Affordable, long-term liveaboard?

Discussion in 'Projects & Proposals' started by Filmdaddy, Aug 4, 2005.

  1. Sailor Alan
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    Sailor Alan Senior Member

    Ama's; If i understand correctly, and observing the you currently favor a 45' 'V' with a very shallow slope above that to the deck. You assume this will give a rapid rise in displacement with immersion, then a much lower rate as the chine is immersed. If I understand correctly, and I probably don't, the leeward AMA needs to maintain it slowish drag whilst being immersed, otherwise the AMA will slow and drag the main hull downwind, a disaster waiting to happen. As the current ama's are only half the length of a typical sailing trimarans ama’s, this characteristic will be*exaggerated. This is totally acceptable as long as your do not ‘press’ the boat under sail. In many cases, early trimaran ama’s had long overhangs, specifically to avoid or suppress pitch-poling. Eventually, the racers at least determined that a vertical stem, and eternal vigilance were faster, and fashion prevailed with many ‘cruising’ cats and tri’s following suite.
    The ama’s should be about the same L/B ratio as the main hull, or better. In this case 10:1 or better 12:1. This is an area at which I am a bit vague, but I prefer a deeper 'V' so the displacement rises fairly fast over the whole immersion process. To this end I cartooned a narrow flat bottom and quite a lot of flair on the inside side of the AMA. I showed this as a 'straw horse' though it certainly could work. I'm assuming the AMA will be above the waterline above 10-15kt so it's not involved in the lift off procedure.

    I'm open to suggestions here. Here are some suggestions too.

    http://www.sailingcatamarans.com/hullshapes.htm

    My own experience was; the deep “V” ama shape with no chine, was really successful. I was influenced by someone, i forget whom, Piver possibly, but the only thing i would do differently would be to add freeboard.

    I want to suggest an internal arrangement much like the Hughes -38 power trimaran, which will allow the biggest motor under the front bunk. No one will be sleeping there while the big motor is in use. The generator can be under the aft bunk, along with other heavy items, though fuel should be stowed around the CG. This internal arrangement allows the most effective arrangement of fore and aft structural members looking like joinery, but in reality structural members supporting longitudinal loads. Hence the framed oval cut outs for stowage. The bunks fore and aft, and their associated half bulkheads below them will also contribute to structural rigidity.

    The aspect ratio is quite good for this class of airplane, but as cruise height is about one semi-span, half the total span, I wanted to keep the span up. Increasing weight to increase wing loading also increases cruise power required, an upward spiral to be avoided. I will explore reducing the wing area linearly, the usual way of curing these issues on our big planes. The wings final position will also need to wait for final weight and balance, but should not be far off. *
     
  2. Sailor Alan
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    Sailor Alan Senior Member

    No IP, and this could quite probably be built for $250k, as long as you use the materials suggested.

    I seem to be lagging one behind your questions with my answers, oh well.

    The VTOL flying sport bike uses 180kW, about twice the power of a typical sport bike today. It is more or less a machine for turning power into noise. Perhaps this is why there is little interest.

    Of control latency, there is none, at least I think so as I might not understand the question.

    Please observe the photos here.

    http://www.delta-club-82.com/bible/photo.php?id_aile=861&langue=en

    The forward wings, the canards, are controlled directly by the pilot. They are pivoted slightly back from the leading edge, about 0.2 MAC to balance out the forces, and allow the pilot to move them easily. The pilot must be careful to never let the control surfaces point down to the point where they are accepting air above their leading edge, just like a hang glider.

    In the 40' version, these canards will be controlled from a normal pilots control, either a wheel (roll) with push/pull for pitch, or a stick giving roll and pitch in the usual way. The pilot is controlling the canards together for pitch, and differentially for roll. They will be connected to the controls just like a light plane, using steel wire cable, bell cranks, pulleys, and/or push/pull rods. The pilot will have to 'fly' this all the time, just like a light aircraft. Any passengers will have to sit still too, just like a light aircraft, any moving about will move the CG, and change the balance. I have several colleagues, friends really, that might help with design, then test fly this in some form. They have all built several airplanes each already, so this is not new.

    Once fixed in place, the masts, or spars, do not move. The spar itself has a wire stay (not shown yet) from the mast truck to the bottom of the main hull, as 'flying wires'. The wires shown are the 'landing wires' from the king post to the mast truck. The spars will be steadied fore and aft by the wires in the luff of the canard, and the leach of the main sail.
    The mainsail, or wing sail, attaches to the spar using a normal bolt rope with steel wire in the leach and foot. These two wires are attached via separate turnbuckles at the stern. These will be adjusted during flight test, and then left.
    See the cartoon below for details of the mast and king post attachment, and the AKA's etc. The green bits are metal, the pale blue composite, and all the rest aluminum.

    Your original suggestion of a Ford 4cylinder 300hp turbocharged engine seems fine. The biggest issue is cooling at full power, and an oil spray on the underside of the pistons is virtually obligatory. As a turbocharged engine, by design, it will probably have this feature already. I imagine it will turn the propeller at engine rpm, just like a Thai long tail. I now think the long propeller shaft (one piece) will simply hang via gravity it's full length, from somewhere forward on the hull. It will sink, but as soon as it is spinning, it will rise until half it's blade area is in the water, and half out. I.e. hub at the surface. This is ideal for a Thai type surface propeller, and should be self regulating in height etc. The engine will need a fairly sophisticated rpm limiter, so it can never over rev over waves.

    The most sophisticated step hull was developed at huge government expense for the Corvair Seamaster, and is still the most efficient water based hull extant. It's L/B watio, dead rise, step position, and step fairing is the best possible to use. I would if i thought it necessary, but the Seamaster, like virtually all seaplanes designed since the 30's, was developed for use in sea state 4 or worse. You should not be operating this as an airplane in anything except fairly calm conditions.

    I am planning to build a 16' X 30" canoe type boat this summer with my grand kids, and I am considering putting these wings on it. They will be silver tarpaulin (not blue, too gauche) and supported on a tip to tip aluminum spar, probably a repurposed sailboat mast. The rig will be a near exact analogue of the rig in the photo above. The thing I lack at present is a boat to tow it into the air. It will only need about 15kt, and will fly about 6' altitude.

    All this is a bit mad really, I am a retired old coot, and not really up to all this flying about, but still it's fun to speculate.
    Yobarnicle, you are not mad, merely a little eccentric, and we eccentrics can only get better if we practice, ie we are 'practicing eccentrics'.
     

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  3. Yobarnacle
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    Yobarnacle Senior Member

    I admitted I was nuts, so proves I'm not crazy. Truly crazy people think everyone ELSE is nuts, not themselves.
    Now my wife says everyone is crazy except her and I, and she sometimes has doubts about ME! Crazy lady, but I love her. Seriously, she has multiple personalities. Psychiatrist diagnosed. I'm married to 5 women in one body. I'm NEVER bored with her.
    And you thought redundant propulsion on my boat was excessive! :) Options are golden.
     
  4. Sailor Alan
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    Sailor Alan Senior Member

    To review, please correct me if your understanding is different.

    This vehicle, (it needs a name, itself, and for the class) is a ‘true’ WIG, i.e. will fly, be 100% supported by its wings, at a constant, or at least consistent altitude. Notice how the Do X is flying about half its wingspan above the water. This was a WIG, mainly due to lack of power, long befor the phrase was coined.

    http://en.wikipedia.org/wiki/Dornier_Do_X

    The keel (hull bottom) will be between 10-20’ above the water surface whilst in this mode. It will fly straight and level under the control of the pilot at all times. Unlike a hovercraft, ram wing, lifting catamarans, Russian Caspian Sea Monster and its cousins, 3 point hydroplanes, planning boats, stepped hydroplanes, hydrofoils, sidewall hovercraft, surface effect ships, and all others of their ilk, which follow the surface of the water fairly closely. The only exception being some hydrofoils which attempt to stay level using sophisticated height control, all of which have failed so far. Here is a picture of the Boeing Pelican, a proposed WIG. This report, mostly miss-information, is not what was designed (well we did, but for public consumption) but does give an idea of what can be done.

    http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml

    To Review; The hull is a ‘bartender’ stretched to 39’6” LOA, and narrowed to 4’ WLB, 8’ at deck level. Plywood frames, or bulkheads with cut outs, with stringers and skins, a bit like the ones here. This picture is not terribly accurate, i will draw the proper bulkhead shape further on.

    http://dudleydix.blogspot.com/2012/08/plywood-kits.html

    Notice in this series the similarity with aircraft structure. The aircraft is taking extreme pains to reduce weight, and increase strength, which you do NOT need to do.

    http://www.homebuilthelp.com/BeginnerWood.htm

    This vehicle is unique for several reasons. As it is never intended to fly above ground effect, its requirement for very light weight simply does not exist. As it is designed to fly at slow speeds, 70kt is its MAXIMUM, 50-55kt will be cruising, drag is really not an issue either. Because the speed is so low, a less efficient airfoil, in fact a single sided one, is perfectly adequate. As a single sided airfoil is being used, the wing can be of exceptional simplicity, and therefor light weight. Because the flight speed is so low, and drag is not an issue, we can brace the wings using steel wire over quite a large “base’ i.e. the base of the triangle is quite large, and wire bracing angles quite large too.

    All of which add up to the extreme non criticality of the weight, at least in airplane terms. 6,000lb would be normal for such an aircraft, but as it would be expected to cary a paying cargo, the actual EOW (Empty Operating Weight) would be a lot less.


    The hull (and ama) structure is fairly typical of some aircraft, but with double the skin thickness for water impact etc. The 6,000lb loaded weight is generally limited by power, not lift, though power, lift, drag, and weight, as well as CG and controllability need to be balanced. in this case they are, or nearly so, close enough for preliminary design considerations. My old SW at Boeing would have already told me the weight of the structure, but my current home brew will not.

    The turbocharged 300hp Ford sound excellent. A turbocharged, or supercharged Wankel would also work. Three lobe Wankel motors are really two strokes, and so have very poor induction. This is cured totally by adding a supercharger, turbo or not, to pressurize the intake. I am surprised this is not more common, but sealing the pistons may be the issue.

    http://www.racingbeat.com/mazda/performance/rotary-tech-tips/turbo-supercharging.html

    I would avoid air cooled engines, too hard to get cooling air into the engine area.

    The ONLY reason the propeller touches the water is to take advantage of its far higher efficiency in water, and that by so doing, the vehicle cannot be described as an aircraft. An aircraft, by definition, must be built and signed off by a federally certified A&P mechanic, and though not legally required, they will not build something that is not designed and signed off by an FAA certified DER (Designated Engineering Representative), who then must sign off the final product. This paper work would quadruple the costs, and entail the provision of redundant structure and systems etc.
    Note; i know several people who are licensed A&P mechanics, certified FAA DER’s, and flight test pilots. This means they can legally design, build, certify, and flight test their own airplanes. i would have thought a bit risky, but possible. Perhaps this is why they might involve me, as I have already helped these guys with some of their planes, and truly remarkable they are too.

    I am assuming the propeller and its shaft will ‘fall’ down into the water by gravity, though it might need to be ‘forced’ as well. I want it to ride about at hub height as a ‘surface piercing’ propeller, though the Thai propeller is not the ideal model. The Thai propellers are usually 2 bladed, and as only one blade can be in the water at a time, this will set up torsional shock waves along the propeller shaft. A multi-blade, odd numbers, will reduce this characteristic, but the long thin shaft may still whip around. It cannot be braced with wires, too much water drag, but a carbon outer tube, and carbon inner shaft might work. These shafts would be made by wrapping aluminum tubes of suitable diameter with carbon pre-preg (surplus from Boeing surplus store) then wrapping the whole with stretch film, and baking under a temporary oven of aluminum foil and insulation. Once cooked, soak in hot caustic soda to rot the aluminum tube out.

    The pilot and passenger(s) will need to be sitting in seats, with 4 point harnesses during flight. These seats can be simple plywood affairs, but the harnesses will need to be attached to frames, adjacent to stringers, but this is quite easy as well. I suggest the upper of the two ‘windscreens’ has laminated safety glass at a very serious slope (as shown), to try to resist bird strikes. The lower of the two “windscreens” should be plywood, no view.

    There should be no 'openings' in the hull except those needed for ventilation and cooling purposes. these ae large drag producers, even at these speeds. Ventilation is easy, with a 55kt wind behind it, and we might still cool the engine with sea water, scooped just as the Thai's do it from behind the propeller.

    I keep mentioning the Kurt Hughes 38’ power trawler trimaran as an example, but in this case the helm seat is about right for the pilot, and any passengers should sit behind him, or beside him in a similar seat.

    http://www.multihulldesigns.com/designs_stock/38tri.html
     
  5. NoahWannabe
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    NoahWannabe Junior Member

    WIG sail boat, specification is firming up.

    I think this is becoming more of its own boat rather than an affordable liveaboard, but this is very fascinating stuff. I think this maybe better as a tuna chase boat. Float out 50-70 miles to tuna water then troll around for tuna, then float out to another spot then float back to shore. Saves lots of time, weight and cost is justifiable. A true 1-day tuna fishing boat. Leave 6 in the morning and back by 4 pm.

    The name, this is your baby Sailor Alan, you need to name it. I love this.
    As such, I think I am in good agreement with your summary above.

    The helms may need to be separate for displacement and floating for easier and less confusing control. The boat helm in cockpit and the WIG float helm in cabin. The canard control would need full yoke(?) or stick steering justlike biwing plane of old :)

    If I am near you, it would be fun to visit and discuss your WIGsail canoe project. I can pull your canoe too. Haha, I am being way too optimistic. As it is, I am still planning a small affordable, fuel efficient, low maintenance fishing boat building later this year. We'll have to see how I am going to pull that off with my new start up :).

    Aerodynamic requirement is proper. All vents and cooling intake are understood. I was thinking keel cooler with liquid cooled engine. During floating, an aircooled radiator with liquid cooling should work. Keel is not a typical sailboat keel, but more like powerboat keel cooler located near stern. Air intake would be a concern during floating but I think that can be arranged in cockpit area. And, the cockpit can be enclosed with canvas for improved drag.

    Engine! The 300hp EcoBoost engine isn't out yet. It will be the engine for new 2015 Ford Mustang. A supercharged wankel engine has lower torque doesn't it? I think rotary engine piston sealing is resolved in early 90s with ceramic edges. I have a friend's son that modifies several RX-7s for racing.

    I agree the propeller should be more like a surface piercing and shaft may not be as stiff but has sufficient compression to transfer forwawrd thrust through the shaft. However, it still needs to retract when high power engine is not used for propulsion during displacement mode. It needs to retract for less draft depth and to minimize drag under water.

    I've read some articles on Boeing Pelican as best troop moving craft while back in navy magazine or military aircraft website. I forget. They were pretty positive about the WIG technology for military but who knows what the real issues are.
    Are you saying that aerospaceweb article is misinformation because it states it needs to be larger to work better and have more commercial value? I've read about how some of the Pacific nations are researching WIGs for coastal patrol and military uses with small to large WIGs.

    As far as certification goes, it is something that needs to be done when time comes I guess. I guess as long as it stays in water like propeller in water foil then it would be good. I don't think you want to promote floating ceiling too much. Just state lower cruising altitude and don't mention highest ceiling. The jumping ski boats can do ~20' flight too, although you would never see that on their specification. Old ChrisCraft from 70's in Marine World.

    Kurt Hughes 38' trawler is becoming more acceptable if it is less of a live aboard but a fast tuna chaser. It does have a good form for what you are describing.

    PS: Dont feel like you have to respond to all my questions, although your posting has been main cause for my lower work prodcutivity recently :) This is all for fun, and I do appreciate open minded crazy alchemy we are discussing. Maybe we can make a flying canoe with a Honda motor and attract some VC funding like Tesla did :)
     
  6. NoahWannabe
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    NoahWannabe Junior Member

    Yobarnacle, I can't mention anything about other guy's woman, especially if she is 5 in 1. But, I don't know if I should be envious or glad someone else is taking care of her. I guess it all depends on which 5 characters, ones I want or ones I don't want.
    I prefer this guys approach, but I doubt it would work with my wife either.

    http://news.yahoo.com/husbands-harm...-050006264.html;_ylt=AwrTWf3sRLZTgGcAV8vQtDMD
     
  7. Yobarnacle
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    Yobarnacle Senior Member

    In closing this side topic, I like variety, I like a challenge, and I like loyalty and fidelity. I like other things too. My wife and I are exclusive. Monogamous. And it's a lifetime adventure together. I consider myself a fortunate man.
     
  8. Sailor Alan
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    Sailor Alan Senior Member

    To go back to your original discussion/requirements. The original requirement was, if i remember correctly, a cheap, live-aboard, capable of sailing, and cheap motoring using electric (solar), but also capable of 30+kts for emergency. This boat was also supposed to be trailerable over the road, and/or capable of transshipment in a container, and occasional off shore work. It also needs to be very stable for anti seasickness concerns.

    Now i think we did pretty well with this. Fits in a container for international repositioning, road trailerable, wide stance for stability, sailing, low speed efficient operation, 50+kts for emergency on only 300hp, 2 X double berths, separate galley and lav, shower, etc. Whats not to like.

    The biggest possible platform dictated by road trailer, and confirmed by container transshipment, is 40’ X 8’ whole or folded. This is not a lot for live aboard, though certainly many people use far less. Some of course actually live in containers, but typically have some land surrounding the container. My sister has one as a beach cottage. My cosines live on a 44’ yacht, in some luxury, but that is 12’ wide.

    To satisfy your stability requirement, and incidentally your speed requirement, long and thin water-plane is necessary. In trimaran form, this can usually be folded for 8’ wide trailing and container, but not usually as a practical catamaran. i.e. two 4’ wide hulls, or decks don't usually contain the volume or width necessary for live aboard. If these hulls are displaced vertically in the container, about 2’ vertically is as much as can be gained, we are still stuck with about 5-6’ total beam for each catamaran hull. Wharram and some other designs use this concept, but assume a lot of outside living. Not very practical in the PNW, and elsewhere. Here is a practical example, but even scaled up a bit to 38’ long, its still a bit small for live-aboard. I can imagine a small skiff hull with a 300hp OB attached under the aka’s detachable for fishing, and available for high speed. I would want the masts folded though, and the propeller would be wrong for one or other function.

    http://boatbits.blogspot.com/2010/11/catamaran-design-id-build.html

    If the beam requirement is relaxed, dispensing with easy road transport, and container shipping, a whole raft of twin hull options become available. My favorite would be the ‘ram wing’ concept, where as speed increases, the weight of the hull (displacement) is partially borne by the air rammed under the bridge deck. This bridge deck can be narrow, like this one my son’s marine yard is currently re-furbishing.

    http://www.m2motoryachts.com/pages/m2-60.html

    Or one of Glen-L’s designs.

    http://www.boatdesigns.com/32-Cruise-Missile-tunnel-slot-express-cruiser/products/809/

    Or it can be wide like a genuine ‘tunnel hull’, again from Glen-L. In this case it would need serious scaling up, though perfectly possible.

    https://www.glen-l.com/weblettr/webletters-2/webltr16tkg.html

    These wide stance ‘tunnel hulls’ are also perfectly at home under sail, though they suffer terribly from ‘wave slap’ virtually all the time in any chop.

    Next would be genuine catamarans. Here is a classic which would respond to power or sail, but would be very hard to get up to the speeds you require.

    http://www.multihulldesigns.com/designs_stock/36ccat.html

    On a much more extreme path, i would favor sidewall hovercraft, occasionally called ‘surface effect ships’. This is a satisfactory form of design, and could be modified for your purposes.

    http://www.boatdesign.net/forums/boat-design/new-hovercraft-design-change-38258.html

    Like all the above, and unlike the ‘flying’ solution, these will all follow the surface of the water, and will sustain quite high vertical acceleration at speed.

    Did you want to explore the solar radiation boiler/steam turbine at all? I liked that one too.
     
  9. NoahWannabe
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    NoahWannabe Junior Member

    WIG live aboard practicality & DIY build weight

    I think your design comes very close to what we have said. Trimaran is the best for reasonable liveable space in the hull, minimal wind drag even for sailing alone without WIG sailing (flying), transportable size, and speed potentials are all there.

    Two major concerns are the maximum displacement and the WIG sail.
    The initial displacement requirement was (I think if I remember correctly) 4,000# light ship for a weekend use and 8,000# for an ocean passage. My preference for the dory hull is that it provides narrow BWL (beam at waterline) in light ship mode and acceptable BWL at heavy ship. And if ship is overloaded to 11,000# it would still be reasonably within speed performance range due to angle of the dory hull side wall angle. (my modified dory main hull would have ~45 degree deadrise from flat bottom to 8000# displacement line then ~80 degree vertical angle hull to minimize BWL for 12-18" then flares out untill 8' wide.) But with 6000# WIG take-off displacement, light to midweight displacement is crucial. And, I am concerned about the ability to build 4000# light ship.
    The second concern is WIG sailing seems very feaseable, but I think it would take couple of concept model testing. Maybe one at canoe size then something in 24-26' length proof of concept prior to full 40' build. That could be quite a bit of time and resource as an owner-builder project.

    Yes, I am looking for a pickup camper/RV style live aboard, not quite condomaran, but the weight will creep up. And, I also have a tendency to overbuild little here and there and end up with stronger but heavier end project.

    What would be the minimal beam for a 40' ram-wing catamaran for it to work? What would dimensions be with out any preconditions? I am guessing wing deck should be wide and short for best lift :(
    What is your concept of solar radiation/steam turbine? If we can derive practical energy from temperature differential of 100-140 degree Farenheit then we can harness more energy from Sun easier than PV or any solar thermal collector in production so far.
     
    Last edited: Jul 8, 2014
  10. Yobarnacle
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    Yobarnacle Senior Member

    This may seem off topic, but I promise to make the connection in the end.

    I have been looking at making freshwater from salt water.
    RO (reverse osmosis) has gotten cheaper, but isn't cheap when you have to replace expensive filters regularly, are only available for sale in limited areas, and system maintenance is critical.
    Solar stills are cheap and dependable but slow and use a big footprint most sailors would prefer to devote to solar power production.
    I stumbled across a bit of chemistry that I can't find the source now, that said "adding ethanol (vodka or grain alcohol) to seawater would cause the salt to precipitate out as crystals", which can be filtered out with a coffee filter.
    I began thinking, alcohol evaporates easier and faster than water. A small solar still to recapture the ethanol for reuse, would leave a quantity of potable freshwater.

    Now the connection. Could you use ethanol vapor in your steam turbine? If you could, you can make your own. Fermentation and distilling aren't high tech.

    Found a different source for the ethanol saltwater reaction.

    http://bouman.chem.georgetown.edu/S02/lect8/lect8.htm

    "Addition of ethanol (a compound very much capable of hydrogen-bonding with water) reduces the amount of available
    water molecules needed for separating the Na+ and Cl- ions. Thus, one can look at this situation as an increase in the effective
    concentration of the dissolved ions (due to less solvent available) and, likewise, causes precipitation of NaCl. "
     
  11. NoahWannabe
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    NoahWannabe Junior Member

    Mix alcohol and seawater for desalination? unless you drink ethanol first!

    Hmmm, Yobarnacle ;) You may have something interesting...

    C2H6O + (NaCl + H2O) = ethanol + (salt + water) = ?
    If this equals NaCl + (C2H6O + H2O) then you may have found a money tree. I will drop everything and be your partner. Then use solar heat to separate C2H6O from H2O.

    Surely, ethanol is hygroscopic meaning ethanol attracts water molecules. Just like ethanol gasoline absorbs water vapor from air. But you can't mix ethanol with seawater to grab water away from salt. Usually it works other way around. Lots of salt is added to water absorbed ethanol to make ethanol more pure.

    (C2H6O + H2O) + NaCl = C2H6O + (NaCl + H2O)

    So salt likes water more than ethanol likes water.

    Let's say some how we made ethanol and seawater to mix (and they will mix somewhat) and we made salt to crystallize and separated ethanol with water molecules attached to them. You will need somewhat sophisticated still to separate ethanol from water. The still will need to be at least good as a Kentucky bootlegger moonshine still. I would say difficult on the boat rolling around on waves.

    Disclaimer: I have not tried this at home. This is purely theoretical mind game I played with basic Chemistry from many decades ago. I do not have chemistry work experience and I don't work with any ethanol derivatives. No ATF visit will be necessary!
     
  12. Yobarnacle
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    Yobarnacle Senior Member

    http://www.instructables.com/id/How-to-Salt-Out/

    Salting out is a process that can be used to dehydrate Isopropyl alcohol

    I don't find any information on salting out ethanol.

    I did find the following PDF which says ethanol is more polar than isopropyl. which means ethanol likes water more than isopropyl.

    Searched for hydroscopic table, expecting a galvanic series sort of list, but got this:
    https://images.search.yahoo.com/sea...=ymyy-t-545&va=hygroscopic table of compounds

    I headed inshore gasping for air. Last chemistry class I had was 1964 in high school.

    I suspect the ethanol precipitation of salt is for high concentrations of salt. Seawater is a bit over 3% and varies sea to sea. Maybe ADDING salt to seawater, then ethanol to precipitate the salt, would leave water with LESS concentration than 3% after filtering and distilling off the alcohol. I only have questions.

    A solar still easily made with a black or dark green (suspect is better color at collecting sun energy, looking at plants) sealed box placed in sunlight, top is inclined glass lid whose bottom edge rests in a slotted collection pipe or trough. The alcohol will boil off at lower temperature than water. Both will evaporate and collect on glass and trickle down to trough. A breeze on the glass would help condensation. So what if the ethanol distillate is watered down a bit? The intent is purify the water left behind , not the booze collected. The ethanol promptly gets more water added to it anyway, the next batch of seawater. I'll experiment when in Florida working on my boats. September.

    Wasn't trying to hijack your thread.

    Could your solar powered turbines mentioned earlier in the thread, run on ethanol vapor?
    Ethanol is very similar to water in many ways. And I think has a higher vapor pressure enabling it to evaporate quicker.

    Ethanol is flammable while water isn't. But water vapor can blow up! I bet more men have died from steam boiler explosions than from ethanol vapor fire balls. :D
     

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  13. Sailor Alan
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    Location: Gig Harbor WA

    Sailor Alan Senior Member

    Looks like someone has also been listening to your requirements. The last one listed here, the two dory like ‘longboats’ is really reminiscent of your discussions.

    http://catamarandesigns.com/lotek.htm

    Then there is this, a serious attempt to reduce motion at sea, though how successful i have no idea. I suspect structural loading might have really surprised the builders of this, and i for one would not feel to happy off soundings in one.

    http://www.solarnavigator.net/boats/spider_marine_advanced_research_proteus_boat_ugo_conti.htm

    Now this is my all time favorite construction method, and i have built quite a few boats exactly this way. A pair of bulkheads (holes cut out later), a stem and stern, with full sides complete with stringers. This is more or less similar to Boeings new wing building process, and ensures an accurate result with no tools or jigs etc.

    http://www.thecoastalpassage.com/cheapcat.html

    His designs are pretty good to.
     
  14. Sailor Alan
    Joined: Mar 2014
    Posts: 299
    Likes: 12, Points: 18, Legacy Rep: 85
    Location: Gig Harbor WA

    Sailor Alan Senior Member

    Generally speaking, ‘ram wing’ vessels like lots of chord i.e. long length, and restricted beam. In fact it is astonishing how narrow this ‘tunnel’ can be and still be effective.

    “Ram Wing” vessels fall into at least three groups. The first uses air flowing both over and under the central ‘wing’ to produce lift, and as such work a little like a very inefficient WIG. A subset of this being modern racing hydroplanes. i was part of a group from Boeing helping (unofficially) an unlimited hydroplane racer balance lift on his boat. It turned out the last thing he needed was more ‘lift’ and we spent a lot of time making his front aka produce limited lift over a wide range of AOA’s. In fact it turned out the first such hydroplane with a separate ‘wing’ in as a front aka, rather than a full length bridge deck.

    The second kind, typified by the offshore power racing community, is the catamaran with a shaped bridge deck, where air is ‘rammed’ under it by forward velocity alone. Narrow such tunnels are usually to reduce vertical impact velocity during wave jumping, but wider ones really do try to derive some displacement reducing lift. Typically, air flow OVER the bridge deck is ignored as a lift element, and shape is dictated by reducing drag. These boats, like this Glen-L example http://www.boatdesigns.com/32-Cruise-Missile-tunnel-slot-express-cruiser/products/809/ use the rammed air to cushion each landing from wave jumping. They sacrifice initial stability, and will roll very badly too.
    Note; as total lift is influenced in a non linear fashion by AOA, this can be very dynamic. I ‘think’ this lift could be controlled by automatic bypass air-ducts, faintly like the ones on the roof’s of NASCAR cars to prevent liftoff. The issue is not so much 30kts, as 30kts into a 20kt wind.

    Another group has auxiliary air ‘pumped’ under the bridge deck, and sometimes trapped there by fore and aft skirts (or valves) for extra lift. A classic example being http://www.boatdesign.net/forums/boat-design/new-hovercraft-design-change-38258-2.html Post #17.
    A subset of this being the Russian Caspian Sea Monster, where jet engine exhaust is pumped (blown) under the wings, and somewhat trapped there by the trailing edges running very close to the water surface.

    Characteristics are such that a ‘normal’ catamaran, one that sails, and has a normal bridge deck, needs about 1/2 the internal width, between the hulls, as height above the waterline. This is to reduce wave ‘slap’ to acceptable levels, partially acoustic, but mainly structural. Catamarans often reduce this risk by omitting a solid bridge deck, and substituting netting instead. Extreme examples being the French and other ocean crossers, that look like a refinery of aluminum pipes, less extreme being some Wharram designs. One of the most scary situations being uncontrolled lift of the 'wing decks' in a storm, leading to 'flight' or flip over.

    Many power catamarans, especially those that want to add bridge deck accommodation, rely on ram air to provide lift when traveling, but suffer appalling wave slap at anchor, in fact structural damage must be an issue at times. Examples of this being the excellent Glen-L “Tunnel King” http://www.boatdesigns.com/16-Tunnel-King-tunnel-hull/products/368/ which unfortunately cannot be scaled to your size very easily (square/cube law).

    Here is a fairly satisfactory hull cross section that could be used.
    http://www.marinelog.com/DOCS/NEWSMMIII/MMIIIJun10.html

    Or better yet, http://glen-l.com/designs/hankinson/bearcat-pho-1.html

    Notice how the Bearcat uses almost exactly the principle you suggest of a “V” hull with the chine at maximum Heavy Load. This is a very sound approach indeed, and i would recommend this with a pair of symmetric hulls too. The keels should remain horizontal whilst the bridge-deck tapers from near the deck at the bow, to above the water, or higher, at the stern.

    All the above accept wave ‘slap’ as a destructive force to a greater or lesser degree as a fact of life, either avoiding chop altogether, or attempting to speed over it.

    Though a sailing catamaran, including my own trimaran, and catamaran proposals, all had a fairly straight outer hull WL, and a heavily curved inner WL, so the leeward hull would lift to windward, power cats do not benefit much from this. In fact my boats, and many others, have NO keels or dagger boards whatsoever, and the deeply immersed ama; or leeward hull is more than sufficient for windward performance in all weather conditions.

    Having a narrowed venturi section between the hulls of a ‘power cat’ is of no use unless you pump raw fuel into this section, and ignite it (a ram jet!). Yes, under certain conditions of calm water, and fairly slow speed, a little bit of dynamic life is created between the inward curved hulls, but hardly enough to warrant the trouble. i.e. the slightest wave or slop will destroy the effect, and you have to start again.

    All effective ‘ram air’ boats use an absolutely straight and parallel inner sides to their hulls. Typically the bridge deck is tapered down to virtually WL height at the stern, but this is usually for easy accommodation etc. It virtually guarantees both a wave slap AND a structural strain issue (though the deeper rear center hull helps structural issues too).

    Successful boats have used a generally flat (parallel) bridge deck, about 1/2 internal beam above the water, with a ramp up at the bow, and a large movable flap at the stern to ‘trap’ air rammed in from the bow at speed. This flap is raised fully for slow speed, and anchored, but lowered proportionally for speed. Within reason, the slower the speed, the closer the bottom edge is to the water surface. Note: there are limits, and too much speed with too low a flap will promote nose diving, and probably rip the flap off.

    The biggest design issue is your range of speeds with efficiency. Generally it is impossible to proved for both, so the hull stern will be optimized for one or the other. A narrow, pointed stern, as you desire, will be very efficient at lower speeds, but the stern will ‘suck down’ as speed increases. This is mainly because the accelerated water flow past the aft bottom sections, heading toward the propeller, or away from the propeller, creates lower pressure, which sucks the stern down. One notices this is WW1 and WW2, destroyers, and even battleships.

    My preference is to make the stern about hull width, no flair or taper, and accept slightly higher low speed drag. If the hull lines can be such that the bottom rises to nearly the WL at low speed so much the better, but not to the point it forces the bow high.

    My preference would be a pair of 4’-5’ hulls with a 16’ total beam on 38’ for a cat. It would look faintly like the Glen-L Bearcat, scaled up, but need two power plants.
     

  15. Sailor Alan
    Joined: Mar 2014
    Posts: 299
    Likes: 12, Points: 18, Legacy Rep: 85
    Location: Gig Harbor WA

    Sailor Alan Senior Member

    My original suggestion for solar power was a semicircular reflector with clear (glass) wind shield, and black metal (Boeing surplus Titanium) pipe as a collector. This would be mounted such that some length of collector/pipe would heat a medium (TBD) so its gaseous state would drive a repurposed car turbo (from a turbocharger) driving a car alternator. The actual configuration would be TBD, but originally i thought a sort of ‘layer’ of 12-18” diameter reflectors, cut in half, i.e. 6-9” deep/thick. The exhaust side of the turbo would go to a condenser with seawater. This would give a temperature range of 150’F+ down to 50’F. Car turbo’s are typically radial flow, and a partial vacuum on the exhaust side will give better efficiency.

    The alternator will give 50-55V 3 phase running ‘free’ and frequency will be proportional to RPM. This is a small set, built from repurposed junk parts, and can be installed as multiple separate units for redundancy, power regulation, and control. As all these various waveforms and frequencies would all be rectified into DC immediately, no complicated regulation system would be required.

    I am consulting my experts on the best fluids to use for this, other than water that is. generally speaking water is fine, but too high temperature, pressure, and regulations involved.
     
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