Re: [electricboats] New prop 10KW motor

Thanks Peter. You LWL and displacement is likely similar to mine (Rawson 30) and these numbers are similar to mine except at the high end, where I see more of an exponential power curve the faster I go... 

On Jan 11, 2021, at 08:30, Peter Zephyr <Pcbeckett@gmail.com> wrote:



Actually the boat speed is around 5.6 knots when the regen starts.  My boat gets to that at around 8 knots on the wind.

 

Just FYI.  These are the figures I get when using the motor with no sails up. 

I did the readings in a fairly calm sea.  I have a Catalina 30 tall rig.

 

Catalina 30	Zephyr
boat speed data  8/31/18 - No sails up. Seas calm.			four, 215AH/batteries
Direction	Knots GPS	DC Amps	AC Amps	RPM	Volts
East	2.5	17	33	1110	48.9
East	3.2	31	44	1384	47.9
East	4.0	44	57	1584	47.9
East	4.6	78	90	1912	46.8
East	5.1	105	110	2108	45.8
East	5.2	106	108	2110	45.8
East	5.3	104	104	2100	45.9
West	2.5	7	18	845	48.2
West	3.2	11	22	1014	48.2
West	4.0	27	42	1379	47.9
West	4.6	38	54	1554	47.9
West	5.1	53	66	1727	47.0
West	5.2	68	78	1865	46.9
West	5.7	101	100	2103	45.8
Average	2.5	12	25.5	978
Average	3.2	21	33	1199
Average	4.0	35.5	49.5	1482
Average	4.6	58	72	1733
Average	5.1	79	88	1918
Average	5.2	87	93	1988

 

Rgds  Peter

From: electricboats@groups.io <electricboats@groups.io> On Behalf Of Carsten via groups.io
Sent: Monday, January 11, 2021 10:44 AM
To: electricboats@groups.io
Subject: Re: [electricboats] New prop 10KW motor

 

Hi, Peter

 

You mean that the boat speed should be more than 8 knots, not the wind speed, I guess ?

 

 

On Monday, 11 January 2021, 23:22:16 GMT+8, Peter Zephyr <pcbeckett@gmail.com> wrote:

 

 

Hi Carsten. 

  I don't really know how the regen works. All I can think of is by applying some power to the motor it somehow starts the prop to fee wheel and once it reaches a certain speed the amount of power it generates is greater than what it uses.   I had seen posts by others who have seen this happen and that is why I tried it. I usually get 1 to 2 amps when it generates and the wind has to be above 8 knots.  I have a Sevcon controller. 

 

Rgds Peter

On Jan 10, 2021, at 9:31 PM, Carsten via groups.io <Carstensemail=yahoo.com@groups.io> wrote:



It seems that some of you have actual experience with letting a fixed prop and motor "wheel" when under sail !

This is an option for daycruisers, but probably not for ocean cruising.

 

Any of you have some data (prop size and pitch, speed, Watt input) to make the prop spin for "no drag" ?

 

Peter Zephyr, you wrote : "in this situation the prop actually generates electricity and charges the battery".

If you send power to the prop, how can it generate power ?

Very interesting, so please enlighten us.

 

Carsten

 

 

On Monday, 11 January 2021, 01:34:35 GMT+8, Matt Foley <matt@sunlightconversions.com> wrote:

 

 

Michael, 

 

 With a traditional diesel engine, its kind of all or nothing. Typically you are either sailing or motoring. Motors sailing is an option but generally not an enjoyable one. 

 

With electric you will find yourself almost almost always motor sailing. Lets face it, the wind is usually not quite as strong we would like. If you want to make your prop "invisible" it doesn't take much power at all. If you want to add a little speed, help point higher and get you through lulls, it takes just a little more power. 

 

For those reasons, I recommend going with the most efficient prop you regardless of drag. This way you will have the more range when needed and still have the option of no drag by adding a few watts into the system. 

 

 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

 

 

 

On Saturday, January 9, 2021, 09:04:25 PM EST, Carsten via groups.io <carstensemail=yahoo.com@groups.io> wrote:

 

 

Michael, consider a big folding or feathering prop, which will give you far less drag.

Then find the proper ratio for engine rpm and prop rpm.

 

A toothbelt solution will give you the opportunity to change the ratio.

 

 

On Sunday, 10 January 2021, 04:29:08 GMT+8, Michael Blackstock <mdblackstock@gmail.com> wrote:

 

 

Thanks for your responses, all. I think I'm just going to go with another stock 2 blade to reduce drag under sail. I plan on utilizing the motor very infrequently, so more speed under sail sounds good to me. 

There are so many resources for Catalina owners, but I thought I would check with you all first. 

I will definitely be chiming back in when I begin my motor and battery install!

Thanks

Michael Blackstock

Cell phone 503-913-8217