About motorized models...

You could try this, taken from:

http://www.repairfaq.org/filipg/RC/F_Ship_Kombat.html#SHIPKOMBAT_028  , a group who do radio controlled model ship battles.

"All ship models use a "stuffing box" to allow the prop shaft to pass through the hull of the boat. Most people use an 1/8" brass rod for the shaft and a 3/16" brass tube for the shaft housing. A small piece of 5/32" tubing is solder inside the ends of the 3/16" tube to support the 1/8" shaft. If a little bit of grease or vasoline is inserted into the tube before the prop shaft, then no water will be able to force its way up the tube. (By the way, this is essentially how real prop shafts are installed also.) "

Am not sure whether you would need to use smaller diameter rods, but the principle should be the same.

Hmmm... very interesting!!!

So lubricating grease can actually prevent water from entering? That's a very simple, yet interesting solution...

I also thought of that during planning, but I never actually think of it actually working...

Now the next question is...

What kind of grease or lubricant would you recommend that I should use? Should I choose the ones from Tamiya, or petroleum jelly, or vasoline would be a better solution?

BTW, this may sound absurd,but my plan for the second titanic is to let it sail across our school's lake park during our university week, and take pictures of it. The water is not turbulent in that place, in fact its almost mirror-like, not many ripples (the big ones I mean), and waves are often rare, but when occuring, they're very small to knock the model off...

Can it survive that trip alone? (the longest distance between the 2 ends is about 30-50 meters I think)

Thanks again for this valuable idea!!!

On the grease question, I don't honestly know for sure. I would have thought a medium one would have been the best choice. Too hard a grease & it might be to slow/ stiff to seal the moving shaft & water would enter. Too softer grease wouldn't be resillent enough & would get moved out of the way by the rotation.

I think that the link said to use vaseline?, which I think is softer than petroleum jelly.

To sir david:

Thanks for those suggestions for the grease!!! I guess I'll choose the white lithium variety

To sir Umi

Thanks for that info about the stuffing tube/box!!!

But now that you've mentioned the stuffing box...

I looked once again on the hull of the model, and the instructions for the assembly of the propulsion system, and there it was. The stuffing box is already built-in on the hull of the titanic model, along with the other half of the gearbox and the motor mount...

But I guess I'll go with the stuffing tube, I'm more confident using it for the prop shaft than the stuffing box...

The shaft that was included in the kit (along with the motor, motor mount, gears, gearbox, rubber tubings, wiring, battery terminals & some lights), is about 2 mm in diameter... So I guess I'll just look at the hardware store for tubings that would fit (If they have one...)

Thanks to all for the suggestions!!! That's one big thorn off my neck!!!

Now that's settled another question popped into my mind...

Let's say I've built and installed the stuffing tubes nicely on the titanic without leaks or the like on the hull...

So if I let it run on a 50-100 foot-long stretch of water (say a lake), will it survive (with no big ripples or anything on the water)? Or will it end up just like the real boat? ...Steering is not an issue, 'cause I plan to run a length of nylon string on the model with both ends on either side of the lake..

Apologies for the stupid question, I'm kinda paranoid I think, since this will be my first serious ship build (with motors ) ...

First, let's assume that you have sovled the stuffing box /grease issue. 

On truly calm water, the model could run until the batteries gave out with out a problem. 

But the surface of most lakes is not truly calm, most of the time.

What you are really asking is if the model is seaworthy?  To make it so, make sure that water can't get into the hull.  Open portholes in the hull are an invitation to disaster.  You mentiuoned lighting--so I am guessing at least some of the windows and portholes are open to let the light out. You should fill them with some sort of clear material-- very thin clear plastic is probably the best. 

Sealing the bow and foredeck is important, too- will any water that splashes up on deck drain overboard, or into the hull? 

If the lake or pond you're using is closed, with access all around, I wouldn't worry about using string-- I'd let the model run free,  If the rudder is straight, and there is no wind, the model should sail in a straight line, or close to it.   Keep in mind that a length of wet string is heavy-- the model will be supporting it and trying to pull it across the pond. 

If you test the model ahead of time (in the tub or other test tank) for leaks, and take care of them before settign out, you'll be fine.

Hope this helps...

well, actually, the kit's parts is not intended for a single prop only...

The gearbox delivers power from a single motor to the 2 outboard props of the ship... in other words, the motor spins not one, but two props (and they are spinning in an outboard direction)...

An RC conversion is out of the question I'm afraid... First reason is the expense, I really don't have anything to spare except for the materials for the stuffing tube you've kindly suggested for this project, and my modeling equippment and supplies (I can't even buy online...)... Second is the availability... our place don't carry any RC equippment that can fit on a mere 1 foot titanic, servos, even a 2 channel radio is a rare find...

So I have to rely on alternatives for "navigation"...

and also, the reason for the string idea is that I don't want to have any directional control for the ship at all... since I'm also holding a camera for taking pictures, and a columnist for our school paper is interested to have a copy...

I kinda like the idea of the model to travel without any intervention, to somehow have a "natural" look for the ship, as if its really the real thing sailing to some "unknown" destination...

rcboater wrote:

First, let's assume that you have sovled the stuffing box /grease issue.  On truly calm water, the model could run until the batteries gave out with out a problem.  But the surface of most lakes is not truly calm, most of the time. What you are really asking is if the model is seaworthy?  To make it so, make sure that water can't get into the hull.  Open portholes in the hull are an invitation to disaster.  You mentiuoned lighting--so I am guessing at least some of the windows and portholes are open to let the light out. You should fill them with some sort of clear material-- very thin clear plastic is probably the best.  Sealing the bow and foredeck is important, too- will any water that splashes up on deck drain overboard, or into the hull?  If the lake or pond you're using is closed, with access all around, I wouldn't worry about using string-- I'd let the model run free,  If the rudder is straight, and there is no wind, the model should sail in a straight line, or close to it.   Keep in mind that a length of wet string is heavy-- the model will be supporting it and trying to pull it across the pond.  If you test the model ahead of time (in the tub or other test tank) for leaks, and take care of them before settign out, you'll be fine.   Hope this helps...

Oh I see!!!

the Lake that we have in our school is so calm that the only waves or that can be seen is the ones that I create when I throw some stones into it... along with some small fishes...

And yes sir, the lake is closed, which is a great thing!!!

For the portholes, I have to admit I planned to drill them for the lights, but after some tests in the sink, I ditched the idea, and after all, I don't have any micro drills in my tools!!! hehehe!!!

The open parts that are in the boat are those that are way up high, practically all of them on the deck...

The beauty of the model is that the bow and stern deck parts are intended to be glued permanently on the hull, the only removable part is the center deck, for battery replacement and maintenance...

The string that I will use is the plastic (or nylon) variety, and I'll use the thinnest available, so that its also practically invisible underwater...

The string thing is for insurance only so that the model will run to the direction I want it to, and the two ends will be (obviously) taut on the two ends, but at just the right tension, not too tight, not too loose

If your going to attach strings of any kind then why would you need motors at all?

Just pull the model through the water with the strings.

Keep the string off.

I'm sure it will run a straight enough course as to be of no concern. 

reklein wrote:

I'd fill the hull with as much sytrofoam as possible before glueing the decks on, and forget about portholes for an operating model. Also keep the speed fairly slow for proper scale effect.Hardly any battleships could get"up on the step".

Ok sir checked!!!

mikepowers wrote:

If your going to attach strings of any kind then why would you need motors at all? Just pull the model through the water with the strings. Keep the string off. I'm sure it will run a straight enough course as to be of no concern.

Um, that's not really the main purpose of the string, its intended to be as a loos "guide" for the path of the model, with the two ends on both sides of the lake, and the model travelling through it like a bead...

I expect the ship to travel in a straight line, but the setup is just to make sure that it arrives precisely where I want it to, if there's any external factors that may affect its travel

Ok... I've finally started this build...

But there are some modifications for the stuffing tube setup I've made...

First is the materials used...

Unfortunately, I wasn't able to acquire some brass tubing for my stuffing tube... the diameters required are just too small... even or local HS don't have 'em...

So after much thought and rummaging on some junk, I've made a possible solution...

first, for the main tube, I used 2 pieces of plastic straw that came with my tetrapak juice drink (cut to conform to the model's hull and to match the exposed length of the shaft (with holes and seams filled with gap-filling super glue), one each propeller shaft) and for its plugs/washers, I rolled a piece of bond paper, and used super glue as adhesive, letting the glue seep to the paper to make it waterproof (I hope so), and AFAIK, super glue soaked paper is impermeable to water and/or oil-based fluids... and also, before the props would go, I'll also put a plastic washer between the tube and the prop for better spin (and better waterproofing I hope)...

and second, I made it to be a "combined stuffing tube and box", meaning, the stuffing tube is connected to the stuffing box which is already molded on the model hull... both of which will be filled with grease...

I've made some trial "dry runs" with the motor turning and the stuffing units without grease to see if the props are turning well, and they are (with some ocassional grinding sounds because the motor is not properly mounted, and the gearbox not secured well)...

later, after the hull is completely done (electronics, paint and all), I'll do some trial floats with the motor running to look for possible leaks...

to ship builders out there... would these mods work? My dad says it will work, since the setup would be waterproof according to his observations...

Sounds like a really good improvised solution for you your stuffing tubes. I would still be a little concerned that the paper at the back side or someplace may still get wet and expand or swell. This could sieze the shaft. A little water time will let you know if the paper bearings are thoroughly water proofed.

If it becomes a problem, use the smallest brass rod from the hardware store, and the next two or three sizes of tubing for your stuffing tube. You can drill out the propellers to fit the shaft, and a small piece of rubber of vinyl tubing should still be able to connect the shaft to the motors.

Umi_Ryuzuki wrote:

Sounds like a really good improvised solution for you your stuffing tubes. I would still be a little concerned that the paper at the back side or someplace may still get wet and expand or swell. This could sieze the shaft. A little water time will let you know if the paper bearings are thoroughly water proofed. If it becomes a problem, use the smallest brass rod from the hardware store, and the next two or three sizes of tubing for your stuffing tube. You can drill out the propellers to fit the shaft, and a small piece of rubber of vinyl tubing should still be able to connect the shaft to the motors.

Hi sir!!! Nice to hear from you again!!!

About the paper, like I've said before, I used super glue for rolling the tube...

But here's how I did it... Upon rolling the tube, I made sure that the super glue spreads evenly on the paper strip, even allowing the glue to overflow on the edges for further waterproofing. then after the rolled strip is done, I put a little more super glue on the paper edges to prevent the water and oil/grease to seep through the fibers. When the finished "washer" was dried, it was as hard as plastic, even sounds like one when I dropped it... The part in contact with the drive shaft received the most super glue during rolling so that even if the paper grinds away after prolonged friction (in the event that the grease ran out during rotation), the super glue backing would be the one exposed to the drive shaft...

then I mount the washer to the plastic straw (I rolled the strip so that it fits very snuggly to the straw), and glued it in place using super glue again... Then before inserting the shaft, I put some more glue on the exposed portion of the paper washer... but also, to make sure, I'll make a plastic washer to shield the exposed part and to provide the screws a better spin...

 I'll be using tamiya's grease for the units, since they offer different consistencies for their Mini 4WD greases... (BTW, how thick should the grease be for the stuffing tube/box? Very thick or not too thick?) (I wasn't able to find the white lithium grease, but I'll ask my father if he knows where to get it, or if he has one...)

But, I'll take your suggestions very seriously when I conduct water trials when the stuffing units are finally done... and if anything went terribly wrong, I'll find myself the materials you've mentioned...

Thanks sir for your tips for my project!!! It sure is a great help!!!

That would be "Mame"...

<<<<<---------

A medium or light grease should do fine. Too heavy, and it will not only be good at stopping water, it will create a lot of friction. Don't "pack" the grease in there either, about 1/4- 1/2 full is all that should be required.

Hans, I have built quite a few R/C models and I can tell you that the greased shaft works really well.. You should find that almost no water leaks in at the shafts.   I would like to recomend that you make your ship R/C (Remote controlled.) 

Paul 

Paul5910 wrote:

Hans, I have built quite a few R/C models and I can tell you that the greased shaft works really well.. You should find that almost no water leaks in at the shafts.   I would like to recomend that you make your ship R/C (Remote controlled.)  Paul

Hey guys, thanks again for your suggestions!!!

I've finally started the deck of the ship, and its so far, so good... well, its the first plastic model that I'm building for about 2 years, with card modeling filling the gap of those 2 years...

sir Paul, the R/C idea was great, but the size of the model won't let it... plus, R/C parts are hard to come by here (servos, electronic stuff etc.)...

but maybe I'll consider that once I build a second one in 1/400 scale... ;)

A colleague of mine had a model 1:600 scale Airfix RMS Queen Elizabeth that was somewhat beaten up so he decided to motorise it.

He cut out part of the bottom of the hull and fitted a small speedboat inside as its propulsion.

The model speedboat had two electric drive motors, which also steered the model.

Although the installation was rather crude, it did work very well.

We had an official launching ceremony and the ship was put through its pool trial without any problems.

It was a little on the fast side, but that was all part of the fun.

Regards,

Beau.