TEV Wahine 1/35 Build

[Richard SimpsonParticipant @richardsimpson88330]

Unfortunately as with so many things there is no quick and easy answer Richard and a lot of it comes down to personal preferences.

My own preference is enamel because, as a result of its longer drying time, it is so much more forgiving to apply, either by brush or by airbrush. It is also a harder finish, more resistant to knocks and scratches. The downside is that it dries very hard so, on a very large surface can lead to cracks as a result of the base material flexing over time.

Acrylics can be water based or solvent based, with the solvent based ones probably being a little bit more durable. They are trickier to apply because they dry so fast but the resultant finish is flexible so are much less prone to cracking.

Automotive paints, which used to be mainly cellulose based, tend to now be far more solvent based acrylics. Car body primer in a spray can is actually a very quick, easy and convenient way of getting a really good overall finish that is slightly flexible, good coverage and quick and easy to apply. If you have access to a supplier that can make you a specific colour in a spray can in an automotive paint, I would probably go for that.

Having said that I have just painted a hull in what is known here as 'Coach Enamel', which is a very tough enamel paint. I brushed it on and was really surprised at how easy it was to paint, how well it covered and what a stunning gloss finish it produced. This paint is designed for things like car restoration work and industrial machinery such as traction engines. I might live to regret it if I see cracks after a few years as it is on a wooden hull.

In your case I would go for the automotive paint, it is probably your best bet for getting a good finish on a large area. I would also go for matt or satin as gloss can look too toy like on a model despite the real ship being painted with gloss paint.

[Richard H DunnParticipant @richardhdunn]

Well I know people probably think I have gone awol again so thought I better show what I have been doing.

[geconParticipant @gecon]

Lovely ships Richard. I like the looks of the Waikare which reminds me of the Glen Line ships which sailed into Hong Kong harbour in my youth. 1951 to1960 -ish.

My family travelled several times to and fro the Far East on the Blue Funnel ships from Liverpool. These cargo ships had up to about 12 cabins for passengers -as did the Glen Line too I think. I stood on deck for hours watching cargo being unloaded/loaded in the various ports. These ships stopped 'everywhere'. Took 4-5weeks Liverpool to HK!

George

[Richard H DunnParticipant @richardhdunn]

Yes they were similar, a bit bigger than these but look very similar.
These were referred to as "Slow Greens" and the Union company had a whole lot of them built.

Kaimiro Kawerau Katea Koranui,Waikare Koraki I am sure there were more to but all almost Identical

[Richard H DunnParticipant @richardhdunn]

The new toy ready and waiting

[Richard H DunnParticipant @richardhdunn]

Still doing the 3d model for the cnc so I can cut all the superstructure parts, should be cutting in a week or 2 , anybody got any suggestions for good scale halogen bulbs for spotlights and also smoke units that produce white smoke?.

[Richard H DunnParticipant @richardhdunn]

Just a quick question I would like an opinion on, if anyone is still watching

I require a max rpm on my props of just over1300 rpm and my motors free speed is 2800rpm(radiator motors)

Do you think I need to gear it down or just use the speed controller, its close considering the load speed on the motor could be just over 2000 rpm i would guess.

[Richard H DunnParticipant @richardhdunn]

I guess I am asking if gearing down 2:1 is smart as it leaves no residual spped power in case of emergencies

[Richard SimpsonParticipant @richardsimpson88330]

Gearing introduces further complexity so while relatively simple and should be trouble free for life they are another moving part that can go wrong. They also absorb a small amount of power but that is probably not a concern with a model boat set up and they can be noisy.

If you are turning 100mm props and pushing 200kg you might find the load speed is even lower. What might become a concern is the current absorbed and consequently the heat generated.

I have a couple of models that were fitted with ridiculously fast motors, way above what is required, however I am happy to control them at a realistic speed and know I could use the excess in case of an emergency.

[Richard H DunnParticipant @richardhdunn]

I would use a toothed belt system to make it a bit more fix friendly and silent.
I just wish there was set formula for motor size.

I have had so many different inputs, including doing it myself from info on the web, Simon reckons I need a 750 w 24 v motor but my calcs reckon a 150w 12v would do.

[Richard H DunnParticipant @richardhdunn]

https://www.motiondynamics.com.au/united-my6812-12v-dc-150w-2750-rpm-electric-motor-belt.html

 

these motors according to this formula

https://www.building-model-boats.com/model-boat-motor.html

should work right?

Edited By Richard H Dunn on 05/09/2021 09:00:12

 

The SHP of real ship was 18000shp btw

Edited By Richard H Dunn on 05/09/2021 09:01:32

[Richard H DunnParticipant @richardhdunn]

This is where I fall apart , because I really don't want to mess this up and need to get the motors in now.
Building the hull and ship….not a problem but all this math stuff…nah

[Richard H DunnParticipant @richardhdunn]

This is the info for the full size. if anyone wants a go.

Edited By Richard H Dunn on 05/09/2021 09:10:25

[Richard H DunnParticipant @richardhdunn]

main engines

Located in the Wahine's main turbo-alternator room:
Two propulsion turbo-alternator sets manufactured by Associated Electrical Industries Ltd (AEI) of Rugby, England. Each comprised a single cylinder, high pressure, horizontal impulse type, 13 stage steam turbine rotating at a maximum 3,080 rpm (revolutions per minute). Maximum designed power for both turbines, either ahead and astern: 18,000 shp (shaft horse power) and 220 propeller revolutions per minute. Normal service speed power, both turbines, either ahead and astern: 12,000 shp and 193 propeller revolutions per minute.

[Richard H DunnParticipant @richardhdunn]

propulsion motors

Located in the Wahine's propulsion motor room, immediately aft of the main turbo-alternator room: Two double unit, salient pole electric motors manufactured by Associated Electrical Industries Ltd (AEI) of Rugby, England. Each double motor had a maximum rating of 9,000 shp (shaft horse power) at 220 rpm (revolutions per minute). Each double motor was coupled directly to a propeller shaft and able to function independently of the other.

[Richard H DunnParticipant @richardhdunn]

Scale speed is 1.8m per second and final accurate weight is 193 kgs with 2 x100mm 4 bladed props

Edited By Richard H Dunn on 05/09/2021 09:13:38

[Richard SimpsonParticipant @richardsimpson88330]

Richard I think there are one or two points here worth considering.

The first is that we are dealing with an area of model boating that very few have ever gone into before. This means that there is little experience out there to draw on and so theoretical approaches are really the main way of dealing with it. I suspect that most modellers would be very reluctant to put their necks on the line and give you definitive guidance as regards the size of motors you require as they would be concerned as regards repercussions should it not prove to be correct. I also suspect that you will get quite a wide range of varying answers depending on the individual's thinking.

From your own point of view I think you are getting too focussed as regards the details of the figures. I think the link above to "building-model-boats" is actually a very sensible and reasoned approach and I completely agree with the authors consideration that power increases as a cube of the scale, or volume ratio. Even then, I notice, that he suggests a factor of safety of 25 to 50% over the estimate to allow for inaccuracies and the unforeseen.

I would suggest that you follow through his thinking and relate it to your own model to reach a figure and then add 50% at least to give you a reasonable comfort zone. It is relatively easy to deal with too much power than it is to deal with not enough.

Finally I would have a good dig around on the internet, YouTube would be a good start, and try to find a modeller that has produced a model ship of a similar size to yours. There are one or two out there that I have seen. There are also manned models out there that perform re-enactments so there is experience to draw from, it might just be a case of finding it. Those are the sort of modellers who might just be able to offer some more constructive advice than we can here and may well be worth contacting. As an example "Manned Models" operate models of a similar size to yours so are probably better placed than most to advise you.

Manned Models

[Richard H DunnParticipant @richardhdunn]

Thanks Richard,

Yes I have contacted some manned ships people as well as electrical engineers and motor suppliers.
I have got it down to one figure, the torque.
What is the best way to calculate the torque I need or at least a good guess at it, is anyone able to advise on that at least as it will help me decide between 2 motors, the ones I have as on page 7 of this blog or a smaller one.

[Richard H DunnParticipant @richardhdunn]

Never mind I have it sorted now, I got an electrical engineer to calculate it all and come up with a solution, worth the money in the end.

[Richard H DunnParticipant @richardhdunn]

So for anyone in the future who has this ordeal here is the result

Motors2 x 450w 24v with 2600 rpm as per Simon Higgins initial advise who made the props.

https://www.motiondynamics.com.au/xyd-6d-450w-24v-2600-rpm-with-chain-sprocket-en.html

Speed controllers also on

https://www.motiondynamics.com.au/12v-36v-dc-speed-control-bi-directional-50a-pcb-model.html

Batteries 2 of these

https://www.batteriesdirect.com.au/shop/product/36661/.html

although got a much better price and charger

https://www.victronenergy.com/chargers/blue-smart-ip65-charger

Manned craft are too far the other way and have a scale of 1:25 as a rule and that is a whole new area of calcs also they are not as accurate to scale in the sense that the propulsion systems are not to scale, I spoke to bloke who builds them over here(Thanks Richard).

So running time at 450w looking at about 18A current draw and should provide in excess of 4 hours if each motor has its own battery.

If motors share one battery then about 2.6 hours.

[Richard H DunnParticipant @richardhdunn]

The last question is whether to reduce the speed with a 2:1 ratio toothed belt and gears to get scale rpm but inclined to direct drive and rely on speed controller, interested on thoughts here re efficiency.

Edited By Richard H Dunn on 06/09/2021 06:59:10

Edited By Richard H Dunn on 06/09/2021 07:09:05

[Richard H DunnParticipant @richardhdunn]

What is the best way to calculate the battery needed to run small led lights, i might need to run up to say 20 on a single string and I am still weighing up series or parallel wiring with resisters etc as I don't want the one goes all goes problem but with a led of

Forward Voltage (Unit:V,IF=20ma):

Typical 3.0 Max 3.4v

 

with 20 lights what would I need for 2 hours say?

I might have 20 but will have many more in total, could be up to 4-500 in total but will split the circuits..

 

Thanks in advance

Edited By Richard H Dunn on 05/10/2021 23:04:19

[Richard H DunnParticipant @richardhdunn]

And yes I have been working every day on model but not updating as much, still cutting it all out on cnc.

Currently have kidney stones.

[Richard H DunnParticipant @richardhdunn]

Update

[Richard H DunnParticipant @richardhdunn]

And far as cladding the hull with first layer of 2mm ply, this is the fit of the parts.

[Author]

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