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Forum Index : EV's : Ma-Sea Solar boat

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Boppa
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Joined: 08/11/2016
Location: Australia
Posts: 807
Posted: 02:17am 22 Feb 2018
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Not too shabby, I get about 35 by the gps with 25hp on a 4.2m glass hull flat out- but it empties the (little) tank in about an hour doing that, cutting it back to 1/2 power I get about 20kmh but over 2 hrs -nearly 3...

Its a heavy boat tho, right at the limit for a unbraked trailer when it had the big inbuilt tank filled right up, dont use that tank atm as it has a leak and puddles fuel at the back next to the motor, not good

So you're getting pretty good speed out of it, have you weighed it yet?
 
Trev

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Joined: 15/07/2006
Location: Australia
Posts: 454
Posted: 08:03am 22 Feb 2018
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Thanks for your input Boppa. I was wondering, how do I compare to a petrol outboard. I want to run a 20HP petrol on this boat to compare but I don't want to own a 20HP petrol motor.

Yes we did weigh it.
As originally made, 114kg .
With the second pontoon width added, 130kg.
Golden Motor weight is 50kg.
Lithium batteries, 48v (16 cells) x 100Ah-B, plus box, 72kg

The Golden Motor is 10kW. At 52v x 189A = 9828W. My conversion makes 10kW to be 13.4HP. But they say it has the performance of a 20HP petrol.
Trev @ http://www.thebackshed.com/basiclynatural/
 
Boppa
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Joined: 08/11/2016
Location: Australia
Posts: 807
Posted: 08:20am 22 Feb 2018
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Comparing outboards in hp is always misleading as so much depends on things like prop pitch, revs etc that its hard to directly match HP to speed.

A mate of mine had a 50(I think) hp motor that had been fitted by the previous owner with a racing/ skiing prop, he replaced it with a 75 stock, and actually went slower. Many manufacturers fit a prop that will peak below redline, so much so that many can never actually get to their redline. This is a good idea in one sense as many outboards dont have instruments on them, and many boat owners simply run 'flatout', so setting up the motors in this way stops people blowing their motors up

I have a little 78lb electric trolling motor that came with two props- one is a hard plastic jobby that gets about 5kmh, the other is a floppy 'jelly' prop, meant for mangroves etc, same size, same pitch, but only makes 2kmh (due to its bending I suspect)- it really is 'floppy' and you can bend the tips back to the hub!
 
Trev

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Joined: 15/07/2006
Location: Australia
Posts: 454
Posted: 10:49am 06 Mar 2019
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We received some new design outboards from Golden Motor.

Kerme has been sitting under the tree since we had it in the water back in February last year. It has faded a lot and was very dirty. Had to put the gernie over it and scrub it with brooms. It really looked neglected for a long time.

Fitted up a new motor.

The new motors are adjustable in leg height. Absolutely a brilliant idea. They also have heat exchanger, no sea water through the motor or controller. It takes the normal car coolant for corrosion resistance, another brilliant idea. I do like the coolant pump too, much quieter than the older design. Also for corrosion resistance, it is fitted with a zinc anode. No air through the propeller centre. The old design still had an air line where a petrol exhaust would have been, which let air through the centre. This new motor stopped the water spray up the front of the leg much better than the old design. 10kg lighter than the old design, this new outboard measured to be 40kg. The motor shaft is horizontal and runs a tooth belt to the prop shaft, much quieter running, and very smooth. Well done to Golden Motor for developing a brilliant outboard.

Some performance data
Amps Km/hr
30 9
40 10
45 11
54 12
70 13
72 15
88 17
100 18
110 19
125 20
142 21
182 23 182A was full throttle.

We lowered the leg a little bit, and achieved 24km/hr at 175A.





Trev @ http://www.thebackshed.com/basiclynatural/
 
Trev

Guru

Joined: 15/07/2006
Location: Australia
Posts: 454
Posted: 12:51am 03 Dec 2019
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Some more changes to Kerme.
Cut out the second width pontoons. Added a V-Bottom. More planing surface and more tunnel space. A little less buoyancy though, so draft is more. Fitted 2 Golden motors.







Off to the water for testing.
It feels to skip a lot better at high speed, but the numbers don't indicate anything better. With the 2 motors, it never achieved any better speed than with one motor, but used more electricity. Pulling power is ok. Knee board was easy, and I got up on 2 ski's, but single ski could not get up.

Pack voltage at rest measured at 52.6v
6.3A      2.4 km/hr
8.3A      2.4 km/hr
13A        3.2 km/hr
28A        6.8 km/hr
35A        7.5 km/hr
48A        8.2 km/hr
56A        8.8 km/hr
78A        9.7 km/hr
120A       13.2 km/hr
128A       15.2 km/hr
148A       18.6 km/hr
185A       17.8 km/hr strange result
259A       21.3 km/hr
275A       24.0 km/hr
but later, another strange result
250A       26.8 km/hr








Trev @ http://www.thebackshed.com/basiclynatural/
 
Boppa
Guru

Joined: 08/11/2016
Location: Australia
Posts: 807
Posted: 05:40am 03 Dec 2019
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I suspect you are running out of revs rather than power...
Certainly sounds like it- if the revs is the limiting factor, then it really doesn't matter how many motors you had, you would still have the same top speed, just faster acceleration and more 'towing ability' (you could put a dozen motors on there and still have the same top speed if this is the case)

In a normal IC outboard motor you often have the same issue, which is why 'racing props' are available- they trade acceleration for top speed with a different pitch angle (they do have drawbacks, both acceleration and slow speed suffers, and taken to their extremes, can allow an ICE motor to over-rev, making for an expensive 'bang' moment lol)
 
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