Eric's electric propulsion & other electric motor discussion

[starcrest]

*** Eric's electric propulsion idea deserves it's own thread, so I have split it off of the Olson25/ SF to Hawaii.   s/v Faith

coming up from mexico is even worse.I have never done it but it requires a very powerful engine with range.its only the first 600 miles north from hawaii or so until you get out of the intertropical convergance zone.then  a moter of even slight power is really all you need as the wind and current is virtually nil.even aboat like ours only needs a 3 or 4 hp motor to move it some what.one of the things Ilearned from drifting 10 days altogether on that first return was patience.even the slightest wind to move at the slowest possible pace is a wellcome relief from utter silence and stillness of doldrums.the a-4 was removed before I aquired this boat(I had them remove it) and I am going to experiment with a portable diesel generator and the electric motor from a table saw.during a recent power outage here in florida due to the storms,some one here had a 4kw portable generator(diesel powerd)and it ran 2 10 inch table saws simultaineously.after seeing the power these saws have I got to wondering....what about removing the powerhead from a dead outboard .....putting this moter from the saw.....now wait a minute....that generator ran TWO tablesaws.........now I am thinking TWIN SCREWS>>>>>

[Zen]

"I am going to experiment with a portable diesel generator and the electric motor from a table saw"

Ok, sorry I'm slow at times. Your going to use a portable diesel generator to make electric  to run a electric outboard, to move the boat...   :-\

And your not using a regular inboard diesel engine to to do this because...  ???

[starcrest]

installation of a complete diesel powerunit is not cost effective for this boat.a diesel engine ,transmission,cutlass bearing stuffingbox,propshaft,propellor controls,fuel tanks,guages,alternators,variuos other unknown requirements,not to mention  atleast a month in dry dock....this expense is too prohibitive for a boat that only cost me less than 3 grand. this boat was derelected and dismasted when I got it.a portable genset is available here for less than 1000 bux,its removable,dead outboards abound here,and the table saw motors are cheap.this entire idea is "modular"and is something I could put together in no time.rite now there is nothing where the old a-4 was

[Zen]

ah so, Ok now I get it!
I thought it maybe the cost. I forgot about all the stuff that goes with the motor and you are bare to start with.

[s/v Faith]

Eric,

  Single phase, 110v table saw motor is usually .5 hp, 1.5 max (rare).  You might be better off to consider some of the high thrust trolling motors.

  I drug a Coronodo 27 AND a 14' skiff out of the weeds with one (36# thrust) one day, one a friends dingy.  I was quite impressed.

 

.........now I am thinking TWIN SCREWS>>>>>

You would be able to back that thing like it had wheels on the bottom!

[starcrest]

you may think I am alittle out of it but I am being completely inspired bywhat these cuban rafters are coming over here on.....I mean they are using weedwackers as outboards.not only that but this diesel electric thing is what ww2 subs used so its nothing new just a scaled down version

[s/v Faith]

Not at all Eric,

  I think your idea has merit.  I know there are some big name Yacht peddlers looking into this design also. 

  The diesel/electric idea is a good one, and with a solar array and a decent battery bank I think you could have the additional advantage of silent anchoring, or close qtr's maneuvering.

  I think it might be cheaper to buy a trolling motor then a table saw and an old outboard (unless you had both on hand).  But then you will have to rig the motor to the lower unit on the outboard, and deal with a motor that was not designed for the marine environment......

  I do not think the horse power issue is a huge one.  You might not make hull speed with a trolling motor, but then again I think most boats tend to be over powered.......

  There is a 21' Lugar (not the classic open Lugar, but the small fiberglass model) that sported a 15HP Evenrude! He could push a bow wave like you would not believe......
  He was finally convinced that motor was too big for his boat, I suggested a 3 to 4 hp.  He bought an 8hp 4 stroke Johnson.

  I have a 6 hp on my boat, but have used my 2hp dink motor to push it (prop barely reaches the water).  Some folks row boats like mine for short distances, I guess it is just a matter of what you are looking to do.

[s/v Faith]

Here is a good link to an 'electric boat' site.

  They desccribe the requirements to move a boat is much more modest terms then most Sailors are used to;

What you now know is how much power your hull needs to achieve cruising speed.
Essential though this is, it is far from the complete story, and several other factors need to be taken into account if you are to get an accurate estimate of the design motor power.

Before doing that, it is worth pointing out the very low powers needed (0.5 to 1 hp) to achieve the cruising speeds typical of an electrically-powered craft. I.C. engine zealots tend to be disbelieving that such low powers could be of any use at all in driving a boat. What they forget is that the power required increases approximately as the cube of the hull speed, so that very small speed increases need major power increases, as the boat speed approaches its hull speed. Other significant loss factors for an I.C. engine are in the propellors used (small diameter at high revs.) and in the gear box and drive train. When these factors are combined, it isn't suprising that motors of 20 hp or more are often fitted to quite small boats (see Lynch .pdf above).

  Here is another good link on sizing an electric motor to drive a boat, "HULL DRAG and POWER REQUIRED - MADE SIMPLE"

[starcrest]

I already have a bran-spankinnu 8hp yamaha out board that I have on a costom made transom mount.I made the mount myself out of galvaized steel pipe fittings.this mount can hold 2 motors just like it.necessity it the mother of invention.when I made land fall on the triton the a-4 peeeterd out on me,and I quickly improvised an outboard mount by placing a plank of wood across a rung of a side mounted boarding ladder.so instead of drifting powerless on to a lee shore I had an auxiliary 4 hp outboard side mounted.I improved on this idea with my current boat and indeed already motored about 300 miles along the icw with it.

[wildman]

Check out these steam engine outboards!  Paul

[starcrest]

anything is better than having to get out and push

[s/v Faith]

Eric,

Came upon a Minn-Kota with a couple corroded connections in the control head (should not be too hard to fix).  Big power head on the thing..... Maybe a 65?

  I will let you know what I find out (as to how well it moves Faith) once I get a 'round tuit) and get it fixed......

[captedteach]

When I had the marina here I was going to build a little tug boat to tow in broken boats and put around on - about 18ft in length with a nice enclosed pilot house.  I had a few options for power - an inboard engine and tranny - an outboard in a well OR I could install a foot from an outboard and power it with a small engine for a riding mower via a belt drive and the impeller could feed a water box for the exhaust.  This last idea came to me one day while moving all the junk around in the shop and it could be converted to your use by swapping an electric motor for the small engine.   IF you were to cut a hole in the boat and mount the foot in that it would be like a saildrive  - the elec motor could be placed a few feet away if needed.  It would take having the boat out of the water and some glass work but it would be there

[Jack Tar]

Hey I had one of those weed wacker outboards. It was sold by Sears some years ago. 1/2 hour of listening to that thing and I would want to shoot myself. I have a friend with an electric powere Coronado. He posts on  www.latsandatts.com under the name carrickbend.

[Garry]

I've been interested in electric propulsion for a long time. Here is an interesting plan from Glen-L Marine.

http://www.glen-l.com/designs/special/electricdrive.html

[starcrest]

I have leads on portable diesel generators.for the up and comong storm season I am hoping to get one soon.the place is called CORMAC and it is in hialeah florida ph# 305 477 6922.a 6kw generator is 1200 bux.they have smaller ones .the 4kw is only 900 bux.I will put one where the inboard should be and exhaust it thru the existing motor exhaust.the problem I may have is fitting it thru the companionway. I will put the biggest one in possible.

[Coastal Cruiser]

Just passing through, so I will leave you with this one to ponder for your next project.  ;D

http://www.ev-america.com/

http://www.ev-america.com/page4.html

[starcrest]

looks good.I really think I am onto something.this electric propulsion I feel will do very well in a no wind/current situation---as is in the high pressure doldrum no -wind-for-days situation.even the slightest power is all that is needed---any thing is better than having to get out and push.I am still curious as to the power and torque or just the plain old abilities of those dc powered bass boat type trolling motors.if anyone out there in sailfar land has any experience with longterm use of these motors on the typical 30 foot or so sailboat please raise your hands.....not all at once please

[krissteyn]

I have a dream of a cruiser catamaran with twin electric sail-drives and mooring in a tidal area to ensure good charging twice a day. Props in the water and wants to turn - let it. I assume the prop size will be larger than normal and will be a drag when sailing/charging - so what - I'm cruising...

my dream boat will be electric powered  8)

[captedteach]

I had a trolling motor on a Venture 21 - 28lbs of thrust  Boat weighed less than 2000lbs. It would take EVERY BIT of power in a group 27 battery to push the boat 7 miles at around 2knts.  I think you need to think about what you will need for power and at least double it. I tried to use a 50lb thrust motor on my Cal 25 and almost ended up on the bank when the wind shifted a bit while I was coming off the mooring and I did not have enuff thrust to power the boat into the wind.   You also need to think about the weight of your battery bank - If the genset is going to be where the old engine was where are the batteries going? 

You will still need to have a waterbox installed in your exhaust to be legal so that has to be pumped in.   For a really clean looking install I think you will need to pull the boat and do some fiberglass work but when its all done I think you would be happier with the results both in performance and appearance. From the description of pipe fittings to build the bracket I can only immagine that in the future if you decide to sell this boat that this would not be a good selling point no matter how well the system works. I know I have ripped stuff off of a boat that the previous owner thought was great just because it looked like poop to me.  I'm sure as the galvanize wears away, the rust streaks on the hull will be a pain to remove too.