Weedhatch Gasket Seals

[Byeckerslike]

How did this happen? My partner was concerned about our weedhatch possibly leaking – it was dryazabone!

 

I released the weedhatch and examined the gasket – it was a mean miserable thin bit of rubber foam, about 1mm thick, but did not leak – I was owed a favour, so I contacted one of my pressure leak test suppliers and got a custom piece of leak test rubber seal material cut to the required dimensions 485 x 280 x 6 mm thick, cut from one piece of sheet - no joins what so-ever!

 

I removed the old seal, sanded down the mating surface, wiped clean and dry, and glued the new one in place. Refitted the hatch, fired up the engine, engaged forward, and revved up, good! No leaks so far, engaged reverse, revved up only to find water being sprayed over onto the upper surfaces of the swim and pouring down into pristine, dry bilge!

 

I had to crawl back to our marina, moor up without using reverse at all costs! and spend an hour mopping out the grand union from the back of the boat!.

 

Either the rubber is of too hard a shure hardness, the wrong type of rubber (Solid Polypropylene – 80 Shure Hardness) or, I am doing something wrong?

Edited October 21, 2007 by Byeckerslike

[John Orentas]

I would say that if you are going to use 'solid' rubber it needs to be quite thick, 10 or 12mm.

 

I have always managed to find a source of industrial type foam rubber sheet, 8 - 10mm is ideal.

 

Better to stick it to the hatch cover rather than the hatch itself, less likely to get damaged, I have aways found sticking it with bitumastic paint works OK.

[charles123]

weed hatch rubber 2 inches quarter inch for 15 metres (not sure what you do with the spare 14 metres though) from Midland Chandlers £18

[magnetman]

Its possible if its the wrong way round it might leak. (edite)

Edited October 21, 2007 by magnetman

[blackrose]

What are you using to glue it on? A PU adhesive/sealant is probably best.

[wonderdust]

All that is on ours is a couple of layers of of a white polystyrene foam. Looks like the stuff used for wrapping parcels in, not the hard type, must be no more than an 1/8" thick. Sounds like its the wrong stuff to use, its been there at least two yrs (when bought boat) so i suppose it is a case of "if its not broke"!

[blackrose]

All that is on ours is a couple of layers of of a white polystyrene foam. Looks like the stuff used for wrapping parcels in, not the hard type, must be no more than an 1/8" thick. Sounds like its the wrong stuff to use, its been there at least two yrs (when bought boat) so i suppose it is a case of "if its not broke"!

 

It does sound a bit odd, but if it's working ok...

 

Neoprene strips stuck on with PU sealant is good as it compresses better than rubber.

[Maverick]

I beleive the bottom plate of the weedhatch that goes down into the water is designed to fit flush with the underside of the boat. By putting a much thicker gasket under the top it would therefore be lifting the weedhatch up and possibly leaving a void underneath.

 

Hence when putting into reverse the water could possibly be being forced up the sides of the bottom plate which would mean the top gasket is under more pressure to do its job than normal.

 

Fact or Technical Bo****** you decide

[John Orentas]

I beleive the bottom plate of the weedhatch that goes down into the water is designed to fit flush with the underside of the boat. By putting a much thicker gasket under the top it would therefore be lifting the weedhatch up and possibly leaving a void underneath.

 

 

They are normally called cavitation plates and are there to reduce the turbulence there would otherwise be in that area, I recommend a thicker gasket simply on the grounds that one twice as thick will if required compress twice as much and give a better seal.

 

As with most things on narrowboats precise measurements are not so vital, the odd 1/2" here and there really will not make a perceptible difference. What is vial is keeping the water out, never seen it but people have told me that revving an engine when in gear with no weed-hatch fitted would fill a 50 gallon drum in a very few seconds.

 

No proof of course but I believe that out of those boat sinking "Because the weed hatch leaked", 99% of them were as a result of someone not refitting the hatch or doing it incorrectly.

[Alastair]

Check that you've tightened up the bolts evenly.

[Byeckerslike]

Check that you've tightened up the bolts evenly.

There is only one centre fixing, this is a quick release hatch, the bolt looks about 3/4" Acme thread. I've tried fitting the Hatch Cover / Cavitation Plate Assemly both ways round - and it always leaks in the same area.

I beleive the bottom plate of the weedhatch that goes down into the water is designed to fit flush with the underside of the boat. By putting a much thicker gasket under the top it would therefore be lifting the weedhatch up and possibly leaving a void underneath.Hence when putting into reverse the water could possibly be being forced up the sides of the bottom plate which would mean the top gasket is under more pressure to do its job than normal.Fact or Technical Bo****** you decide

I beleive the bottom plate of the weedhatch that goes down into the water is designed to fit flush with the underside of the boat. By putting a much thicker gasket under the top it would therefore be lifting the weedhatch up and possibly leaving a void underneath.Hence when putting into reverse the water could possibly be being forced up the sides of the bottom plate which would mean the top gasket is under more pressure to do its job than normal.Fact or Technical Bo****** you decide

It sonds more than a plausible fact, I'll remove the gasket and try to determine how much clearance there is betwix the cavitation plate and the nether regions of the boat

[DHutch]

We're using stick on neoprene foam, inch wide, about 4mm thick, laid down the full lenght two sides, then cut slightly over side for short sides and stuck in.

- Works a treat. Not that the mess prevously didnt seal, but its was deffonatly very dodgy!

- Its nice and soft and i just tighten it up medium tight and its good. Thanks really all to yanamx.

 

Also, i stuck it on the underside of the cover, rather than the topface of the actually exposed face. I guess half of you are already doing that, but it was a bit of breakthough for me!

 

 

 

Daniel

[David Schweizer]

God there are some cheapskates around here. Proper self adhesive, Weedhatch rubber cost about £1.50 a metre from any decent Candlery, and most boats will need less than two metres, Why not just buy the proper stuff and do the job properly, rather than mess about with material which is designed for a different purpose?

[Byeckerslike]

God there are some cheapskates around here. Proper self adhesive, Weedhatch rubber cost about £1.50 a metre from any decent Candlery, and most boats will need less than two metres, Why not just buy the proper stuff and do the job properly, rather than mess about with material which is designed for a different purpose?

 

Wooo-Hooo!!! )

We went to midland Swindlers last week-end and purchased the afore-mentioned self-adhesive weed-hatch gasket.

I fully cleaned the mating surface of the upper mating surface of the weed-hatch and I applied one length to the long side, carefully butted up the two short sides against the first applied strip, trimmed back these two strips with a fresh sharp blade to the exact width of the seal and then carefully butted up the final length against the two short sides. I finally tidied up the two lengths (so that no gasket seal was visually evident, when viewed from above) and positioned the weed-hatch cover and secured with just one turn of the quick release handle – Totally water-proof! No leaks what so-ever!!!

Thanks to all who gave great, wise and invaluable advice!

 

Many thanks,

 

Rob

[John Orentas]

God there are some cheapskates around here. Proper self adhesive, Weedhatch rubber cost about £1.50 a metre from any decent Candlery, and most boats will need less than two metres, Why not just buy the proper stuff and do the job properly, rather than mess about with material which is designed for a different purpose?

 

 

I would turn your comment on it's head David, more likely it is the chandlers and even the builders that are the 'cheapskates', I don't think there is such a thing as 'Weed-hatch rubber' at some time someone called in a rep from a rubber stockist then they purchased what was thought to be adequate.

 

I go along with Byecerslike's first post, ideally the gasket should be cut out of a single sheet of rubber, though I would say go much thicker, it is possible to buy sandwich configuration 1/2" thick foam with rubber sheet both sides, I would say this would be the ideal but expensive.. I used what was lying around in the stores but it was heavy duty stuff and still going strong.

Edited November 5, 2007 by John Orentas

[David Schweizer]

I would turn your comment on it's head David, more likely it is the chandlers and even the builders that are the 'cheapskates', I don't think there is such a thing as 'Weed-hatch rubber' at some time someone called in a rep from a rubber stockist then they purchased what was thought to be adequate.

Well yes, Weedhatch Rubber is just closed cell foam rubber, however the advantages that this has over solid rubber sheet or strip is that it has a higher degree of "give" which will accomadate any irregularities in the two mating surfaces, whilst not permitting any air gaps.

 

As a matter of interest I did a search for some closed cell rubber strip, and the nearest thing I could find was not wide enough (at least for my boat) cost over £2 a metre and could not be bought in lengths less than 5 metres. could this be a first where the Chandlers are a more cost effective supplier.

Edited November 5, 2007 by David Schweizer

[Boot wharf man]

I to have tried to replace my weed hatch gasket with a solid sheet of rubber 10mm thick. Back when i tried this my boat did not have a cavitation plate, but was fine with the original gasket (just thought it would make a nicer job of it). This was one solid sheet of rubber with no joins and after a relaxed two hour cruise the bilges were ready to spill into the cabin. Swapped it for the chandlry supplied stuff and all was well.

 

As an aside the addition of the cavitation plate has made the boat much more responsive in reverse giving the boat a much shorter stopping distance. I would recommend one to any who lack one especially if the end of your swim is squared off as opposed to the usual point (springer trait) as it gives one less obstruction to the water flow.

[Yoda]

I'm going to experiment with bubble wrap.

[Maverick]

I'm going to experiment with bubble wrap.

 

 

Nah you'll just pop a gasket

[chris w]

I'm going to experiment with bubble wrap.

 

I don't think bubble wrap will make a good cavitation plate!!

[Yoda]

I don't think bubble wrap will make a good cavitation plate!!

 

No I guess your right, about as useful as Branston pickle icing.

 

I was thinking about gasket material.

[Chris-B]

"Proper" boats dont have weedhatches ..just a shaft n hook to clean the blade !!

ergo : no leaks !!

 

 

 

 

 

 

ok I'll get me coat on

[carlt]

"Proper" boats dont have weedhatches ..just a shaft n hook to clean the blade !!

ergo : no leaks !!

ok I'll get me coat on

Usk has (had?) a weedhatch.

[Chris-B]

Usk has (had?) a weedhatch.

 

 

As "original" build ??

[carlt]

I sincerely hope not!

 

No it was put in by Ken Keay when she was rebuilt.