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Drainage channel downpipes


Galilee

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When it rains my boat's engine bilge catches all the water. It's a cruiser stern.

 

The surveyor said "Rear deck channels found painted but containing detritus which should be removed. Pipework leading from the very rear back deck drainage channels to the hull side to both port and starboard, was missing. Ducted rainwater currently drained into the engine bay."

 

So I need to remedy that this weekend.

 

I'd like to get some downpipes bought to take to the boat, but I'm not sure what to buy as I'm away from the boat right now. What is traditionally used for these downpipes please? Is it just 1" hosepipe?

 

Any pictures of the arrangements on other member's boats would be very gratefully received.

 

Thanks, Stuart.

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Just now, Galilee said:

When it rains my boat's engine bilge catches all the water. It's a cruiser stern.

 

The surveyor said "Rear deck channels found painted but containing detritus which should be removed. Pipework leading from the very rear back deck drainage channels to the hull side to both port and starboard, was missing. Ducted rainwater currently drained into the engine bay."

 

So I need to remedy that this weekend.

 

I'd like to get some downpipes bought to take to the boat, but I'm not sure what to buy as I'm away from the boat right now. What is traditionally used for these downpipes please? Is it just 1" hosepipe?

 

Any pictures of the arrangements on other member's boats would be very gratefully received.

 

Thanks, Stuart.

There's no standard way of doing it, so other people's photos won't help you much.

 

I have seen everything from 2" pipes down to 1/4" pipes and a whole variety of channels leading out through a hole cut in the hull.  Yours obviously should have pipes, but unless you have closeup photos of your arrangement we can't even start to guess.

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2 minutes ago, Galilee said:

Okay thanks, I'll have a look this weekend and report back, with a view to fixing it the following weekend :)

 

Take plenty of photos and show us what it looks like.  It's possible the pipes were so small and prone to getting blocked that the previous owner deliberately removed them and relied on the bilge pump instead.  

 

 

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Just now, Galilee said:

Okay thanks, I'll have a look this weekend and report back, with a view to fixing it the following weekend :)

When I addressed this on WotEver I drilled two 1/2” holes (one each side) at the rearmost end of the channels. I then welded on a short length of steel tube below those holes. Then I pushed some 3/4” pipe over those stubs, leading to two new hull fittings. I did a poor job of welding the tubes because 1) I’m a poor welder and 2) access to the rear of the pipes was difficult. So the join twixt channel and stub pipe was sealed with Sikaflex. 


I still got rainwater in the bilge, but a lot less. 

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My boat has 40 to 50mm U channel steel to duct water to the sides from the channels around the deck boards. Semi trad stern, but still exposed to the rain. The channel is welded to the hull sides at each end. The ends of the deck board channels drop water in to this, then to the sides and in to the cut. As others have said, lots of ways of doing it. Access to the hull sides is probably the thing that is going to decide the method for you. At some point too much stuff in the way makes welding too difficult. A skin fitting in the hull side might be the way to go, with the biggest diameter hose you can get away with between there and the deck board drain channels. No welding and easy to drill the hull side opening with a hole saw. A big bore hose won't block so easily from leaves and crud and is easier to rod out if it does. It also won't be overwhelmed in a cloud burst. A straight run for the hose and a slight to moderate downhill, without getting the outlet too close to water level.

Jen

Edited by Jen-in-Wellies
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Here we go. The gutters have holes that drain into the L bends below the deck. I cleaned out the gutters and stuck a bucket under one of the L bends on Saturday night when it rained heavily. The bucket was full in the morning and the engine space relatively dry, so the gutters are working fine.

 

I've tried to measure the L bend outlet and it's about 1.25", so I figured to get 1.25" hose and jubilee clip it on and run it out to the hole in the hull, which seems smaller. I can get a reducer to take the hose through the hole in the hull. Although there is a thread on the L bend, I can't find anything like a tap connect of the right size, hence the jubilee clip idea.

 

What do you all think?

gutter 1.jpg

gutter 2.jpg

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13 minutes ago, Galilee said:

 

I've tried to measure the L bend outlet and it's about 1.25", so I figured to get 1.25" hose and jubilee clip it on and run it out to the hole in the hull, which seems smaller. I can get a reducer to take the hose through the hole in the hull. Although there is a thread on the L bend, I can't find anything like a tap connect of the right size, hence the jubilee clip idea.

 

That will probably be a 1" BSP connection.

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You can get a proper hose tail fitting to go on to the 90 degree bend under the channel. As @David Mack says, it is probably 1" BSP if you are measuring around 1.25" outside diameter at the thread. BSP thread sizes have no resemblance to their stated nominal size! You can get a 1" BSP to 1" hose tail fitting to make it a proper job. Almost certainly available cheaper somewhere. Use PTFE tape on the threads to make those waterproof. Stick the hose in boiling water for a few seconds to soften it up before pushing it on to the hose tail. Put a jubilee clip on too and it will be good for years to come.

Jen

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3 minutes ago, Galilee said:

Thanks, that would simplify matters, Presumably I could use one of these and then just use normal garden hose?

You could, but then you'd need another fitting from there to the garden hose. That is a fitting for quick connect/disconnect. It would cost more than the one I linked to with the second fitting added. Plus, garden hose is often less than 1" inside diameter and you want the bore for this to be as big as possible to prevent it blocking up with leaves and general crud. 1" hose is easily available.

 

Jen

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4 hours ago, Jen-in-Wellies said:

you want the bore for this to be as big as possible to prevent it blocking up with leaves and general crud

Absolutely this.

 

4 hours ago, Galilee said:

I can get a reducer to take the hose through the hole in the hull.

Can be a pest if you do this, as debris gets trapped where the reducer is.  You end up having to empty a couple of feet of hose worth of stagnant water, usually down your leg, before you can clear the blockage.

 

I'd say if you want to do a "proper" job of this enlarge the holes at the sides and put 1" BSP skin fittings in them, then run appropriately sized hose between the fittings at each side.  That's big enough to allow you to clear any blockage by shoving a bit of wire up the hose without disassembling anything.

 

You might get away with this with 3/4" skin fittings, but there will always be a ridge that can hold debris at the end of the hoses.

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53 minutes ago, TheBiscuits said:

Can be a pest if you do this, as debris gets trapped where the reducer is.  You end up having to empty a couple of feet of hose worth of stagnant water, usually down your leg, before you can clear the blockage.

 

I'd say if you want to do a "proper" job of this enlarge the holes at the sides and put 1" BSP skin fittings in them, then run appropriately sized hose between the fittings at each side.  That's big enough to allow you to clear any blockage by shoving a bit of wire up the hose without disassembling anything.

 

You might get away with this with 3/4" skin fittings, but there will always be a ridge that can hold debris at the end of the hoses.

There is this:

https://www.midlandchandlers.co.uk/products/skin-fitting-3-4-x-1-brass-ad-028

A 3/4 BSP skin fitting with a hose tail incorporated that will take a 1" ID hose straight off. I've got similar, though for smaller diameter hoses for the shower pump outlet and for the bilge pump outlet in my boat. One of these in the hull, a 1" BSP to 1" hose tail at the other end and a bit of 1" hose in between would be a neat, robust, cheap and simple solution I reckon.

 

For clearing blockages, I've found that bike brake, or gear cable outer works very well to rod them through.

 

Jen

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1 hour ago, Taslim said:

Galelee. I the lower 'photo in #7 there seems to be a cobweb covered hole on the RH side. Was this where the rigional flexyble pipe from the elbow passed through the hull?

Dunno, I only took ownership of the boat two weeks ago, but it looks a likely candidate, and that's where I'm going to aim to exit the pipe I'm adding.

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My boat has just been built, unfortunately I don't have many pics at home which show the system. The boat builder welded 30mm tube to the hole in the gutter and another 30mm piece of tube to the side, I bought flexible water pipe and joined the 2 pieces of pipe together. I used clear pipe so I'm able to see if anything gets stuck inside. Hope you can see that in the pics. If you haven't got any exit holes, drill some and fix a skin fitting to take the other end of the pipe.

 

 

20170117_052314A_001.jpg

P1020150_001.jpg

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6 hours ago, TheBiscuits said:

Absolutely this.

 

Can be a pest if you do this, as debris gets trapped where the reducer is.  You end up having to empty a couple of feet of hose worth of stagnant water, usually down your leg, before you can clear the blockage.

 

I'd say if you want to do a "proper" job of this enlarge the holes at the sides and put 1" BSP skin fittings in them, then run appropriately sized hose between the fittings at each side.  That's big enough to allow you to clear any blockage by shoving a bit of wire up the hose without disassembling anything.

 

You might get away with this with 3/4" skin fittings, but there will always be a ridge that can hold debris at the end of the hoses.

 

When my deck drains block, i rod them through with a length of the small bore flexible plastic hose intended for the condensate drain of a tumble dryer. No more wet legs as the blockage gets pushed out of the skin fitting.

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