Building RC boat blues

I would do it this way:-
Mark where the shaft will exit the hull and drill a 3mm hole.
Enlarge the hole in a fore and aft direction until the shaft when at the correct angle touches the top and bottom of the slot. (top after end.)
Then use a filler like Isopon or PlastiBond or what ever is available where you live)to fix the shaft in place. While the filler is drying place the hull into cold water to absorb the heat generated by the two paft filler.
I'm not sure that the model car radio will give you the range you need though.
Dai

I was thinking about building a "packing box" and filling with vasiline or other heavy grease.

go to www.rcboats.com
and look at this:

SBS - 2 Stuffing Box w/Seal

Combining a very high sealing ability with very low friction, the SBS - 2 Stuffing Box with Seal provides a substantial waterproof seal without a heavy dose of messy grease. Low friction results in lighter load on the battery which gives more run time. For 3/16" dia. shaft.
Available 2", 4", 6" lengths

costs $12...you may want to contact Skip(the owner, Skip Asay) and see if a 3mm shaft will work, or if he can help you with a metric size.

There ya go. That would do the trick

http://www.rcboats.com/hardware.html

Here is a tutorial I did for the micro car people. It took 20 minutes to perform.
It can be upscaled to any size shaft and stuffing tube.
http://www.microrccenter.com/forum/index.php?showtopic=18181&st=15

You can also have a look at this short section of the LST build up.
http://groups.msn.com/ModelersAndHobbyForum/japaneset103lstbuildup.msnw?action=ShowPhoto&PhotoID=112

Or

TonyO's Revell conversion build up here,...
http://www.rcgroups.com/forums/showthread.php?s=&threadid=173262

If these bring up more questions, let us know.

If you can't get the commercial stuffing boxes to fit your hull, get a piece of brass tubing that sleeves over your prop shaft and use that. Don't try and fit the shaft directly to the hull; the hull will quickly wear and it will always leak.

Drill the hull for the tube and fasten it with epoxy; reinforce as required so it is rigid in place. Fill it with vaseline and then push the shaft through the lubricated tube. Enough vaseline will stay in the tube to make a watertight seal and this will also reduce friction.

You should also have a U-joint on the shaft as it is almost impossible to get the motor shaft to line up properly. Anything from a piece of vinyl tube, a spring, or a commercial joint will work fine.

Let us know how you make out,
Bruce

wow, thanks everyone. This is really been a HUGE help for me, as I had all the pieces and subassemblies ready go to (save a few) but I've been stuck for months on this.
Thanks a lot!

hey Umi_Ryuzuki, I have just a couple of questions if you don't mind, since I'm a little confused by the instructions on the other post :)
I'm confused about how the plastic tube is fitted over the whole assembly.
Is the prop-shaft soldered to the motor? Also, I don't quite understand how the plastic tube is attatched. Can you maybe elaborate on that. I understand that one end of it is attatched to the outer tube, but what about the other end. Also, what do you fill the tube with, if anything.
As well, what is the ideal difference in thickness between the prop shaft and the outside tube. I'm going to assume that the best is as small as possible :)

The plastic tube connects the motor shaft, and propeller shaft. They are not soldered together.

As LeCren mentioned, the plastic tube is used to connect the solid inner "propeller" shaft to the motor. I typically apply a little super glue to the inside the plastic connector, and then slide it over the motor shaft, and then press the propeller shaft into it.
You can see the picture of a larger connection Here, in TonyO's North Sea Trawler build up. No solder the tubing flexes in case the motor and shaft are not exactly aligned
http://www.rcgroups.com/forums/attachment.php?s=&postid=1538425

You can also buy u-joints. Dumas sells several sizes.

The LST build up described a typical clearance for shaft and outer tubes
http://groups.msn.com/ModelersAndHobbyForum/japaneset103lstbuildup.msnw?action=ShowPhoto&PhotoID=112

The Micro build up was pretty much a direct sleeveover the shaft. More friction, but it would be difficult to oversize the shaft for such a small motor.

k, that makes sense. Thanks for the reply. I will definitely need to follow your example, since I'm using two standard electric motors, which are not very large. I'm just afraid that it will leak a lot :)

It seems that i could have inadvertently misled you with my reply to your question.
When I sail shaft I meant the complete inner and outer assembly.
I usualy use a 4mm shaft assembly with brass bearings. If the inner end is above the waterline then I just rely on the bearings to keep the water out of the hull. If the inner end is at or below the waterline then I pack the assembly with petroleum jelly.
One important thing try to use dissimilar metals for prop shaft and bearings. Brass on Brass is not a good idea as they will bind. I usualy use steel and brass bearings.
I tend to use a graupner coupling from the motor to the shaft to make up for any misalignments although it is a good idea to get the alignment as accurate as possible to cut down on battry drain. use an ameter to check current and move the motor about until the lowest reading is obtained. If you dont have a meter move the motor about and listen to the revs when you hear the revs reach a peak the motor should be in its optimum px.
If specialised couplings are not available then plastic tube or two L shaped pieces of piano wire or similar will also work.
I built R/C scale model boats for about thirty years until an accident forced me to give them up and take on static models.
Dai

Thanks Dai. that will help. I've found brass tubes that I plan to use as the housing (outer tube). THe prop shaft going to be aluminum or steel. I'm having someone who owns a metalworking shop to find me some scraps, so whatever they find is what I'll be using.
I'm sorry to hear about your accident. I've just started with RC models, having built exclusively static models before. But I found them to be absolutely great fun, as I'm sure you will too!