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I am redoing all of the bilge pumps/hoses on Ra.
Currently, I have 3 thru-hulls, about 10” above the water line where the 2 electrics and the manual exit.
I thought it would be prudent to install a vented loop high in the transom, to eliminate the possibility of water siphoning in the even that the boat taking on water lowered the thru-hulls, bad following seas etc.
Here’s my problem, the larger (2000gph) electric pump uses 1 1/8” hose, and I can’t seem to find a vented loop in that size (or even close)
How would you-all recommend tackling this problem?
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Hi Aaron
There are 1-1/2″ vented loops for heads. There are also 1″ vented loops. My suggestion is to adapt the 1-1/8″ to 1-1/2 and use for the rest of the line. Your suggestion for the whole system is a really good one!
Bob
On Wed, Apr 16, 2008 at 8:20 PM, Aaron Lynch < ([email][/email])> wrote:
I am redoing all of the bilge pumps/hoses on Ra.
Currently, I have 3 thru-hulls, about 10″ above the water line where the 2 electrics and the manual exit.
I thought it would be prudent to install a vented loop high in the transom, to eliminate the possibility of water siphoning in the even that the boat taking on water lowered the thru-hulls, bad following seas etc.
Here’s my problem, the larger (2000gph) electric pump uses 1 1/8″ hose, and I can’t seem to find a vented loop in that size (or even close)
How would you-all recommend tackling this problem?
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Bob Fine
Fine Software LLC
Your data on the web your way. No kiddingPost generated from Pearson424 Forum using Mail2Forum
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Aaron
10″ sounds low. I’m pretty sure that mine exit much higher than that, but you have me thinking. I’m pretty sure that the transom is at least a foot above the water line, so the only way I think you could have one that low would for it to be mounted below the transom. I’m pretty sure mine are at least 2 feet above the water line and no more than 2 feet offcenter.I’ve observed that when under power, the stern wave climbs up the transom at least a foot or so as the boat approaches hull speed. If I had a through-hull that low on the transom, it would be under water. Having a pump exit below the water line not only invites flooding, but also restricts the capacity of the pump. This is not good.
If the through-hulls exit near the centerline of the boat and if they are up a couple of feet or so, they would only be submerged for a very short period of time if you got hit with a wave. I’ve run my bilge hoses up high in the locker in a loop. This isn’t vented and doesn’t need to be as long as the through-hull isn’t submerged for long periods of time. From your description, it sounds like yours are lower. All the 424’s are different, but it would be odd for Pearson to have done something so dangerous; maybe a PO screwed up.
I’ve seen vented loops that are made with stepped barbs on them. You cut the thing off at the hose size you need.
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Rich Carter
Original message
<.. snip>Post generated from Pearson424 Forum using Mail2Forum
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I seem to remember reading a bunch on this topic in some book once. Here
is what I recall…I assume your bilge lines run out the stern and not the sides of the
boat, as they should. Here the problem is not having the thruhull under
water, as it is for those in the side of the boat when the boat heels.
Here the problem is following waves splashing up in to the thruhull. The
simplest solution for this is to run the hose so that it briefly ascends
from the thruhull, so water splashed up into the thruhull flows back out
the thruhull instead of down the hose into the bilge. Of course this
means the bilge pump has to raise the water that much further and thus
lowers the real GPH output of the pump, so don’t over do it.Pete
wrote:
Quote:Aaron
10″ sounds low. I’m pretty sure that mine exit much higher than that, but you have me thinking. I’m pretty sure that the transom is at least a foot above the water line, so the only way I think you could have one that low would for it to be mounted below the transom. I’m pretty sure mine are at least 2 feet above the water line and no more than 2 feet offcenter.I’ve observed that when under power, the stern wave climbs up the transom at least a foot or so as the boat approaches hull speed. If I had a through-hull that low on the transom, it would be under water. Having a pump exit below the water line not only invites flooding, but also restricts the capacity of the pump. This is not good.
If the through-hulls exit near the centerline of the boat and if they are up a couple of feet or so, they would only be submerged for a very short period of time if you got hit with a wave. I’ve run my bilge hoses up high in the locker in a loop. This isn’t vented and doesn’t need to be as long as the through-hull isn’t submerged for long periods of time. From your description, it sounds like yours are lower. All the 424’s are different, but it would be odd for Pearson to have done something so dangerous; maybe a PO screwed up.
I’ve seen vented loops that are made with stepped barbs on them. You cut the thing off at the hose size you need.
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Rich Carter
Original message
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I knew I'd seen a 1-1/8″ loop, it just took a little while to find it.
http://www.thebosworthco.biz/accessory.php?ID=VL-30-1-1/8&S=879
It's a little pricey. I think if you can find one of those stepped vented loops that Jack mentioned they are likely much cheaper, however they may not have a 1-1/8 step on the hose barb.John
On Thu, Apr 17, 2008 at 9:30 AM, < ([email][/email])> wrote:
Quote:Aaron
10″ sounds low. I'm pretty sure that mine exit much higher than that, but you have me thinking. I'm pretty sure that the transom is at least a foot above the water line, so the only way I think you could have one that low would for it to be mounted below the transom. I'm pretty sure mine are at least 2 feet above the water line and no more than 2 feet offcenter.I've observed that when under power, the stern wave climbs up the transom at least a foot or so as the boat approaches hull speed. If I had a through-hull that low on the transom, it would be under water. Having a pump exit below the water line not only invites flooding, but also restricts the capacity of the pump. This is not good.
If the through-hulls exit near the centerline of the boat and if they are up a couple of feet or so, they would only be submerged for a very short period of time if you got hit with a wave. I've run my bilge hoses up high in the locker in a loop. This isn't vented and doesn't need to be as long as the through-hull isn't submerged for long periods of time. From your description, it sounds like yours are lower. All the 424's are different, but it would be odd for Pearson to have done something so dangerous; maybe a PO screwed up.
I've seen vented loops that are made with stepped barbs on them. You cut the thing off at the hose size you need.
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Rich Carter
Original message
<.. snip>Post generated from Pearson424 Forum using Mail2Forum
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I was guestimating from memory, the thru-hulls are at the bottom of the vertical part of the transom, so you’re correct they are about 18” off the water.
I’m still thinking of adding vented loops though, just to meet current abyc code. There’s no downside to that (other than cost) is there?
On 4/17/08 6:30 AM, wrote :
Quote:Aaron
10″ sounds low. I’m pretty sure that mine exit much higher than that, but you have me thinking. I’m pretty sure that the transom is at least a foot above the water line, so the only way I think you could have one that low would for it to be mounted below the transom. I’m pretty sure mine are at least 2 feet above the water line and no more than 2 feet offcenter.I’ve observed that when under power, the stern wave climbs up the transom at least a foot or so as the boat approaches hull speed. If I had a through-hull that low on the transom, it would be under water. Having a pump exit below the water line not only invites flooding, but also restricts the capacity of the pump. This is not good.
If the through-hulls exit near the centerline of the boat and if they are up a couple of feet or so, they would only be submerged for a very short period of time if you got hit with a wave. I’ve run my bilge hoses up high in the locker in a loop. This isn’t vented and doesn’t need to be as long as the through-hull isn’t submerged for long periods of time. From your description, it sounds like yours are lower. All the 424’s are different, but it would be odd for Pearson to have done something so dangerous; maybe a PO screwed up.
I’ve seen vented loops that are made with stepped barbs on them. You cut the thing off at the hose size you need.
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Rich Carter
Original message
<.. snip>Post generated from Pearson424 Forum using Mail2Forum
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You do lose a little of the pump's capacity because it is pushing a greater head. Not sure if you could measure the difference though. Given the depth of our bilges, the bilge pumps on our boats need to be fairly powerful just to get the bilge water above the waterline.
On Thu, Apr 17, 2008 at 1:44 PM, Aaron Lynch < ([email][/email])> wrote:
I was guestimating from memory, the thru-hulls are at the bottom of the vertical part of the transom, so you’re correct they are about 18″ off the water.
I’m still thinking of adding vented loops though, just to meet current abyc code. There’s no downside to that (other than cost) is there?
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Regards,
John Stevenson
http://www.svsarah.comPost generated from Pearson424 Forum using Mail2Forum
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Hmmmm… if there is a vacuum breaker on the line, would there be siphon
effect?Rich Carter wrote:
I’m not sure there would be any difference. The extra height would
be offset by the siphon action of water flowing down to the through-hull.Rich
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