Jump to content
Sign in to follow this  
DrWatson

Electric Drive H28

Recommended Posts

Guest

This is fron Thundrstruck EV ( see link above in Ogres post)....."With a no-load speed of 1800rpm, the motor achieves peak output at 1,600rpm under load. Hull speed can require 2.5kW per ton of displacement, while 70% of hull speed requires just 500w per ton (credit to the Danes for the numbers)." The "Danes" don't get much wrong Wheels I know cause I'm one of them! 8)

Also...." This motor is rated to propel up to a 32’ sailboat and up to 15,000lbs of displacement, and offers 24v, 36v and 48v options at 3kw, 4kw and 5kw depending upon your needs for power."

Sort of a Toolman Tayler type hot up thing.

I've read these are great when sailing in large swells as they charge on the wave and propel the yacht in the slow part when set correctly. So making the power and then using it for a no loss help in certain conditions.

Share this post


Link to post
Share on other sites
Guest
J

But Hp is Hp (or Kw's) and the figure of 3-5Hp per tonne is based on the requirement needed to safely control your boat in whatever situation.

 

Like I said - depends on your expectations, Hiscock said 1hp per tonne? . I had 13 hp in a Cav32 and was never disappointed, but I've heard others say that boat would need over 20hp. I think most modern auxiliaries are overpowered.

 

Agree I'd like to know how many hours to recharge after an hour motoring (6:1 or better would do me), can't find that, and I'd really want to be able to feather the prop or get it out of the water altogether once charged. Overcome those two and I am convinced.

Share this post


Link to post
Share on other sites
Guest

Might be good to have a feathering prop and a water generator also. I don't believe the prop would be well set up for generating current. Probably do better with a towed generator or two.

A 9 kw motor will draw 180 amps so one hour of motoring will be recharged in about 4 hours with a 50 amp charger. this motor should be good for up to 34 foot yacht. Thats full throttle so you would do much better at say 4 or 5 knots.

Share this post


Link to post
Share on other sites
Guest

These are interesting......http://www.hybrid-marine.co.uk/5.html

If you had one of these and you were berthed in a marina with 240 volts the engine would not need to be used. The electric motor would be enough to get out and back in to most berths with say 200 amp hours at 48 volts lead acid.

 

If cruising wind and solar would not be necessary, with 5 kilowatts of generator aboard I'd forego the eco trip.

 

With the above batteries house loads would be easily and quietly met, that is 800 amp hours at 12 volts would be plenty for us.

 

I'm guessing the diesel engine would last a lot longer due to the increased efficiency.

 

These batteries would be great for this http://www.aasolar.co.nz/AA%20Solar%20L ... eries.html

 

100 amp hours at 48 volts may be enough for a energy frugal couple due to the deeper cycling of the lithium batteries. Less than 0.2 cubic metres and 52 kg!

Share this post


Link to post
Share on other sites
The way of the future, fossil fuels are on the way out.

 

I agree. But the price needs to come down considerably before the business case for ownership stacks up - hence my earlier thread on water as energy storage.

Share this post


Link to post
Share on other sites
Guest

I think its more like twice the price of lead acid. The advantage is in the increased lifespan. They may outlast the diesel engine. With this setup it would be good to have batteries that accept a lot of current quickly so the charging time is reduced. Sealed lead acid at least. Coupled with a nice quiet Lombardini engine it would be a really sweet setup.

Share this post


Link to post
Share on other sites

But Hp is Hp (or Kw's) and the figure of 3-5Hp per tonne is based on the requirement needed to safely control your boat in whatever situation.

 

 

Thats a figure which is often mentioned as being the "right" amount of hp for a yacht.

 

However - I do wonder if you have forgotten that 5hp at the motor does not equal 5hp being dissipated via the propeller. Can easily loose 20% through a transmission - not always, but power is easily lost there. Also, does the recommended 5hp include an allowance for battery replenishment, water pumping for cooling etc? I am not aware if it does or not, however, judging by the power most yachts have, this is allowed for in the "5hp/tonne" suggestion. Maybe by the time we have lost up to 50% of the total Hp/tonne into transmissions, generation of power, pumping water, etc, we can consider that the 1.5Kw/tonne dissipated by the propellor ( as an electric drive would achieve more or less ) to be not so incorrect. Thats around 2hp.

 

Also, another reason for the 5hp/tonne guideline, as noted by a few on this thread, yourself being one Wheels, is the efficiency of the internal combustion motors at moderate load vrs high load is dramatically better. And, the cooling characteristics of most diesels other than heavy industrial engines do not support 100% loading for extended periods - even if the water temperature is being correctly maintained, there can be localised hotspots in the engine which can cause issues. And electric motor is more immune to this - and will happily run to its maximum current all day long as long as its correctly specified, and has sufficient cooling ( which being immersed in water, I suspect it would have )

 

I like the idea in many ways. With a moderate sized diesel electric power generation setup. I suspect that there would be less to go wrong, and you are free to place the engine/generator in a sensible place, where access is easy and weight distribution is superior. If such a place exists!.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...