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Well deck scupper size?


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For those with bow well decks, how big are your scuppers, and does it follow that a larger widebeam deck should have larger scuppers because the area required to drain is bigger?

 

Mine were the size of half a melon (honeydew, not watermelon) and looking at some other boats this winter with much smaller scuppers, I decided they were way too big so I've reduced them to about the size of a lemon. I'm not sure why all the fruit comparisons but there you go.

 

On tidal rivers it's possible that water could come in through the scuppers if hit by a wave but that wasn't really my concern. I think I reduced the size as I just didn't like the look of those big holes knowing that the bottom lip of my bow doors is only 4" above the deck. My deck is quite low - about 5 or 6" above the waterline depending on how full the water tank is. 

 

But have I reduced the size of the scuppers too far? After I'd finished the job I got thinking that if I was in some big waves on an estuary and waves were coming over the bow, the water might not be able to escape fast enough through the new reduced size holes. Likewise if someone opened a gate paddle above my bow deck. But in that case I suppose no scupper hole is going to cope with that amount of water...

 

To be honest I've never really liked the self-draining bow well deck design and I'd much prefer an enclosed bow, but it is what it is. I could get a canopy made I suppose.

 

Anyway, smaller or bigger scuppers, what's your view? 

Edited by blackrose
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A bigger risk is a flow over the top of the top gates of a lock as you are heading up. No paddle to close and if your boat is a similar length to the lock, no chance of escape. Could be on a river in flood, on the Rochdale 9 through Manchester anytime, or someone coming down the flight above you overtopping the pound as they empty their lock.

If water is coming in from the sides, with a bit of swell on a river, then the flow rate that comes in is probably going to equal the flow rate going out when the peak passes. With water coming from above, the bigger the better, within reason to reduce the risk of the well deck being overwhelmed.

Jen

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1 minute ago, Jen-in-Wellies said:

A bigger risk is a flow over the top of the top gates of a lock as you are heading up. No paddle to close and if your boat is a similar length to the lock, no chance of escape. Could be on a river in flood, on the Rochdale 9 through Manchester anytime, or someone coming down the flight above you overtopping the pound as they empty their lock.

If water is coming in from the sides, with a bit of swell on a river, then the flow rate that comes in is probably going to equal the flow rate going out when the peak passes. With water coming from above, the bigger the better, within reason to reduce the risk of the well deck being overwhelmed.

Jen

Or even the most dangerous locks in the country , the Bingley 5 rise . I saw it on video

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If you are seriously concerned about waves coming over the bow you could always add a bulkhead as John Liley showed on Arthur, and to prevent waves coming in via the scuppers you could tack a simple flap onto the outside to act as a non-return valve. A bit OTT probably, but it does depend on where you expect to be boating now.

 

Tam

 

 

 

343003213_ScreenShot2021-03-11at21_57_23.png.598d6ff2159c92b33df9524516009dd9.png

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26 minutes ago, Jen-in-Wellies said:

A bigger risk is a flow over the top of the top gates of a lock as you are heading up. No paddle to close and if your boat is a similar length to the lock, no chance of escape. Could be on a river in flood, on the Rochdale 9 through Manchester anytime, or someone coming down the flight above you overtopping the pound as they empty their lock.

If water is coming in from the sides, with a bit of swell on a river, then the flow rate that comes in is probably going to equal the flow rate going out when the peak passes. With water coming from above, the bigger the better, within reason to reduce the risk of the well deck being overwhelmed.

Jen

 

Yes flooding in locks is a risk, but with a 57ft boat my approach has always been that there's no need for the boat to be anywhere near either set of gates. As I said in my original post, if the bow well deck is flooded going uphill in a lock then it's unlikely that scupper holes of any size will cope with that amount of water.

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Just now, blackrose said:

 

Yes flooding in locks is a risk, but with a 57ft boat my approach has always been that there's no need for the boat to be anywhere near either set of gates. As I said in my original post, if the bow well deck is flooded going uphill in a lock then it's unlikely that scupper holes of any size will cope with that amount of water.

Depends if you come up north at any point. A 57' Calder and Hebble lock won't leave you anywhere to go!

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22 minutes ago, Tam & Di said:

If you are seriously concerned about waves coming over the bow you could always add a bulkhead as John Liley showed on Arthur, and to prevent waves coming in via the scuppers you could tack a simple flap onto the outside to act as a non-return valve. A bit OTT probably, but it does depend on where you expect to be boating now.

 

Tam

 

 

I wouldn't say I'm seriously concerned about either scenario, just wondered what size other people's bow well deck scuppers are.

 

 

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You could always just chuck a few buckets of water into the well and see how quickly the water runs away - that should give some sort of intuitive feeling about the effectiveness of them.

 

Tam

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8 minutes ago, Tam & Di said:

You could always just chuck a few buckets of water into the well and see how quickly the water runs away - that should give some sort of intuitive feeling about the effectiveness of them.

 

Tam

 

Yes, that's probably a good idea. I'm just painting the reduced size scuppers now between rain showers, but I'll test them once I've got the top coats on and the paint is dry.

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7 minutes ago, ditchcrawler said:

Could they handle this?

 

No, could yours?

 

As I've already said a couple of times. If you put your bow directly under badly leaking lock gates or someone opens a gate paddle above your bow then no normal size scuppers are going to be able to cope with it. You'd need scuppers the size of footballs.

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If you mke the apperture the right width and shape for a foot/toe hold, you have the possiblity of MOB self-recovery into the front well-deck.

just a thought.

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Posted (edited)

Have you ever tried getting back into your boat when your first foothold is above the waterline? I used to swim in the river and I've tried and it doesn't work. I've got pretty good upper body strength but you need your first foothold to be well below the waterline.

Edited by blackrose
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29 minutes ago, Grebe said:

If you mke the apperture the right width and shape for a foot/toe hold, you have the possiblity of MOB self-recovery into the front well-deck.

just a thought.

I think if you could do that you could get a job as a contortionist in the Cirque du Soleil.

 

Tam

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Presumably you have an opening either side at the lowest corner, how about  similar sized openings at the highest corner as a just in case measure. Small openings can block with dead leaves and gubbins and probably won't sink the boat but water is supposed to be on the outside if at all possible.

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If possible a plate that clamps over outside of doors would be a final defence from flooded well deck, only needs to be up to level of side deck, just use it in dodgy locks or rough open water. I planned to do it on Innisfree until we sold her, we had barn type front doors which would have allowed top doors to remain open but it would be a good insurance in any case. 

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Working narrowboats used to have something like that that clamped across the bottom of the engine-hole doors when they traded onto the Thames.

 

Tam

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17 hours ago, blackrose said:

That's quite small. I think mine are still roughly double the size of yours now. 

 

Yebbut your boat is nearly twice as wide as mine, so thr well deck can hold  ore water! ?

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  • 4 weeks later...

I've just had plastic scuppers fitted on either side of the the bow well deck on my 54' x 11' river barge. The steel tube protecting the scuppers, which have flap valves, is about 12cm in diameter, and the internal diameter of the plastic scuppers is 4cm. Although the photo doesn't make it clear, beneath the scupper, but still within the steel ring, is a horizontal slot, about 4 x 1 cm, at the floor level of the well deck which allows any rainwater to drain away.

 

The point of the scuppers valves is to prevent flooding in the event of, say, a serious wave breaking over the bows. Better safe than sorry!

 

(A very nice bit of welding by Matt at Stoke Boats, Longport).

20210413_165115 copy.jpg

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One point that was overlooked on our boat was to remember that the boat usually sits in the water tilted towards the back.  Because the holes were to the front of the space, it doesn't drain very well.  To answer the original question, the holes are 1 1/2" square.

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Big enough to let a handfull of soggy leaves get through, semi circular with the flat bottom flush with the deck and as big as possible 

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