Did a dream got shattered?

Good idee, but I have a problem in how to put it easy in the keel and take it out again. I am getting older!! Also the 2 x keel wil be welded and it is not easy to make small "doors" to put the weights into the keel.
For that reason I thought maybe "liquid metal" would do the job better.

I had to laugh, I don't think I will be even allowed near the yacht club house, let alone passing the gate.

Thanks for your info, I take it thus for granted that nobody is violently against this idea.
Bert

 

You are still talking about the electric boat, aren't you? If so, I find it amazing that you are considering any ballast other than batteries. The biggest problem for an electric boat is that they just can't carry enough batteries because the batteries are too heavy. So you are planning to add additional weight that is just weight?

No offense intended, but that just violates my sense of elegant design. Surely you can come up with some way to get heavy batteries in and out of the boat. Special-built crane combined with a removable cabin roof? A rail system? Maybe a removable keel that connects to the main hull over a couple of thru-hulls for ventilation and power leads?

 

Hi Dave,

yes that is correct. It is still an electric boat I am building.

What have I learned from all the replies I have received:

a) I should have a boat lenght of minimum 7 meter. (experienced South African sailer reply)
b) I should not go with a planing hull onto the sea (number of replies)
c) By reducing an exsisting 28 feet boatplan by 13%, my stability is badly affected (number of replies) Therefore I am calculating the stability and richting arms (give me some time and I will publish them on the net)
d) I should go for Lithium batteries (LiFePO4 total weight +/- 200Kg for 25 Kwh)
e)I need in blue sea water conditions approx 1 Kw power with this design I have in mind. I am busy building the electric powertrain and will try this first out on the sea before I will start building the hull and boat I like(borrowing another similar size boat to do the tests)
f) I need a small emergency storm sail. (going onto the sea requirement from local authorities in my case, with my design)
g) Should I need to fill the two keels with ballasts, which houses the electric motors and props, I could do that with various ballast methodes. (one reply)
h) And many more very usefull tips and hints.

Thanks Dave, Like I have said once before, if we all have the same taste, we would be married all to the same girlfriend or wife, or have the same boat designer, would that not be a hell of a problem. My taste probably differs from yours and I am convinced that you are pleased that my taste differ. It would be very boring everybody having the same boat and the same looks.

Dave, thanks for your reply, as soon I am ready, I will publish all test and photo's, but this will be estimated sometimes in February 2011.
Bert

 

I missed the part where you were going with lithium batteries. In that case, the limitation will probably be cost rather than weight, so I don't find the use of non-battery ballast quite so offensive.

 

Good evening Dave,

I may have met you, aren't you a director of a software company in San Fransisco?

Dave my problem is that I took a sailing boat plan, threw all sails, diesel engine and large mast "overboard". Kept a small emergency sail, don't need the full ballast anymore of 1250 Kg Reduced the plans by 13% to suit my needs. I have calculated all the weigths and now battling it out for weeks in the little time I have, to get an accurate new waterline. As I suspected before, the new waterline will be quite low and I most likely will have to put some ballast on the drawing board. Except, if the new stability calculations and righting arms tells me that I am fine. I am just preparing for the worst that I may need some ballast I can handle. If it does not work out, I have to capatulate and go for another boatplan. However in the meantime it is great fun to learn so much about boats.
Bert

 

If you have to add weight, add sealed lead acid batteries instead and don't take them off the boat until they are expired and ready to be "recycled".

-Tom

 

Very valid point. I have been using smaller Sealed Lead Acid batteries for more than 15 years in the hundreds and some of them lasted some 8 years, but were not deep discharged. I was looking at the KIA Sportage motorcar sealed battery they are using. I am keeping it at the back of my mind. But I am really battling with my higher maths (last used some 50 yeras ago and very seldom thereafter) to calculate the new water line. As soon that is overcome, nothing keeps me from manupulating weights. Until then, I have made a note from all your good suggestions and will evaluate it at the right time. Thanks Tom.
Bert

 

Attached a view on the prototype electric power drive I am making to be build into the keels or for the “whatever boat I will making at the end of the day” I still have to drill, do the threading of the cover plates and mount and make the middle plate which secures the gear/shaft/bearing of the electromotor. Also I have to finish the Twin blade Prop and a few other parts. Yes, I have a reason why I made the shaft 30mm.

As soon it is finished, I will do some test in the harbour with a borrowed boat. Just to get the feel for what power is required.

CDK, at end I have decided for your proposal and make the keels “open” , whereby I can mount easier the ballast weights. Also it is easier to spray paint the inside of the keels. Thanks for your suggestion.

I have however some other questions for the forum:

I am planning to fill the gearbox and ½ of the motor with transformer oil. This for two reasons, cooling, as you know transformer oil is electrical insulator and used for cooling transformers. Secondly for lubricating the gears. Any violent objections?

What would be better. Having the prop shaft and large gear pushing against the small gear on the motor when the boat is in forward motion, or have the large gear in opposite direction and is only pushing the small gear when the boat is in reverse motion. I have still the opportunity to do it either way.
Thanks for any suggestion.
Bert

Sorry, I have tried everything to copy and paste the pictures, but somehow I am not able anymore to copy them to this thread. What do I do wrong??? I changed from WinXP to WIN7. I am allowed to post attachements, and only the text is transferred from MS Word to the thread, but not the pictures.

 

Here is the picture you couldn't upload.
I am not quite sure what I'm looking at except the front of someone's car. The motor seems to be floating in the air and the main shaft only has two ball bearings which I assume to be radial support only.
There should at least one axial bearing to handle the thrust, two tapered roller bearings is the preferred construction. Is this going to be an oil filled box?

I cannot look inside the electric motor, so I cannot foresee the consequences of the presence of oil. Motors designed to operate under these circumstances, like submerged fuel pumps, have a very smooth rotor, sometimes encapsulated in epoxy. If the rotor was designed for normal operation, oil may cause a lot of drag and "aquaplaning" of the brushes, limiting the rpm.

 

My apology CDK, I should have waited untill everything is mounted and in place. But summer holidays are filling the camping grounds and factories and business have closed as from today and some coming Friday.
Explanation.
The shaft has two thrust bearings, each on one side. The "fillers" between gear and bearings I still have to turn on the lathe.
The motor is a brushless motor.
The gear and shaft is not yet in position.
On the motorshaft just above the small gear sits the bearing which will keep the shaft in place. The horizontal bracket I have made today and will be mounted on Saturday. (Tomorrow is my wife's birthday and I do not think she appreciate me being in my workshop the whole day, she is also as from today on leave)
Yes, I am planning to fill the oil up as much the system can handle ( This is only the first prototype)

Thanks for up-loading it. I have no idee why I am not able to upload anymore

Bert

 

Bert, I think your design looks OK based on what I'm looking at. Also I agree with CDK's comment about epoxy.

You need to establish a method of full control and adjusting, in regards to pressure between pinion and ring gear.

The motor in oil will put out far more heat than that amount of oil can handle, a small circulating pump and external heat exchanger will most likely be needed.

Just my first impressions

Ron

 

Thank you. My hands are still sore to file the 70 mm holes out. That is the reason why the motor is not yet placed into the correct position. I still have to take the motor appart to mount the 3 magnetic sensors and to see whether I am able to comply with the solution of CDK (epoxy)

Yes, I have. With those 4 bolts and 8 nuts, I am able to align the shaft between the two thrust bearings. One for sailing forward and one if I like to reverse the boat. The other adjustment is not yet mounted. Will come soon and with that adjustment I can control the two gears.

I was hoping with this experimental system to cool the oil via the seawater. The surface is quite large +/- 0,44 m2
Bear in mind that this kind of elektromotor has an efficiency of +/- 90% i.e. if I use 2 Kw , I will only produce 200 watt of heat. Only if I start using 3 or 4 Kw per motor, I may run into an overheating problem. But time will learn. I am more worried that the (transformer) oil may eat into the insulation used in the motors.
Thanks
Bert

 

Bert, yes if the metal surfaces have a liquid to liquid heat transfer through the metal shell, I think it will be enough for a safe temperature.

One other thing you might be aware of, having liquid cooling offers some interesting possibilites (refrigeration) for getting more power from the motor (higher voltage and current) and still remain in the safe zone for continous duty operation.

Best wishes

Ron

 

Indeed Ron, I am hoping for that, although I will only need between 1 and 2 Kw. Both motors could deliver 2 x 4 - 6 Kw, it depends on how high I am willing to go in Voltage. Current is not a problem. I am busy building a 300 Ampere controller in a very special way (all with N powermosfets) I hope it will work out. Again time will learn.

I have finished the stability calculations and they (I think, but I am useless in reading results) seem to be not too bad.
LCG = 497.452486 divided by 1376.3 Kg = 0.36 meter above waterline (36 cm)
VCG = 5196.25845 divided by 1376.3 Kg = 3.7755 meter from station 0 or otherwise said 0.4994 = 49.94%
This is without any special ballast nor extra ballast, just batteries and motors in keels.
Now I have to do the richting arm.
Bert

 

Bert--hope things are well...i read through all the last posts- i gotta agree on the lead acid batteries. only because my last boat used a dc system. and any other batts were hard to charge fast.

In using gel cells, or other types--the charge times are longer. this may not be a problem for you if you not using a onboard charging system. but lead acids are cheap too(relatively). The modern D.E. military subs to the best of my knowedge still use lead acids for thier ease of recharge. i.e. they can be charged quickly...just a thought Bert--glad you got your lcg figured out!!