Bungs

[David Bewick]

No, not another story about bribery and corruption in the world of overpaid player transfers but something that is altogether more important (in the world of boats, at least)!

The plans for Aber show a drainage bung that goes through the lowest part of the hull but I have never managed to find one that is designed to work in thin (6mm) ply.  I did try to modify one of the grey plastic screw-in types but I was not very happy with the result and I never fitted it in the end.  It is still on my list of winter jobs for the boat to fit one and I wondered if anyone has ever managed to source such a thing.  It seems there are all sorts of bungs from plastic to bronze that are designed to work in skin thicknesses from about 9mm upwards but nothing intended for thinner materials.

Has anyone ever managed to source a decent bung designed for thin materials or found a good work around for using one of the other off-the-shelf products?

Many thanks and best regards,

David.

[alopenboat]

On 11 Jan 2013 at 9:04, David Bewick [via UK HBBR Forum] wrote:

>
>
> No, not another story about bribery and corruption in the world of
> overpaid player transfers but something that is altogether more
> important (in the world of boats, at least)!
>
> The plans for Aber show a drainage bung that goes through the lowest
> part of the hull but I have never managed to find one that is designed
> to work in thin (6mm) ply.  I did try to modify one of the grey
> plastic screw-in types but I was not very happy with the result and I
> never fitted it in the end. It is still on my list of winter jobs for
> the boat to fit one and I wondered if anyone has ever managed to
> source such a thing.  It seems there are all sorts of bungs from
> plastic to bronze that are designed to work in skin thicknesses from
> about 9mm upwards but nothing intended for thinner materials.
>
> Has anyone ever managed to source a decent bung designed for thin
> materials or found a good work around for using one of the other
> off-the-shelf products?
>

Probably not a good idea to listen to someone who refuses to have any
holes in his hull below the water-line (or ply as thin as 6mm), but
can't you just locally thicken up the ply where the bung fitting goes
in?

--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[David Bewick]

Al,  

To a large extent, I share you reluctance to put holes in a perfectly sound hull.  I could just about bring myself to do it if I thought I was implementing a quality solution but not if it was something just cobbled together - hence the status quo.  I thought about putting a ply doubler in but I would not do it on the outside where it would look ugly and (minimally) affect the flow of water around the hull and, if I did it on the inside, I would still end up sponging out the last bit of water so it hardly seems worth the effort of putting it in.  A sponge does do the job pretty well, actually.  Perhaps I should be looking for a way of tying one of these to the boat, instead .

David.

[BrianP]

The neatest non plastic drain bung i have come across is this one from my local chandlers £7.15. have seen them at other chandlers as well.







It measures 45mm across. The upper flange in the boat is just 4mm. The lower section going through the hull is 10mm, so you could either machine it down a bit, or by the time it was bedded in, and there was some curve in the plank, little will show below the hull.

The hole size you would drill in the hull is 25mm. The flange measures 23mm, so just enough room for some mastic or epoxy

Brian

[alopenboat]

On 12 Jan 2013 at 1:55, David Bewick [via UK HBBR Forum] wrote:

>
>
> Al,  
>
> To a large extent, I share you reluctance to put holes in a perfectly
> sound hull.  I could just about bring myself to do it if I thought I
> was implementing a quality solution but not if it was something just
> cobbled together - hence the /status quo/.  I thought about putting a
> ply doubler in but I would not do it on the outside where it would
> look ugly and (minimally) affect the flow of water around the hull
> and, if I did it on the inside, I would still end up sponging out the
> last bit of water so it hardly seems worth the effort of putting it
> in.  A sponge does do the job pretty well, actually.  Perhaps I should
> be looking for a way of tying one of these to the boat, instead .
>

If you go for a sponge get it from a painters supply. They use
sponges which hold enormous quantities of water without serious
dripping.

My normal bailing system consists of a sponge stored at the lowest
point, which is occasionally squeezed over the side

If the sponge is rejected can you set up the boat up in the attitude
where the draining would take place, then pour in some epoxy (with
microballoons but not silica, so it flows) to a suitable depth? This
should ensure that the bung is at the lowest point.

--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[alopenboat]

Do people generally have bungs that screw in from outside the hull,
or inside?


--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[John P]

I think that it is a good idea to have a drain point at the lowest point of a small craft hull, although I suppose that if you keep your boat always under cover when not in use you may not need it.

One often sees sailing dinghies left in dinghy parks with rain water filling them up, a simple drain would avoid that so I think that Francois Vivier is quite right to include one, but it would seem that most other boat designers dont do so. Having said that, if Vivier includes a drain point then I think he should indicate on his drawings exactly how the drain is to be fitted, together with details of supplier and part numbers for suitable fittings. As a mechanical engineer I am used to every part of a piece of machinery being detailed in drawings, specifications and parts lists, right down to the last screw, washer and split pin, so I am rather surprised that boat designers seem to get away with not doing that!

On our boat a home made self bailer serves the purpose, but I can see that might not be appropriate for a more traditional design. Also I think that some self bailers leak when closed, mine has a rubber seal and is watertight as long as the seal is replaced every few years.

I think my choice for a boat like yours would be to thicken the hull with a small piece of wood on the outside, this being streamlined to make it less conspicuous and avoid extra turbulence - but its your boat, and a very nice boat too.

John  

[momist]

Hi David,

I'm in the lucky position that my boat is small enough for me to stand it on end (or balance on it's side) to empty out any water collected, and I store it either lashed to a wall (stood on the transom), or upside down on a beach or grass.  I don't therefore have a bung, but carry a sponge.  I've lost a number of sponges during a capsize though, even though I keep a big one that is a tight squash into the bailer tied into the boat.  The trouble with having one tied on is that this is yet another bit of string to get tied in knots or tangled round your feet during capsize or recovery.  I'd rather lose the sponge to be honest.

Ian

[Port-Na-Storm]

Hi David.
I've used plastic bungs on both my Whilly Tern and on The Coot. On the coot I fitted a plywood doubler on the outside to thicken up the ply round the bung. The bungs are just forward of the transom either side of the keelson.  The Plans didn't show bungs so I just followed what the d esigner had done on his own boat. Andrews boat is about 20 years old and I've never seen this type of bung anywhere. Its probably out of production.
  

The downside is the boat won't self drain-unless it is tipped up at the bow. but it does drain on the slipway.

For a boat as smart and well built as yours I'd consider trying these, Classic Marine Posh Bungs. I think they'd be worth the investment.

cheers Graham.

[Chris Waite]

I agree with John

And it is one of the things I ought to be adding to Polly Wee, though she is kept inside at present.  There are so many ways water can get onboard from 'shipping it green', to being swamped in the surf of a lee shore, to rain through a leaking cover.  Not being able to drain the last spongeful is a mere trifle, by comparsion with trying to drag a hundred extra kilos of surging briny out of the breakers, or finding your pride and joy half full, topped off with an inch of ice in the boat park.

I think your boat has a watertight stern locker/buoyancy tank, but a bung through the base of the transom is another way to go, even if you have to have a skin fitting through the bulkhead and some hose taking that to the bung in the transom fitting itself.  Then the boat can be left propped with the bow up - the way dinghies used to be before they were all double skinned plastic.  Other options include through the hog, or even into the side of the centreboard case.  Just be sure to put the thing in before taking off - this can be difficult to remember if it is hidden by a floor board for instance.

I have told this story before, but I forgot once when taking off from a beach and as the cat happened to be wandering around taking an unnecessary interest as usual, and had never been to sea before, I popped her in the boat as I slid it into the water.  The cat remained quite apprehensive, but everything was just about alright for a few minutes, until I realized that we were filling up.  The cat got the Titanic message at the same moment and within seconds I was trying to steer, lift a floorboard and screw in a reluctant bung, all with a frantic cat trying to scale my face


 
A pad faired in on the outside of the hull, holding back that spongeful inside is up to individual choice.

Chris W

[David Bewick]

Hi Guys,

Many thanks for your comments and pics.  I think something "brassy" probably is what is required on my boat and I have found a few examples online.  For some reason, though, it is one of those things that I really feel the need to have in my hand before I commit to buying it.  I will have another look around some of the local chandlers and see if I can find something that could be machined down to match the ply thickness.  The problem will then become one of how to fix it!  Incidentally, I wonder how these things actually seal - some of them mention a leather washer and some don't.

I was certainly thinking of having the screw on the inside.

Thanks again and best regards,

David.

Note to self - never take a cat on a boat!