Did a dream got shattered?

There would have to be a good number of pluses for me to do the hydraulic drive thing.

I haven't researched it as an option because I'm not in that position but, again, unless there was more than one really good reason to do it... no.

Keep It Simple...

-Tom

P.S. I haven't read your whole thread... but I can tell you if I was building your hull, I'd put a small diesel in it.

 

Thanks Tom. I agree with you to keep it simple. I am a little confused. Do you mean that Tugboat should put a small diesel in his 25 feet steel boat, or do you mean that I must abbolished the idea of making an electric boat?? Tugboat gave 3 reasons why he like to change, one of them, he likes to have 2 props.
Bert

 

BertKu,

Neither, I was simply saying what I would do in the tug hull design. My mistake, sorry, I was thinking the tug was your design, it is not.

-Tom

 

Thank you Tom, that explains it. Not too worry, if we all had the same taste, we would all go for the same boatdesigner and builder. Would that not be a problem for them?
Bert

 

Hi Tugboat,
I may have mentioned before. There is a reason why it take quite some time to calculate the stability. I have reduced the plan by 13%, thus it means that every item has to be recalculated and verified with strenght and with what wood is avialable on the market. The material list is no longer valid. Either I have to plane the wood down to the new sizes, or compromise or take the nearest size and re-calculate.

My plan of operation is:
First make the controller, motor/reduction box with shaft and propeller, go the local yachtclub and ask somebody with a similar boat to help to do some tests on the sea / bay. Any power problem encountered, this helping boat should have all the means to come back in the harbour. If the tests are very satisfactory, I cary on with making the Hartley 28 minus 13%. If I encounter tremendous problems , also with stability, I caputulate and make the Fisrherman 18. I understood that metal below the waterline is a recipe for problems, therefore the metal in batteries thus also. I was planning to have all batteries below the waterline.


In your case, I like your plan with the 2 x 12 H.P. DC motors. Provided you can mount them under the hull, otherwise you haven't saved anything with regards to long shafts etc. Although I would ask the professionals still an opninion of having this with hydraulics and a short shaft with propeller under the hull.

Bert

 

Hello Bert, Ok i am understanding what your saying. Sorry if i am being redundant here.
good idea to do some tests using a boat of a similar size. when are you planning on doing that??,...I will be excited to hear what the engineers say about your stability calcs.
One problem with a small commercial/pleasure tug, is economy vs power. Tugboats should have good bollard pull and this means power and power means more fuel.

but i also want economy...I have my bulldozer engine and a 3:1 gear which will turn a 36 inch prop. (that prop calculator you sent me is one of the best little toys ive had in a long time to mess about with!!) but this Cat engine will burn 2.5 to 3 gals an hour. thats great if i dont do too much travelling with her. But I would like to have the manoeuverability of a twin screw- You do lose 20% of your power in a twin screw compared to single. but you dont have the canting to outboard when the big prop kicks in either. and you can flank a tug with twin screws. My thinking is- small engines around 12-20 hp(but hard to find a high torque 36 volt 20 hp electric!) but geared to large ratios- say 5:1 and using larger props.
so using two small electric engines i.e. 12-20 hp at 1750/2500 rpm max, and 24-48 volt, then i have an easy to charge system-low voltage , and easy on fuel. as well as using twin props. but a sacrifice in power. all checks and balances

the beauty of ev motors is simplicity- they do not need tranmissions, as they can be set to counterclockwise rotation and simply reversed in polarity to get F-R. gearing can easily be done with either chains or belts to get any gear ratio you need. you could gear 10:1 if necessary -of course you wont go more than three knots- but you'd turn a 60 inch wheel with immense torque.
also they can direct reverse instantly.They are small and need little space too! they dont throw out lots of heat and they are quiet too even when running with a genset to power them.
they last and dont break down often. electric motors have a lot of low end torque - even though it is said hp is hp thats not entirely true...lower rpms means more torque. which means more power. it all went bad when people started wanting speed. then they needed higher rpm diesels. so today a higher rpm diesel say a 250 hp DD would not turn the same prop as a cat 80 hp with lower rpms. its the same with electric motors.
I dont know much about hydraulics. so I would tend to stay way from what is unfamiliar to me. so now that i have my hull decided on--i must now figure out the best way to power it to be both powerful and economical--A difficult task...
what type of wood are you planning on using?

 

Bert--i JUST saw your post about hydrualics at northern tool..maybe i will look at that--whats needed to run one?? how does this system work?..never heard of it--i have a older petter diesel too- it is 20 hp at 1500 rpms...yes I could use it in the tug- but again i wanted twin screw-- but what set-up is needed to run a hydraulic motor?..im intrigued...you have me thinking...

 

It certainly would be...

-Tom

 

Hi Tugboat, I am in Johannesburg and 1200 km away from home. I will give you more information when I am back on Monday. All what it means is that you put a hydraulic pump on the diesel, There are 3 types, a very noisy one, a reasonable noisy one and a very quite circular pumping one. That is the one you must consider. It is all very simple. You have a shaft which turns the hydraulic pump. The pump pushes the oil through the flexible rubber pipe to your motor. Your pump needs a certain gallon per minyute to push thru the pipe and thus the pipe has losses. The pump therefore needs to be bigger than the motor. i.e. if the motor needs 14 GPM you need a pump, which can handle let say 16 GPM. Your pipe must be able to push this sort of flow without that it becomes a frixtion and high losses. i.e. for a 1/2 inch inner diameter high pressure pipe, you cannot go over the 14 liter per minute, otherwise your losses are too high. 14 liter = about 3,5 gallon. You have to ask the hydraulic people for mor info.

But one thing is for sure. You will have a much better system with hydraulics than with ev motors. Very, very reliable. All what you need to do, is to learn how to calculate the thickness of the pipe, the torque required, the maximum speed needed and how to do the connections for high pressure. With ev, you have to isolate the alternators from earth, except the first one and have the 3 alternators running for 48 volt as follow.
Alternator one = minus to ground, plus 12 volt to minus next battery and minus of isolated 2nd alternator. Then you have the plus of the second battery to the minus of the third battery and minus of the third isolated alternator. The plus of the third battery is connected to the minus of the fourth battery and minus of the fourth isolated alternator. Now you have 48 volt ( 4 x 14,4 Volt = 57,6 Volt) available for your ev motors.

HOWEVER, i would not like to touch, with wet hands and bare upper body part the 57,6 volt and ground. I AM NOT TOO SURE THAT MY HEART WILL cope with that. DC voltage and current of 20 milliAmpere (2880 Ohm body resistance)through my heart muzzles means a certain lonely death.

Consider strongly hydraulics. You will stay alive. Much more powerfull.
Will write to you when I am back
Bert

 

You may have to root around for info, but one of the Columbia river cruise ships uses a hydraulic motor on a paddle wheel to propel a 230 ft boat. I know they've had problems with the system, but it can work on a pretty large scale.

Look up the "Queen of the West" (or worst, depends on who you ask )

This is probably the best description of her powerplant I've seen. look on page 12 for a description:

http://www.ntsb.gov/publictn/2009/MAR0904.pdf

 

No Bert, this really hurts my eyes.
Isolating alternators from ground is a dangerous game, no one expects them to be isolated. And it also isn't easy.

Take a big one, solder 3 wires to the terminals where the stator windings meet the diodes. Then have a 1:3 triple phase transformer made (or make one yourself), add some diodes and you're done.
You could also rewind the alternator but that would require modifying the regulator as well, which isn't simple for most people.

 

wow you guys make me look like the true amateur that I am...after considering all this--(and im not saying I may not change my mind again)--but it seems you guys are quite correct and that it is more complex than im willing to experiment with...soooo, Ill just go with a single diesel. Its easy- and It works..and i dont have to learn whole new skill sets. After all my goal is to be on the water- DRIVING THE BOAT- not my goal to become an experiemental engineer and i always go with simple = better!
Much appreciated- i digress--this is berts forum--ill take a bow and come back when i can contribute to help him--which may mean I have a lot to learn before that happens...


Bert!! wow-- you are almost near me your so far from home!!

btw- Im going to go look up the 18 ft hull you like...i havent seen it yet.
but you really know your stuff..im always impressed.

CDK!- good to see you here...your one of the most helpful posters on this site. cheers I wish i could offer you advise but you certainly dont need any from me...again always impressed with your level of knowedge and expertise. you and Bert are like "guru's' of the electric and mechanical propulsion world.

 

Hi CDK, I will buy you some sunglasses. All jokes aside, I like to differ from you, if I may. Yes, it is very easy.
a) the belts are an insulator.
b) you run 4 alternators on the same belt, in such a way that it does not slip. i.e your belt goes around one and then around the next one, letting the alternator turn in the other direction. This to avoid slip
c) You use nylon bushes to insulate 3 of the 4 alternators.
d) you make a plastic cover to avoid accidental touch.

Yes, that could be done, but hell, that is then an hell of a bigger generator. Where can one buy a 660 Ampere 12 Volt alternator for the same price as 3 mass produced automotive alternators?

Yes, indeed that could be done, but you would have a generator with a quarter of the charging power.

Lets have a beer together and philosophy about it.
Bert

 

HI Cthippo,

That is indeed quite a story. I love to know whether the diameter of the piping was correctly designed or why was there not some elecronic/electric temperature warning system installed, like we all have on our motorcars. Just a thermostat which triggers the alarm when your car engine is overheating.

2 weeks ago a tugboat with Sinter Klaas, the equivalent for the Christmas Santa Claus, capsized in the sea rivermond in IJmuiden on the way to Amsterdam. The Belgian Captain lost his life unfortunately. This does not mean that all tugboats in the world are dangerous to sail on.

I personnaly feel that if an hydraulic system is properly designed, the above would not have happened. It is so easy and simple. Even with reversing a boat, you just have a valve, which reverses the flow of oil.

But, Cthippo, thanks for bringing it to this forum, for sure it can be used to make sure that such an accident, will not happen again. The report was very interesting.
Bert

 

Tugboat, You must be pleased that you did not reduce your plans by 10%, that would have been a much greater headache then converting your boat to hydraulics.

Only 11 hours away from you.

Hai, hai, not so fast. I am still planning to make the 13% reduced Hartley 28. Only if I encounter problems which I cannot overcome, I will capatulate. Untill then, it will be flat out for the "complex" one.

Tugboat, I agree fully with you here.
Bert