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Underwater Tape

K

Kuewa

New member
We all have tapered wooden plugs tied to our thru-hulls in case of failure (although I'd still have to run and find the hammer to install it). In the last 30 years, I've never heard of a thru-hull fitting failure of the type requiring the installation of a wooden plug to stop the flooding. What I HAVE heard of is stuffing box failures causing significant flooding (3 in the last 5 years). These involved a degree of disintegration of the packing gland while motoring leaving no way of stopping the flooding from the inside. The one of these three instances that I witnessed was in the marina, and the only way they could get the water to slow down at all was to jump in the water with a plastic Raley's bag and a small screw driver, and stuff the bag from the outside into the small, irregular gap between the shaft and the cutlass bearing. This worked in the marina, but the bag would not stay put at sea.

Which got me to thinking that a device to help in this regard could be far more useful than the tapered wooden plugs I have everywhere. So I cut a piece of black hose with an inside diameter that just fits over the end of the packing gland (the smooth part inboard from the hex surface). I hose-clamped a wooden plug over the other end. I made the length of the hose such that I could uncouple the shaft from it's coupling, slide it back a little ways, and wiggled the hose over the shaft end and then clamp it to the packing gland. (It clamps at the very edge of the packing gland where the smooth part is, only about 3/4" of area, but it seemed to hold great. I could also now remove the shaft and prop to work on or replace it without having to haul out, which I did. My dock neighbors were surprised when I surfaced in my snorkeling gear with the prop and shaft in hand, and the boat still with a dry bilge.) So now in such a packing gland emergency at sea, I can't use the engine but at least water can't come in.

The problem with all this is that I would probably drown down in that compartment trying to rig all this up. Which leads me, FINALLY, to the questilon: I need something like electrical tape that can be applied and holds reasonably well underwater, to tape around that troublesome shaft and cutlass bearing mating surface from outside the boat, so the flooding slows enough for me rig up my hose. Has anyone heard of such stuff? Next time I scrub the boat's bottom, I'll try electrical tape and let you all know if it works.

Tony
 
Hi Tony -

there are several companies that market self-fusing silicone tapes that will fuse underwater. Some of the tapes have an adhesive, and some do not.

Here is one:
http://www.cshyde.com/Silicone Self Fusing Tape.htm

A simpler solution to catastrophic stuffing box leaks is to place a hose clamp onto the prop shaft such that if the shaft comes undone from the transmission coupling the hose clamp will jam against the stuffing box nut as propeller drag pulls the shaft aft - this prevents losing the shaft overboard. Then wrap the silicone tape around the box/shaft to stop the leak. Later you'll need a knife to cut away the fused silicone, something you might do at anchor in Hanalei.

You do want to make sure the shaft cannot slide so far aft that the propeller jams against the rudder.

- rob/beetle
 
Rob, thanks for the link to the silicone tape. Looks like good stuff -- I ordered some. As for the shaft backing out, I already have a collar on the shaft with a set screw to lock it in place wherever I want on the shaft. My concern was not from the shaft leaving the boat, but from water coming in around the shaft if the stuffing box failed the way it did on the boat I saw. The water was coming in at a surprising rate with the shaft still in place. Lots of people were scratching their heads trying to figure out a good way to stop the flooding from inside, but the only way they succeeded was the plastic bag from the outside.

Thanks again!

Tony
 
I also ordered some of this tape. Not only do I think it will be great on the boat for emergency repairs, but I think I can use it on my drip sprinkler system around the house to tape up leaks without having to cut out hose sections and fit connectors! If I can just wrap a leak and be done with it that will make my irrigation maintenance a lot simpler.

- Mark
 
Kuewa said:
The water was coming in at a surprising rate with the shaft still in place. Lots of people were scratching their heads trying to figure out a good way to stop the flooding from inside, but the only way they succeeded was the plastic bag from the outside.
Click to expand...
That tape is good stuff, I like it.

I routinely change the flax in the stuffing box on my boat while in the slip and you're right - a significant amount of water floods in around the prop shaft when the old flax is pulled out. One element of changing out the flax is to keep repeating the mantra (to the new flax): "You will fit... you will fit..." and remember to not get too excited about all the water pouring in.

For pulling the prop shaft in the slip I have a short slug of prop-shaft material (about 8" or so) such that I can from inside the boat back off the stuffing box, press the shaft out with the slug, the slug slips right into the stuffing box, then tighten up the box and the flax clamps down on the slug. Then I hop in the water and pull the shaft clear of the strut.

Hopefully you'll find a use for the silicone tape *other* than on a failed shaft/box!

- rob
 
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