How much water comes in when the drain plug's out?
Esteban Nunez
"A one and a half inch hole located two feet below the water line will admit
70 gallons of water per minute..."
Esteban
este...@voicenet.com
Ed wrote in message <36abeb89...@nntp1.ba.best.com>...
>How would one go about figuring out how much water flows into a boat
>with the drainplug out?
>
>Assuming that I will eventually forget to put it in when I re-launch
>from a tow, I'm thinking that I might try to size the backup bilge
>pump I'm planning to add this year to be able to (in combination with
>the existing pump) keep up with the inflow from the missing plug.
>
>Is there a formula for flow based on the size of the drain hole and
>maybe the displacement of the boat?
>
>Thanks,
>
>-Ed
Ed
Osrick
>with the drainplug out?
all of it?
"Too soon old. Too late smart."
BikeMan1
it unless you were moving at plan but as soon as you stop you are done .
just make sure you put it in you should always have a per ck list on a boat
Larry
trying to figure out why my Sea Ray had a manual switch on the
dash....how silly.
Hook your garden hose to the open hole while it's in the driveway.
Turn it on full force. The actual water guggling in at the boat ramp
isn't near as much....but it SEEMS IT IS! How embarrassing....(c;
Larry...anyone who says they never forgot, is a liar!
On Mon, 25 Jan 1999 04:02:18 GMT, ed_g...@mindspring.com (Ed) wrote:
>How would one go about figuring out how much water flows into a boat
>with the drainplug out?
>
Paul Kamen
Here's a simple and intuitive way to figure this out "from first
principles."
Suppose the hole is right in the bottom of the boat. Assuming no "entrance
losses," the water will squirt into the boat with just enough energy so
that the plume of water will just reach the height of the waterline.
Think of it as a projectile problem. How fast do you have to throw an
object straight up for it go just that high before it falls back? Same
speed as it would be going if you dropped it from that height. So, if you
know the vertical distance from the hole to the waterline, and you know
gravitational acceleration, and you know the diameter of the hole, then
you can solve for the flow rate as a function of the depth of the hole
below the waterline, with nothing beyond high school physics.
In practice there will be some entrance loss and frictional loss, but
sizing the pump based on the above calculation should get you in the
right ballbark.
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Phoenix
You need to make sure you get used to looking at your dash, if you see your
bilge pump light on for more than 30 secs at a time you probably have a
problem and need to find out why you are taking on the water.
Just knowing you have a heavy duty bilge pump will not eliminate the
possibility of you sinking.
Ed wrote in message <36abeb89...@nntp1.ba.best.com>...
Jeff
Enough to swamp it.
Here's a tip.... when launching the boat, you
climb out of the tow vehicle, head out on the dock
to tie up the lines, and you notice water shooting out
the side like a garden hose, jump back in the tow
vehicle and pull your boat back up the ramp.
Then install the drain plug!
-Jeff
R. Lee Wheeler
bunch of plugs on boats that were on lifts don the lake from us.
Several of them sank completely and I understand that they went down
fast. I keep my boat on a lift all the time and, until that incident I
never even thought to check the plug since I never remove it.
Reinhard Sprenger
> How would one go about figuring out how much water flows into a boat
> with the drainplug out?--
I have some hydraulics experience and can offer some information for
interest sake only. You would apply the equation for orifice flow;
Q = cA SQRT (2 g h) where
Q = flow in cfs
c = orifice coefficient = 0.61
A = flow area of the hole in square feet ; for 1 inch dia. A = 0.00545
sq. ft.
g = gravitational constant = 32.2
h = head on center of orifice = depth of submergence in this case
To get gallons/minute multiply the cfs by 449 and since bilge pumps are
usually rated in gallons per hour multiply by 60.
So, for 1.0 foot of submergence flow would be;
Q = 0.61 * 0.00545 * SQRT (2 * 32.2 * 1.0) = 0.0267 cfs = 12 US gpm = 720
gph
for 2.0 feet of submergence substitute 2.0 for the 1.0 and get;
Q = 0.03776 cfs = 17 US gpm = 1020 gph
For comparison note that a 0.5 inch garden hose turns out 2.5 to 5.0 gpm.
There is a lot more to it than simply matching pump capacity to computed
flow - the water in the bilge must accumulate to sufficient depth to
permit the pump to operate at full capacity and thus you would be playing
catch-up to pump it back down. Also, bilge pumps are very bad for meeting
the rated capacity in actual installations. This is because the rated
capacity assumes very little vertical lift and almost no hydraulic losses
in the discharge piping and fittings. Most installations create enough
lift and losses to reduce capacity to half, or much less than half, of
the rated capacity. Also the fittings typically sold for boats never seen
to me to be designed for optimum hydraulics.
In my opinion, bilge pumps and all aspects of the installations are
designed to keep the bilge dry as opposed to meeting any hydraulic
capacity conditions. They most certainly are not intended to keep a boat
afloat in any sort of extreme conditions where maximum hydraulic capacity
is required.
Things like pump capacity ratings are no more than guidelines like small,
medium, large, xl, xxl, xxxl, etc. The ratings are usually given as so
many gph at such a head or lift, e.g. 2000 gph at 5 feet lift. This
implies it can lift 2000 gallons as high as 5 feet every hour. This is a
true statement but actual installations hardly ever meet the 5 feet lift
requirement. This is because all hydraulic losses from flow through the
intake strainer, friction loss in the hose, loss in the fittings and even
the velocity head in the outlet fitting must all be converted to units of
feet and added to the vertical lift from the bilge to the highest part of
the hose. If you have a vertical bow in the hose an airlock could occur
that would knock pump flow down to a very low rate.
The loss of capacity caused by the hose and fittings requires that you
must use a large safety factor in selecting pump size; something in the
order of 2 to 5. So the answer to your question is that the pump size
should be in the range of 2000 gph to 5000 gph for a 1.0 inch diameter
drain plug hole that would be 2 feet below water. This assumes that the
hose and fittings are sized properly and that the pump can make the
required flow against the actual installation lift and hydraulic losses
which for an engineer is largely guesswork - for a layman it is foolhardy
to assume you can size and then find for sale the required fittings.
Chances are that the standard hose size is inadequate for the size of
pumps needed for this application and that the thru-hull fitting on the
discharge is much too small to allow the pump to make anywhere near it's
full capacity. Even 1-inch inside diameter fittings on a 4000 gph pump
could cause enough headlosses to drag pump capacity down to very low
values, especially if lift is high.
I would guess that most bilge pumps actually turn out a fraction, say 20%
to 50% of the rated capacity. It is likely that many pumps turn out only
10% of the rated capacity.
So the real answer to your question is that you must run a trial of the
actual installation to determine if it will do the job. This is actually
what we commonly do in the business because hydraulic losses are
difficult to compute accurately and the effect on pump capacity is often
very dramatic. There are a number of ways to do this but the only actual
proof of the installation is a field test - leave the plug out and see if
the pump keeps up, if it does the installation is O.K. If not, the best
reaction is to increase the size of hoses and fittings and eliminate
things like bends or kinks in the hose. Increasing pump size while
leaving fittings alone probably wouldn't work well because hydraulic
losses are proportional to the flow squared and pump capacity drops
quickly as losses increase. Twice as big a pump could well yield only 5%
or 10% improvement in the large pump range.
Note a further concern - a 4000 gph pump could suck 20 amps or more.
Wiring must be sized according the pump requirements.
Please note that because of the complex inter-relationships between pump
capacity and installation details, bilge pumps should never be relied on
to keep a boat afloat. Where financial loss or loss of life is possible
NEVER rely on an electric bilge pump. Minor things like a piece of paper
in the intake screen, a kink in the discharge hose, an airlock in the
hose, fouled float switch or even disconnected batteries could reduce
pump flow to zero or near zero with attendant consequences.
In particular, the above information is NOT suitable for any particular
boat installation because it relies heavily on design assumptions that
may not have been stated or be apparent to a reader - this information is
offered only for the purpose of discussion. You got it for free and it
may be worth only what you paid for it.
Reinhard Sprenger
Winnipeg, Manitoba
The "10" in front of and behind the name in the return address is for
anti-spam protection.
Remove the "10" 's to reply.
Russ Glindmeier, CFP
could suck a chocolate milkshake through a straw, you'd be the guy to ask.
As for drainplugs:
1. Always carry a spare.
2. Always do a pre-launch checklist at the ramp.
3. Immediately after launching with engine running, always do a visual and
olfactory bilge inspection for water and fuel leaks.
As your calculations have proven, this will serve you much better than
trying to deal with the issue via pumps.
RG
Russ Glindmeier, CFP
Larry wrote in message <36ac02b8...@news.nations.net>...
>Just make sure you install an AUTOMATIC FLOAT SWITCH. I'm still
>trying to figure out why my Sea Ray had a manual switch on the
>dash....how silly.
>
switch. This is in case the float switch fails, or you want to pump water
that isn't deep enough to trigger the float switch. Your dash switch also
probably as a light on it indicating when the pump is working, even if
triggered by the float switch. If my bilge pump is running, and I wasn't
the one to turn it on, I want to know about it pronto. That is what the
light is for. A siren would be even more effective. Not so silly after
all.
RG
Russ Glindmeier, CFP
Upon analysis, your answer, despite being delightfully twisted, would appear
to be the most accurate.
RG
JPulley457
before launching. I did use my dads for several years before I owned one.
Thats no lie.
Charles T. Low
>Assuming that I will eventually forget to put it in when I re-launch from
Ed, it's good to be prepared for contingencies, but my own personal bias
here is that putting the drain plug in before launch is a sacred ritual. If
you assume you will eventually forget (and I know that it does happen), I
wonder if you aren't increasing your odds of forgetting.
You wouldn't leave your house naked...(?)
Charles
PS I've just jinxed myself, haven't I? (about the drain plug, not the other)
****
Charles T. Low, author of "Boat Docking"
<mailto:ct...@boatdocking.com>
<http://www.boatdocking.com/>
Harry Krause
You know, there are some small boats that are so buoyant that even if
you leave the drain plug out, they will not fill with water.
--
Harry Krause
- - - - - - - - - - - -
I've got the biggest Wang in southern Indiana.
Bud Feuless 14
to drain excess water from the bilge after washdown and reinstall it
immediately thereafter. Why in the world would anyone want to remove the
drainplug and then do god knows what with it after that? The only case I
can think of for this would be a boat on a trailer in outside storage, where
you are concerned that rain into an open bilge might wear down your battery
when the bilge pump runs or that too much water would accumulate and blow
the trailer's tires. If the boat is stored in a shed, however, I just can't
see any reason to keep the plug out... especially when modern boating lore
is so filled with stories of the resulting catastrophes. Anyone care to
enlighten me on this topic...?
Regards, Bud
Terry
speed. In my old 12' aluminum we reach down and pull the plug out while we
are moving (rubber plug inserted from the inside of the boat) which allows
water to drain out. No solution suggested here, just noting that
(normally) when a boat is moving forward on plane there is no water coming
in, instead it's probably going out.
Ed wrote in message <36abeb89...@nntp1.ba.best.com>...
>How would one go about figuring out how much water flows into a boat
>with the drainplug out?
>
>Assuming that I will eventually forget to put it in when I re-launch
Larry
On Mon, 25 Jan 1999 12:59:52 -0700, "Russ Glindmeier, CFP"
<ru...@goodnet.com> wrote:
>Your Sea Ray has a manual switch on the dash so you can overide the float
>switch. This is in case the float switch fails, or you want to pump water
>that isn't deep enough to trigger the float switch. Your dash switch also
>probably as a light on it indicating when the pump is working, even if
>triggered by the float switch. If my bilge pump is running, and I wasn't
>the one to turn it on, I want to know about it pronto. That is what the
>light is for. A siren would be even more effective. Not so silly after
>all.
>
>RG
>
My Sea Ray came with ONLY the manual switch. IF it flooded while you
were in the marina eating lunch, tough luck. I took out the cheap
Atwood pump and installed a 1100 gph Rule with Rule's magnetic float
switch. Paralelling the original wiring...running the float switch
from a different fuse and direction to increase redundancy...it is
nice the original switch's blue light comes on when the float
activates to let me know something's amiss below.
Larry....
Cbdonospam
>dash....how silly.
Mine (1986, now for sale) has a manual switch on the dash for each pump--but in
the "off" position, the pumps are on auto. The only way to truly turn them off
is to disconnect at the battery. Sure yours isnt the same way?
Cbdonospam
I can truly say I never forgot the plug through our years of
trailerable/rackable boating; but then, I never had the plug out longer than
enough to drain what was in the bilge at the time, largely for that reason.
The marina did forget it once, though; they'd had it out for some reason I
can't remember, and the next time we dropped it in (rack storage at the time) I
noticed after a few minutes that the stern seemed to be settling. They were
the same folks that hadn't quite tightened the hose clamp at the thermostat in
commissioning one year, which led to my inflexible rule to NEVER go out without
a tool kit. Finding a fisherman (with a screwdriver) close enough to limp to
when your Mercruiser is pumping Lake Michigan INTO the boat is not a lucky
break I want to have to repeat.
Nothing personal at all, Dave--I strongly suspect your shop is about as
fail-safe as it can get.
Rick and Lisa Marinelli
To paraphrase a line from the old show "Night Court"....
"You gotta be a special kind of stupid to forget to put the drain plug
in."
It's right up there with forgetting to lower the landing gear in an
airplane.
Of course, I may be jinxing myself by posting that... :)
Rick Marinelli
rickandlisa"deletethistoemail"@erols.com
Soon to be the owner of a '99 Cobalt 226
Michael Pilar
Cbdonospam wrote in message
<19990125212656...@ng-fa1.aol.com>...
My 1981 Sundancer 26' also has both switches on the dash...however, as I
found out last weekend after filling up the water tank, they are quite
automatic and successfully get rid of the 30+ gallons of water that was
promptly delivered to my bilge.
(Should have checked the drain plug on the water heater. Doh!)
-Michael
-----------== Posted via Newsfeeds.Com, Uncensored Usenet News ==----------
http://www.newsfeeds.com/ The Largest Usenet Servers in the World!
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Michael Kallelis
more confidence over the pump you may have had. 1100 gph is the rating of the
pump WITHOUT the 1/4" hose attached to it. The limitation on most systems is
not the pump but rather the small hoses attached to them combined with the
vertical distance (head pressure) encountered between the pump and the through
hull.
Ed
<10spre...@autobahn.mb.ca> wrote:
Now THAT was a well informed, complete and useful answer......
Thank you for the thorough response.
-Ed
Ed
<ct...@boatdocking.com> wrote:
>
>Ed, it's good to be prepared for contingencies, but my own personal bias
>here is that putting the drain plug in before launch is a sacred ritual. If
>you assume you will eventually forget (and I know that it does happen), I
>wonder if you aren't increasing your odds of forgetting.
>
>You wouldn't leave your house naked...(?)
>
Geez, I didn't think anyone saw me.....
-Ed
Cbdonospam
>in."
>
>It's right up there with forgetting to lower the landing gear in an
>airplane.
>
going off when the drain plug's out but the hull's near the water.
Then again--would the system to produce same be a Marketable Item?
Larry
<ja...@mediaone.net> wrote:
>Larry, the larger bilge pump is a fine idea but don't let it give you too much
>more confidence over the pump you may have had. 1100 gph is the rating of the
>pump WITHOUT the 1/4" hose attached to it. The limitation on most systems is
>not the pump but rather the small hoses attached to them combined with the
>vertical distance (head pressure) encountered between the pump and the through
>hull.
>
Of course, I changed the hose and thru-hull fitting to the appropriate
size for the new pump. Rule has adapters for the smaller hose but
when my ass is sinkin' I don't like to skimp on plastic hose, ya
know...(c;
Larry...
Larry
Hmm...the plug's just hangin' there on it's cheap plastic keeper....We
could put a little sensor on the end of the plug hangin' down that
would lower its resistance to fire an IC alarm chip when it senses
water....There'd have to be a "plug-in-tight" switch to disable the
alarm when you screwed the plug in....
Yeah, we could do that....
What'll we charge for this new gadget? Of course, it'd have to have a
fancy electronic display mounted on a 2-bolt gimbal mounting bracket
made outa black anodized aluminum....It'd have an LCD display to show
how deep the water's already gittin' while the alarm is blastin' away
and the big light on it's blinkin. It'd have an output to fire the
DSC-equipped VHF radio's Channel 70 Emergency alarm, noting our
current position from the radio's GPS NMEA-0183 data stream. Our LCD
display would announce the radio's been fired, then respond with
another LCD alert when the CG answers the call. Wonder if we'll need
an output to fire off the 406Mhz EPIRB beacon on larger boats??...
Well, anyways....Can we build one for you??
Larry....in Market Engineering
Larry
Didja ever see a poor SOB tryin' to lift the hitch tongue on a 15'
runabout, he can usually pick up, when the hitch has been layin on the
ground with the ball hole in the dirt for 3 months....when he forgot
to pull the damned plugs out because it was 10PM and his wife was
bitchin' at him for comin' home from fishin' drunk and late AGAIN??
The axle only bent a little from the gunwale-deep load of rainwater,
frogs, escaped fishin' equipment, one left sneaker - kid's size 8, and
the 3-month-old six Striped Bass in the big Igloo Cooler he forgot
about the next morning before goin' back to work at Massive Trucking
and Storage on a 3-month, long haul, to Vancouver where the Peterbuilt
blew a tire in Tulsa and needed the #4, bent, piston rod replaced in
Seattle, a 9-day layover waitin for parts.
That's why.,....(c;
Larry....mine left.....no, silly, not the boat or the plugs...THE
WIFE!
Charles T. Low
>...Why in the world would anyone want to remove the drainplug and then do
god knows what with it after that?...
Bud - My drain plug is out all winter. The boat site on a cradle with 80
others in a yacht club yard, under a tarp, and some rainwater and
condensation gets into the bilge. I don't want it freezing and thawing in
there, so the boat has to drain freely all the time.
The plug is on the helm console, so it's very hard to miss in the Spring.
The harbour master also walks around and checks all the plugs before our
mass launch. Still, every year, some boat leaks (usually not the plug), and
it's quite exciting. Often the bilge pump alone is inadequate, and it's
emergency haulout time, or else big pumps are brought aboard and run from
the 120 AC.
Charles
Rick and Lisa Marinelli
>>"You gotta be a special kind of stupid to forget to put the drain plug
>>in."
>>
>>It's right up there with forgetting to lower the landing gear in an
>>airplane.
>>
>Well, almost....I haven't yet found a boat that has all those alarms and lights
>going off when the drain plug's out but the hull's near the water.
That's because boat pilots are assumed to be not as stupid as airplane
pilots... :)
Phoenix
plug, but to keep it simple the answer is "a shit load of water will come
in"
I am not sure how you put that into an equation, but let me try
1(drainpug) x 1(brainfart) = 1(sunkenboat)
Terry wrote in message ...
PTHoracek
Marcus G Bell
> Y'know, I've never really understood this one. I only remove my
> drain plug to drain excess water from the bilge after washdown
> anyone want to remove the drainplug and then do god knows what
> the boat is stored in a shed, however, I just can't see any
> reason to keep the plug out... especially when modern boating
> lore is so filled with stories of the resulting catastrophes.
You balance the risk of your roof springing a leak -- filling your
boat with tons of water, bending your trailer, allowing the boat
and all that water to come crashing down, all while you are off
somewhere else-- against the risk that you'll forget the plug when
you launch and are there to do something about it.
Ask my friend who keeps a canoe lashed to the rafters of his
boathouse so that he could put more stuff under it. One winter, it
took out the floor and everything else under it. Now, his canoe is
hung upside-down. It doesn't have a drainplug, you see.
-- -- Marcus. ( be...@mail.med.upenn.edu )
CBDO
>Hmm...the plug's just hangin' there on it's cheap plastic keeper....We
>could put a little sensor on the end of the plug hangin' down that
>would lower its resistance to fire an IC alarm chip when it senses
>water....There'd have to be a "plug-in-tight" switch to disable the
>alarm when you screwed the plug in....
>
>Yeah, we could do that....
>
>What'll we charge for this new gadget? Of course, it'd have to have a
>fancy electronic display mounted on a 2-bolt gimbal mounting bracket
>made outa black anodized aluminum....It'd have an LCD display to show
>how deep the water's already gittin' while the alarm is blastin' away
>and the big light on it's blinkin. It'd have an output to fire the
>DSC-equipped VHF radio's Channel 70 Emergency alarm, noting our
>current position from the radio's GPS NMEA-0183 data stream. Our LCD
>display would announce the radio's been fired, then respond with
>another LCD alert when the CG answers the call. Wonder if we'll need
>an output to fire off the 406Mhz EPIRB beacon on larger boats??...
>
>Well, anyways....Can we build one for you??
>
Of COURSE we need the EPIRB-firing output, as well as an additional output to
trigger the mandatory Navy-surplus submarine klaxon along with the digitally
synthesized sound byte of "Dive, Dive, Dive."
I like it....
Larry
>>
>Of COURSE we need the EPIRB-firing output, as well as an additional output to
>trigger the mandatory Navy-surplus submarine klaxon along with the digitally
>synthesized sound byte of "Dive, Dive, Dive."
>
>I like it....
Aha! Great idea!...
Well, headed back to the basement for more engineering drawings.
Looks like we're gonna be workin' a little late tonight....(c;
Market Engineering.
Paul Kamen
>That's because boat pilots are assumed to be not as stupid as
>airplane pilots... :)
No, it's because most people can swim without a boat much better than
they can fly without an airplane.
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Rick and Lisa Marinelli
wrote:
> rickandlisadel...@erols.com (Rick and Lisa Marinelli)
>
> >That's because boat pilots are assumed to be not as stupid as
> >airplane pilots... :)
>
>No, it's because most people can swim without a boat much better than
>they can fly without an airplane.
>
Like I said.... :)
Rick Marinelli
rickandlisarem...@erols.com
Phoenix
Let us know how you enjoy your Mercedes of boats.
Is the Cobalt 226 an open bow or a cuddie design.
Rick and Lisa Marinelli wrote in message
<36b11cd6....@news.erols.com>...
Rick and Lisa Marinelli
<jgallo...@mindspring.com> wrote:
>Rick,
>
>Let us know how you enjoy your Mercedes of boats.
>Is the Cobalt 226 an open bow or a cuddie design.
>
Thanks. I sure will.
It's a bowrider. I owned a cuddy before, and found that for the type
of boating I do, the cabin space was wasted. Better for me to have
the riding area up front.
But I am amazed at the storage space this bowrider has. We plan to
stash a portapotty in one of the bow storage compartments.
Rick Marinelli
rickandlisa"deletethistoemail"@erols.com
JJames915
Bud Feuless 14
them in mind. For now, I'll just count myself lucky that its over 70
degrees outside in Houston right now and that I take my boat out every
weekend come hell or high water (maybe even especially then); thus, most of
these concerns do not apply in my case. Even if water came into my boat,
unless it was a constant week-long unending deluge from a leak in the roof,
my bilge pump would still handle it. And, since I often rise at 3am, after
about 3-5 hours of sleep (IF I can sleep at all before my blessed escape
after the work week), on Saturday, to drive bleary eyed the 1 and 1/2 hours
to my boat, I think I'll keep that plug in. The plug is the only thing I
have NOT forgotten on a fishing trip, including tackle and rods, bait,
undoing the tie downs before launch, putting that spark plug wire back on
that I had pulled earlier...
Regards, Bud
Nick Smeltzer
because mine doesn't, just a bilge pump. My last boat had a drain plug,
so I'm now wondering if the previous owner filled it in and did a good
job with the glass...
--
Nick
Bud Feuless 14
caprail, interliner or separate deck, and more specifically, no hull to deck
joint, just a gunnel made out of the excess fiberglass rolled over the outer
edge of the mold, thus the name) that have no plug. The reason, I believe
is that these boats have no separate blige. The floor and deck, are one and
the same. Another case would be a flat-bottomed jon boat, most of which do
not have plugs either.