August 2020 #13
Starting to take shape quickly now. The tender is eight and a half meters long. It is just the boat to go ashore with the ferry itself will be 24 meters long. So we literally have a big job ahead of us.
August 2020 #12
Due to circumstances beyond Rob’s control there was no work Monday. Howeveryesterday and today was business as usual. I have managed to prepare andinfuse the 3rd tender bulkhead. Rob cut me loose and let me do it on my ownwhile he and Roan busied themselves on the deck mold, glass layout andbagging. That will be tomorrow’s excitement infusing the first deck half asit’s a pretty complicated looking layout. Again the cautious decision was made to only do one half at a time so there’ll be a second infusion needed, which will probably be next week. Helping to speed up the cutting and layingout process this week is our brand new electric scissors. I think Rob willfind it’s some of the best money he has ever spent – they’re fantastic!
August 2020 #11
Demoulded the tender bulkhead and glued it together. Looks good, but a lot of work. Laid up the second one. Infused the first tender floor, which went well.
Laid up the second tender floor and infused the second bulkhead. Went well so we infused the floor as well. Vacuum was lousy, so we added a second, small pump. Bang, down it went. However, as the infusion progressed, the flow rate slowed alarmingly, including missing an area where there was obviously a leak in the table which probably would have shown up if we had a gauge instead of doing a pull up test. We swapped pumps with the bulkhead, which helped, but not much. At about 6 pm, the flow stopped, presumably because the resin had started to gel in the feed line, so I broke my promise not to fiddle and inserted two more feed tubes. These worked reasonably well, so I plugged in a third, which hardly worked at all. Almost certainly because the fiddling had caused leaks. The resin gelling is caused by the occasionally excessive heating we expose it to to get it up to the recommended >30C in less than 20C ambient. It would be less hassle, but more money to buy winter hardener. I turned the heaters off and left at 9 pm with about 10% not wet out.
Next day, dry area had halved so I removed the bag, diffusion cloth and peel ply and applied resin with a brush and hot air gun. Wet out 5 layers of 400 gsm and the stripes in the peel ply against the mould became visible. Later in the day, we removed it and there was no visible line so presumably it is OK.
July 2020 #10
Prepped the table for the tender floor, Rob R laid up the foamless bulkhead and Roan did some more tests, including a successful Soric one and a less successful tow in pvc one. He also serviced the vac pumps, which now work much better (more suck) and 3D printed an adaptor for the pump inlet. Handy guys to have around.
Rob R infused the bulkhead, looks good. Used a bit more resin (2 kgs vs 1.5) than expected, but there are a lot of places for it to hide. Will see tomorrow. The 1st half of the tender floor is ready to go when the pump is available. There are 4 components that require a wide table (ww hull sides, tender floor and deck). Decided it is less work to build them in halves and join them rather than extend the table. Plus the joins are all in the floppiest part so will act as stringers. Another test piece seeing whether perforated plastic between 2 layers of 6 x 400 uni would work. It does. We will probably lay up both deck halves in one shot, possibly also the ww hull halves. Volunteer insurance is apparently sorted, should have a few more workers soon. Weighed one of the tender hull shells: 50 kgs/110lbs. Not bad, on course for <150 kgs all up.
July 2020 #9
Roan and I joined the other tender hull. Easier than the first one. Had an idea for a foamless bulkhead, should be ready to infuse soon.
Tender information: LOA is 8.4m/28′, hull beam 650mm/26″, BOA 2m/6’8″. Reasoning behind the hull shapes: It needs to carry a ton or so, fit between the beams and have room for solar panels (some of which will be removable or on a raisable roof). The hulls have no rocker as they will always be trimmed bow up. They are double ended to avoid submerged transons under high payloads for drag minimisation. It is also easy to build, but adding rocker to the mould would not be difficult.
Previous pics and reports are on http://harryproa.com/?p=3788 and https://www.facebook.com/Harryproa/?ref=page_internal
Explanatory notes at http://harryproa.com/?p=2561
July 2020 #8
Glued the hull together. Remarkably quick and easy. Did some more test pieces, some successfully, some not so much. Prepped the other half hull for joining. Had a meeting with the other partners to discuss samples for testing and meet the engineer who will be doing the FEA stress analysis and laminate details for the beams, mast and hulls. Ordered some samples of an interesting ‘eco resin’ for testing.
July 2020 #7
Infused. Best one so far. Used 16.8 kgs of resin with double the weight of laminate (only one layer of flax, the rest uni glass). Rob R and Roan controlling the measuring and the temperature meant I could spend time watching and worrying. But not fiddling, which often leads to problems. Fun part was using the temperature to control the resin flow. No heater on the part near the vac outlet meant the resin front got to the end of the spiral, then evenly to the end of the laminate. The three of us should be able to produce a 9m/30’ panel every two days with time to spare for joining components next week.
July 2020 #6
Beam sample infused (see pics) although far from perfect due to the inlet port losing contact with the spiral and an unexpected (as always) resin raceway developing. Will try a second infusion next week. Glass tow infuses easier than carbon. Laid out the third half hull. Female joins on both edges which made it finicky. Rob R made a cool set of scales which saves 500 bucks and made weighing much easier. “No glove” measuring and mixing (ie, no contact with the epoxy) is now reality, the resin bench is near(er) pristine and we can look at further fine tuning of the layout, heating and minimising materials.
July 2020 #5
Too cold last night for the resin to cure so spent today repairing a couple of small infusion misses, moving heaters around and making a mould for the beam sample. Infused it just before we left.
Spent the morning driving to the docks to get the material (1 tonne/ton) from China. Unloaded it solo, should sleep well tonight! Have now got the glass tow for the test piece for the beams and the carbon extrusion for the mast sample and the rudders which should stop us getting bored. Got the bag on and infused hull half #2. I had repaired a chip in the melamine with brown tape (stupid!) which leaked, but apart from being frustrating and slowing things down, it did not make any noticable difference. Used shade cloth and perf plastic and a single feed. Took 3 hours, resin usage numbers tomorrow. Looks good apart from a dry spot on the edges next to where the heater was, presumably too hot, too quick. Easy fix with some resin and a clamped on flat piece. Sorted out the resin measuring/mixing so it is now glove free. Need scales which weigh more than 1 kg at a time before we start on the serious bits.
Rigged some strings from the roof and lifted half hull #1 off the mould and got it outside. Took a bit of effort and a little grinding to get the spacers out due to inadequate taping, but nothing major. Also a small resin puddle where the bag was not applied evenly. Might come out with the peel ply, but grinding is more likely. The secondary infusions look good, a faint line on the peel ply on the outside. Finished cutting the materials for half #2 and got them laid out apart from the bag.
July 2020 #4
Repaired the dry spots by running a length of spiral across them and infusing. Not perfect but not far off. Photos show the extra length of spiral. Heated it, cut the materials for the next half hull then demoulded it. The plastic mould liner worked well. I should have plastic taped the mould edge but nothing a sharp chisel didn’t fix. The vertical looks good, I can’t lift it solo to see the horizontal surface.
Infused the first half of the first tender hull. A few dry bits from vacuum close outs which were not a problem on the samples where the resin front spread across the laminate. Solution is a strip of infusion medium down the middle of the mould and one feed line instead of two.
Could have been fixed during the infusion by poking a vacuum source into the dry area, sucking in resin, removing the source and taping the hole. Uncharacteristically I decided not to risk the whole job for a couple of dry spots. Should be easy enough to fix them tomorrow, but it would be a lot better if it wasn’t required. The pictures were taken before the resin stopped flowing, the end result was not quite as bad as it looks. The other glitch was the not extending the feed close enough to the vac outlet. The samples infused 300mm/12” across the stack but today only 100mm. Not sure why but suspect the resin cured quicker than expected due to some pretty aggressive heating.
Resin used 15.8 kgs, 400g in the lines and buckets. Maybe 2.4 kgs in the spiral peel ply and medium leaving 13 kgs in 8 kgs of flax. I might have to work harder on getting the laminate tight in the corner of the mould.
June 2020 #3
Flax samples were impressive.Thicker than the glass so stiffer and heavier as more resin was required. However the economics work as the flax is gratis. Flax is easier to work with in some ways, does not itch and is more stable as it is tightly woven. Hard work to cut will be good when the electric scissors arrive Hand laid a sample bulkhead as the pump was in use. Pretty rough but the method has merit. Will test it in the morning along with a sample join Cut the flax for the tender and prepared the mould. Infusion next.
June 2020 #2
Assembled the mould for the tender (one side and half the bottom). Prepped an infusion of some flax and glass. To compare. No vac pump so infusion tomorrow. Flax rudder mould was not fully cured so put it outside in the sun. Sat it on a couple of rocks which indented it. Heated the affected area, put some weight on it and the bumps disappeared. As near as I can see it is about the same stiffness as equivalent glass weight but used more resin.
Infused 2 stacks of flax and 2of epoxy. Couple of dramas caused by using black poly pipe instead of clear soft pipe. Not only can’t you see the resin but when you clamp it the poly pipe splits. Plus it was 12mm and my biggest drill here is 10mm so the resin inlets were not as robust as they could be. Nothing a heap of tacky tape couldn’t fix. Pics show the infusion rate which is near enough identical for flax and glass but the flax uses more resin.
At 20C 300mm/12” is about the limit of resin travel with this resin. So 2 x spirals will work for the tender half hull.
Day off tomorrow, infusing samples for join testing on Monday might get the first half infused by the end of the week.
June 2020 #1
Cleaned out the shed. Found 2 rolls of 400 gsm woven flax that we can borrow for the tender subject to some tests.