Only 2.5 days this week due to a branch falling on the power lines behind the sheep shed. The joys of a farm build site.
Big news is that Rob R donated a fridge and microwave! Cold drinks make a huge difference when it is 35C and high humidity. He also bought in a box of delicious home grown grapes, most of which I devoured on the drive home. Too much sugar, my brain was still whirring (in circles, unfortunately) at 2 am.
We got the sides on one 6m end of the lee hull. Several lessons learnt, but it all ended well. Male and female joins on flat panels work well. Right angles are easy. The volunteers got the 2nd deck/bottom infused, looks good apart from a kink where the mould frame moved due to too small a bag. A pretty easy fix, but probably not worth the effort. They also prepped the 3rd piece for infusion. Bulkheads are next. I am making these by adding stiffening (the eps from Bunnings, $Aus50 for 30mm x 2.4 x 1.2m/1.25″ x 8′ x 4′) to one of the side panels which is of dubious quality. It was a great infusion, but a cold night. The next morning, to ensure it had cured enough to demould I heated it without vacuum. The resin softened and air got in. Patience, grasshopper! Square section hulls are so easy to make, it is a pity they look so ordinary. 800 x 800/32″ x 32″ looks small on 24m/80′ long drawings, but the 6m/20′ piece is quite large. Certainly large enough to get inside to install the bulkheads, which will make it easier. The first truss we built is a 2D piece of beam size. Rob R adjusted the test jig to take it and magnify the weight by 2.5. Loaded it up and at 500 kgs/1,100 lbs, the diagonals buckled, but due to the shape of the sample, didn’t break. Fascinating. We will beef up the diagonals and try again. Rob R has also made the bottom piece of the ‘light, easily broken’ sample beam. Diagonals and testing next week, followed by some table repairs (grinding off resin which did not go where it should during infusions) and full size beams which will be a change from making flat panels. We are still having discussions about how to build the beams, so it’s probable that they will be different.
Another busy week, the students are now good enough that we can use some more volunteers after Xmas when the next shipment of materials arrives.
The photos show:
The 3d printed mould for the rudder leading edge. This will be built in short sections which are sacrificial. Damage one section and it is easily replaced. The rudders should kick up before damaging the actual join.
The bridgedeck panel with holes drilled for the strings that will support it. The aim is the benefits of a tramp and a solid deck: impermeable to water upwards and dropped items downwards without the weight, cost, tension and build drawbacks. Of interest in the unrolled panel is the pink stain. Each time we infuse, I wonder where the first drop of resin to enter the laminate ends up. We added red dye to the first mix to see. It spreads out from the resin inlet, indicating that the first area to cure is that closest to the resin inlet, but excluding the spiral hose resin feed line. This implies that resin added towards the cure time will flow to the dry laminate, not get stopped by cured resin, which is great. Seems obvious now, but didn’t before.
Coreless bulkheads. Bit more work and a little heavier than say 600 gsm either side of 20mm foam, but a lot stiffer and cheaper. The next ones will have half the laminate, and flanges on all sides for easy fitting in the lee hull.
Cork cored step. I had a sample of cork which we infused to see how it went. Soaked up a lot of resin, but looks nice clear finished. The only non work boat part of the fit out until someone scratches it or drips paint on it. Also the only wood in the boat so far.
Lee hull bow panels: The volunteers arrive at 10 am, remove yesterday’s panel, have an hour for lunch and lay up today’s panel, which we infuse at 4 pm, go home at 5.30. Panels are 5.6m/19′ x 0.8m/32″, 8 layers thick, plus female joins on both sides. The surfaces are paint ready, no one needs gloves or suits, and assuming 1:2 resin:cloth, the waste is about 150 gsm/0.5oz per sq. If care is taken, the tacky tape and the plastic mould release sheet can be reused, despite me ‘knowing’ it was not possible and advising against it. The record so far is 3 infusions on the same tacky tape and plastic, and a large mouthful of humble pie for me.
Ring frame edges: Ring frames are usually cored with a back filled edge and a minimum of 150mm/6″ wide. We have halved this and put a rounded, solid tow edge on a non cored laminate. The result is a very stiff, strong frame that takes up less room. We will be exploring the limits to this when we add some new shelves and frames to the galley and nav areas on the ww hull.
Access into the hull was not easy, so I lowered the top step. Much easier to get in and out, but a couple of day’s work which may be unnecessary when we see how the deck and hatch work.
Half stub mast mould with pultruded carbon strips. Bit of a learning curve which will come in handy for the masts.
Toy box bulkheads. The toybox has been much more work than I anticipated and I am still not sure it will be stiff/strong enough. Easy enough to add more laminate, but we are also looking at more radical solutions, similar to the bridge deck support. Assembly will be a lot of fun/brainstorming.
Toy box hinges: The edge stiffening tubes are used as hinge pins for the toy box covers. Takes longer, costs nothing and requires no metal or fastenings. Should be nearly indestructible.
WW hull floor stringers: These will be included in the infusion in future. Possibly with non structural foam, but more likely hollow.
Xmas party: Highlight of the week, put on by marvellous Martin, the UQ prof who made the build possible. We spent the morning tidying the shed, finding lost tools and throwing out stuff that ‘might come in handy, sometime’ and the afternoon eating pizzas and talking.
December 2020 #1
Time flies when you are having fun. Which I most certainly am. Got the toybox assembled, the ring frames in it and Yvon and Dong laid up the lid for infusing. Learnt some catch pot tricks and how to make a too small vac bag bigger. Surprisingly (to me), this was a success. Prepared the bulkhead infusion. Be interesting to see how/if these work. Turned the tender over to work on the bottom.
Rob R got the first rudder ready to join, Nakul CNC cut the frames for the stub mast mould and Sylvia 3d printed some sheaves for the model beam diagonal construction.
Teguh set up and infused a 30mm sq x 300mm long sample containing 250 pieces of carbon tow. This is the likely laminate for the beam if carbon is used. One end worked, the other was dry in the middle. We will have another shot this week, with a different arrangement of fibres. He also built some of the tubes for stiffening the toybox edges and acting as hinge pins for the lid. I spent most of it organising/running around not doing much, but spent the quiet time (6.30-8 am) before the troops arrived getting most of one hull of the tender ready for applying the copper/epoxy antifoul. This is definitely an early morning job as we are getting 30C+ days with hotter to come. Decided to keep the ww hull in the shed for a while to avoid anyone getting heatstroke. I also glued a stringer in the ww hull bottom to see how many would be needed to stiffen it up. Not as many as I thought and it is far easier and more pleasant than adding a floor to a round bilge hull. Also designed the steps, which will add more stiffening.
This week; Rob R made an anchor roller for the tender and a f’glass anchor cleat from a test piece offcut, then a neat mould for shelf edges which will jazz up the ww hull interior. I played with edging the ring frames with glass tow then Roan and Sylvia did it better. Put in some offcut windsurfer masts as handholds near the hatch. We joined the toy box. It looks bigger than I thought (8.5m/28′ x 1m/40″ x 500mm/20″), room for 4 friendly double beds, which increases our visitor potential significantly! I showed Nakul and Teguh how to cove and left them to it. Neater than me. My management skills are still not wonderful, but it is great to be able to stand back and see what is happening and come up with improvements, which does not always happen when I am immersed in doing the job. The first ring frame took me 30 minutes to install. The last one 2 minutes. Nakul cnc cut the rudder mould supports at the UQ Maker Space (a magnificent set up with a large range of technicians, tools and equipment that the students can use to build things) and attended the latest round of testing. The results show the ultimate compression load of the specimens and the area under the curves indicates their stiffness. The samples are short so that they fail in compression rather than buckling. The civil engineers finally impacted a concrete beam with no fibreglass on it. Smashed it, concrete all over the place. The glass makes a huge difference. They are now finished and we can move the ww hull outside, turn the tender over to complete and epoxy/copper the bottom and set up individual projects inside. Joining the rudder halves, infusing tow under tension, a model beam that will break in our test jig, stub masts, tube manufacturing and infusing the toybox lid, test bulkheads and the cockpit floor.
An interesting week. Finished attaching the topsides and deck to the ww hull. The structure is starting to stiffen up nicely, but some of the panels will need stringers added. Experimented with recycled glass chips from Rob R’s swimming pool filter as non slip. Applied them to a piece of fibreglass and wiped my size 11’s on them each time I passed. No noticeable damage so we will use it on the tender when we can figure out a reliable application method. The grip is excellent, even when wet, but falling on it will probably draw blood. see pic The areas are reasonably small so this should not be a problem. We are running out of materials to finish tabbing the ww hull and fine tune the truss beam samples, so started on the toybox. Volunteers prepped and infused the bottom on Wednesday/Thursday, and we’re almost ready to infuse the sides on Monday. The bottom looks good, (see pic) we are experimenting with some stringer options on the rest of it. Interesting to compare it with the tender panels we started with. The higher ambient temperature, Rassy scales, leak/bat detector, gauge, catch pot, unlimited amounts of reusable tacky tape and experience with the set up result in a more relaxed approach and accurate result. I am placing an order, so anyone who wants materials from China at half or less the price from Aus, should let me know this week.We added composite ends to the first full size truss sample so we could test it and Rob R adjusted the holder to suit. We made and split a 50mm dia glass tow sample to assess the straightness of the fibre and toughness. The tow alignment was not perfect, but it took a lot of work with a big hammer and chisel to split it. see picRob R built a neat composite fitting for the tender anchor, including fibreglass roller axles. The simple first one did not allow the anchor to sit flush. I had a fascinating conversation with a group which has developed a solar panel that produces hydrogen. Not ready for production yet, but they may supply us with some normal panels. We’re also having a conversation about a Pacific shipping line using cargo proas. Rob R and I spent a day at Uni watching some compression tests on truss members we made. They are stronger and have higher fibre resin ratios than expected but lower stiffness, not sure why. Means the beams may bend, but are unlikely to break. We are looking at options including deeper beams, using carbon in the horizontals and better process control. Also had a look around the labs and some interesting projects including sonic testing of composites, producing carbon/carbon laminates with exceptional properties including heat resistance better than steel and a scram jet test tunnel activated by compressed air blowing a 150mm dia hole in a sheet of 3mm thick steel. Highlight was the Maker Space workshop for student use including a dozen 3d printers, lathes, water, laser and router cutters, milling machines, a robot laminator and a bunch of friendly helpful technicians to help and advise. If there is a heaven, I expect it will look something like this. ;-). I am working on getting access. Thanks Martin and John for organising the visit.The full size truss beam laminate range is narrowing down. Looks like it is going to be smaller than originally expected. We are also reassessing the full size build method so we can infuse as much of it as possible and not have contact with wet resin. Not quite there yet, but each iteration is less messy than the one before it. PhD students exploded some fibreglass wrapped concrete rods in the shed. 16 ton end load, and a 4 kg steel projectile fired into it at 80 kph/50 mph. A loud bang, but surprisingly little damage. On one test, the projectile was ~20mm/0.75′ off centre. The impact sheered the 6 x 8mm/0.3″ bolts holding it together. Fortunately, we evacuate the shed for the firing. The little boy in me is waiting for the non wrapped concrete tubes to be impacted. Should be concrete all over the place. 😉
Rob R says it better than I can: The second beam test again surprised us when we were still unable to break it. This time it was supporting in excess of 500Kg before the load tray started to bottom on the runners supporting the test bed. The test more or less started after we had stacked on the 274Kg achieved the previous test and checked the deflection compared to the last test. It was just a bit less than the first test so the new top web was a bit stronger and a bit neater. Both Rob and I were gaining confidence in the little beams structuralintegrity and were guessing 400Kg before failure and thinking 500Kg would be a magic unobtainable number. With the extreme load came extreme bending with 200mm of deflection proving the forgiving nature of composite materials.Having proven the material strength the design will now be tweaked for more rigidity. So more testing to come. Meanwhile work is continuing on the tender and windward hull while I have started on an internal model truss for the leeward hull, which of course we will be testing. Mostly just Rob and I working this week as it is exam time for the student volunteers. Rob has been going from job to job on the WW hull all the while trying to work out the best assembly procedure. A similar thing is also happening with the truss development as we try to come up with a plan for the actual truss beam build. Meanwhile the truss model experimentation continues with the building of a one fifth scale truss to go between the masts in the leeward hull. The truss building ideas continue to change and evolve leaving behind some cool ideas that seemed like winners at the time only to be replaced by more practical, efficient and less sexy concepts. I’ve lost count of how many tow wet out methods have been tested, with the best wet out so far being done by hand. Needless to say that won’t bepractical for a full sized truss where the tow numbers will be in thehundreds, instead of the 30 or 50 we have been using for the test beams. Amy and Teguh spent a day on the boat, graduated from cutting fibreglass to laminating it. Quick learners. Roan built a fibreglass axle for the anchor roller and installed it in the tender. Unfortunately, the cat sat on his 3d printer so the Opti rig is on hold for the moment. The solar panels for the tender moved several steps closer, and we have started talking with the Power and Drive people at UQ about motors and installation.