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DDW

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  1. I'd like to be counted in the class of "younger engineers" but I think that opportunity has flown several decades by. If you are welding a loaded tang or cleat in the middle of some unsupported deck plating with stiffening nearby but not under, you will either need FEA or some very complex and dubious math to predict what will happen. That is a complex structure. At the corner of the transom you make the assumption that that corner is infinitely stiff and then the world gets simple. MFH125: yes something like that is what I was thinking. I do not know how dyneema acts when pulled a
  2. If the intent is to use soft shackles, would it be a good idea to have several holes and pass the shackle loop through all of them? I'd be worried about bearing on the steel at very high loads. In theory it could deform the steel.
  3. If you are expecting a 13,000 lb load on one chainplate, dinner napkin calcs: The bearing stress on the fixing bolts is 13000/(6 bolts x 0.25 plate thickness x 3/8 diameter holes) = 78ksi. That is beyond the yield of cold rolled mild steel and well beyond the yield of annealed 316SS. The shear stress on the bolts is 13000/(6 x area of one bolt minor dia) = 30ksi. Near the yield of 316SS but the six bolts will not carry the load evenly. If the 1/2" hole is 1" from the edge of the plate, 13000/(1" x 2 (because there is material on two sides) x 0.25) = 26ksi. Below the yield of 316
  4. Two possibilities: a shoulder bolt which has a defined bearing length (available from McMaster or other hardware supplier); or a length of round stock with a thread run on each end as required and tow nylocks.
  5. Never been in survival type conditions, but from extensive reading, the drogue is an active management type of thing while the JSD (fully deployed) is more of a passive "we are exhausted" kind of solution. I imagine each has conditions that favor them. I considered the JSD as first priority because it seemed like the ultimate solution, less optimum in lessor conditions but still useable. Something like a galerider doesn't weight that much or take much space so might as well add it to the quiver. A full JSD is pretty heavy and takes some storage space. Regarding Estarzingers comments, it
  6. You are only going to need a tiny bit of metal to line the holes, there is labor involved in the build, why not do it right and use titanium? Grade 2 would be fine for this (it is stronger than stainless steel and 1/2 the weight), significantly cheaper than grade 5 and a little easier to work.
  7. It is very difficult to be certain without dimensions and thicknesses, but I'd be wary of those deck cleats and chocks. The chocks aren't a very strong section, looks like simply bent round stock. The cleat arms look like they are tubes welded to the deck plating, you will concentrate high stress in a very small section. With dimensions, it would not be terribly difficult to calculate a SWL for the fittings themselves and the welding, but much will depend on the deck plating and how it is supported, probably requires FEA to get a meaningful answer. Those are the reasons to weld on purpos
  8. Is that last one a busted off carbon post being replaced by a SS?
  9. It is pretty easy to configure the Axis encoder, but apparently not possible to configure it to work in a Raymarine hosted e-net. I've now had this confirmed by both Raymarine and Axis, and tested it myself. The Raymarine MFD assumes a trusted network, and expects no security on the IP video source using ONVIF. You have to disable all the security features of ONVIF, this was possible (and the default) for the Axis prior to 6.0 firmware, but now it isn't the default and can't be done. Axis will not supply the 5.9 firmware to downgrade. Raymarine is no longer recommending the Axis as a solution.
  10. Finished product looks good, but: I guess you are using the original post and tangs. A bunch of tangs butt welded to the shaft has pretty low torque capacity. They should be triangulated, even better if something can be bonded to the skin, otherwise the tangs are just floating in a pool of soft foam. One of the reasons a carbon post is better, it can be firmly bonded to the skins.
  11. The D2/55 also has some Perkins DNA. I don't think it shares anything with the Perkins, but Catapillar bought the rights to Perkins some time ago. Cast into the block near the top it says "Perkins/CAT". But the engine is a development of Shibaura, the same company that makes the ubiquitous IHI turbochargers. The D2/75 has the IHI turbocharger, curiously the ONLY other difference in the engine construction is the setting of the fuel rack stop screw. Every other part has the same part number - injectors, pump, pistons, governor, etc.
  12. The installation instructions with the engine state that you just turn the lower leg 180 degrees. The gear shift can be mounted in either direction. I think the saildrive is the same one as on my D2/75, built by Hirth/ZF. It is as good as saildrives get in my opinion. The anode can be changed without disturbing the prop, and the Hirth style clutch does not suffer the problems of the Yanmar cone clutches. It even states that full throttle shifts are permissible if necessary, though not recommended as standard practice.
  13. It wasn't the English. The D55/D75 is a Norwegian (Volvo) branded marinization of an American (Catapillar) company's joint venture to produce a Japanese (Shibuara) engine in China. It is a pretty good engine, found in a lot of construction and farm equipment. All of the normal service items are accessed from the proper right side, on the left is the alternator, starter, heat exchanger, and fuse box. Most engine parts available from a New Holland tractor dealer. I believe the Ford Performance division's https://performanceparts.ford.com/part/M-6880-B50right angle filter adapter fits
  14. It is strictly a question of access. Saildrives have the same ratio in forward and reverse, and don't care which way you run them. In the conventional "engine forward" mounting, you can run either a left hand or right hand prop, by merely reversing the shift lever. Bow and stern thrusters on a sailboat indicates the target market is first time boat buyers.
  15. Covering a GPS antenna with your hand will almost certainly lose the signal. Your hand is solid and quite opaque to the frequencies GPS uses. A boom, bimini, mast etc. covering a small fraction of the sky a long way from the antenna, not so much.
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