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DDW

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About DDW

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  1. Thank you. That very nicely answers my question about whether they are susceptible to mildew and mold. This is - still - the Achilles heel of all laminate sails.
  2. In your physics, you are missing an important fact: the SA/D ratio. Speed is a function of power to weight, and a given increase in weight will have more effect on a light boat, without doubt. Many light planing hulls are very beamy, so yeah, they will carry a lot of weight without the rails going under. I own a Porsche and a one ton Ford truck. Guess which is faster? Now guess which is faster with 2000 Kg loaded in the trunk for a trip?
  3. A simple passive one is just two diodes. They have to be big enough with enough heat sink capacity to carry the entire current service. These used to exist, but current ABYC recommendations prohibit them, because they will fail into the open condition, ABYC requires they fail "safe", that is, shorted. That isn't easy to do, and the reason they cost so much now.
  4. ^^ Again, this depends on the type of cruising you do. A daysail or overnighter between ports, you can pick your weather ideal for your boat. About 3 or 4 days out you take what you are given, and can only motor until the fuel runs out. If you can cherry pick the weather your averages will be high. If you have to sail in average weather your averages will be average. In that respect, racers (who must sail at the posted starting time) are similar to longer distance cruisers.
  5. My boat D/L ratio is 273. Will do an upwind VMG of about 16 knots. But that is the trawler, and the 380 HP Cummins has to be wound up to full chat. One big problem with sailing fast upwind is that in the seaway developed by the necessary wind, the motion is appalling, no matter the boat (well, above 100' or so LOA it gets better). In flat water and good wind, great - when you can find those conditions. In lighter wind your VMG sucks anyway, and a fast boat only makes it worse unless it is extremely weatherly.
  6. With an offshore corporation and a local shell LLC, the liability will be minimal.....
  7. Yeah, not thinking "manufacture and sell", just "design and test". I doubt large fortunes are being made in the yacht anchor business. Most yacht buyers of anchors value price first and performance second, if at all. However a nice DYI design knowing what you do would let a select few with the skills to make one enjoy it. Right now if I was building one it would probably be like the Spade except with a solid shank. Ti and W would be the next step. Perhaps spent uranium as ballast, the business proposition would be to accept large amounts of cash to dispose of spent uranium, and give the anchor
  8. Steve, liked the self launch test but there is one thing you skipped over: the self launch chain drag for the Spade? My Spades have been fine at that, just wondered how it compared with the others. I have two boats now, on both I designed or modified the sprit/roller to fit the anchor(s) for launching and secure storage. I guess no one else does that? Often quite a lot can be done just by changing the roller size. Have you considered designing your own anchor? You probably know as much or more than anyone in the world on what makes them work at this point ....
  9. Only on the Yanmar, not on Volvo (or at least some Volvos). My Volvo D2-75 has a single boot and no sensor. There are more than a couple of saildrive manufacturers. My aforementioned Volvo has very little on it manufactured by Volvo - the engine says Perkins/Catapillar in the casting but is actually a Shibaura (IHI), the saildrive is manufactured by ZF/Hirth. I think the label on the top might be made by Volvo and perhaps the shade of green paint. Many of the engine parts can be purchased from a local New Holland tractor dealer. Lots of people make anodes for saildrives, I can pick f
  10. With modern seals, a shaft can be as dry as a saildrive. There is a (vanishingly) small possibility of the seal failing and flooding the boat, but no more risk than a saildrive boot failing and doing same.
  11. Those things are resistive loads, and the amperage draw will be proportional to voltage, not regardless of it. For a rough test, since you are going between about 12.5 and 10.5 volts you can ignore that and be within 20% or so.
  12. We did this to mine when it was new. In addition to keeping the barnacles out, it now corrodes only from the outside in, rather than also from the inside out. Having owned both: two identical boats in identical condition, I'd take the shaft drive. Any significant difference in them, I'd let those differences decide, rather than the drive type. It isn't just ease of install, my boat was custom built, could have had whatever I wanted. But the plan dictated either a saildrive or a V-drive, and I took the saildrive over the V drive (with stuffing box under the engine/trans). The positi
  13. This is becoming common. Powersonic for example has a whole line of these in a large variety of sizes (for a couple of years now), very reasonably priced. I am using one for the instrument battery in my glider, and have tested the accuracy of the monitor by charging and discharging several cycles on lab equipment, and it is accurate. I think the parasitic draw is minute, less than the self discharge rate of the battery.
  14. Firefly are a unique technology, considerably more expensive (about 1.5x), and only available in two sizes. LFP batteries are approaching their price point from above. Lifelines (if properly treated) will last a long time. I'm just replacing the 10 year only ones in the trawler, the ones in the sailboat are due for replacement too (15 years old).
  15. 38' boat don't know, but for my 45' boat, the proposed SS rudder post was around 160 lbs, the carbon one we made for it was about 40. And stronger. A minor consideration: with the SS post we were going to need a thrust washer on top to carry the weight, with the carbon we needed a thrust bearing on the bottom to carry the floatation.
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