Powered water seat

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 ...........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 .............to be continued i think?????????????

 

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.

 

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).

 

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

 

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.

 

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.. 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 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

 

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.

 

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 .

 

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.

 

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 and make the right decision.

 

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.

 

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 .....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

 

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

 

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.