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[Tug-Kenny RIP]

The motors have been finally fitted.  What a job, lining them all up correctly with no friction or bends in the pipe work.

[Tug-Kenny RIP]

The deck has been cut and placed on to show how little room there will be for big hands to mess around inside.

This will not be affixed until more heavy work has been completed inside.  You may have noticed the screws holding the rear motors on actually have nuts under their heads.  This is just in case I have to remove them when the top is on, as access with a screwdriver is limited..

[Tug-Kenny RIP]

I have been working today on wiring up my twin 600's in my Fairmile boat.  The 500's will be tried tomorrow.

I wired in an amp meter before testing and was severely surprised with the current consumption. As I was still lining everything up for smoothest running I was able to watch the current loads under different circumstances and have some info which you may find interesting.

Initially one motor took over 16 amps  (on the bench, with no water to push around) at full throttle.  After re-greasing the prop shafts and getting them true, it dropped down to 11 amps on full speed.  (noisy it was as well). At half throttle things seemed much better and it ran at 4-5 amps.  If I run two, with 35 mm blades I should imagine I'm not going to get more than half an hour running on a 7 amp hour battery.   

I shall be testing the 500's separately to see what their results might be.  The plan is to switch them over for cheaper slower running.  I think the idea of running all Four motors at the same time might be a bit too ambitious for my battery.

[thunderchild]

Good Day Kenny

According to the stats, the Grauper 500E are rated at 2A current drain at max. efficiency.

Richard

[Tug-Kenny RIP]

The bench testing of the 500's was very pleasing. First of all they only took 4 amps each at full speed driving dry Prop tubes, and secondly the noise was extremely quiet and smooth.  The R.P.M  is much less than the 600's and also the whistle on the speed controllers is much reduced when compared to driving the 600's.

I have now wired in a 20 amp double pole switch which controls the Esc's output to either pair of motors.  I decided not to go with all four motors at once as the current consumption is extraordinarily high.  Approaching 25 amps before I reduced speed in fright ......phew !!!! 

My 500's are not  E's  Richard but the results are very similar to your records. Thank you for your input. I do appreciate help, so keep em coming. 

[John W E]

Hi Ken
Your build is coming along nice, it looks good.
May I make a comment on the MTroniks motors which you are using    As you have found out through bench testing; they are extremely hungry little critters for the amps they draw.  But, having said that – they are a good performing motor – I am not sure if you can recall the very first Wickstead that we all attended – you and I met – violins now playing.......     I brought with me the model MTB488 – I ran it once or twice on the Lake.    Martin asked if the speed boats could be run later on in the day – it wasn’t a speedboat – but by it can shift.....and inside there are 3 MTRONIK 500s (fan cooled).
The 2 outer motors are switchable on/off.   This allows one to manoeuvre with the centre motor – and all-out speed in a straight line engaging the 2 outer motors.   The way I achieved the switching was to switch the signal wire to the speed controller.   The speed controllers are the ‘old’ Electronize type with the ZN409 chip in them.   The one which drives the 2 outboard motors was beefed up by adding an extra output transistor and the switching is done via a servo which is on the channel 5 or 6 (i.e. the undercarriage channels)  - the one with the switch on a 6 channel transmitter & receiver 
The model is also powered via 2 x 4 amp  6 volt lead/acid batteries.
Sad to say, as you can imagine – it only runs for mere ‘minutes’ flat out.   I do have batteries and plans to convert it to NICAD but .......its still in the pipeline, which is getting longer by the weeks 
We know we cant tamper with these modern day speed controllers with auto-reset cos if you switch the signal off to these modern controllers half way on throttle opening, it will remember that position as neutral.
Suppose you could use Modern day EEC (switching the signal on/off) if you remember to set your throttle stick at neutral, before you engage your 2nd speed controller to bring in the 2nd pair of motors.
This will bring – or should in theory – bring everything in line.
KEEP UP THE GOOD BUILDING mate, hope to see you at Wickstead in the future.
I have put some pics on of the MTBs 488 internals – and the blurry picture is the microswitch and servo.
Aye
John

[Tug-Kenny RIP]

Hiya John,  so nice to hear from you. I hope you're feeling better these days.   

Regarding the switching, I figured I couldn't change the motor loading during run time as the current would melt some switchers !!  This is why I've gone for a large manual switch to be used at the dock side.  I shall be trying her out soon on the water by running one test with the 500's and another test with the 600's.  Decisions can then be made how to complete the layout for general use. I'm considering changing to all 500's as they are lovely little motors and I could run four at once.

ken

[16-21]

Hi Ken,

Fairmile is looking good!!!
I remember reading about a Fairmile a few years back and if memory serves the builder passed comment that if he did one again he would leave the rudders slightly oversized as he felt them a bit small / not enough surface. Think that was a kingston mouldings 1/24 scale job
and ruuning gear was george sitek/ radstock

Anyway she's looking good.

[Tug-Kenny RIP]

Thank for that.  I've re-shaped them so it's all down to the launch to find out.

[Tug-Kenny RIP]

It's finally warm enough to get to the water side.  Testing proved I could do without four motors, so I've opted for the 600's.

I have torn out the insides and started again by assembling the 600's to the inner props and putting blanking caps on the outer shafts. The wiring has been reduced to a neat set up with two speed controllers.

It was time to continue with the cabin construction. This was then sprayed to see what lumps show up. These were sanded smooth and it was resprayed again.