The sanding did take me about four hours, but I did it in one go and almost got to enjoy it. Mind you, I don’t get out much. If it’s proving a struggle, perhaps try a coarser grade of wet and dry such as 150 (I assume grits are the same there as in Australia) and finish off with 180-220. Some people smear the whole hull with automotive spot putty (also known as stop putty or stopping) and then sand off, this will help if you have a lot of small low spots, but I don’t think it’s good to leave large areas of putty on the hull in case they crack off, perhaps years down the track.

Advert

21 April 2009 at 08:18 #20355

Barry Foote

Participant

@barryfoote68385

Yabbie 1,

Thanks for that. I have not tried using stopper for the reason you outline. That said, I think it will be needed in a couple of places a bit further down the line!! I will keep you posted

27 April 2009 at 22:11 #20499

Barry Foote

Participant

@barryfoote68385

Still sandinga way at this hull. Sore fingers but getting there slowly. Will pop some pictures on when the dust settles down a bit!!

10 May 2009 at 10:57 #20765

Barry Foote

Participant

@barryfoote68385

A day to celebrate…..Applied first coat of primer, simply to highlight areas not quite up to the mark. I am delighted to say that it does not look too bad. There are one or two areas to apply a little more filler, mainly tiny holes in the glass fibre. I can now treat these areas and then prime it properly, before moving on to the next stage..

I knoe the primer ran, but I was more intent on getting the paint on rather than a good surface at this stage.

12 May 2009 at 11:01 #20802

Barry Foote

Participant

@barryfoote68385

Blimey I feel like I am galloping along now, having made up the card template for the deck. When I find the right wood, I will cut it out….Next running gear to look for.

Edited By Barry Foote on 12/05/2009 11:02:09

24 May 2009 at 18:52 #21079

Barry Foote

Participant

@barryfoote68385

Not much work done on the hull, apart from construction of a sub deck, as I have still not decided where to buy my prop and prop shaft from, so I got on with the stand, which has been finished with a little antique finishing oil.
I also started a basic frame for the superstructure, but that is about it for now until I get hold of some more 1mm ply, shaft, prop and some figures…

24 May 2009 at 19:00 #21081

sammyk

Participant

@sammyk

looking good barry looking good regards sammyk

25 May 2009 at 00:51 #21083

Peter Fitness

Participant

@peterfitness34857

Barry, what size prop and motor are you intending to use?

The build’s looking first class, and I’m still tossing up whether to build one myself as my next project.

Peter.

25 May 2009 at 09:25 #21086

Barry Foote

Participant

@barryfoote68385

Thanks fellas..

Peter,

I am going to use either a 60mm or 63mm brass prop. The moter I am thinking of using is an old 540 electric, as I have one and am trying to keep costs to a minimum. I am told I will need a 2:1 gear reduction on it, but will have to give it some thought.

Barry

25 May 2009 at 12:45 #21088

sammyk

Participant

@sammyk

hi barry you would be better if the motor had a gear reduction on it thats a big prop to turn .the 540 will turn it but it will get very hot and the battery will go flat fast regards sammyk

25 May 2009 at 20:04 #21103

Barry Foote

Participant

@barryfoote68385

Thanks sammyk,

Unfortunately as i have limited access to water, my builds tend to sail a couple of times and then end up in a case, so i think I will go with it. If I am fortunate enough to find a good sailing water, I can always change it..

26 May 2009 at 02:02 #21115

Yabbie1

Participant

@yabbie1

Barry,

sammyk is right – directly connecting a typical 540 motor to such a large prop would be a grievous mismatch requiring the use of fireproof paint in the engine room!

Given the great work you’ve done so far, it would be worth getting this right even if you will only sail it occassionally, rather than have to change things later. There are quite inexpensive gearboxes available for these motors, designed for model aircraft, that bolt on to the end of the motor. I would suggest about 3:1 ratio. If you are concerned about possible gear noise you could use a toothed rubber belt drive.

The gear reduction will also give you better low speed control, important for a tug.

Yabbie 1

26 May 2009 at 08:32 #21121

Barry Foote

Participant

@barryfoote68385

Yabbie 1,

Great to know you are still checking in. I really am enjoying this build, it rreally tests the brain and skill levels. I will do as you suggest and get a gear reduction for the motor.

In the mean time, I will try to make some progress on the superstructure…..

27 May 2009 at 00:40 #21132

Peter Fitness

Participant

@peterfitness34857

Barry,

As Yabbie1 suggests, a belt drive is definitely the way to go for quiet running. I make all my own pulleys and use 1.5 mm or 2mm O rings as belts. If extra grip is required, such as in your case with a biggish prop, then I would use double belt pulleys. However, if you don’t have access to a lathe, then a gearbox would be your alternative.

Peter

27 May 2009 at 08:54 #21133

Barry Foote

Participant

@barryfoote68385

Thanks Peter, sound sa great idea, but I only have asmall lathe attachment for wood, so looks like I will have to get a gearbox. I think I will try ACTion Electronics……Mind you if I do that Dave will persuade me to part with big money….that said, his gear is great..

28 May 2009 at 21:15 #21157

60watt

Participant

@60watt

Model

Voltage

NO LOAD

AT MAXIMUM EFFICIENCY

STALL
TORQUE

OPERATING
RANGE

NOMINAL

SPEED

CURRENT

SPEED

CURRENT

TORQUE

OUTPUT

EFF

RPM

mN-m

–

mN-m

RE – 800

12.0v

12.0v CONSTANT

5167

1.058

4289

5.28

–

82.08

36.84

58.2

–

482.8

I think I’ve discovered another limit placed on forum posts.This is going to take more than one to make my point.

Barry,you can appreciate a 60mm prop wont do more than 2000 RPM so you have to gear a 540 until the shaft RPM is above 7000.

2:1 won’t be the right ratio

540 and a 5-pole Mabuchi 775 to follow

An 800 and 775 are like a 540 geared 2.5:1 albeit a larger size and shaft diameter

A 775 will set you back $13 US and $11 airmail per packet at most

28 May 2009 at 21:34 #21158

60watt

Participant

@60watt

Model

Voltage

NO LOAD

AT MAXIMUM EFFICIENCY

STALL
TORQUE

NOMINAL
Volts

SPEED

CURRENT

SPEED

CURRENT

TORQUE

OUTPUT

EFF

RPM

g – cm

–

mNm

RE – 540

6.0
CONSTANT

14000

1.00

10800

7.10

254

28.1

66.0

190

28 May 2009 at 21:38 #21159

60watt

Participant

@60watt

Performance
Model	M5-RS775-12
Operating v	: 6v – 18v
Nominal v	: 12v
No Load RPM	: 7300
No Load A	: 1.1A
Stall Torque	431.5 mN-m
Stall Current	: 30A
Kt	14.4 mN-m/A
Kv	: 608 rpm/V
Efficiency	: 76.8%
RPM – Peak Eff	: 7300
Torque – Peak Eff	82.6 mN-m
Current – Peak Eff	: 5.7A

Physical
Weight	: 12.4 oz	(352g)
Length – for motor	: 2.62 in	(66.5mm)
Diameter (with flux ring) / Diameter	: 1.85 in	(47mm)
Diameter (no flux ring) / Width Across Flat	: 1.66 in	(42.2mm)
ShaftDiameter	: 0.2 in	(5mm)
Shaft Length	: 0.3 in	(7.6mm)
Mounting Screws (2)		M4

Edited By 60watt on 28/05/2009 21:46:26

28 May 2009 at 21:52 #21160

Barry Foote

Participant

@barryfoote68385

Oh my……Confusion reigns………Not having much knowledge of electronics all that means absolutely nothing to me, although I do understand the principle that the prop will slow the motor down so a gearing will increase it’s speed…

28 May 2009 at 23:32 #21161

60watt

Participant

@60watt

The figures say you need to run the 540 shaft up to 7,000RPM – 10,800RPM on 6 volt

A 775 requires 3600 to 5000 RPM 800 requires 2600 to 4290 rpm on 12 volt .

The lower figure is at maximum motor power and the upper RPM figure is at maximum efficiency.

They also show an 800 and 775 on 12 volt are like a 540 already geared 2.3:1 and 2:1

A 900,from memory, is 1,000 mNm stall torque,540 is 190mNm so the 900 is like a 540 on a 5.5:1 gear.

2000RPM figure for the 63mm is only an educated guess and if correct you can calculate the gear ratio it would need maybe between 3:1 to 6:1.

You are quids in if you opt for a direct drive 775 and pick a prop to suit.

Edit

I spotted an error on the 775 data.-not my mistake.The speed at max eff. should be around 5000 RPM for the figures to tally.Copied it from here

Edited By 60watt on 28/05/2009 23:36:23

31 May 2009 at 15:14 #21203

Barry Foote

Participant

@barryfoote68385

Onto some detail for a change. I have started to build the main superstructure, planked the bulkheads in the galley, made up a workbench and started the stove, which will be finished when I know what type it would be. Also made up a kitchen wall unit, which has to be painted white.

Edited By Barry Foote on 31/05/2009 15:15:18

1 June 2009 at 01:35 #21207

Peter Fitness

Participant

@peterfitness34857

Looking good. What did you use for the cooktop, Barry?

Peter.

1 June 2009 at 07:49 #21209

Barry Foote

Participant

@barryfoote68385

Peter,

1mm ply, carefully cut out. A coat of sanding sealer and gloss black. This will be followed by matt varnish to dull it down. The rest of the worktop is done with a product I hardly ever use…..plastic card..

3 June 2009 at 05:21 #21249

Peter Fitness

Participant

@peterfitness34857

It looks good, Barry. Will it glow when you turn it on?

Like you, I haven’t used plastic card / styrene sheet much either, apart from the Model Slipway kit of HMCC Sentinel. However, I believe it has possibilities in certain situations, such as deck superstructures, as it is very easy to obtain a good paint finish. Much easier than wood which requires much filling etc to hide the grain.

I am seriously considering using styrene sheet for all of my next project, an Armidale Class patrol boat of the Royal Australian Navy. I think it should give a good representation of a metal (aluminium) hull.

Peter.

3 June 2009 at 09:44 #21251

Barry Foote

Participant

@barryfoote68385

Peter,

Only once did I make a complete model using plastic card and I totally lost interest in it, long before it was finished…….Never again…As for a glowing cooker range…..well now there is a thought!!

Barry