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Weed hatch drainage


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Good morning everyone ?

 

I have recently fitted a access lid above the weed hatch, put in a gutter and drain pipes into the weed hatch.

Will I need to put a tap inline to stop back wash coming back up the pipe when cruising or is it too high to have an effect?

 

Looking forward to your views again thanks for your guidance.

 

Kind regards Tim

IMG_20190722_101753.jpg

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What have you made to hold the weed hatch tightly in position?

 

Are those pipes long enough to allow you to remove the weed hatch fully when you need to get your hand inside to remove the rubbish wrapped around the propeller? 

 

Nice tidy job though.

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4 minutes ago, Kendorr said:

What have you made to hold the weed hatch tightly in position?

 

Are those pipes long enough to allow you to remove the weed hatch fully when you need to get your hand inside to remove the rubbish wrapped around the propeller? 

 

Nice tidy job though.

There is a clamp to hold the plate down picture is work in progress ?

6 minutes ago, Kendorr said:

What have you made to hold the weed hatch tightly in position?

 

Are those pipes long enough to allow you to remove the weed hatch fully when you need to get your hand inside to remove the rubbish wrapped around the propeller? 

 

Nice tidy job though.

Yes the pipework is long enough for it to lift out of the way ?

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5 minutes ago, Sea Dog said:

Whenever I take my weed hatch off in anger, there's quite a vacuum to overcome. I suspect you may have introduced an undesirable source of air to ventilate your prop. The drainage might be better through a skin fitting.

I did consider putting them out a skin fitting but decided this way as having moving pipework would gradually loosen the skin fitting and could cause problems.

It's simple enough for me to fit a small tap into the line and just close it off when cruising.

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I  think you going to have difficulty removing it especially if you have a cavitation plate fitted, also those small bore pipes are going to get quickly blocked by muck. It would be better to drain directly through the sides using larger bore pipes and skin fittings. If you fit taps then it won't drain if you're cruising and it rains.

Edited by Flyboy
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3 minutes ago, Flyboy said:

I  think you going to have difficulty removing it especially if you have a cavitation plate fitted, also those small bore pipes are going to get quickly blocked by muck. It would be better to drain directly through the sides using larger bore pipes and skin fittings.

It has a cavitation plate trust me it's easy enough to lift out ? tried and tested that bit.

As for blockage yea it might do that has yet to be put to the test.

Worsted case would be to weld the hole in the cover up and as you say stick it out the side. ?

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Neat job.

 

I don't think you need a tap to stop backflow up the pipes .  The cavitation plate should do that,   just make sure it is a good fit and tight down against the counter plate.    The small diameter of the pipes will also help.

 

A small amount of backflow might actually help with the problem of getting the muck out of the pipes, which are far too small.    All the boot debris, grass, mud etc that you get on the back deck during a wet day's cruising will be washed into the upper weed hatch surround and then into your flexible pipes. 

 

As pictured,  both pipes have a 'sump' section where the water will settle and that is where the first blockage will occur.  The port side pipe has the biggest loop and will be worst affected.

 

I suiggest you put a triangle of plate, with upstand,  across each of the back corners and then weld in at least a 1/2 in pipe, better 1 in (so you can rod it,  paint inside it etc.) direct to overboard.

 

N

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1 hour ago, Sea Dog said:

Whenever I take my weed hatch off in anger, there's quite a vacuum to overcome. I suspect you may have introduced an undesirable source of air to ventilate your prop. The drainage might be better through a skin fitting.

I fully agree with that

My gutter has 2 stubs of pipe welded under it for drainage, then spiral wrap plastic hose to 2 skin fittings , one each side of the hull. I sometimes rod them out with a wire drain cleaning thingy.

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On 29/08/2019 at 09:37, ditchcrawler said:

I fully agree with that

My gutter has 2 stubs of pipe welded under it for drainage, then spiral wrap plastic hose to 2 skin fittings , one each side of the hull. I sometimes rod them out with a wire drain cleaning thingy.

I find one of these to be very useful (think somebody on here suggested them)

https://www.amazon.co.uk/Micro-Trombone-Snake-Brush/dp/B00TE7Z442/ref=asc_df_B00TE7Z442/?tag=googshopuk-21&linkCode=df0&hvadid=256111375122&hvpos=1o4&hvnetw=g&hvrand=7584216267808084487&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046457&hvtargid=pla-771328531367&psc=1

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It's an interesting way of doing it but those pipes are way too small and it's complicating the removal of the weed hatch cover.

 

I've seen drainage pipes in this situation that go straight down to the uxter plate, but it always seems to me that's creating a corrosion trap.  Larger bore pipes to a skin fitting above the water line is how to do it. 

  • Greenie 1
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I agree those pipes are two small. Mine is almost an inch ID and gets blocked, though it does run at a very gentle slop to the side of the boat.

 

An additional issue is that with very heavy rain, or more likely a leaky lock, the water will get into the drainage channel quicker than it can drain down those pipe so will find its way into the boat. You lid is a very neat fit so you might just get away with it (till the pipes block).

Finally, how are you going to secure your lid? It currently looks like a novel access for inventive and agile burglars.

 

..............Dave

  • Greenie 1
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14 minutes ago, dmr said:

I agree those pipes are two small. Mine is almost an inch ID and gets blocked, though it does run at a very gentle slop to the side of the boat.

 

An additional issue is that with very heavy rain, or more likely a leaky lock, the water will get into the drainage channel quicker than it can drain down those pipe so will find its way into the boat. You lid is a very neat fit so you might just get away with it (till the pipes block).

Finally, how are you going to secure your lid? It currently looks like a novel access for inventive and agile burglars.

 

..............Dave

For ease of explaining the only image I have with the clamp in place.

IMG_20190831_211547.jpg

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My neighbour cut out a similar weed hatch access hatch on his trad stern, but he didn't bother with a gutter or drainage pipes. He just made a cover from 6mm aluminium plate and bolted it down onto the deck with some of that self adhesive neoprene tape between. The downside is that he needs to remove about 8 bolts to get to his weed hatch.

 

I'm not sure why some of these trads aren't built properly in the first place?

Edited by blackrose
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5 hours ago, blackrose said:

 

 

I'm not sure why some of these trads aren't built properly in the first place?

The deck hatch can be of limited utility.   In many boats, the distance from the stern deck to the base of the weed hatch proper is such that unless you have really long arms it is very hard to reach the prop shaft, let alone the bottom blade.   That means either getting on the counter and diving the weed hatch that way, or poking around with a shaft or, even worse, Bargee Bill's Prop scratcher.  In that event you are better off having a rake out from the bank in a bridgehole or a (full) lock.  The OP's hatch really only makes it a bit easier to get the real weed hatch lid off.

 

The trunk version, where the weed hatch tube extends to the stern deck, is  better only if the builder has flared the hole so it is as big as possible at the top, but it still tends to be a head and shoulders down the tube job to reach anything.

 

N.

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On 31/08/2019 at 20:42, Neil2 said:

It's an interesting way of doing it but those pipes are way too small and it's complicating the removal of the weed hatch cover.

 

I've seen drainage pipes in this situation that go straight down to the uxter plate, but it always seems to me that's creating a corrosion trap.  Larger bore pipes to a skin fitting above the water line is how to do it. 

Our share boat was like that, two upstands of box section with the supporting deck gutter on top. It was a GT hull and the boat was called "Waterwitch"

On 31/08/2019 at 21:01, dmr said:

I agree those pipes are two small. Mine is almost an inch ID and gets blocked, though it does run at a very gentle slop to the side of the boat.

 

An additional issue is that with very heavy rain, or more likely a leaky lock, the water will get into the drainage channel quicker than it can drain down those pipe so will find its way into the boat. You lid is a very neat fit so you might just get away with it (till the pipes block).

Finally, how are you going to secure your lid? It currently looks like a novel access for inventive and agile burglars.

 

..............Dave

Like going down the Wigan flight

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8 hours ago, BEngo said:

 

 

The trunk version, where the weed hatch tube extends to the stern deck, is  better only if the builder has flared the hole so it is as big as possible at the top, but it still tends to be a head and shoulders down the tube job to reach anything.

 

N.

 

Yes, well having the builder do the job sounds like a better option than having to cut your own hatch in the stern deck!

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