T-Pain Is On A Boat: Re: [Electric Boats] reverse solenoids

Monday, September 12, 2011

Re: [Electric Boats] reverse solenoids

Ned,

I had never considered planing. I wanted deadrise and rocker to lift ends and chine out of the water, as well as seaworthiness. I was a little disappointed in the transom, I had hoped it would have been clear but it ended up with an inch into the water. Probably that extra 12V battery I added for the bilge pump. As for the box keel, I figured in terms of wetted surface it was a wash (pardon the pun) over a narrow keel, just add up the bits. The box keel does have quite an effect on steering though. As in non-responsive. Sometimes I have to increase RPMs just to turn in a reasonable time. (I have no rudder, just a pivoting outboard. I don't know how I would do it differently. The problem (and I knew it would be) is the damn rockweed and laminaria constantly getting fouled up in the prop. With being able to reach the prop through the well I can get rid of it by hand.

The box keel and all the weight in it makes upright grounding a breeze, though I haven't tried it yet. We lack sandy beaches here.

Before I broke our bathroom scale I measured 275 lbs without batteries and cargo. I have 7x62 pounds of batteries for 432lbs so I think I'm under 1000 lbs. My amp and speed measurements were with just me in the boat < 200 lbs.

I did have a brief fantasy about the boat lifting up onto its box keel, but I'll need more kilowatts for that. My boat is quite beamy, over five feet, so it's not as easily driven as many electric boats. Are there pictures of your boat or is it still in the planning stages? Bruce

On Mon, Sep 12, 2011 at 11:14 AM, Ned Farinholt <nedfarinholt@comcast.net> wrote:

Bruce,
Thanks for the info. I had been curious about the effect of the boxed keel, though I was thinking of combining it with a flat bottom rather than your shallow vee.

I was thinking that the narrow box keel would act like a narrow hull displacement craft not much limited by S/L. The remaining displacement load on the rest of the hull would allow it to plane at relatively low power. Yours seems to be remaining in displacement mode.

I forgot to ask what your displacement is. It sounds like you are carrying about 500 lb. of battery, maybe 300 to 500 lb of hull and motor and 200 lb pilot and stuff for 1000 to 1200 lbs. total. Is that about right?

My total is more like 750 lbs and it is a planing hull 15' x4.5', very flat in the aft sections but with a rounded chine. My curve is a little steeper than yours, at 120 watts, I get 2.7 mph compared to your 3.2. However, at 1100 watts I am up to 6.5 vs your 5.4 mph. I think mine is beginning to plane or move into semi-displacement range.

And yes, as with any boat, there is no end to what you can spend on it.
Best wishes,
Ned

On Sep 11, 2011, at 7:06 PM, Bruce Gillett wrote:

Thanks for the compliments, Ned. My lack of social graces means I have no inhibitions about making a fool of myself, so here goes.

As you may have seen from the data/records (18' Eleccentricity) page I have just adapted a donor outboard to direct electric drive, so the ratio and prop are not necessarily optimized for electric. The outboard came with a three bladed 8" prop. I don't remember the pitch, but it looks like a 45 degree angle at the hub. I borrowed an ammeter from my mechanic (the kind which clamps around a wire) and with my GPS obtained the following data:

3.3 amps 3.2 MPH
8.0 amps 4.0 MPH
17.0 amps 4.6 MPH
30.0 amps 5.4 MPH
92.0 amps 7.0 MPH (over hull speed, I assume.)

When the values are plotted the last entry sweeps up like a kite in a hurricane. I think I need to avoid full throttle. With 180-225 amp hours at 36V I have a decent range. I am happy with the numbers but still don't have a good way of determining my range status (how full is the tank?) besides using my GPS and hoping the headwind/wave variations cancel out. I have been thinking about the Trimetric 2025 but am still reeling from all the other 200-300 dollar hits. Does it ever end? Bruce

On Sun, Sep 11, 2011 at 1:31 PM, Ned Farinholt <nedfarinholt@comcast.net> wrote:

Bruce,
Eleccentricity is a nice looking boat. Can you share a speed/power curve with us or just a table of kw vs knots or mph.
Ned

On Sep 2, 2011, at 2:09 PM, Bruce Gillett wrote:

Dennis,

Thanks for the kind words. It was a fun project.

I sort of avoided the issue of recharging because I came up with a scheme which works, but probably breaks all the rules. I ran a GFI protected 20 amp line to 5 feet above the high tide line and put an outlet. Then I bought 100 feet of rubber garden hose and stuffed (3) 12 gauge THHN wires through it. At the outlet end I spliced in a short length of #12 extension cord with the male end and at the other end I attached the hose to a 2 foot length of 4" PVC pipe (with all the right fittings, including a screw-in cleanout plug). Inside this pipe I have coiled up about 6' of the other end of the extension cord. The whole mess winds up on a reel next to the outlet. At charging time (I have about 6 hours around high tide) I run the hose out to the boat in a dinghy. It uncoils as I row. I connect the charger and row back and plug it in. It works great. If the business end is dropped in the water the pipe floats and keeps water out, although the cleanout threads are supposed to be doped, so they do leak a little. I have a second mooring close to shore for the charging. From it runs a line to shore, with bow and stern connection points. My charger is a 25 amp (at 36V) Quickcharge. I have six 6V Trojan T105s.

The motor and gears are noisier than I'd like, at least at full speed, which I rarely use. At lower speeds I find myself moving faster than I think, frequently coming up to my mooring or a dock too fast (hence the desire for reverse!). I have left one side of the motor cover open for cooling (and steering), so if I closed this up it would be quieter. I considered other drive options, but my problem here in Maine is vast amounts of rockweed and lobster gear constantly getting fouled in the prop. With an outboard and well I can just reach down and pull it off. Bruce

On Fri, Sep 2, 2011 at 9:34 AM, Dennis Wolfe <dwolfe@dropsheet.com> wrote:

Jeremy nailed the solenoid answer but I just wanted to say congratulations on a very nice project. You will love the electric power.

I read your blog and noted you are going to keep it on a mooring. How will you recharge?

Also, how is the motor / gear noise?

Denny Wolfe
www.wolfEboats.com

Hi EB people

I have built an 18 foot launch of my own design named Eleccentricity http://www.affordableacadia.com/2011/eleccentricity-launched/ and I have been stymied over reverse. Naturally, I should be asking how others have done it so here I am. It currently cannot go in reverse unless I shift the gears on the electrified outboard; a bother to do remotely. Obviously I could reverse polarity to the motor (PM Mars 0909)and this is how I would like to do it with solenoids or relays if I can find ones rated for 80 amps.