Powered water seat

[Luis Cunha]

Dear Sirs,

My name is Luis Sarmento Cunha, I live in Francelos, V.N.Gaia, PORTUGAL close to Atlantic Sea.
I have just created an innovative water vehicle, the Powered Water Seat (PWS), but I have some questions regarding whether it is a feasible concept.
The PWS is mainly composed of strong tubing, a power assembly mounted on one side of the tube, the seat system mounted on the other side and a hull (like a floater). The power assembly is mainly made up by an electric motor, electronics, batteries and a rudder. The seat system is the seat, controls and cardan.
The hull is mounted on the tube and can move up and down, controlled by a driver.
In my opinion the motor which powers the PWS should be electric but there are probably other better options.
When the PWS is stopped, it stays balanced by the vertical tube and the seat positioned above the water surface. In this position the driver can look around or fish in a very comfortable position.
To take a swim, the hull can move up and the person can then jump into the water.
To start driving, the hull moves down, the person inclines forward and it start moving. The movement should feel like one is surfing.
I'm not quite sure if I have explained my idea sufficiently well. I'm attaching some CAD photos that may elaborate further.
I would very much appreciate your comments regarding this new concept and whether, in your opinion, it is feasible to build the PWS.
If it is feasible, I will appreciate to have the cooperation of a fantastic designer in order to create a completely new concept of power boat.
Thanks in advance for your co-operation.

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Luis Cunha
Francelos, V.N.Gaia, Portugal
Tel: 351 93 7894106
luisscunha@clix.pt

[alan white]

This seems to be very similar to a Starling Burgess design proposed maybe 75 years ago. I am trying to remember where I read about it.

Alan

[Luis Cunha]

Dear Alan White,

It is an honour thinking that some of my ideas are close to the great and well known Starling Burgess.
Thank you.
Waiting your comments

[alan white]

Somehow, I can't mentally place a person on it.
Can you sketch a person where they belong on this thing?

[korvello]

LUIS still waiting on a little better drawings :it looks like riding a unicycle ; propeller needs to be enclosed or is it a jet of some kind and may need a foil ,can't see why the seat has to move it will make it too complicated and harder to ride,may also need some kind of handle bars for atitude control......... oh well just my 2 cents and one will need good balance and luck probably.

[Luis Cunha]

Korvello,


Concerning propeller versus jet, I think both solutions are possible. It is necessary to check prices, power, weight and volume.

In my opinion the seat has to move in order to give more comfort to the driver. You can get it using a special cardan.

My idea is that the driver can control the position of the hull (red buoy), speed and direction of the movement.

New drawings comming soon

Regards

[korvello]

I can see the seat being up or down affecting balance ,i just don't get is moving foward with buoy in the water how does pilot control toy;.... with leaning back or foward? ....it needs bars for atitude control, the motor will go foward and drag the pilot behind ,now there is an idea a one man ski machine........motor needs to be mounted on a tube or longer shaft with foils or something for some way or stabilizing it ......fascinating how fast are we talking about 2mph ,why not pedals and a human powered propeler there you will have a unicycle and maybe some balast will help too .......LUIS i hope you massage your drawings so far you have a sit -on buoy as i see it!............ but hey i have even crazier ideas so i'm sure we'd get along just fine .

[Vega]

.......... but hey i have even crazier ideas so i'm sure we'd get along just fine .
:D :D :D

Stability and balance seems very problematic...I would say acrobatic. If you join the imponderables of sea motion I suspect only an acrobat or a computer controlled gyroscopic system will be able to control the craft.
But I can be wrong and certainly it is an unusual approach.

[korvello]

VEGA now that the big guns are getting involved maybe LUIS has a chance ,it also could be called the portuguese tread [nao sei se sera uma coisa boa]..........a lot is at stake here if the all thing fails .........still waiting on LUIS's new drawings ,what about a prototype?

[Luis Cunha]

Hello Vega and Korvello,

Thank you very much for your comments.
My “defence” is as follows:

1. Stability
The natural position of the Powered Water Seat (PWS) is vertical with the seat up and motor down because the power assembly is weightier than seat system plus pilot.
When occurs something that causes instability PWS return to vertical position not only because of weights but also because the hull helps it.
It is important to have big difference of weights in order to turn faster the returning to natural position.
In my opinion gyroscopic is needed if the natural position is not what we need. This is not the case.

2. Balance
The seat system with cardan absorves balance, not all but a big part.
In small boats everybody feels balance.
Another idea, consider that the hull as a sensor that permits it follows exactly the shape of the wave. In this case pilot doesn’t feel any balance; he is always at the same position. This can be done with electronics.

3. Control
Pilot can control position of the hull, speed and direction
Position of the hull can be controlled with a motor, drive and a cable system.
Speed can be controlled with motor, drive and, for example, propeller.
Direction of the movement can be controlled with a rudder.
It is critical when pilot starts because of inertia there is a trend to lean back. The solution is also control the direction of the propeller or jet around a perpendicular axis to movement plane.

4. Speed
My idea is more than 20 mph

Best regards

[korvello]

LUIS we now are getting some where or are we? ........ it appears you are making this thing to heavy and complicated ...........if one wanted a big buoy to sit on,fish from it ,cruise at 20 mph ,have a trailer to carry it and deploy ,i think it's called a PWC [ sorry couldn't resist,you set yourself for it]........on a more serious note i was hoping you where trying to make a self propelled hydrofoil or something where the buoy would be used at slow speed and at rest and the motor and some form of foil and rudder would control it ,you are loosing me here ........why don't you put the motor on the buoy if all you want is to drag a buoy on the water the motor could be in front of it and .......oh well here i go again .

[Luis Cunha]

Hello Korvello,


Thank you for your comments.
A Jet Ski weights around 300 kg, to carry it you need a trailer, you can reach much more than 20 mph driving it, it has complex systems and people buys it. How do you explain this phenomenon?

I would like and appreciate to receive comments from someone like a professor or experienced architect in order to confirm if you are right or not.

Anyway and because I think this idea is good I will do a small model where each part has either the same density of full-scale or a scaled weight of the full scale ensuring the same centre of gravity for the model and full scale. This suggestion was done by Mr. Jorgen Jorde from LMG Marin (Jorgen, thanks very much! Great company, great people!)

[korvello]

LUIS sorry just testing your idea !
you're the one that mention that motor and suspended mechanism should weight more than buoy and pilot , are you going to find someone that weights 40 kg or do you intend to make this thing for adults; so let's say a normal person plus buoy would be what 85 kg [imagine how much one would have to weight to balance someone like WALRUS, and you tought a PWC was heavy ..:D :D . ] how are you going to carry your PWS around unless you carry plates like in weight lifting and just insert plates has needed or this will be only for bodybuilders ...............i like your idea and i hope a real engineer or professor has you say would say something ,i just think they have to much to loose by even commenting on it , unlike me [the silence speaks for itself]...............that's why i say make it light so one can carry in the back of the car,make the buoy come out of the water at speed there one could go fast and would also required balance and skill to drive the thing , then you'll have a real fun toy that anyone could take to the beach ..............has i said if it's just a self propelled buoy that weights a lot would that just be an exercise in futillity or do you think someone would real be interested in one?

[Guest625101138]

Luis
You do not need a professor to determine the weaknesses of your design. You should be able to do the calculations yourself.

Stability/Balancce/Weight
Typical adult males that might be interested in using the device will weigh around 100kg. Seat, stand and controls will add another 15kg say. Your centre of bouyancy will be around 1.5m from the rider and seat CoG. The offsetting weight of the drive system will be about 0.6m from the CoB. So using moments the weight minus bouyancy of the drive will need to be:
Drive Weight (less its bouyancy) = 115 * 1.5/0.6 = 287.5kg
You now need to add the extra bouyancy of the drive. Could easily be 20 litres in volume so add another 20kg. You end up with a PWS weighing in at more than 307.5kg. We have not added any weight yet for the float. It will need to be quite large. You usually like to have 100% reserve bouyancy so it will need a volume of 600 litres. Not something you can fit in the back of a station wagon.

Speed
To do 20mph (8.9m/s) something of this proportion needs to plane so you will need to flatten and straighten the bottom of the float. We have a craft that weighs around 350kg with light weight construction. With a 100kg rider and lets say 20kg of nibbles/refreshments and fishing gear the total displacement will be 470kg. The simplest way to determine the required power is to calculate the drag as 1/8th of the total weight:
Drag = 470/8 = 58.75 kg
Power = 58.75kg * 9.8N/kgf * 8.9m/s = 5,124W
You could assume a propeller efficiency of 70% so installed power will need to be 7.3kW or roughly 10HP.

Design Development
Since the required hull would be much larger in proportion than you have drawn it could be designed to have an elevated centre of roll (large KMT)and this would improve things dramatically - enable less weight in the drive and therefore reduce the required power. It would look more like a small flying saucer maybe 2m in diameter rather than a water buoy.

If you want something more compact than a jet ski you have to get low in the hull. Have you seen the powered kayak here:
http://www.youtube.com/watch?v=8aJhnkR_FF0
Sitting high above the water means you need a big hull even if it has a weighted keel.

Rick W.

[Luis Cunha]

Hello,

Thanks to Rick Willoughby. Your comments were much appreciated.
I think the main weaknesses of this concept are:

1. Portability (weight and dimension)
2. Hull design to reach speed and stability
3. Starting up

Considering the following ideas / comments of Rick Willoughby, Korvello and myself I think I can solve all above problems:

1.a. Insufflate hull
1.b. Easily assembly / disassembly

2.a. Flatten and straighten the bottom of the float to turn possible higher speed
2.b. New seat design (I’m still developing this idea)

3.a. Direction of the propeller or jet around a perpendicular axis to movement plane due to start up issue (I need to think better about this).

Soon I will revert.

Luis

[korvello]

Hey RICK are you a professor or a architect or something similar i shure hope not, because other than making sense your opinion is killing the all idea :D :D ...........yupp the weight is killing the PWS butt that we already knew ,i think LUIS is not convinced yet ,i'm sure one could inflate the hull i just didn't got that one completely what about the weight is it going to be inflatable too or just water ballast:confused: .............to be continued i think?????????????

[Guest625101138]

Korvello
I can relate to Luis as I have tried heaps of half workable ideas. However I guess with experience you learn you cannot cheat physics but often we do not have a complete grasp of the physics involved so a trial can provide education.

I have attached a photo of my version of the PWS. Actually I referred to it as submerged buoyancy when it was built. It sort of works in theory but in practice the central hull would need to be deeper to reduce wave drag. I did fit little foils to the stern outriggers that enabled me to get over 12kph.

In practice the boat was difficult to mount. It took me about 2 hours the first time I tried. Once under way the main hull was completely submerged and it looked like I was sitting on a chair supported on a tripod. If I accelerated hard I could get the forward outrigger to lift 2m clear of the water and it would hold this attitude until I stopped pedalling.

After I learnt how to use Michlet I worked out the main hull would need to be at least 1m under the surface to make wave drag negligible. This would have resulted in a draft of 4ft and again not practical for the lake I wanted to use it in.

Rick W.

[Vega]

Interesting machine, nice try.:)
Are you going to modify it or have you abandoned the concept?
I mean you can always have a more rigid set-up and have bigger and longer lateral floaters and a much smaller central one (less wave drag).

[korvello]

way to go RICK : we are trying to be nice here.........:rolleyes.........: unlike LUIS you didn't sumitt your idea to a professor or architect ,or did you?.....somehow i think that you must have become one after you build that PWS a few of those would make you an expert on something......i still didn't got the real objective of your PWS was that to pedal your way on floats ?on submerged floats ? walk on water ?....................... or just like LUIS too much time on your hands and just playing around:o :o :D

[Guest625101138]

I can sustain 120W of power output and I have been experimenting with all manner of water craft to determine how fast I can go and hold the speed all day.

Submerged buoyancy does not suffer as much wave drag as a surface hull so there is no notion of hull speed. This is why submarines can travel fast and efficiently under water.

Also the optimum length of the underwater hull is much shorter than the optimum length for a surface craft. This make transport more convenient. The boat shown in the previous photo was easily dismantled for transport. The longest bits were the aluminium tube.

I now realise that to get wave drag low enough to be better than my best surface craft I need to set the main hull even deeper and this makes it impractical. It would be impossible to keep the hull under water. If you reduce the buoyancy of the main hull then you quickly lose the benefit of less wave making from the main hull by transferring it to the stabilisers.

There have been some low power assisted hydrofoils that use submerged buoyancy but it is not an idea suited to get the best from 120W.

Rick W.

[korvello]

so RICK your project is ongoing sorry i thought you'd given up on it !.......... anyway and please take this with a bag of salt because i'm neither a professor or architect or engineer ,i do know a few if that even mathers,some do know even less than i do and i don't want to become one..:D :D as it so apears with you ,you rather do it than talk about it !...... good for you! anyhow here is what i see you want:.... a small hobbie cat without the mast a recliner on top of it maybe a small ice box:D :D :D and a mechanism to propel it by pedalling right?... i don't see the problem and i don't think your accessment of the need to be 4 ft deep is correct i don't get why the bulb/propulsion device has to be so big either i don't know if a pedal propelled jet is viable or some other way but if you keep the propulsion mechanism kind of stable [less span longer hulls]i think that 2ft of water or less should do it specially on a lake ,has i said my 1 cent ......regards

[Guest625101138]

Korvello
I have made 13 pedal powered boats. This is a video showing two of them - the yellow and black one are both mine:
http://www.youtube.com/watch?v=ckWqIgmVM4Y
I have posted this before on another thread. I have pushed the black one to 18.2kph and it does 11kph with 120 - 130W. The yellow one has done 17.8kph and is about 0.5kph slower than the black one at 120W.

I am no longer developing the submerged buoyancy concept shown earlier. In fact I am not doing much development on the pedal boats as I am moving on to solar power and bigger boats. I have learnt a lot about hydrostatics, hydrodynamics and foils from my hobby with the pedal boats. When you have 120W to play with you have to design for efficiency.

Rick W.

[korvello]

13 BOATS are you serious !!!!!!!....i hope you're not superstitious maybe you should build another :) :) :) ..... now that you're an expert what are you building or going to?..... and how would you build a 60x30 AL cat .

[Guest625101138]

..... now that you're an expert what are you building or going to?..... and how would you build a 60x30 AL cat .

I am working on the design of an easily driven boat for coastal cruising. I have made posts on other threads.

At this stage I have a design that is 14.7m long and 1.1m WL beam. Maximum beam is 6ft. I am trying to keep displacement within 1 tonne and am considering a dual power system using solar and a small wind turbine.

The hull will do 10kts with 2kW and 8kts with 1kW. Aim would be to carry enough battery storage to hold 8kts over night in still air.

The other feature I want is to have it trailerable so I am planning on making it with a main central section and light weight bolt-on end sections.

Big cats have limited appeal to me. If you were doing something to live aboard then OK. I owned a 28ft moderate displacement deep keel yacht for a few years and eventually traded down to a 24ft trailerable yacht. Unless you live with the boat or pay someone to really look after it they give you more angst than fun. It is fine for a few years but boats that stay in the water are time consuming and money absorbing.

I am after low cost, low impact but safe and reliable transport on the water.

Rick W.

[korvello]

RICK what's the purpose of your boat just limited coastal cruising ,lake use ,day use or will you have some accomodations 1 ton 14.7m X 1.1 m wl are you just trying to push the envelop here or making something pratical ?........... you're right about the cat beeing big and expensive to maintain /store and so on at this time i 'm still debating it, the only thing that will decide if i will build it or not is if i can find a waterfront property reasonable enough so i could park it and pull it out of the water because the interior size ,speed and flat sailing appeals to me that's why i'm still planning to haver it my first choice even if i've explored building a 8 foot wide by the max allowed lenght permited on the road without special permits main hull trimaran with the arms and side hulls removable not foldable like the smaller trailerable tris that are just too small for me ,so i could remove it out of the water and into my yard for storage [ no marina for me, at least permanent ] the problem is that interior space no mather how i slice it it's full of compromises......... oh well i'll get it some how; for now it's just paper i hope i don't screw up too much :o :o and make the right decision.

[Guest625101138]

Korvello
Purpose is overnight cruising for two and day cruising for maybe four. It is a means of transport not really long term live aboard but should be capable of an ocean crossing if someone was really inclined.

This length and beam is what Godzilla produces as an optimum for a boat that does 10kts and with KMT high enough to be stable when 200 - 240kg of batteries are packed on the keel and 90kg of solar panels are on the cabin roof.

What I have in mind is roughly 2.5X this one:
http://www.youtube.com/watch?v=PYoW3XjHRbw
Wide enough to sit two people side-by-side, high enough for me to stand in, two bunks and limited amenities for food storage/preparation and other natural processes. I prefer hotel rooms or friends houses when I travel rather than bobbing about in a boat at anchor. It always took me a couple of nights on my yacht to get used to the running rigging clattering inside the mast. (wonder what a CF mast sounds like at anchor?)

Rick W.

[korvello]

interesting idea but crossing oceans i don't know about that one ;RICK is it submarine sealed or something like that?..........it's going to be a fun ride on heavy seas on that boat ,you may have friends in a lot of places and a water car is your thing just park it and leave it well don't they make a vehicle for that already, like a..... real car :D .....show me your concept in a real pratical ocean scale with accomodations for two and hable to take on some weather and still do what you claim yours do and you have my attention otherwise it looks to me this will be the number one of your next series ;)

[Luis Cunha]

Hello,

Last days I have been thinking how can be reduced the weight of PWS.
I can advance you that I got an idea! The weight of PWS can be reduced very much and it is possible to fulfil the korvello’s condition: make it light so one can carry in the back of the car
In one week I will publish.
Regards


Luis Cunha

[Luis Cunha]

Hello,

My idea to fulfil the Korvello's condition "make it light so one can carry in the back of the car" is based on a power system that pumps horizontaly and verticaly water.
If the power system pumps water from down to top the water vehicle can be balanced even if only the weight of the power system is not sufficient to balance.
Meanwhile I have designed two versions:

- Power Water Seat (PWS) for fishing
- Power Water Stand Up Boat (PWSUB) for fun

Please let us know your comments.