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Solstice Planking

On the 21st June at noon local time the sun, directly overhead it seems had no problem tracing an imaginary path around the world at 23.5N latitude as the Earth rotated creating the Tropic of Cancer on Winter Solstice (for us down under).summer-solstice-large  Image – NOAA

My planks are not so easily directed and prefer meridians following a great circle path. Consider a plank running along a lines of latitude on each edge. The sphere’s radius is smaller on the pole side but the planks edges are the same length so it is deflected towards the equator.

The rugby ball approximates the Eric’s hull shape, the first green tape almost follows meridian and starts to kick up (downwards on the ball) at the ends. The orange and subsequent yellow tapes are displaced significantly down towards the ends.

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As my planking progresses in parallel runs similar to lines of latitude it starts to get very unhappy as tension and compression forces built up in the opposite edges. This compounded by wind tension as the planks are twisted. Running a wider batten  flat against the hull surface establishes a happy curve for the planking to follow.

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Cutting off bits of boat is not so happy.

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The unhappy planks are soon replaced and with happy planks, much easier.

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Despite happy planks progress is so slow, a tack to change course may be needed, but not just yet. The GGR 2022 has been announced by Don McIntyre in the TCP magazine a free e_magazine which is worth a read.

GGR 2022

For the GGR 2018 my goal is to improve on Suhaili’s time in 1968 of 313 days according to wssrc. Based on a distance of 30000NM the average speed was 4 knots. .
PT 1

Displacement yachts seldom exceed a speed to length ratio of 1.3 , with 1.5 just possible. The typical average Speed to Length ratios is 0.9.

Marcaj.C.A – Aero-Hydrodynamics of Sailing

Achieving an average Speed to Length of 0.9 would result in a RTW time of 265 days for an Eric design or 221 day for a Joshua Design.

PT2


 

Taking Shape

Nine of the eighty or so planks are now laid and edge glued. The boat is taking shape, a very exciting time. One of the planks cracked and broke between bulkhead 10 and 11 today, hence all the clamps. First thing tomorrow a further three planks each side will be fastened. Each plank is 10.4 meters so a total of 12 per side x 2 sides x 11.4 = 260 linear metres of planking, done. Each plank is 36mm wide, and allowing for 100mm offcut each end gives almost 9 square meters of approximate total of 40, done.

P1040237SThere are a few more lights in the shed and with tarps for walls its getting quite cosy.

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Standing on my head and looking forward one gets an idea of the sweeping sheer.

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First nine planks with edges planed off. Very soon I can remove the jig extensions to get better access as the hull ends are almost self supporting.

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If you think this is a lot of work try this planking a longboat. Have a look at the bow shape when the boat is launched, remarkably similar to the Eric’s bow.

One more photo, I love these lines.

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At last some planks

First three planks glued in position, at last.

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I extended the jig to get a strong secure mounting for stem and stern post.

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Temporary battens at 1/3 and 2/3 midsection girth to check planking run. The batten nearest to the keelson kicks up at fore and aft. The runs seem easy with my 36 x 19 mm strip planks. The original design calls for planks 120 x 32mm which would have been a challenge!

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Final shaping of the keelson

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Then drill the ballast keel bolt holes.

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Then clean up bulkheads and prepare for planking.

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A trial dry fit of planking.

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Then final checks to ensure bulkheads are straight.

And after a number of trials planking is fitted to starboard side using finger clamps and stainless steel brads.

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Reclaiming Cedar

About ten years back I was able to rip and recover the western red cedar planking from the central section of a Volvo 70 mock-up. At the time I had no idea what it would be used for, except that I hoped it would be an offshore boat of some description and likely to be 9 to 10m length overall as this is I believe the sweat spot for affordability, accommodation and minimum off shore capability. My lunch breaks were spent dodging brads as they were shot out at high velocity whizzing past my ear by the circular saw nail cutting blade. Those that could not be dodged and made contact created a warm sticky mess with my ear lobe dripping blood down my neck and resulting in frantic clean ups before heading back to the office.

OLYMPUS DIGITAL CAMERA

The Eric midsection half girth is about 2.5m. The recovered strip planks 36mm wide. So 2500/36 = 72 planks per side. Each plank is about 10m long so 72×10 = 720 linear metres per side. A total of about 1.4km of planking required. At AUD  $5.30 per metre I hope to save almost $7500 on material costs. BUT there is some work in this.

First I must remove the remnants of the brads, fortunately they are stainless steel so apart from damaging tools and fingers they won’t case much harm if the occasional one is overlooked.

Nail nippers then..

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.. an old matador nail extractor passed on to me by Bill our neighbour when moving to retirement accommodation, he was in his mid eighties, many years ago, are the tools of choice.

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Then the faces are lightly sanded to avoid losing too much thickness using a bench mounted drum sander.

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And finally thicknessed and straightened to 36mm.

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And stored ready for scarfing.

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In the foreground is the penultimate bulkhead #7 with laminates just finished after grinding the edges.

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At about 34kg I can manhandle back to the jig.

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Bulkhead #5 the last bulkhead only needs a light sheathing and keel floor laminates. But the Elu sander had had enough, and seized the lower bearing. All fixed, but now can only resin coat tomorrow AM.

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Almost ready for planking

The plan is now to have everything finished to allow planking to start on the 1st. of May.

  • Bulkheads need finishing
  • The scarfing area needs to be set up
  • Sternpost (deadwood ) needs to be chamfered to suit planking
  • Keelson needs to be trimmed and fitted.

Starting with Bulkheads:

  • Bulkhead #5 needs sheathing and floor laminates , both sides.
  • Bulkhead #7 needs sheathing and floor laminates, one side.
  • Bulkhead #9 needs sheathing and floor laminates, one side.

The weather is perfect , 11 to 26C. But getting through the work is taking so much time, why? I took a few photos to get an idea., a bit of time and motion study.

After removing the 47kg bulkhead from the jig  and moving it to the flat bench, the first job is to remove the epoxy/colloidal silica/western red cedar flour glue. I add a touch of wood flour to keep the glue line dark and unobtrusive. The old Hitachi belt sander with 80grit paper makes short work of removing the hard resin without digging into the soft birch plywood. The bearings sound like they need regreasing, there’s always unplanned work. Actually, before sanding I first gave the bulkhead another wipe down with oxalic acid to remove any traces of black mould.

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The good old Elu orbital kicks up a bit of dust whilst removing the belt sander score marks.

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Confession Time! It looks like I did not allow for planking thickness when preparing the CNC cut files.

BHD 9

Fortunately its a case of removing material, first I need a fair curve to cut to.

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Then a very careful jigsaw cut.

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Right, all done. That was a stupid mistake.

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Now to mix up 130 grams of epoxy per square meter as a seal coat. This bulkhead is about 2.5 square meters, so 130 x 2.5 = 325 grams. I’ve mixed up 320 gram of resin plus 80 grams of hardener giving a total of 400 grams to allow for waste. The scale photo below is for the resin only.

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On it goes.

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And while it soaks in, I can cut glass.

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The day is warming up and we getting typical outgassing from the plywood.

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After an hour or so its time to squeegee to remove excess resin.

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A few hours later and the epoxy resin has cured sufficiently to allow the plain weave sheathing to be applied. To reduce waste I’m using offcuts in the bilge area. The epoxy is just tacky at this stage.

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The puzzle joins get an extra double bias tape reinforcing.

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Its 1AM next day, the integral floor reinforcement laminates are done, and a peel ply  added. There’s condensation on the tin roof, a tarp is rolled over the bulkhead to keep it dry and protected from drips.

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A quick glass of buoyancy wine, and then bed.


 

TC Debbie, Black Mould, Fore cabin

Interior view 2

Hamilton Island saw some incredible 100 knot winds with the arrival of  TC Debbie last week.

TC Debbie
Sail World Australia

Fortunately my shed is almost 1400km South of Hamilton Island and apart from a lot of rain and damp, no damage.

hamo
goggle maps

A bit of trench digging kept the water run off level below the shed floor and kept it relatively dry.

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And a liberal rubdown with oxalic acid to get rid of the black mould on uncoated plywood panels resulting from the damp.

In between the rain showers the internal panels were sheathed with a single 200gsm plain weave Eglass cloth in epoxy resin. This layer will keep the plywood dry and protect it. Tropical timber is naturally decay resistant, birch from Finland has little immunity and the sooner all plywood panels are protected the better. Sealing the panels will also prevent warping.

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My main objective was to finish the fore cabin panels.

structure

The anchor locker is located under the sole at the aft end of the cabin.  Spot the lunch pick!  The black water tank will be located in the bilge area immediately aft. Then three fresh water integral tanks under the saloon sole.

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One day the fore cabin may look a bit like this

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At the moment there is only a slight resemblance

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Moving aft in to the heads area, we have a bucket, almost done.

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According to the redline concept mark-up the heads will be big enough, just.

arrange redline

Interior view

Back to work…


 

 

 

Tarps are off, tarps are on

Its seems to have been raining non stop since Hobart, the rainfall records show 180mm so far for March, with shed floor 20mm underwater it was not really conducive to working. Progress has suffered badly. Building walls seems to be the “cure all”  fix these days, so I have done the same and the 2100mm high wall on the southern side has made a huge difference in reducing wind born rain ingress from that that side. Roller doors and polycarbonate sheeting above the wall are high on the shed building priority list.

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Before erecting the wall it was necessary to move the boat. A hydraulic jack made quick work of pushing boat and jig about 300mm further into the shed.

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In gumboots I took the Chinese jack hammer to smash a few rocks in the ditch that were causing a hindrance to water drainage. No more water over the shed floor. I really should not complain as the first three William Atkins Erics built for Henry Bixby appear to have been built outdoors exposed to the Huntingdon Long Island weather with average annual temperature of about 11C and 1138mm rainfall.

3 Erics - Huntington HarborFaith, Hope and Charity the first three Erics under construction by Richard Chute.

Of Yachts and Men – William Atkin

I’ve been concentrating on cutting all the internal panels which could have been done on a CNC router.

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The cockpit was tackled first, two panels run from deck to hull forming a water tight compartment below the shallow cockpit locker sole which is at the same level as the cockpit sole allowing any water that finds its way into these lockers to drain into the cockpit well. The buoyancy compartments will be filled with used milk bottles.

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The bulkheads form part of the furniture.

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Bunk tops and sides extend to the hull creating a strong structure.

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A peek inside the forward cabin which will used for sails, tools, anchor and ground tackle and equipment spares.

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The main cabin looking forward from the engine compartment with galley on the left hand side and water tankage below the cabin sole.

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And finally the pilot berth bunk top.It will be snug.

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And the Engine Compartment and ice box access to the right, looking aft.

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