Stuffing tube seal on the outside.

[785boats]

After reading through Propperchopper's thread on sealing the stuffing tube on the inside, I thought I'd show how I seal the tube from the outside to stop the water getting in there in the first place.
This is based on the premise that where we leave a 1/8" or 3/16" gap between the drive dog & the stinger/strut, the shock wave of water off the face of the dog is forced past the bearings into the tube. I read that somewhere ages ago.
What I do is place a piece of soft silicone fuel tube on the shaft just shorter than the gap. It acts like an O ring seal.
Never get water in my boats up the shaft.
Some guys at our club used to, but not now that they use this method.
In the pic you can just make it out between the dog & the stinger.
Cheers.
Paul.

[Fluid]

The problem with that method is the drag caused by the silicone as it compresses between the drive dog and the end of the strut. The flex cable shrinks under load - that's why we leave the gap otherwise the drive dog rubs on the strut. Putting something into that gap doesn't allow a free compression of the cable, causing driveline drag. Plus the silicone swells past the outside of the strut, causing underwater drag.

Propp's vacuum plug causes almost no drag on his wire drive. You have solved one problem and probably created another. I use the method below, which causes almost zero drag on the cable if adjusted correctly.

http://i55.tinypic.com/2qx2luc.jpg


.

[785boats]

Thanks for bringing that up. But I've tested flex cables a long time ago by twisting them with a pair of multi grips while the other end is held in a vice. I placed a piece 6" long stuffing tube over the flex butted up against the vice. Marked the flex at the other end of the tube with a black pen. I twisted the flex until it started to bind up in the tube which is more load than is applied in a boat one would think or it would be creating a huge amount of friction in the tube. The black mark did not move. I've said for a long time that a 6" piece of flex cannot shrink 3/16" under load. But the silicone tubing is shorter than the gap & I use the very soft stuff. There is no added friction as far as I can tell.
Besides if the shaft were to shrink that much & there was that much friction it would tear the silicone tubing to bits. But it's always still there at the end of the run.
Anyway. It works for me.
But an ordinary little O ring on the shaft against the strut would do the same thing And you can still have the gap behind that.
Cheers.
Paul.

[drwayne]

I use the silicon idea, all my struts are rollers, so the silicon doesnt bind there.
If the silicon made the flex bind, the silicon would persih.. 7 months since last boat build, lots of use, crisp as the night it was cut. a few drops inside, not the water tank as before.
W

[FRED]

When i read what Paul and Fluid typed ; this came to mind what Paul Pachmeyer told me years ago to file the front of the dog drive so water flows over dog drive instead of butting the vertical front of the dog drive which would force water up the stringer. Strenght of dog drive would not be affected. Now another factor is how straight is the stuffing tube, especially on solid shaft and how low the motor is in the boat. Cable type seem not to be affected. The cable stuffing tube is bent upward as the motor is angled downward for alignment of the two. I use liner but have to sand liner so to slde liner into tube to fit and has always worked. Ernie Lazenby told me of these things and he was spot on and never missed once on his suggestions. BTW, the thicker the flex, the less the twist will be, so less gab is needed at the dog drive and stringer. Oops, i just read what Paul typed, sorry. I sand my flex cable till it shines so less friction and also the cable wind won't act as an auger bringing water up the stuffing tube.

[PDR447]

Thanks for bringing that up. But I've tested flex cables a long time ago by twisting them with a pair of multi grips while the other end is held in a vice. I placed a piece 6" long stuffing tube over the flex butted up against the vice. Marked the flex at the other end of the tube with a black pen. I twisted the flex until it started to bind up in the tube which is more load than is applied in a boat one would think or it would be creating a huge amount of friction in the tube. The black mark did not move. I've said for a long time that a 6" piece of flex cannot shrink 3/16" under load. But the silicone tubing is shorter than the gap & I use the very soft stuff. There is no added friction as far as I can tell.
Besides if the shaft were to shrink that much & there was that much friction it would tear the silicone tubing to bits. But it's always still there at the end of the run.
Anyway. It works for me.
But an ordinary little O ring on the shaft against the strut would do the same thing And you can still have the gap behind that.
Cheers.
Paul.

It's hard for me to believe that it shrinks too but I saw the results for myself on my geico. too small of a gap and I was loosing 5mph on the top end. I opened up the gap and instantly got those mph back. I don't run the full width of the cable like a lot of people say but I run about .5 to .75 of the cable width.

[rdmanone]

I am new to the boat thing I have planes and heli's. I just purchased a genesis form HK and have had problems with the motor getting hot. I only left a gap of about a paper width. I guess that could cause some binding.

[Jeff Wohlt]

Leave a min of 1/8" but I like at least 3/16" The longer th cable the more it will shorten.

[rdmanone]

I have to write all this down on list of things to do. Thanks

[785boats]

Jeff is right with the gaps rdmanone. Dont get me wrong guys. I do leave a gap too. All I'm saying is that if you cut a sliver of tubing half the width of the gap you leave, it will stop the shockwave off the front of the drive dog forcing water up the shaft past the bearings.

Fred.
I like the idea of Paul Pachmayer's about angling the front face of the dog. I'll have to give that a go if I start to get water up any of the shafts. Such a simple solution.

Cheers.
Paul.

[sundog]

I sand my flex cable till it shines so less friction and also the cable wind won't act as an auger bringing water up the stuffing tube.

I thought cable wind always 'augered' the water towards the prop? :confused2:

[Boaterguy]

What I would do is drill a hole through the pipe, put a water outlet in there, and use a little tubing to get the water right out of the tube, zero drag on the line

[Shooter]

I thought cable wind always 'augered' the water towards the prop? :confused2:

I thought so as well. But we are still getting water somehow?? Anyone??