture and board

Christmas time in Adelaide can be too hot for this palaver, but luckily the season is just right, so I’ve poured time into this. It has been mindless and very physical but rewarding.

I would like to have been prepping for fibreglassing the hull and perhaps painting, and in my wildest dreams, turning the boat, but life got in the way and I am not unhappy.

Forgive the video, it is a bit long, even though I have edited out most of the scenes where I am mixing epoxy. The mixing is laborious, it takes most of the time, even the sanding goes quicker!

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Purbonding time-lapse.

I am still messing with time-lapse photography, I had intended for the entire build to be recorded, but the failure of the DSLR I had employed has left me high and dry. Leaving a replacement $3k camera bolted to the rafters is something I could not afford and setting up a remote control-able camera time-lapse system was out of my desire range. So I will settle with recording interesting snippets when they occur to me.

The action of this Purbond is fascinating, you will note it foaming during the clamp up, also watch for the bit towards the end when I dive inside the hull and prop up a sagging plank.

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Purbonding

ImageWhat a fascinating little product is this Purbond from Botecoat. It is much quicker to work with than traditional epoxy, or even e-glue. Just spritz down the timber with a mist bottle of water, spatula on the Purbond as evenly as you can, spritz the underside of the piece you are joining, clamp it up and watch it fizz.

It is bizarre, it foams up to a honeycomb look and It builds up quite a pressure, just using weights was not enough. It lifted my 14kg lead ‘helpers’ I was using to clamp the ply down! And give up trying to clean up the squeeze out, you get most of it, but then you turn your back and it’s oozed some more! By the time it is setting, scraping it off pulls too much out of the joint. Still it sands very easily, and a sharp chisel cuts most of it off. I really like it.

The big benefit is the gap filling. I am sure it is not very structural, you would not want to fill big gaps, but those voids that appear between layers of ply are well filled with Purbond. My sharpie’s first bottom layer was quite un-fair. The 6mm ply strips bend nicely over the bulkheads, but sags between them, so with the aid of some props I have made to push those pieces back up to fair, and the foaming glue, the second layer is much more yaaar.

ImageThe props are made out of scraps of timber, with a wing-nutted bold allowing adjustment to it’s ultimate length via a slotted piece of timber. The part I am most proud of is the glued-on piece of sandpaper that allows the wing-nut to lock up the two pieces. I have made four props, and may need more so I can attach more than one plank at a time.Image

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First layer complete.

ImageI am really please to have reached this mini-milestone. Whilst the boat would leak due to the gappy first bottom, it feels like a real boat!

My next task is to fashion a flexible prop to wedge up under the bottom so I can begin on the second layer. This is important because the 6mm ply flattened off between the bulkheads, leaving high points. I also have left the edges free of glue so the planks can move. The prop will push it back up and provide some resistance to the attachment of the next layer.

I am going to be using an unfamilar product for this next task; Purbond. Apparently it is very fast to apply and fluffs up with a mist of water, filling voids. I expect the speed of application has a lot to do with it being a single part glue…haha! No mixing!Image

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Bottom progress

First layer bottom plank looking port aft First layer bottom plank looking port forward First layer bottom plank looking stbd forward First layer bottom plank looking stbd to portI am pleased to announce my priorities are in order and I have been doing work on my boat, but not my blog.

It has been slow progress, and as usual, slower than expected and requiring more fancy thinking than expected.

I have been vacillating  over dealing with the gap between the flat keelson and the curve of the new stealth bottom. The 6mm ply makes a graceful but shallow arc that touches each edge of the 2o0mm wide keelson and lifts off it by about 6mm in the centre. The choice was to fit a piece of timber in there and shape it to the curve, or use the magic of epoxy.

I thought about it too much, then felt bad about not doing anything, then decided to go with epoxy because I was sick of my indecisive state and it seemed easier.

I am using a lot of thickened epoxy (e-glue). It is working and seems to be very strong. In hindsight I would probably have laminated a piece of 6mm ply to the keelson and shaped that. But….

Another decision I have had to make on the fly is;  the first layer of  strips of 6mm planking don’t exactly fit nicely edge to edge. This happens when one strip is on bulkhead and the adjacent one is not, the former always sits higher and makes a curve, the latter flattens between the touch points. I have discovered that by propping up the latter, you can make them join nicely, they will bend and stretch the few millimetres to match.

I have decided to not edge glue the planks on this first pass, this allows them to flex when I put the second diagonal layer on. I do prop them into position when gluing to ensure they sit on the chine logs, in the epoxy, at the right angle. I will edge glue them either when I am putting the second layer on, or when the boat is up the other way and I am working on the floor. That decision can wait.

Meanwhile it’s fun rapid progress, three planks at a session. Three planks equates to a single mix of thin epoxy to pre coat all of the glue surfaces. I could probably stretch it to four planks, but that would take away from the time needed to admire my work and drink tea.

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