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William last won the day on February 5 2018

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About William

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  1. This is just a rough model to illustrate, using the forward bulkhead and mast collar of the Spindrift as an example. The assumption is that the green mast stub can rotate in the collar. The tabernacle is rigidly attached to the stub with through-bolts. Hinge bolt in red, locking pin blue. Shown here with mast 15deg from vertical and locking pin removed. My own mast is ali, 63mm diameter, 3mm wall. I will be making the tabernacle out of Bulletwood. I am sure you are right regarding the flex, but I cannot yet say if it will be a concern.
  2. I have recently snapped a free-standing rotating mast. In the process of fixing it I also plan on adding a hinge for ducking under bridges. The basic idea is to split the mast above the mast collar, fix the tabernacle to the bottom mast stub. Now the entire tabernacle can rotate. The rest of the mast hinges in the tabernacle as before, with the advantage that the tabernacle is always aligned to best support the direction of force on the mast.
  3. Ash gunnels, not full thickness but enough to give a fair curve to the sheer for now. Just finished laminating the carbon inside. It was difficult to tell dry areas from those already wetted out, but a good deal easier to wet out than the Vectran! I added the straps to maintain the correct beam just in case the topsides get too rigid once the carbon skin cures.
  4. Chines are all taped inside. Time to flip and get the outer skin on, but first I had to clean up the chines on the outside. I used a wood file to rasp open the core cells on the edge of the bottom panel and filled them with thickened epoxy. After curing it was easy to clean it up with the same wood file, but I soon also started using a plane which worked surprisingly well. The remaining holes and hollows were filled up before adding tape to the edges. I tackled the Vectran with a brand new pair of scissors. It made it about two
  5. What are the factors that would typically swing a choice between the Core Sound 15 and 17? Space/capacity? Performance?
  6. The recent supermoon gave us higher that usual tides, so this morning we explored some nooks of the estuary that are not normally accessible. The canoe is a 12ft adaptation of the B and B canoes that I recently completed. Then on to open the butterfly and go 3D. I don't plan on doing a full series of build videos like I did for the little canoe but I did take some timelapse of today's progress. The camera's battery died before I got everything fully stitched but at least it captured the essence of the whole exercise. Stitching is with thin galvanised binding wire. No drilli
  7. Having set up a spreadsheet to calculate the wood-replacement layup schedule, I started thinking about the spars. To replace the boom would require a rather generous amount of UD carbon to match the bending strength and stiffness of solid spruce. A rough estimate indicated a weight saving of about 50%, or 1kg. Such a small saving might not seem worth all the extra work and cost as far as overall weight reduction goes, but I was surprised at the impact it has on stability. I calculated moments and center of buoyancy at 5 degrees heel and with the boom sheeted out 15deg from the cent
  8. I have thought about it but since all the cells are technically open I dismissed the idea, reasoning that the vacuum will simply suck the resin into the cells. But now that you brought it up again I think it is worth investigating a bit further. One reference I found used a light vacuum to press down the dry core onto pre-wetted glass. Since the polyester scrim adds no strength apart from something for the epoxy to bond to on the actual cell walls, I cannot see the need for full wet-out of the entire scrim surface. As long as the glass itself is properly saturated and evenly bonded along
  9. Walt, just remember that your gunnel's cracks are quite likely of a different kind and orientation than those illustrated by Alan, rather running parallel to the grain and not quite as localised. Have you removed the paint in that area to get a better look at the damage yet?
  10. What percentage of the sail area does the CS carry in the main? I would like to scale my drawing's sail areas to similar proportions and see what the layout options present.
  11. A few more questions: How many people can comfortably sail at once in a CS-15, assuming that at some point everyone needs to sit on the same side? Does the cat-ketch rig allow more usable cockpit space than a sloop configuration? Would there be any preference between the ketch rig and a yawl in the 13-14ft range? At a glance it looks like a ketch might not leave enough room for the helmsman behind the mizzen mast while at the same time complicating tiller operation.
  12. Butt-joint on the nidacore. Glassed one side first, flipped the whole thing over after about 12 hours, flexed the joint half open and filled the half-open cells with thickened epoxy and then added the last bit off glass to complete the joint. The tissue-like scrim is quite thirsty and requires about 30-50% more epoxy that plywood to wet-out. Part of the problem is that it does not allow easy re-distribution of the epoxy once it is on the surface, resulting in the inevitable over-saturated areas. That is why the peel-ply is there, helping to absorb some of the excess.
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