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DDW

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Everything posted by DDW

  1. Keeping in mind that Defender itself has now been sold to some corporate entity thingy.
  2. Just an example grabbed at random from the interweb: The problem with a normal prop is, you don't get to specify the torque, it is a fixed function of speed pretty much. On diesels this is also problematic because the available torque is always greater than the prop can absorb except at one point. A gear shift - or a variable pitch prop - gives you some control over this, decoupling the fixed torque-rpm relationship. The Autoprop is a brilliant design in that it does mostly the right things automatically.
  3. As I said before, cooling the motor on a boat isn't a problem if that is what is required. I noticed that the efficiency of BLDC motors drops off fairly steeply once out of the sweet spot. I wonder if the solution for a boat is a variable pitch prop? The motor could be run at it max efficiency rpm all the time, and the power needed adjusted with pitch. It might also greatly improve the efficiency of regen when sailing, too.
  4. I think the Tesla still uses an induction motor, but as you say the same holds true. Tesla claims something like 400 hp from each motor. In consumer vacuums and air compressors the manufactures claim "develops 5 hp" for a motor that is at best 1 hp based on an instantaneous value. Same deal - I've not seen a claim from Tesla as to what the maximum continuous power is but I'd be very surprised if it was even 100 hp. A 100 hp induction motor intended for continuous output weighs more than that whole car. A Tesla is fast as shit - just don't try to use that power more than a few seconds. Th
  5. Probably circling Cox Island at the tip.
  6. A very small BLDC motor can put out a very large amount of power for a very short time. Then the thermal time constant catches up to you. This is why a Tesla S can do 0-60 mph in 3 seconds, but can't tow a trailer. That is a problem that can be solved with a large seawater cooling system - which ICEs have had for a century.
  7. A sheave is not the easiest thing to turn on a manual lathe. Turning the groove in particular. You either need a form tool and a very rigid lathe, or a spherical turning fixture for the tool post. Second to that are hacks like manually filing the groove smooth. On a CNC, very easy to do.
  8. If you mistook me for "dissing" LFP, you are - well, mistaken. A theme of this thread and a couple of other repeating threads on different topics is the selling honestly, vs. the oversell of a thing. LFPs are better in almost every way than LA of any flavor, the main remaining drawback is price and some installation complexity. But they should be sold for what they do, not what they don't do. So for example the energy density is about 2x or 2.5x LA, not 4x. And most responsible vendors will not guarantee 5000+ cycles. Lithionics for example guarantees 2000 cycles @ 100% DOD.
  9. While cycling LA deeper than 50% affects their life, it does not greatly affect the total lifetime AH delivered. As an example, the published life figures for an Odyssey AGM is 630 cycles @ 50% and 400 cycles @ 80%. That is a reduction of 36% in cycles, but an increase of 60% in energy delivered per cycle. In energy delivered over their lifetime, that is about a wash. You do have to replace them sooner, but the cost per AH delivered is the same. Lifeline's data is similar: 1000 cycles at 80%, 550cycles at 80%, or a reduction of only 12% in AH delivered/life.
  10. Jack Webb is certainly not my role model. The quote though, stands on its own. Anybody can choose to be offended by anything. That's a you thing, not a me thing. I doubt the overwhelming majority reading this thread (if there is anyone left) considered anything I have posted as "dissing" electric cars. If stating accepted fact is "dissing", then I guess I am guilty.
  11. I guess "dissing" can be in the eye of the beholder. I do challenge you to point to one single instance in this thread, or any other, where I had said anything factually incorrect or even derogatory about electric cars. Truth in advertising is all I strive for - "just the facts, Ma'am".
  12. Progressed yes, just not very rapidly. This was what I said upthread. And you confirm, current LFP approximately 2x the energy density of 100 year old LA. In the same amount of time, ICE efficiency has improved a lot more. Not that it means anything - just that battery technology has been relatively stagnant. I have said this more times than you can count on your fingers and toes, on this very thread (about boats). I'll say it for cars too: many people, perhaps a majority would be well served by electric cars, except the cost is still high. So your comment that I am only "focus
  13. 4D weigh about 130 lbs. Two golf cart batteries take the same space, cost the same, have the same capacity, are more readily available, and weigh only half as much (each). I'm done moving those suckers around. Comparing AGM to lithium, in logically sized banks, it isn't the acceptance rate during bulk or absorption that makes much difference (the smaller lithium bank is likely to accept less initially). Rather it is the long charge tail above 80% SOC, combined with its affect on AGM life, that is the big difference. FLAs are cheap, and you can put a lot of amps into them between say 40
  14. Tesla mainly did this by simply cramming a lot of batteries into the car, by designing the car around the batteries. The Model S long range battery is about 1400 lbs plus the enclosure. The biggest vehicle I have (one ton truck) carries 250 lbs of fuel (36 gallons of diesel), will travel about 700 miles on that, even with a Tesla loaded in the back. And can be recharged (pumped full again) in about 5 minutes. I can fill it up even at today's prices just about 450 times for the base price of a Model S. Not dissing the Tesla or electric cars - they have come a long way - but will need to g
  15. Should be counted as station wagons or estate wagons. That's what they used to be called.
  16. The Coho has looked like that for years. Launched 1959. I was launched before that, and don't look much better....
  17. Yeah, on the original sail, about 5' of luff separates them. I am moving batten positions around to better accommodate reef positions and vang strut clearance. This sail designer likes the gaff and next batten close together - just worried about them being too close together.
  18. It isn't leaving in the rain that is destructive. It's leaving it in the sun that is destrucive - a low risk in Maine.
  19. My Ford diesel 1 ton, 450 Hp and 880 ft lbs torque, 8000 lbs empty curb weight, gets about 20 mpg on the highway unloaded. 2005 yr model is a bit in the doldrums as far as efficiency goes. A new small Ford pickup is > 25 mpg if you don't go crazy on the power.
  20. Of course I do. In fact the very first prototype is still installed on the mizzen. The device releases the headboard from the headboard carriage, allowing the head to lay back and furl. The problem I'm envisioning is with a hard batten receptacle for the gaff batten mounted just above and right next to a hard batten receptacle for the next batten, when furled the sail has to bend and collapse sharply in-between the two as the two battens must end up parallel in the sail cover. Or if enough distance between the two to fold without stress, little support for the considerable compression fro
  21. Most that I've seen put out about 14.2 when cold (still low for fast AGM charge) and reduce that to around 13.8 once warm. Of course that is not temp compensated or remotely sensed. Internal regulators are not designed to charge and maintain a house battery or (usually) any AGM battery.
  22. Yeah, pretty familiar with that product!
  23. I don't see the Wakespeed 100 offering any advantage over the Balmar offerings. The Wakespeed 500 is nearly unique in the industry in that it measures actual current going into the battery. This is important on an AGM house battery because it is the only way to know that they are really charged. The other methods used are poor guesses at best. Other than that model, they all seem to do more or less the same thing so pick on other criteria. If you have very few house loads while motoring, then the others do an OK job. They get confused by any significant load, can't tell if it is charge current
  24. Thus turning a 50 mile trip into an 8 mile trip......
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