Building by Numbers

P1040496S

Completed

  • 2.5 months since planking started mid May 2017
  • 1.164 km of planking, fetched and carried, brads removed, sanded, cut to 36mm width and straightened, scarf joined, fitted up and edge glued and nailed
  • 4.08 minutes per linear meter to recover scrap strip planks =  80 hours
  • 2.08 minutes per linear meter to cut and glue scarf joins = 54 hours
  • 60 minutes to fit up and edge glue one plank = 110 hours
  • 150 grams of epoxy resin ( excluding fillers) to edge glue one plank = 16.5 kilograms of epoxy resin
  •  244 hours to date for planking

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Still to go

  • 30 planks to go = 300 linear meters = 30.8 hours for recovery and scarfing + 30 hours to fit up and edge glue = 61 hours

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Its time to plan to end planking. The keelson trailing edge is dressed to provide the correct angle relative to planking by extending the power plane’s base with a batten to give a rough finish angle. A follow up with a shooting hand plane will get the angle exact relative to planking. Its also time to add a harness, and maybe a hardhat, to the shopping list.

P1040507S And now also to improve scaffolding as there will be yet plenty of work to come at height. Thanks to Colin H at least I have the basics. AND now you know what the ropes are for!

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Breaking News

Abhilash Tomy will launch his Suhaili Eric Replica built at the Aquarius Boatyard in Goa India, tomorrow 7 August 2017. Looking good…

Abhilash-Tomy-Boat S

Don McIntyre the founder and organiser of the Golden Globe Race 2018 has made a pre release announcement in the The Coastal Passage magazine (free emag worth subscribing to..) of his steel Joshua One Design (as sailed by Bernard Moitessier in 1968 Golden Globe Race). At 15 ton she is twice the size of the Eric (8700 kg). More information in TCP #85, pages 13 and 14. In theory the Joshua will be 21 days faster that the Eric for the GGR see Still Planking Blog based on average speed to length ratio for heavy displacement boat speed. For owner builder GGR entrants a Eric CSP one design offers an alternative solution. More to follow…

GGOD sImage TCP


 

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Still planking after all this time

The end of planking is almost in sight, but formwork is now required. And a friend has offered me his scaffold planks and trestles. Amazingly how help just keeps coming at the right moment.P1040411S

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During the mindless recovery of cedar planks it occurred to me that this boat will be doing a lot of shovelling. Lightship (empty) displacement is about 8 tonnes. The boat length is 10 metres. Every time the boat moves one boat length of 10 meters, 8 tonnes of water is moved aside. If the boat is sailing at say 5.4 knots or 10km per hour. it is moving 10km/10m = 1000 boat lengths per hour. AND that is 1000 x 8 = 8000 tonnes of water pushed aside every hour. Or 192000 tonnes per day. For a 300 day GGR that is a staggering  57600000 tonnes!


 

 

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.