Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => BMPRS - British Model Powerboat Racing Society => Topic started by: craig dickson on March 10, 2015, 09:09:12 pm

Title: The Most Annoying Radio Box Leak Ever!
Post by: craig dickson on March 10, 2015, 09:09:12 pm
Hi Folks


Further to the earlier and very informative topic on radio control issues, this one is back to simple basics. Have you ever tested or raced a boat and ended up with water inside the radio box?
If so was the cause of the leak easy to find and correct?


I ask the questions because having built a new boat recently and from its first run and every one after, it has had after 20 minutes of flat our running, about 5 single drops of water inside the radio compartment.


Now some would say, "Don't worry about such a small amount. Pop some tissue paper in to keep it away from the receiver."


How do you identify such a small leak? I suspected that it must be coming up through the rudder post which is inside my radio box but sealed top and bottom with O-Rings in a brass tube with nylon housings top and bottom, packed with grease.


After nearly writing this new boat off for racing due to this issue, I removed all radio gear and filled the box with water. (Dunk testing it previously failed to reveal the source of the leak.)


So where was the leak?


After 3 minutes, a bead of water appeared at the rudder post bottom of hull, not via the shaft but on the outside of the tube!


After emptying the box of water, and drying it out, I dipped the transom of the boat in a tank of water, and spotted where the bead of water came in....it was via an invisible hairline hole in the fibreglass paste used around the rudder tube!


The good news is that it was easy to rectify, and now I can run and test this boat to the full!


Those of you that know me will realise that I am perhaps paranoid about the importance of totally waterproof radio boxes for fast racing boats.


(http://i734.photobucket.com/albums/ww350/DICKSONUK8/Mayhem%20Forum/Rudder%20Post%20Leak%20Mayhem.jpg) (http://s734.photobucket.com/user/DICKSONUK8/media/Mayhem%20Forum/Rudder%20Post%20Leak%20Mayhem.jpg.html)


Craig :-)






Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: U-33 on March 10, 2015, 10:06:01 pm
You should try building a submarine, Craig...   %)


Rich
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: ids987 on March 11, 2015, 03:15:10 pm
Good find Craig. These things can be maddening. You can also do the reverse. Submerge the radio box, and look for the escaping bubbles. Or if it has an access hole, you can use the access hole to inject pressure, and either try to listen for the escaping air, or again, under water for bubbles.....
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: craig dickson on March 11, 2015, 05:12:38 pm
Oh the submarine comment did make me smile ;)


On the finding of the leak I did initially try the dunk test method but even though one drop of water appeared inside, by the time I had lifted the boat out, it had moved so I was non the wiser as to its entry point. Is someone had have suggested, "leak where the rudder post is glassed in" I would have said, "No chance, more like coming up the inside of the tube between its housings and the rudder shaft!" How wrong I was!


Anyway having cleaned up the inside and applied a thick fillet of glass paste around the rudder post, the boat was tested today for a good run.


Thankfully this time it remained bone dry inside the box - Phew!


Craig :-)
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: TomHugill on March 11, 2015, 05:38:17 pm
You should try building a submarine, Craig...   %)


Rich

I find subs easier as you can usually add positive pressure and then it's a case off following the bubbles!
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: Martin (Admin) on March 11, 2015, 07:01:33 pm
 
MANY years ago. I had a not very racey, multi race boat with a leak.
I tried Everything I could think of to find and stop the leak but no luck!
In the end I fitted a siphon autobailer in the bottom of the radio box a junk pumped out any leaks!  %%
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: ids987 on March 12, 2015, 02:45:26 pm

MANY years ago. I had a not very racey, multi race boat with a leak.
I tried Everything I could think of to find and stop the leak but no luck!
In the end I fitted a siphon autobailer in the bottom of the radio box a junk pumped out any leaks!  %%


I remember reading about this, and lots of other entertaining experiences, in your "My Models" section Martin - back when I first found Mayhem; probably over 10 years ago. Not sure if you had a forum then. If so, I don't think it was so active.
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: ids987 on March 12, 2015, 03:03:41 pm
Must admit, I'm with you on this Craig. Get the radio box as watertight as possible. Especially a leak like this, where it would have been coming in all the time the boat is running. Even if it's only a tiny amount, it doesn't take much, and obviously the longer it's running, the more there will be.
On the other hand, even when you've got a watertight radio box, things can go wrong, a split seal, or if you're like me, throw it in with the radio box bung missing, and don't even realise what you've done.
In the nitro boats, I'm still using 40MHz PWM radio, and as belt and braces, I like the failsafe to be separate from the receiver, and waterproof in its own right. Having a receiver with built in failsafe, in my opinion, is not as robust. If the all in one Rx / Failsafe gets wet, you can lose the receiver and failsafe functions at the same time, or lose the failsafe function first unknowingly, and subsequently lose the receiver function, and it can just stop working with the servos in their last position (like not having a failsafe at all, or sudden loss of power). On the basis that servos are usually more waterproof than receivers, if the receiver gets wet, and the failsafe is still working because it's waterproof, the failsafe will usually detect lost signal - due to wet receiver, and if the throttle servo is still working, shut the engine down.
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: martno1fan on March 12, 2015, 04:22:52 pm
In case of small leaks stick a tampon inside the box it will soak up lots of liquid hehe,honestly they work great but you might get a few funny looks at the pond lol  :o .
Mart
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: tmbc on March 15, 2015, 10:48:17 am
thick super glue round it use an activator  :-))
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: Shipmate60 on March 15, 2015, 12:28:14 pm
I would still try and seal the outside of the hull/tube join.


Bob
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: Brigadair on March 17, 2015, 08:04:39 pm
Pleased y got it Sussed craig?
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: craig dickson on March 21, 2015, 08:22:00 pm
Hi Folks


Thank you for your encouraging feed back and comments :-))


Bob made a good point about focussing upon the outside of the hull and tube exit joint which has a gap in my example. I thought about that but decided that because the boat had been run a good few times, it would be difficult to clean the gunk from that small gap to ensure a good repair without opening it up quite a lot. Doing it inside was easy because I could be aggressive in removing material around the rudder tube to ensure a good clean key to extra fibreglass.


TMBC (Mark Wild), gave a suggestion which in retrospect probably would have sorted this tiny leak in a matter of seconds!  ;)


Mart suggested a Tampon. I can see their uses, and not a bad idea at all...... :o


Martin (admin) mentioned some kind of Auto Bailer. If that worked well for Martin then I say 10 out of 10!  :o


For me personally, if you have water getting into the radio box on a regular basis, however small it may be, as in my example.... it pays to find the problem and fix it.


Thankfully my box remains dry after another long run today. :-)


Craig :-))


 



Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: Shipmate60 on March 21, 2015, 11:15:53 pm
Craig,
Over time if the leak is not cured from the outside the constant damp within the fibres will slowly de-laminate the fibre glass making another leak further away more likely.


Bob
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: martno1fan on March 22, 2015, 10:21:17 am
My idea of the tampon is not if you already have a leak more in case your radio box develops a leak during running ie radio box lid cracks or rubber boot tears etc,it could just save your electrics,also spraying your rx inside and all connections servos internally etc with a dielectric spray will protect from even submerging in water.
Mart

http://www.ebay.co.uk/itm/NO1-Dielectric-waterproof-coating-anti-Corrosion-Spray-For-Boat-Car-Caravan-Bike-/251873183499?pt=LH_DefaultDomain_3&hash=item3aa4cfc70b (http://www.ebay.co.uk/itm/NO1-Dielectric-waterproof-coating-anti-Corrosion-Spray-For-Boat-Car-Caravan-Bike-/251873183499?pt=LH_DefaultDomain_3&hash=item3aa4cfc70b)
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: grasshopper on March 22, 2015, 01:10:57 pm

Hope I'm not 'teaching my granny to suck eggs' but in the picture you posted I noticed the big screw holding the tiller arm on the rudder shaft, do you have a flat filed on that shaft or just relying on friction to hold it in place?


Filing a flat will reduce the chance of losing the rudder if it slackens.
Title: Re: The Most Annoying Radio Box Leak Ever!
Post by: craig dickson on March 22, 2015, 05:36:29 pm
Hope I'm not 'teaching my granny to suck eggs' but in the picture you posted I noticed the big screw holding the tiller arm on the rudder shaft, do you have a flat filed on that shaft or just relying on friction to hold it in place?
Filing a flat will reduce the chance of losing the rudder if it slackens.


Yes a flat is filed on the shaft to ensure a secure lock.


Thank you Bob and Mart for your further interesting and helpful contributions. Both make a lot of sense in my opinion.  :-))


Cheers
Craig