Affordable, long-term liveaboard?

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

  1. brian eiland
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    brian eiland Senior Member

    Here is that portion of his posting:
    Yes, that could be interpreted as 'onboard propulsion', but then again not necessarily. Sometimes providing internal propulsion can be more problematic and expensive than if it were left to external means. There are many commercial barges in this world, both inland and offshore types that are pull/pushed by external propulsion units that may be dedicated units for that particular vessel. Sometimes its just easier to put the propulsion engine in its own little 'pod' for numerous reasons.



    Its been really tough selling this idea. If I'd have had the money and time I would have built one for myself,.....like Tom Perkins did with his very 'unconventional' Maltese Falcon square rigger.

    Probably the closest example of the mast-aft vessel built would be the Hong Kong 40 powersailer

    I would venture to say that a great many of the Thai vessels are fashioned after the 'long tail' examples. It represents a fairly easy way to mate the engine with the prop without getting into problems in thru-hull designs. Its a relatively simple 'above board' application that is carried out in a 'do-it-yourself' society making use of non-specific marine parts.

    You can find a lot of long-tail boat photos over here:
    http://www.boatdesign.net/forums/powerboats/thai-boat-plans-needed-20398-3.html
     
  2. SamSam
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    SamSam Senior Member

    The OP stands for Original Poster, the person who starts a thread. The waking dream of the solar powered catamaran with its GPS dynamic positioning is the exact opposite of what the thread was started about and is not the original brief of the OP, but the HJ. (hijacker)

    Eventually the OP abandoned this thread and started another. http://www.boatdesign.net/forums/pr...e-long-term-liveaboard-design-query-9839.html
     
  3. Sailor Alan
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    Sailor Alan Senior Member

    Thai Engine Instalation

    Noah, Brian,

    There are two kinds of engine installation in Thailand, inboard and outboard. The most common, the “LongTail’, seen in every poster and movie, uses a car (or truck) motor, high mounted on the transom, with a long straight shaft sticking out the back to the propeller. These propellers usually run at engine speed, 3-4000rpm, too fast for a ‘normal’ propeller, and a bit slow for a ‘classic’ hydroplane ‘surface piercing’ propeller.

    Looking at the propeller, they have a lot of pitch, smallish diameter, and blade area seems to vary with power. In ‘cruising’ position, the operator seems to let the propeller drop to slightly below half the propeller immersed, then wedge the engine in place with a wooden wedge. This keeps the hull angle to propeller shaft angle more or less constant, and the boat seems to settle into a state where the boat is semi-planing, and the propeller semi-surface. They run for hours like this.

    The other, inboard installation, is not so obvious, but here is a classic picture, i hope you can open it.


    http://www.travelblog.org/Photos/4692807

    Notice the top of the engine just showing about 1/3rd of the way from the stern. You can just make out the steep angle of the valve cover? and this shows the engine and shaft angle.

    In classic western boats, we ‘flair’ (if thats the right word) the bottom lines just forward of the propeller aperture so the engine has width enough to be close to the propeller, yet with a horizontal propeller shaft. The Thai’s would mount the engine at about the same longitudinal position, but much higher in the boat. This allows the after hull lines to be much finer, or shallower, or both. I believe these lines are called the “run” aft to the propeller aperture and rudder. Though the propeller in these boats is in exactly the same position (vertical and longitudinal) as a western boat, its installed angle is steep, not horizontal at all. So the propeller is pushing the boat stern “UP”, so tending to counter any squatting the apparent lack of buoyancy aft might promote. All in all, a simple way of installing power in an otherwise fairly narrow or fine lined stern boat.

    I’ll use the Pilgrim 44 as an example here. Notice the engine installation and propeller shaft has an angle. This is probably regarded here as a ‘poor’ design here and western designers would want to flatten that shaft to near horizontal. This particular design has sacrificed ‘propeller efficiency’ for a reduction in hull depth, cross section, or both.

    Were a Thai builder to do this, he would mount the engine at least 3’ further back, and accept the very steep shaft angle. It would increase accommodation (in this case), reduce noise, or whatever, but that would be their answer. The extra weight in the stern and/or squatting under power, would be countered by the slight ‘up’ thrust of the propeller.
    I suspect originally this was an expedient installing engines in hulls designed for sail, but the practice has carried on into boats designed purely for power, and heavy pulling/pushing at that.
     

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  4. NoahWannabe
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    NoahWannabe Junior Member

    Brian, thank you for the Hong Kong 40 link. Aft mast is a very interesting rig. I am seeking a single handed sail rig with a free standing mast for fishing friendly motorsailer (clear rear cockpit for outriggers and down riggers). Those Thai longtail photos are wonderful. Why do longtail boats have narrow displacement hull with straight keel and planing board (fixed trim tab) on stern? Do they turn easily? If they are made for planing, then why not just make them with a planing hull? Does narrow displacement hull with planing board provide better sea comfort or seaworthiness? The planing board looks to be submerged even at displacement speed (drag at displacement speed), do they or are they slightly above water at displacement?

    Sailor Alan, I read your description several time to soak up all the knowledge contained in short but robust explanation. Best description of any marine technology concept I have read. Thank you. So the steep angle thrust loss is compensated by transom lift and more efficient aft hull hydrodynamic flow efficiency. I always wondered how those small engines can make 1-2 ton boats go so fast. Is there any fuel economy report/comparison of a Thai longtail versus a similar Western boat of similar displacement/use?
     
  5. Sailor Alan
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    Sailor Alan Senior Member

    Long Tail Boats

    Noah,

    Absolutly correct.

    I do not know of any scientific comparison tests, but they could exist.

    A report some years ago on world fishing boats, by Ian Nicholson, remarked on the efficiency of long skinny boats, and the “Panga” was designed and built by Yamaha as a result. I think they made a very large number. Reports on fishing BOATS are rare, usually the report is on the fishing itself.

    Technically, the long narrow Thai boats, typically the ‘long tails’, are not ‘planing’ but semi-planing boats. They derive tremendous economy benefit from being long and skinny, something boat builders, and marine architects, have known for centuries. It was the Thornycroft, wide planing hull used for the PT boats of WW2 that woke up Western boat builders to the benefits? of wide planing hulls. The German “E” boats, had long, narrow, “Luhurson” hulls.

    Short, wide, hulls in the west, America especially, became popular as marinas became the place to store your boat. Notice, the Chesapeake bay power fishermen were still long and narrow (the Deadrise Hulls) until they had to dock in commercial space. John Gardner did some fantastic long skinny boats in the PNW, Tlingit, Captain Teach, Czarina, to name a few. Fantastic in their environment, but not marina friendly.

    In the Med, stern too, or bow too mooring is the rule. In Thailand, it is rafting up. If either were common practice in America, moorage would be reduced dramatically. Instead we insist on having ‘our’ dock, and boats are designed to accommodate this.

    We in the west would greatly reduce our fuel consumption if we embraced these same long narrow hulls. Notice the “Panga” fishing boats, long skinny, fast, and about 20hp.

    I THINK! the planing boards you see on the rear are from when the engine was replaced with a heavier version, and rather than redesigning, or changing the boat, they add a ‘planning board’, a simple cheap expedient.

    All their boats, long tails, and short tails (inboard) are masters of expediency, and economy. Though fuel is quite cheap there, it is still a significant part of operational cost. their engine installations are beautifully engineered, if executed in a rather crude “blacksmith” fashion, very effective too.

    No the long boats are not at all maneuverable, but when all boats are the same, it doesn't seem to matter, even in a crowd. The operator often uses the propeller shaft as a kind of ‘sweep oar’ to ‘row’ the stern around, and must be a bit careful he doesn't hit another boat with the propeller doing this. After years of practice, and tradition, these operators can put their boats exactly where they want them, not easily, they work hard physically, but deftly.

    The long narrow hull is exceptionally seaworthy, but cannot be driven at any sped into a chop. For one thing, the boats as built have poor torsional stiffness, and warp alarmingly in a cross swell. As long as the boat is kept head to sea, it will survive,

    An english catamaran (Sailcraft?) had its mast on the rear beam, a far aft rig. Only one class was built, and it was not popular, possibly because it looked ‘different’. There is NO reason why an aft mast rig, very skinny/high aspect ratio main; very large, low angle Jib/genoa will not work extremely well. Two Jib's, a 'Cutter" rig, might be best, i don't know. Just don't expect it to win races.

    All sail controls are from the base of the mast, reefing the main is easy, roller reefing jib or genoa. Couldn't be easier. There was a lot of talk about raking masts forward, but i wouldn't bother. Remember, the down force on the mast can be equal and opposite to the instantaneous displacement of the boat? a large force, and at an ‘off’ angle, hard to resolve.
     
  6. NoahWannabe
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    NoahWannabe Junior Member

    Thanks for additional information. The smaller longtails I see on Brian's photos seem to be 20' long and 2-3' wide at water line. My guesstimate displacement would be 1000 kg and driven by 8-12 hp one cylinder diesel motor. How fast do they go? If I take 20x3 rowing dory and mount longtail like them, could I expect similar result? Maybe with two dory hulls side by side as in catamaran?
     
  7. Sailor Alan
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    Sailor Alan Senior Member

    Long thin Boats

    No a ROWING dory would not work, but you are nearly right.

    First the Thai boats are not miraculous, they use standard maritime architecture laws, they just use different compromises from their western counterparts.

    As you surmise, they are about 2-3’ wide for a 20’ long example, and very fast. A modern “Western Power Dory"

    http://www.glen-l.com/designs/workboat/hunkydory.html

    is similar, but 4+’ wide on the bottom. I think power needed goes up at the Square of the beam, so a lot more power needed in the west. Were you to build one of these at 2-3’ wide, you would half the volume, and need a quarter the Power. These are very rough figures, but you get the idea. The “Glen-L” example above has virtually the exact lines of a Thai long boat, merely twice as wide for the length. Look carefully at the photos, and you should see exactly the same hull lines, bottom contour, and shear lines.

    The Thai’s would make the boat longer, not wider. The 4-5’ wide boats i rode on must have been 35’ long.

    The type of motor and drive, the “long Tail’ is not a secret, or particularly efficient, merely an expedient. By all means build a cheap, long, skinny version of the power dory above, but you only need a small OB, not a ‘Long tail’ to propel it efficiently. Note; the Thai “long Tail’ has spawned a kind of imitator in the USA, the ‘mud motor’.

    http://www.copperheadmfg.com/products/18-hp-mud-motor

    These use the ‘surface penetrating’ effect of the propeller to propel the craft through swamps and mud. Again, not particularly efficient, but it works if you are in a swamp, and need propulsion through it. Here in the PNW, we need actual ‘jet’ boats, a water pump, because the rivers bottom is rocky, not mud.

    Please Note; the “Panga” boats in Mexico are the same long skinny form, very fast on low power too, but be warned, as the design crossed the border it got wider and much more expensive. Occasionally someone will get a real one, usually from Cursiao, but the chances of getting a ‘real’ one is minimal. If imported the customs will be all over it, they have been used for smuggling, drugs stuffed inside the hull thickness, far too often.

    Now catamarans. These rely on “form” stability, width, for their performance, and the long thin hulls need to be really thin, and fairly far apart, to make sense. A pair of ‘dory’ hulls, even power dory’s, would have far too much individual stability, and make interference drag from their bow waves interfering with each other.
    I don't know if these are particularly good “cats’ but they are a place to start.

    http://ccplans.com/index.php?pag_id=38

    By all means explore catamarans, but remember, their total displacement is the same for the same weight monohull, and by definition, must be wider beam, longer, and/or deeper in draft, more surface area, hence heavier.

    Then there are wave piercing catamarans, Swath technology, Hydro-lances (TM)

    http://www.hydrolance.net/page8.htm

    and a whole raft of other approaches out there.

    First work out how much weight you need to carry, then the operating conditions, then you can start considering options. Long narrow monohulls tend to be more efficient at slow speeds, but lack stability, i.e. not very wide for a given displacement or length. Catamarans tend to be more stable, wider, and a bit faster for a given length, but have more surface area, and connection beams (in the air) so hence slightly heavier. Faster, at planning speeds, it gets complicated, the flatish bottom is faster and harsher, the cats can get aerodynamic ‘lift’, and deep “V” use a lot more power.

    All this is extremely general, every case is different, and there is no free lunch, no free ride, and weight is weight.
     
  8. Sailor Alan
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    Sailor Alan Senior Member

    Solar haven

    Noah,

    Not wishing to open old wounds, but harking back to an earlier subject. I want you to think about a boat like this in form. The Hydrolance looks a bit fake, but does work after a fashion.

    http://www.yachtforums.com/forums/g...ssion/17053-hydro-lance-harth-technology.html

    i want you to imagine a 1,000sq/ft surface, about 30’ wide, and 35’ long. it will consist of long, fore and aft, reflective semi tubes, open side up. These, being semicircular, are poorly focused on (Boeing surplus) titanium tubes containing water. Poor focus means less adjustment, and more compliance with sea motion, no controls necessary. The sun heats up the water until its steam, which then enters a repurposed turbine from a car or truck turbocharger. This turbine drives a 3 phase alternator. The exhaust from the turbine goes down a slightly larger tube through the hull as a surface radiator, creating a semi vacuum, and condensing back to water. i will have to do some calculation, but i suspect such an area can support 20 or more such steam turbines.

    Immediately under this 1,000sq/ft or 30’ X 35’ surface, is suspended a 8’ high living space. The front is negative sloped glass, the sides mostly vertical glass, and the rear glass doors, a patio, and other features. The interior is furnished as traveling quarters for, say, 4 people. This whole structure is fabricated from aluminum, and suspended some 8'-10' above the LWL.

    Each side of this 30’ wide structure are walls, or columns, perhaps 2’ wide, and perhaps 35’ long, depending on design. These ‘walls’ support the upper accommodation structure above a pair of long, narrow, hulls, perhaps 65’ long, 3’-4’ wide, and several feet deep.

    These hulls will contain simple lead acid batteries, and possibly water and other stores. The extreme rear of each of these hulls will contain an electric motor, and a propeller. These AC motors could be wet stator so they need no sealed bearing.

    Electrical system. The turbo alternators will all run at different speeds, all producing 3 phase AC at different frequencies, but a common, or similar voltage. This mess of waveforms, on the same 3 phase circuit, will be rectified into DC appropriate to the AC input voltage. This DC can be stored in the batteries. Now this DC is inverted, using a tailored pulse width AC waveform (I pioneered their design decades ago), into a suitable voltage and frequency to serve the electric propulsion motors. It would also provide 110V AC for domestic use, microwaves, radio, lights, water-maker etc. The water-maker is necessary to wash the mirrors (and probably the windows) in fresh water every day.

    Please note; the image shown is probably patented by someone, but equally, the hulls are far too skinny for practical use, and the hull body support is some artists fancy. But you get the idea.

    I will work on a better cartoon showing some numbers in due time.
     
  9. Yobarnacle
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    Yobarnacle Senior Member

    I still like the ITB approach. I have two Albin 25 motorsailors. Trailersailors.
    When finished, either can operate alone. but the transom of one has a shallow notch added on, and the other, tow knees added to the stem. If I need to go someplace by water, it's a 50 footer integrated tow. usually, the boats will move by trailer at highway speeds. I have one trailer for the pair. On mooring or at anchor, the living quarters boat anchors and hangs the barge astern. Steadies her up and more comfortable ride. At dock, they raft up.
    There is one large sleeping cabin in each boat. Guests get not only a large cabin, but the privacy of a different boat. The barge boat is the warehouse, tool room, and workshop. Both will be diesel electric. Running one diesel can charge up both boats.
    I can go on about the advantages, but you can begin to see the idea.
    'Intrepidos' (the intrepid pair or couple) is our live-aboard boat, and 'Stowaway' is the barge boat.
     
  10. Sailor Alan
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    Sailor Alan Senior Member

    Fascinating. I for one will be interested in whether you can sail them as a connected unit, assuming you still have masts/sail on both.

    There is a long history of similar boats towing each other, the Great Lakes had many of them during the transition from sail to steam.

    Its a pity they cannot be more connected hydrodynamicly, the propeller/rudder, especially if running, of the front boat will reduce the ‘long hull’ effect of of having them end to end. I’ll also be interested in if you need distinctly different power settings, front to back. More power (relatively) in front should create more drag, faster flow under the rear boat. Lower power (relatively) in front might be best, but might create more wear on the coupling.

    Well done on an innovative solution. There are quite a few power/non-power pairs here in Puget Sound, though all? are dissimilar vessels.
     
  11. SamSam
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    SamSam Senior Member

    Somebody on this site made a pontoon or houseboat that had a notch in the stern that his jet ski fit in and was the power for the houseboat. He could anchor the houseboat and then race all over with the jet ski, annoying people in a much wider area for longer periods of time. I think it worked well, but from what I hear jet skis in general get awful mileage.

    A lot of the small, personal sternwheelers will push a barge, some with accommodations of one kind or another.

    [​IMG]

    http://www.boatdesign.net/forums/boat-design/building-new-sternwheeler-20136.html
     
  12. Yobarnacle
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    Yobarnacle Senior Member

    I like the jetski tug idea. But couldn't hoist it aboard a 25 foot boat and wouldn't want to leave it in the water. :)
     
  13. Yobarnacle
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    Yobarnacle Senior Member

    sailor alan
    I've been working on the project for 3 years as time and funds permit. I'll do a blog of the whole thing when I'm finished.
    but my intent wasn't a "Look at ME!"
    But a suggestion as to the AFFORDABLE and enough SPACE to live aboard full time is: while BIG boats are expensive, and a trailerable boat is too small; TWO small ones are TWICE as big. :D
    Boats in the 24/25 foot range are often cheap. Mine were.

    As to power on the boat being pushed. Just a few amps. A few RPM greater than the speed. So the prop on that boat becomes hydrodynamic invisible. Prop drag and resistance disappear.

    I believe a mizzen may be set on the pushed boat and controlled from the pushing boat. Mostly just to keep the heel equal. If the mizzen wasn't too much to handle, maybe a mizzen staysail could be flown as well. But I wouldn't single hand such a scattered out, multi sheeted rig! :D
    Or maybe JUST a mizzen staysail. Roller furling and furler line led to aft boat along with sheets.
     
  14. NoahWannabe
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    NoahWannabe Junior Member

    Sailor Alan, no old wounds. This is fascinating, some type of evacuated tube solar thermal collectors to drive steam turbine engines then rectified/phased into a useful AC waveform. I like this concept. While back, I did pursue a concept of evacuated tubes driving sterling engine electric generators driving AC motors for propulsion. But I never got a reliable mass produced mini sterling engine supplier and I didn't like inefficiency of typical inverters and current controllers.

    Does your solar thermal collectors have open top half tube with fluid in the center tube? Why 3 phase alternators, if it will be converted to inverted DC (negative voltage?) anyway then to inverted into AC again? What is the efficiency of this conversions? It sounds complicated. Why not just collect all steam energy into a single or twin (redundancy?) turbine for clean AC generation? But do explain more.

    I am not sold on hydrolance or large solar collector barge set up high above water level on SWATH/wave piercing hulls. It seems too high of a floor height on small boat to be comfortable. However, it would work for a larger boat design considering stability and displacement needs.

    Wet stator AC motor? Lubricant wet stator motor? Sounds pretty advanced. I am looking for an electric motor propulsion, AC preferred but DC can work too. An economical and mass produced electric or hybrid motor would be ideal.

    Is there any known electrified (pure electric or hybrid) 5-20 tons fast displacement hull boat cruising 10-15 knots owned by an individual under a $1 million?
     

  15. NoahWannabe
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    NoahWannabe Junior Member

    Yorbarnacle, that twin in-line hulls sound very interesting. Does that configuration improve hull speed or provide any hull efficiency? Could you tow 50 feet legally?
     
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