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Thread: 50' Hybrid Diesel Electric Steel Catamaran

  1. #1

    Default 50' Hybrid Diesel Electric Steel Catamaran

    It is about a year when I posted about this. It was an idea then, now it is more to reality. Need expert advise to refine my ideas.

    Want to make a small boat for photography/research for mangrove in Bangladesh. The core area is 80km away from the nearest town. The travel area is far from human habitation so we need to accommodate 2 armed guards, two kitchen staff, two navigation staff, one engineering and one helping assistant. That means total 8 crew and 10 guests boarding facility with store for at least for 7 days.

    The proposed boat spec is:

    Hull Length: 50' at waterline
    Hull width: 5'
    Beam: 20'
    Draft: 3.5'

    Propulsion:

    2x 30kw induction motor driven by 2x 45 kw silent diesel generator.
    A battery bank and solar system can be incorporated later.

    The reason for electric drive it can run almost silent.

    We do not have fiber glass and aluminum building technology so developed, so we have to go for steel fabrication.

    Now the challenge is:

    1. Can steel structure can be made for this size boat which will have efficient hull?
    2. Can thee be any serious limitation constrain for the drive system? Is the power too small?

    Would like advise from the experienced.

  2. #2
    Join Date
    Aug 2011
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    Default Tubular Hulls of Alum, Steel, or SS

    Have a look over here for a couple of ideas.

    http://www.boatdesign.net/forums/boa...tml#post531819

    http://www.boatdesign.net/forums/boa...tml#post531834

    ...couple of shots
    Attached Images Attached Images

  3. #3
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    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Why not sectional polyproplyene potooons that could easily be transported to a remote area and put together

    http://goodoutdoors.theshoppe.com/pontoons.html

    Images for Plastic Pontoons

  4. #4
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    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Hi Ceasar, interesting mission you're on.

    I don't think you'll find many people who have experience of steel catamarans here. Most people here seem to favour sailing cats. Steel has a weight penalty that pretty much rules it out for sailing cats; your project I assume is purely a motor-cat, is this correct?

    "1. Can steel structure can be made for this size boat which will have efficient hull?"
    - efficient in what sense? For high speed motoring? Silent pottering through mangroves? Or sailing, if this is what you have in mind?

    Do I get it right that the boat will be built in Bangladesh, hence the need to build in steel? How do your projected build costs stack up against buying a boat elsewhere in the world and getting it to your area of operation?

    Have you fully costed the proposed motors installations? Do you and/or your engineer have a good understanding of the control systems for brushless motors? You are proposing a very sophisticated (and expensive) drive system for remote area operations; your spares kit alone would be a sizeable investment, I'd imagine.

    Have you considered operating temperatures for your motors/controllers? Your steel engine rooms will be hot in Bangladesh. Not much breeze in the mangroves. (Your steel decks will be pretty hot to walk on too). I would research safe operating temperatures for motors and controllers. If silent running is a priority, steel as a material will tend to amplify any noise.

    Not trying to rain on your parade here mate, just interested in how you propose to solve problems. Sorry I can't offer more technical advice. You really need a Naval Architect to be advising you on efficient 50ft steel catamaran hulls, if such things exist. Getting a boat that size properly drawn up and engineered will put a big dent in your budget and may make sourcing an existing vessel more attractive. I'd be looking for a foam cored composite, for best insulation, with lots of permanent shade.

    Good luck in your mission, keep us posted; regards from Groover

  5. #5
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    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Hadn't considered the pontoon boat solution that Brian has just suggested above. This could be good lo-tech fix.

  6. #6

    Default Re: Tubular Hulls of Alum, Steel, or SS

    Hi brian eiland, many thanks for your photos. Actually the boat will cruise a lot against strong current and the main reason to go for a multihull is silent and efficient propulsion. So potooon houseboats may not be a good solution.

  7. #7

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Hi ocean_groover, many thanks for you reply, I try to clarify..

    1. Efficient considering displacement hull motor propulsion performance.

    2. Bringing a foreign boat has many red tape hassle. In addition steel monohulls of this size and bigger Bangladesh is doing well and already exporting bigger ships to Germany even. Fabrication is cheaper in Bangladesh too due to low labor and energy cost.

    3. Actually many steel monohulls are operating with the heat and all the troubles. But the smaller ones are very inefficient in speed.

    4. The electrical system is well designed. It needs force ventilation for some devices but should not be a problem.

    I appreciate any criticize before design, do not worry

  8. #8
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    Default Houseboats of Kerala

    Are you fimilar with these 'HouseBoats of Kerala' in southern India?

    I brought the subject up over here, but my weblink is no good any longer.
    http://www.yachtforums.com/forums/ge...houseboat.html

    Here are some others:
    http://www.luxurytoursofindia.com/ke...FUXc4AodnQYATw

    http://www.keralahouseboat.org/

    http://www.thehouseboatskerala.com/

  9. #9

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Yes brian eiland, theoretically. A French guy did made one actually a similar boat but could not run well. Somehow wood become rotten here too easy and it takes too long to rich the destination. Our rivers are too big having too strong tidal flow. In addition weather may go bad in a short time. We need a strong and semi sea worthy vessel.

    The boats people are using are like this. But the problem is the smaller one are slugs.

    http://www.guidetours.com/our-services/our-boats.html

  10. #10

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Just to prove I am not crazy here is a steel hull boat in operation, what I am planning is a smaller and more optimized version with a 16m x 7m size, lighter construction with all upper deck aluminium/glass/fiberglass construction with a very small bridge only in the top deck.



    Nimrod Explorer

    Built in 1984, restored in 2004
    Size — 22m x 8m
    Top speed — 11 knots
    Cruising speed — 9 knots
    2 x 170 HP Gardner diesel engines
    2 x 80 KW Gardner generators
    2 Bauer K14 dive tank compressors
    Aluminium scuba tanks with INT fittings (DIN adapters are for rent)
    Enriched air nitrox
    Electricity — 220V 24 hours per day
    Water capacity — 3,785 litres
    Fresh water maker - 6,000 litres per day
    Fuel capacity — 11,200 litres

  11. #11
    Join Date
    Aug 2011
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    WashDC, Annapolis, Thailand
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    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Quote Originally Posted by Caesar View Post
    It is about a year when I posted about this. It was an idea then, now it is more to reality. Need expert advise to refine my ideas.

    Want to make a small boat for photography/research for mangrove in Bangladesh. The core area is 80km away from the nearest town. The travel area is far from human habitation so we need to accommodate 2 armed guards, two kitchen staff, two navigation staff, one engineering and one helping assistant. That means total 8 crew and 10 guests boarding facility with store for at least for 7 days.
    How long do you intend to keep this vessel? I got the impression you were looking for a somewhat temp vessel to do this study for a year or so?

    And is it your intention to utilize this vessel beyond the scope of this mangrove study?

  12. #12
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    Aug 2011
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    Default Re: Tubular Hulls of Alum, Steel, or SS

    Quote Originally Posted by Caesar View Post
    Hi brian eiland, many thanks for your photos. Actually the boat will cruise a lot against strong current and the main reason to go for a multihull is silent and efficient propulsion. So potooon houseboats may not be a good solution.
    I'm not fully understanding you here....efficient propulsion. Are youn looking for speed under power? I don't understand your desire for speed to explore mangoves? ....maybe shallow draft, and manuering,...but not speed.

    I believe you may be too harsh in your condemation of potoon vessels.

    And if I were going into remote villages/locals I certainly wouldn't be taking 'new technology' electric propulsion. I would find the motor technology that is available for repair most likely in that country....outboards are servicable worlwide, and they don't need to take up valuble interior space on the relatively short vessel your are wishing to house quite a few folks onboard.
    Last edited by brian eiland; 29th July 2012 at 04:13 PM.

  13. #13
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    Default Picnic, Weekender Cat

    As I thought a bit more about your project I thought I might offer this idea....a cat I saw in Thailand and titled it a 'picnic/weekender'
    http://www.boatdesign.net/forums/pow...cat-33751.html

    In reality it is a 50 foot daysail charter vessel powered by twin outboards. It has a very nice open centersaloon area (good ventilation), and berths down in 4 seperate hull entries.

    If you look at the photos (and I have some more recent ones) you will find it is constructed of flat panel wood with relatively simplt frames and stringers. One could utilize this same construction,...or could make use of pre-fab composite panels as many of the kit-boat designers do,..

    ..or could even build her of new sandwich panel construction I am investigating for use about a steel monohull motorsailer. Basically this will be a relatively light weight steel hull surface (outer face) that will have a proproplyene honycomb core (like NidaCore) bonded to its inner surface in lieu of the tradition frames and stringers of conventional metal boat building.

    Part of that inspiration come from this experience with a reconstruction of an Alden design by a Maine boatbuilder
    http://www.soundingsonline.com/boat-...lletproof-boat

    http://www.nida-core.com/pdfs/rigidtech.pdf
    Attached Images Attached Images
    Last edited by brian eiland; 29th July 2012 at 04:40 PM.

  14. #14

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    brian eiland: Normally each trip is about 7 days long and about 250 knot total cruise. I will do my work and the rest of the time it will be rented to others.

    Bangladesh is a country with big rivers and tidal surges and the boat will serve coastal areas all season where tide and weather is a concern. In addition we have regulations regarding passenger vessels like 1m deck clearance minimum, other structural parameters etc. which we can't ignore and use "as you like" deigns. So potoon vessels (I know it is easy to make and cheaper) we have to rule out.

    I am an electronics expert myself and have long experience in lift technology with motors and drives. So I have full confidence about it. One electrical technician on board and redundant design like two motors, 2 gen sets, 2 drives in operation and one set for everything as spare will solve any problem. Induction motors seldom go bad and even a 2 kw gasoline gen set will be able to move the boat - here lies the beauty of electric system.

    What I want is a silent cruising boat with fuel efficiency. Which has relatively low engine power (30+30 kw). That needs a very efficient hull in speed perspective. That is not to run the boat at high speed but at fraction of maximum hull speed to save energy.

    Hope it is a bit clearer to you now.

  15. #15

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    I think your hull width of five feet is way too small--I would make it eight feet for a boat fifty foot in length. That ten percent stuff is for racing cats in a head sea--none of this you will face in the mangroves--and you will accomodate the crew more comfortably and be able to carry enough stores without sinking too far into the water.

    Steel will work fine--nothing wrong with it. A charter cat maned "Drumbeat" operates in Sydney harbour Australia wand is built of steel. I would go for 3 or 4mm and build it round bilge, with steel box girders linking the hulls in a kind of Wharram style. Small deck cabins can be placed on a flat deck underslung between these girders to keep the ship's profile below the level of the mangroves. Masts could be raised or lowered as required and sails stowed in deck lockers.

    Diesel electric is fine--put your batteries on the wing deck rather than in the hulls. Put your water and fuel tankage in the hulls not on the wing decks. Design for the frequent groundings with a good rub strake under each hull. Lotsa luck!

  16. #16

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Hi Mike Banks, thanks for your input.

    If I make the beam 8 feet, then the in 20 feet only 4 feet remains between the two beams, will it put any benefit over a monohull? I agree wider hull will give me more usable space, but will need a much powerful engine. All the efficient ferries, solar vessels I see in modern designs have 1:10 or better hull ratio.

    Thanks for the steel construction advice.

  17. #17

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Because you are building in steel which is about fifty percent or more heavier than any other construction material likely to be chosen for a multihull of that length, and the large crew aboard together with their equipment, food etc I think you are going to need the wider hulls and yes--they will be more stable than a mono hull in that a mono hull plus its keel simply draws too much water in the project you have in mind, mangrove research. The same applies for narrow steel hulls--they will when loaded draw about two metres or more--as opposed to about one metre or less with boards up.

    You will need about sixty to eighty horsepower to reach hull speed in the wider hull version. I have a pall who uses outboard motor legs fitted with hydraulic motors run from a diesel powered pump which also generates 3 phase power. In your case where silence is important the whine of gears etc may be a prioblem--but in-hull electric motors and shaft driven propellors would be fine. Why I like the idea of diesel in remote places (petrol is a potential bomb aboard) is the possibility of using bio-diesel when other fuels are unavailable. Passengers are usually not aware of the safety aspects of vessels--so the less potential for problems aboard the better. Fire in such a situation would be the most likely disaster--and the worst of the potential problems faced in remote places.

    If money is not a problem Wharram designed some vessels for island trading and general purpose uses which would probably suit your purposes. They may be made in steel I think in the longer versions, but I would rather use aluminium. Either way this is not going to be a project that will escape from the requirements of safety of life at sea--so it will not be a cheap project. Just less expensive than some.

    Best of luck--but I think Wharram's designs may solve some problems in that you have proven plans from which to work and a certainty of outcome.
    Last edited by Mike Banks; 2nd August 2012 at 11:28 PM.

  18. #18

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Mike Banks, I agree we have to come to a compromise about hull width considering maximum hull speed and draft at full load. My initial assumption is to keep the displacement at 35mt and with a 2x50'x5' hull at 4' feet draft is giving 36 ton draft at 65%. Now my challenge is to keep the plate and superstructure weight below 20mt. For roof and partitioning walls I will utilize fiberglass and glass-aluminum (4mt). There will be not much equipment except propulsion (3mt), Furniture (1mt), Galley (1mt), Water (4mt), Fuel 1 (mt) and people (2mt).

    Yes, I also believe all safety issues should be well addressed during design. That's why the hull plates will be used quite heavy (5mm). We will not use any plastic material as it creates toxic fume while in fire. The whole boat will be equipped with fire alarm system. In a way with proper protection devices and wiring, I think an electric boat has less fire prone areas.
    As this is a private project, money is always an issue. We can’t go with aluminum, it is too expensive. I will check the Wharram's designs.
    Thanks again for your thoughts.

  19. #19

    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    hello caesar
    i had been following yr post and also nice feed back u r recvng from others.
    As u mentioned aluminum hull will be very expensive and difficult to fabricate in bangladesh, I like to add few info in this regard.
    Couple of shipyard are doing Aluminum fab in Bangladesh and to my knowledgem even few Al-built petrol boat had been exported to some west african offshore facilities.
    Cost wise you can reconsider about your option. Though Al is costier but it have few advantage overall.
    You will need roughly 60-65% of Al (by weight) against steel.
    In terms of welding and fabrication flexibility, aluminum is better choice than still. In long term maintenance cost will outsmart your cost saving using steel.
    Finally power consumption is a big issue now a days in a world of high petrolium price. A steel cat will be more expensive to run as it is heavier.
    In design perspective, most of the cat in this range mostly designed basis aluminum or GRP. If you are looking for a very efficient and proven design, most of the option u will get is based on GRP or Aluminum. efficient steel cat is very rare in this range.
    So I feel u may reconsider about your option regarding hull construction material

  20. #20
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    Default Re: 50' Hybrid Diesel Electric Steel Catamaran

    Caesar, steel, 50', catamaran, and low power are not a good combination. A traditional shallow monohull river boat with a low RPM diesel is best for your use, if it must be steel. If you look for precedents, you will find that only very large (ship size) catamarans are made out of steel, and they aren't low powered. There are good reasons for this. Solar power will never be good for this use, even in the tropics, even with more efficient solar panes than are currently available, based on calculations of the maximum amount of power per square meter that sunlight contains.
    Currently concentrating on http://earthnurture.com .

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