Elwin,
My advice would be to not over think it. You are most likely going to need some kind of reduction gearing so set up a simple pully system using #50 motorcycle chain and sprockets which are very cheap and start with about a 2:1 or 3:1 reduction ratio and see what happens. Then you can easily change it with some different sprockets. The nice thing about chain and sprocket is it's easy and inexpensive to change up Once you find the sweet spot you can switch to a synchronous belt drive if you want to reduce the noise or just put a shroud over the assembly and listen to it grind a little as you go down the canal. That's what I did.
The diesel on the Arc suffers from the same phenomenon that you are experiencing, that is, as soon as you put it in gear it wants to go faster than you like. For me it's about 3.5 mph at idle speed so when maneuvering in tight spaces when docking with the diesel the ship is lurching forwards and backwards and when you're dealing with a 20 ton boat surrounded by a million dollars in liability on all sides it give you a lot of pucker factor. It's also very hard on the transmission. The best thing about the electric drive is the rheostatic control of your speed. If you want to come in at .1 mph you can and adjust accordingly. Then all you have to worry about is wind and current. Everything happens a lot slower and you know the first rule of mooring is never approach a dock faster than you're prepare to run into at.
With the smaller electric motor you will likely not reach the speeds you did with the diesel but you said that is not your goal anyway.
Nice little boat btw. Please show us some pictures of the engine and drive line too.
Capt. Carter
www.shipofimagination.com
On Sunday, July 23, 2023 at 04:34:39 PM EDT, <looije@gmail.com> wrote:
Thanks Bobkart,
I only have references below on 'power consumption', so not really. This if what I measured with my old diesel engine. 340rpm is almost neutral. 9.3 kmh is not far from max speed.
S0 maybe there is more slip? I've added some photos of the boat.
You're suggesting a smaller prop, so I can make more rpm, so the engine will be efficient, right? if max rpm on 48v is 2250 (according to Monterey) then 24v will be 1125, right?
That's not that far off on the max rpm I expect I need with this prop.
If cruising on 50% of that max rpm @ 24v, is that a situation that needs to be improved?
by a smaller prop with direct drive
or
with the same prop with a 2:1 reduction at 48v?
is my thinking correct?
and what would be smart to do :-)
thanks again
elwin
i
I only have references below on 'power consumption', so not really. This if what I measured with my old diesel engine. 340rpm is almost neutral. 9.3 kmh is not far from max speed.
| rpm | kmh |
| 340 | 3,5 |
| 540 | 6,1 |
| 600 | 6,5 |
| 845 | 8,6 |
| 975 | 9,3 |
S0 maybe there is more slip? I've added some photos of the boat.
You're suggesting a smaller prop, so I can make more rpm, so the engine will be efficient, right? if max rpm on 48v is 2250 (according to Monterey) then 24v will be 1125, right?
That's not that far off on the max rpm I expect I need with this prop.
If cruising on 50% of that max rpm @ 24v, is that a situation that needs to be improved?
by a smaller prop with direct drive
or
with the same prop with a 2:1 reduction at 48v?
is my thinking correct?
and what would be smart to do :-)
thanks again
elwin
i
No comments:
Post a Comment