Remember the Subrella? I don’t know if it’s still available but it was a plastic umbrella that you pushed through a breach in your hull, opened it like a brolly and then pulled it back over the hole – water pressure would hold its canopy against the external surface of the hull and you’d be saved. I wonder how many times such a device was ever used in anger? I doubt it’s any significant number but, I suppose, if you were on the one boat ever to be saved in this way it would be a brilliant innovation, to you.
You can get collision mats which you manoeuvre over a breach in your hull using lines at the corners, or you can use a spare jib in the same manner. Once again, I wonder just how many times a boat has been saved in this way.
We’ve seen keel failures crop up quite often recently but it seems to me that these breaches wreak their deadly havoc through instability leading to capsize rather than by water intrusion and sinking.
I’m guessing that most hull integrity problems arise from a broken seacock or transducer. Most of these, I’m sure, manifest themselves whilst the boat is at the dock, unmanned and neglected.
The loss of a through-hull fitting at sea would be very serious, a massive amount of water pours in through a 2” hole a foot below the waterline, but some simple preparation before setting off should mitigate the consequences. Knowing where the seacocks and transducers are located and being sure they are accessible is a good start. Securing soft wooden bungs at each through hull is widely recommended, although I prefer to keep a few different sizes in a bag in a handy locker along with a hammer and other basic tools.
I like the idea of the TruPlug emergency bung, a soft rubber plug that conforms to the shape of the breach more readily than a wooden bung. Then there’s always those traditional standby’s, the potato and the carrot.
To my mind a more difficult breach to deal with is when the stuffing box collapses and water pours in around the propeller shaft. I’ve seen this happen in real life and only the prompt attention of the Coastguard with a massive pump saved the boat. Could you quickly lay your hands on something suitable to plug such an awkward shaped orifice?
Then there’s the Seabung which works on the same principle as the Subrella but on a smaller scale. The Seaplug is pushed through the seacock and the flexible rubber umbrella-like flange on the end opens up and seals the hole as water pressure forces it back against the hull. You can then unscrew the seacock and replace it while the Seabung keeps the water out. Check out the video: www.seabung.com
It’s a useful device if you want to replace a seacock when it’s too expensive or inconvenient to get the boat hauled but it could also be deployed to block a hole where a seacock or transducer has broken off. My only concern would be the effectiveness of the seal against a barnacle encrusted hull or where there is some irregularity in the hull shape that falls within the seating area of the flange.
Who said the most useless device on a boat was an umbrella?