Saturday, 1 October 2016

The Weed Hatch

I suspect there is a slight design defect with our weed hatch.  On several occasions the locking mechanism has failed, unlocking the cover over the Uxter plate.

As you can see in the photo below, the plate is held in place by a ‘U’ shaped crossbar and a long threaded shaft.  The crossbar fits under a short piece of angle iron at either end.  The threaded shaft then pushes the crossbar up against the underside of the angle iron whilst the bottom plate is pressed down over the hole in the uxter plate.

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The problem is the crossbar connection is based upon steel on steel pressure which is slippery.  Moreover the ends of the crossbar have become slimy which further compounds the problem.

It is possible for the crossbar to rotate out from under the angle iron as they have one open side.    A better design would be for the angle iron to be replaced with ‘U’ shaped supports.  This would mean the ends of the crossbar would fit inside an inverted ‘U’ preventing the crossbar from rotating.

I don’t have any welding equipment so my modification involves reducing the lack of friction caused by the steel on steel contact.  For the last four years we have been carrying around a small piece of panel decking left over from the fit out.  My only saw is a bowsaw that I purchased on special in Aldi.  It’s far from ideal, but with a little care I’ve been able to cut two small blocks of wood which will go at either end of the crossbar

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They will be held by Sikaflex adhesive.  If that doesn’t work then I will use stainless steel wood screws.

The ends of the crossbar needed to be cleaned back to bare metal to ensure the adhesive has a good bond.  When doing this I noticed the ends were very slimy.  That wouldn’t have helped with the steel to steel join.

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I was able to extract the last of the Sikaflex from the tube we used to fit the glass splashbacks in the galley.  I don’t have any clamps on the boat so I used duct tape to hold the timber in place whilst the adhesive sets

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Once the adhesive had set I cleaned the crossbar and gave it a coat of paint.

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Hopefully the timber to steel contact surface will provide more friction and go some way to eliminating the current problem.

7 comments :

Don McCoskrie said...

Why not drill the fixed plate and through the arm then tap a short bolt through either part to form a pin that will engage the other when the plate is wound shut. The other thing that may help is a piece of rubber between the steel faces so that they will bed in when the screw is tightened.

Andy Healey said...

Our crossbar sits in 2 hoops of metal to stop rotation when tightening or under vibration, much better solution then the 2 angles on yours. Thought most narrowboats where similar in this area, your troublesome builder was different I expect!

Tom and Jan said...

Don I must confess I hadn't considered a two bolt solution. I'll remember it should the wooden blocks not work.

Tom and Jan said...

Andy That is the design I would have preferred.

Alf said...

To make it easier to remove the locking bar, a slight variation on the bolt method above, just get two carabiners or something similar to prevent the locking bar rotating.

Adam said...

Ours has never rooted off. I just make sure it's done up tightly -- by whacking the screw bit with the lump hammer when I put the weed hatch back on.

Tom and Jan said...

Adam I remember you telling me that on a previous occasion and I have been giving it a whack with the club hammer.