Gravman

Thanks very much for the information on the props. There are a lot to choose from. What size shaft are you using? 3/16? I have an ACE Nautical Comander Radio set that I am going to use. I have had it for a number of years but never had a project that was worth it.

Grav.

slivic003

I am running the 3/16 shaft . It might take a little trial and error to get the exact right prop .

kahaikapu

Hi..im thinking about using dumas 12 volt batteries.one per motor..im using 2 astroflight 25 motors
im hoping to have longer run times...maybe having weight will help in scale apperance as she sits in the water....what do you all think..thx Stan

slivic003

Hey , The dumas batteries won't give you a lot of run time . Maybe about 15 minutes . I have run my donzi on one 12 volt dumas battery and I get about 5-7 minutes run time on it . I am running astro 40 motors . You may want to try two 7.2 volt packs (14.4v) on each motor . Or you could run 4 on each motor @ 14.4 volts and it would give you the weight you are looking for . It may give you a longer run time . I would try some NiMH packs , something around 4000mah . Make sure your speed control will handle the 14.4 volts . The astro motors will handle up to 18 volts !

Rich404

Hi guys,

The Dumas batteries will not give you the runtime you are looking for on the Astro 25.

******The Astro 25's has a maximum of 12V rating, so anything higher than 12V will fry the motors.

***The Astro 40's have a maximum of 18V rating therefore slivic003 could use 14.4V safely.

Astro 25 marine has a 6-12V range with 825 RPM Per Volt.

Astro 40 marine has a 6-18 Volt Range with 643 RPM Per volt.

Just multiply the RPM X Volt so you know how many RPM's the motors will produce on different voltages.

To maximize the runtime on your Astro 25's on 12V, check online for 12V battery packs with high MAH rating.

Best of luck.

-Rich.

kahaikapu

Mornin fellow boaters..Thx for comin to the rescue..many thx for your info..happy boating S[8D]tan

slivic003

I think that the astro 25's would be ok run at 14.4 volts . I have run them at 18 volts before and they did fairly well , I am sure over time it would take its toll on the motors. 18 volts is hard on the motors so I don't recommend it ! I would say @14.4 they would do ok . Call astroflight and see what they recommend as far as voltage and batteries . I tend to push the limit and over do the limit sometimes with things wanting more SPEED !!! Rich is correct as for the ratings on the motors . 6-12 volts on astro 25's . I forgot the voltage rating was lower on the 25's than what it is on the 40's.

kahaikapu

WHAT DO YOU THINK OF HOBBICOS 12 VOLTS BATTERY

slivic003

They work !! I have run them before on my donzi . The run time is around 20 minutes or so ,depending on how much you are on the throttle . They give good scale weight but are a bit heavy if you are wanting to get a high end top speed Also the price is cheap on them which is nice on the wallet!! How long of a run time are you looking for ?You could always do Nimh single cells and build yourself a battery ! 10 cells will give you 12 volts .

Rich404

I agree with slivic003. Nimh cells are the way to go for your Donzi.

here is a link for batteries i have been recently checking out.

http://www.all-battery.com/index.asp...OD&ProdID=1347

All battery.com has a great selection.

I found this 12V 10,000 MAH NIMH battery pack that looks pretty cool.[sm=shades_smile.gif]

-Rich.

Gravman

Guys what is the basic difference if any between a Astro 40 and a Cobalt 40. Will a the Cobalt stand up to higher volts like 18V

Thanks

Grav

Rich404

Gravman,

Here is what i pulled off Astroflight's site.

It seems the basic difference is in voltage and the voltage range is 12-24 volts for cobalt 40 VS 6-18 volts for the marine 40. The cobalt motors are really for airplane use.


Here are the listed specs.



Cobalt 40 Direct Drive Motor

Cobalt 40 Direct Drive Motor, 18 to 20 cells, 600W


Astro 40 Cobalt Motor p/n 640
Model No. p/n 640
Name 40 Cobalt
Armature Winding 8 turns
Armature Resistance 0.121 ohms
Magnet Type Sm Cobalt
Bearings Ball Bearings
Motor Speed /volt 682 rpm/volt
Motor Torque/amp 1.99 in-oz /amp
Voltage Range 12 to 24 volts
No Load Currrent 2.5 amps
Maximum Continuous Current 35 amps
Maximum Continuous Power 750 watts
Motor Length 2.8 inches
Motor Diameter 1.7 inches
Motor Shaft Diameter 0.25 inches
Prop Shaft Diameter 5/16 inch
Motor Weight 14.5 oz

-Rich.

slivic003

Hey the astro ferrite 40 motor is more suitable for marine use . It is designed for that purpose . It also runs ferrite magnets rather than cobalt . It will handle 18 volts . The ferrite 40 is also 10 turns where as the cobalt is 8 turns . The ferrite provides more torque than the cobalt (which is needed to spin a boat prop). Astroflight and dumas also both recommend running the ferrite series motors for model boats.

Rich , checked out that battery ! Man that thing is lonnnng !!! I bet it would work great though !

Gravman

Thanks guys for the information. I guess it pays to do more reading before buying. Well that is water under the bridge. I am going to use the Cobalt 40"s with the gear box and be happy with that. I will know better next time.

Grav

slivic003

Hey , the cobalt 40's will work with the gear box ok . The gear box will give you the extra power to turn the props . Did you ever get some new props ? You may also want to boost up your power and run maybe 18-24 volts on them . Make sure your speed control can handle the power though . I am just guessing but I think that a 2.0X2.2 (3) blade prop and running 18 volts would get your boat up to a nice speed .

kahaikapu

hey thx for the infomation..iwas wondering was that two of those hobbico batteries or just one for a 20 min run time?..thats sounds about a good run around the harbor lol

slivic003

Hey , I ran just one . Check the link below .
http://www3.towerhobbies.com/cgi-bin...?&I=LXL370&P=0

kahaikapu

Thank you sir..im goin to try and use 1 hobbico battery per motor..im using a robbe f 14 radio and want to play with twin trottles...Aloha Stan

rebulx

Is it possible to buy a Donzi kit?

slivic003

Unless you can find one someone has that they haven't put together yet ! Dumas discontiuned the kit . They are probably not going to come back out with it . They are done building fiberglass hulls . All their kits will just be wood .

Pusar

My Feedback: (1)

I am in pretty good contact with Dumas. All the majority of the fiberglass huls will now be made in ABS. Darby, Donzi etc. The are staggering the release of the boats.

1 12v battery is plenty to power 2 Astro'25's Here is my Dauntless at a boat show on 1 12v on Astro 25's WAY more than scale speed:

Here is the batteries I used on my Donzi 5,000nmah Sanyo's I had some money at the time burining a whole in my pocket and spent over $100 on each pack. I was running 1 pack on each motor (Astro 40). LOADS of juice but overkill.

Marty

slivic003

Hey , yea the last I talked to Dumas they were real unsure if they were going to do the donzi in abs . That would be cool if they rereleased the kit although I prefer fiberglass . I wish someone would come out with a hatteras , post or buddy davis kit ! I am changing my batteries over to nimh . The dumas batteries are ok for a short run ! Your dauntless looks great ! How long of a run time do you get with the 5000mah batteries on the astro 40's ?

nyasphalt

looking to start my donzi--- im leaning toward gas---"pusar"-- is the gas a problem for the upper balsa superstructure ---as far as wharping and hi heat

Pusar

My Feedback: (1)

My "professional" opinion is forget the gas. I had in one of my Donzi's 2 OS FS 61 water cooled marine engines. The plumbing for exhaust was a hassle, high temps and trying to electronically synch the two props. Getting clean air into the engines, etc. I gave it up and will never do it again. Nice electric motors can't be beat. No gas, ready to go, clean running, loads of power etc etc etc etc. Just my 2cents worth.

I am sure Matt (u166365) can tell you about his set up and how nice it is and how it runs.

Marty

nyasphalt

thanks for the suggestion---can you help me with driveline hardware---should i use dumas or ?