Model Boat Mayhem

Dry Dock / Shipyard: Builds & Questions => Seaport Tugs => Topic started by: tugboattam on May 04, 2013, 09:22:21 AM

Title: Run time ?
Post by: tugboattam on May 04, 2013, 09:22:21 AM
Hi everybody, I have a Seaport Workboat that I am going to replace the electrics on, I intend to use a Mtroniks Viper 10 amp speed controller with BEC, this will be linked to the reciever and servo I intend to retain the original engine, all this will be run from a 6v 4.5ah lead acid battery. Can anyone give me an idea of what sort of run time I will be able to expect.  Thanks to all in advance. Ian.
Title: Re: Run time ?
Post by: Netleyned on May 04, 2013, 09:30:29 AM
Ihave basically the same setup in mine Tam and I get up to an hour before my grandson gets bored and there is
plenty of life left in the battery.
I actually replaced the motor with a 385 but found she ran a lot better with the original motor and at 6V she looks good at
scale speed. She is now back running the original motor.

Title: Re: Run time ?
Post by: tugboattam on May 04, 2013, 10:05:40 AM
Hi Ned,  Thanks very much for your reply,  1 hour is what I was hoping for. I know there is a formula for working this out exactly but I cannot remember where I found it.   Thanks again.  Ian.
Title: Re: Run time ?
Post by: tugboattam on May 04, 2013, 10:22:44 AM
Hi again Ned,  Did you remove the water ballast tank in you Seaport ?  If you did how much ballast did you need to add ?  Ian.
Title: Re: Run time ?
Post by: Bob K on May 04, 2013, 11:15:55 AM
Unfortunately there is no magic formula for run time, short of running the boat in the bath with an ammeter in line with the battery.  You may get, say 1.5A under load which might indicate 2 hours plus.  Even then you will not be running flat out all the time - which will last longer, but will want to bring it in long before power drops off. 
I get over 2 hours from a 6v 5Ah battery with smallish twin motors.
Title: Re: Run time ?
Post by: Davenotdone on May 04, 2013, 11:20:36 AM
Just done this conversion myself. Chop out as much of the original ballast tank as possible ( just leaving the 'sides ' of it ) and plug the ballast holes with styrene strip / glue.
The battery ( 6v 4.5ah ) will sit perfectly on it's side in the now defunct ballast tank. The battery is now your ballast. ANY screws you remove  from the boat put back exactly, they are all slightly different sizes. I ditched the water pump and fitted a Graupner one. I run using a Zebra 3 channel radio, the 3rd channel operates a servo to  microswitch to pump motor. If you remove the rudder screw from the  black disc moulding to release the Kort nozel DO NOT over tighten it later as it will snap the fitting ( you are only screwing into plastic ) My original motor burnt out because i put too big a prop on it, i now run with a MFA 385 type motor, 30mm 3 blade brass prop ( changed the prop shaft but you don't have to ) and mine now runs at a scale speed, the motor is barely warm and me and my son's get bored with over an hours sailing and that with the pump working for a lot of the time so in effect you are actually running two motors!   Any other help you need? No problem. Just remember to not try and fit the largest prop you can find, it does'nt work that way. The original motor is fine, why nor just paint the prop with some brass / bronze coloured paint. Regards, Dave.
Title: Re: Run time ?
Post by: Netleyned on May 04, 2013, 04:01:34 PM
Just as Dave did the battery makes for good ballast.
I got rid of the pump but kept the 40mm prop which is a good match to the
original motor. A385 does not like turning a 40 mm prop but would be happy with a 30mm
I also added about a pound of ballast to make the stern sit down a little.

Let's see some pictures as you go along.

Title: Re: Run time ?
Post by: tugboattam on May 04, 2013, 06:37:10 PM
Thanks for all your replies, what a friendly forum this is. I will try to put on pictures once I get going. Thanks again.  Ian
Title: Re: Run time ?
Post by: pompebled on May 07, 2013, 11:28:41 AM
Hi Ian,

My conversion runs on a five pole 540 size motor, as the stock 380 overheated during the first run on Lipo's.
The new motor runs about the same speed and with two 4000mAh wired in parallel, I have just shy of four hours of runtime full throttle.
Needless to say, my tug and I make long walks along the canals of our town...

Regards, Jan.