Tender behind

[Catigale]

Back to math again...I think you will find solar recharging of a 1.5 kW device pretty impractical

An 80 watt solar panel will output nominally at 20 watt per 24 hour day, which is only 500 watts charge cap per day...thus you can only use 1/3 of the electric motor capacity without going into charge deficit.

These things probably have their place on my 65 foot Benny with full 240 vac, but not a mac.

[grady]

All the modern Cruise Ships use Diesel generators to power electric motors that actually turn the propellers

The biggest reason they do this if for reliability, they eliminate a lot of moving parts of a transmission. Plus they have better control of the screws now they can mount the motor and screws in a pod that can rotate. also they can shut down one engine for maintenance and still power both screws.

Anyway I was just trying to point out to run an engine just to charge a battery to run a electric motor is not an efficient practice you will have to bring more gas then if you just had a small gas outboard.

[Russ]

Powered a inflatable 9ft.6 in. with a deep cycle Sears best Lawn mower size battery with a 40 lb thrust elect. outboard. Ran fine in calm water at setting #4 out of 6 doing 3 knots . Doing Max. 6 only got me to 3.5 knots with 2 people aboard and would run out of power in less than 1 hr useing the 4 setting.
My Suzuki 2.5 gas 4 stroke will outdo the Elect. at full throttle in less than 1/2 throttle.
Full tank last over 3 hrs at 1/2 throttle on the Suzuki, weighs 32 lbs with tank filled. Add the weight of elect. motor,battery and caseing and see the diffrence.
Sold the Elect. Motor.
Dave

My 2.5 Suzi does about the same. When it gets the dink up on plane it can do about 7 knots and runs forever on a tank. I have a small tiny reserve can just in case.

The idea of a silent electric motor is appealing, especially to a sailor, but I need every watt of power my solar panel and outboard can generate for other needs. My 80 watt panel and 25 amp Suzuki alternator would not appreciate more demands.


--Russ

[Gypsy]

All the modern Cruise Ships use Diesel generators to power electric motors that actually turn the propellers

The biggest reason they do this if for reliability, they eliminate a lot of moving parts of a transmission. Plus they have better control of the screws now they can mount the motor and screws in a pod that can rotate. also they can shut down one engine for maintenance and still power both screws.

Anyway I was just trying to point out to run an engine just to charge a battery to run a electric motor is not an efficient practice you will have to bring more gas then if you just had a small gas outboard.

I don't ever run the Honda just to charge the dinghy battery , but I have been known to run the Honda just to charge batteries , in general . Your right to run the gas motor just to charge the dinghy would be a very ineffiecent practice , thats why I call it byproduct electricity.

The cruise ships find the system more efficent . In general power is wasted when it is transmitted thru a transmission . Wire also waste some power , but not nearly what a system of gears and oil waste, think about it.
An electric motor is one shaft turning . A gas motor is many shafts turning , some of which is only to maintain running the motor itself.

Back to math again...I think you will find solar recharging of a 1.5 kW device pretty impractical

An 80 watt solar panel will output nominally at 20 watt per 24 hour day, which is only 500 watts charge cap per day...thus you can only use 1/3 of the electric motor capacity without going into charge deficit.

These things probably have their place on my 65 foot Benny with full 240 vac, but not a mac.

When I am thru with our Mac she will have two 80 watt solar cells in addition to the Honda for charging. I am sure I can squeeze out enough electricity to power the dinghy as well . Its either generate electricity or carry more gas for a dinghy
Either way , I have to supply it with fuel . With the electric dinghy , some or all its power will be generated from the sun , I like this idea of being a little less reliant on oil .
This is why we settled on a Mac (See this Months Heartland Boating Magazine) We will still require some gasoline , but nearly as much as a typical 26' boat. We will derive some of our energy from sail and solar.
As someone else said (a little differently) , a quiet dinghy is part of the sailing experience .
If I wanted power,speed, and noise I would have kept my V8 engine powered cruiser!