Weed Hatch

[marmaduke]

I've found the cause of my wet bilge, a non existent seal on the weed hatch plate. I'm going to scrape the rust off it and the hatch, then vactan the surfaces.

 

I was wondering if there were was a particular paint I should use on this area? Can I just leave it vactan'd but unpainted?

 

Also, any tips on how to make the best seal with the tape?

[churchward]

I have mine painted with boat blacking and it gets refreshed whenever the boat is re-blacked.

[RLWP]

<snip>

 

Also, any tips on how to make the best seal with the tape?

 

There are two schools of thought on this.

 

One is that the joint should be made diagonally at each corner, giving the longest potential leak path and so the better joint.

 

I'm a lazy git, so I butt jointed mine in the corners as I didn't fancy making the 45 degree cuts. I can confirm both methods work fine

 

Richard

 

Oh yes, black the weedhatch like you black the hull

Edited July 15, 2010 by RLWP

[ditchcrawler]

There are two schools of thought on this.

 

One is that the joint should be made diagonally at each corner, giving the longest potential leak path and so the better joint.

 

I'm a lazy git, so I butt jointed mine in the corners as I didn't fancy making the 45 degree cuts. I can confirm both methods work fine

 

Richard

 

Oh yes, black the weedhatch like you black the hull

I go one step further and put a step in the miter, I also use blacking. Another important point is to always make sure the top of the hatch is clean before refitting the lid. I find that just a blade of grass across the joint will let it leak.

[RLWP]

I go one step further and put a step in the miter, I also use blacking. Another important point is to always make sure the top of the hatch is clean before refitting the lid. I find that just a blade of grass across the joint will let it leak.

 

Are you using the 1/4" thick rubber foam that most chandlers stock? I find that stuff distorts nicely so I don't get any problems sealing .

 

What clamping arrangement do you have?

 

Richard

[ditchcrawler]

Are you using the 1/4" thick rubber foam that most chandlers stock? I find that stuff distorts nicely so I don't get any problems sealing .

 

What clamping arrangement do you have?

 

Richard

Yes that's it, change it every couple of years when it starts to leak. The clamp is a loop each side of the hatch and a bar across the top with a single jacking screw in the centre, If it had a clamp on each corner it would probably seal easier, bit provided I am careful replacing the lid its OK

[RLWP]

Yes that's it, change it every couple of years when it starts to leak. The clamp is a loop each side of the hatch and a bar across the top with a single jacking screw in the centre, If it had a clamp on each corner it would probably seal easier, bit provided I am careful replacing the lid its OK

 

Apart from how frequently you replace the seal, that's exactly the same as us.

 

Perhaps I'm more enthusiastic screwing the clamp down.

 

Richard

[soldthehouse]

I go one step further and put a step in the miter, I also use blacking. Another important point is to always make sure the top of the hatch is clean before refitting the lid. I find that just a blade of grass across the joint will let it leak.

Does your setup have the two plate set up, ie a lower plate next to the bottom opening in the hull?

[RLWP]

Does your setup have the two plate set up, ie a lower plate next to the bottom opening in the hull?

 

You didn't ask me, but ours does

 

Richard

 

Why?

[ditchcrawler]

Does your setup have the two plate set up, ie a lower plate next to the bottom opening in the hull?

Yes

 

Apart from how frequently you replace the seal, that's exactly the same as us.

 

Perhaps I'm more enthusiastic screwing the clamp down.

 

Richard

Always a bit bothered about distortion and making things worse

[soldthehouse]

You didn't ask me, but ours does

 

Richard

 

Why?

No favouritism honest ! I have no experience but would hav thought the bottom plate would reduce washup alot. i obviously dont have a grasp of the activity level inside the weedhatch. I have while mulling over the making of mine that there must be an optimum gap around the lower plate to restrict water entering the weedhatch void and allowing any that does enter to flow back out, thus preventing a cumulative buildup inside the hatch. What are the recognised physics and is a plate higher up ie a few inches below the top plate not better

[RLWP]

No favouritism honest ! I have no experience but would hav thought the bottom plate would reduce washup alot. i obviously dont have a grasp of the activity level inside the weedhatch. I have while mulling over the making of mine that there must be an optimum gap around the lower plate to restrict water entering the weedhatch void and allowing any that does enter to flow back out, thus preventing a cumulative buildup inside the hatch. What are the recognised physics and is a plate higher up ie a few inches below the top plate not better

 

That's a lot of fuss!

 

Ours is a rattling good fit in the bottom with probably a 3/8" clearance all around. In use water entering the space above the plate drives out trapped air (you get a sucking sound when you take the hatch off as the air rushes in). The bottom plate is level with the bottom of the hull.

 

This is a narrowboat you know, not a supersonic jet fighter

 

Richard

[nb Innisfree]

Yes

 

 

Always a bit bothered about distortion and making things worse

 

I cut a square of bottom plate and stuck it with blacking on to the top of the lid, this ensures there is no distortion of lid when it is screwed down.

[soldthehouse]

That's a lot of fuss!

 

Ours is a rattling good fit in the bottom with probably a 3/8" clearance all around. In use water entering the space above the plate drives out trapped air (you get a sucking sound when you take the hatch off as the air rushes in). The bottom plate is level with the bottom of the hull.

 

This is a narrowboat you know, not a supersonic jet fighter

 

Richard

Yet again I dont follow

[RLWP]

Yet again I dont follow

 

Cut a piece of 1/4" plate nearly as big as the hole in the bottom of the weedhatch. Weld it to a couple of bits of 1" square tube attached to the weedhatch lid so it ends up flush with the bottom of the hull. Move on and weld something else.

 

Richard

 

For a more complete solution you will have to engage me as a consulting engineer and fund the computational fluid dynamics software needed to make a full prediction of whatever it is you are worrying about

Edited July 15, 2010 by RLWP

[Mac of Cygnet]

Am I the only one with a round weed hatch? (and a bit cut out of an old conveyor belt for a seal?)

 

Mac

[soldthehouse]

Cut a piece of 1/4" plate nearly as big as the hole in the bottom of the weedhatch. Weld it to a couple of bits of 1" square tube attached to the weedhatch lid so it ends up flush with the bottom of the hull. Move on and weld something else.

 

Richard

 

For a more complete solution you will have to engage me as a consulting engineer and fund the computational fluid dynamics software needed to make a full prediction of whatever it is you are worrying about

Thats what I was going to do I like to keep things simple unlike many on here And when I'm finished it wont leak and I wont get into endless conversations on how to seal it

Edited July 15, 2010 by soldthehouse

[WotEver]

Am I the only one with a round weed hatch?

Yes.

 

Move along now please. Nothing to see here.

 

Tony

[soldthehouse]

Yes.

 

Move along now please. Nothing to see here.

 

Tony

[RLWP]

<snip>

I have while mulling over the making of mine that there must be an optimum gap around the lower plate to restrict water entering the weedhatch void and allowing any that does enter to flow back out, thus preventing a cumulative buildup inside the hatch. What are the recognised physics and is a plate higher up ie a few inches below the top plate not better

 

 

Thats what I was going to do I like to keep things simple unlike many on here

 

<snip>

 

If you like to keep things simple, what was all that bollox on cumulative buildups about then?

 

Richard

[soldthehouse]

If you like to keep things simple, what was all that bollox on cumulative buildups about then?

 

Richard

Just in the spirit of the forum, its what people seem to like on here overcomplication of the most simple things.

Edited July 15, 2010 by soldthehouse

[WotEver]

Just in the spirit of the forum, its what people seem to like on here overcomlication of the most simple things.

Some of them even think that pump-out toilets are a good thing...

 

Now where's that spoon...

 

Tony

[soldthehouse]

Some of them even think that pump-out toilets are a good thing...

 

Now where's that spoon...

 

Tony

Spoon?, I hadnt budgeted for a spoon? what next

[ditchcrawler]

That's a lot of fuss!

 

Ours is a rattling good fit in the bottom with probably a 3/8" clearance all around. In use water entering the space above the plate drives out trapped air (you get a sucking sound when you take the hatch off as the air rushes in). The bottom plate is level with the bottom of the hull.

 

 

 

Richard

Or a great big solid block of Duckweed

 

 

I cut a square of bottom plate and stuck it with blacking on to the top of the lid, this ensures there is no distortion of lid when it is screwed down.

Good idea

[PhilR]

Are you using the 1/4" thick rubber foam that most chandlers stock? I find that stuff distorts nicely so I don't get any problems sealing .

 

What clamping arrangement do you have?

 

Richard

 

My weedhatch is underneath the rear deck and can only be removed by tilting it forward. I found that rubber foam stuck to the rim of the top of the *box* soon became dislodged. The answer which works for me is a piece of solid ¼ ins rubber mat cut to the overall size of the hatch with just enough of the centre cut out so it can be stretched over the bottom plate of the hatch and then fits snugly to the underside of the hatch. This arrangement is sturdy and the seal has no joints and requires no adhesives.