Ed Price wrote:

Well, pardon me for asking you to address my question. In case you didn't
remember, since it always seems to slip your attention during your posts, I
wanted to know why the suppression is applied to the LOAD side of the
alternator diodes. Perhaps you two could stop slapping each others butts
long enough to try to answer that question.

True, there are none so ignorant as those who refuse to learn. Now that
we're even on stupid witticisms, can you try for a technical answer?

OK, I am going to try one more time. What I am about to say was
verified yesterday afternoon by Randy Johnson, formerly of Cruising
Equipment and developer of the Zap-Stop and confirmed by the tech
support people at Balmar and Leece-Neville.

When an alternator is producing a significant percentage of its capacity
to a load, be it a battery, motor or other device and that load is
suddenly removed the output voltage of the alternator will rise. While
the rectifier diodes can handle higher than normal amperage for short
periods they cannot tolerate voltages significantly over their rating
for even an instant. Therefore if this voltage rise is not checked
there is a very good possibility that the alternator rectifier diodes
will be damaged.

The physical law of conservation of energy says that the amount of
energy output by a device must equal the amount supplied to it. The
power output of an alternator is determined by the amount of energy
being supplied by the engine. The amount supplied is a function of RPM
and torque. The torque is governed by the intensity of the magnetic
field. As the engine speed cannot normally be adjusted quickly the
regulator is used to control the magnetic field. This control is fast
but it is not instantaneous. As the field collapses, a back EMF is
inducted in the field coil slowing the process. Therefore there is a
lag in reducing the total power being produced. FOR AN INSTANT TOTAL
POWER REMAINS THE SAME. Power is volts times amps. As there is no
demand for the amps basic math says that the voltage must rise.

The current practice for preventing damage to the regulator diodes is to
place a sacrificial diode between the alternator output and ground to
provide an alternate path for the energy. Both of the alternator
manufacturers I talked to strongly recommend the installation of one of
these diodes whenever there is a possibility that a heavy load might be
suddenly dropped.

This diode will not conduct until the voltage exceeds a certain preset
limit determined by its construction. It has only one function: To
provide a way for the alternator to shed the surplus current so that the
voltage will not rise to a damaging level. The rectifier sees only a
slight drop in current demand and a slight rise in voltage. It does not
know anything about whether it is supplying the original load or the
protecting diode.

The protecting diode however has to bite the bullet and very often gives
its life in the process but it will last long enough to handle the surge
for the fraction of a second required to get the power output below a
damaging level.

That is about as simple as I can get it. If that is not satisfactory,
go talk to JAX. He is more on your level.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

In article , wrote:

Ed Price wrote:

Well, pardon me for asking you to address my question. In case you didn't
remember, since it always seems to slip your attention during your posts, I
wanted to know why the suppression is applied to the LOAD side of the
alternator diodes. Perhaps you two could stop slapping each others butts
long enough to try to answer that question.

True, there are none so ignorant as those who refuse to learn. Now that
we're even on stupid witticisms, can you try for a technical answer?

OK, I am going to try one more time. What I am about to say was
verified yesterday afternoon by Randy Johnson, formerly of Cruising
Equipment and developer of the Zap-Stop and confirmed by the tech
support people at Balmar and Leece-Neville.

When an alternator is producing a significant percentage of its capacity
to a load, be it a battery, motor or other device and that load is
suddenly removed the output voltage of the alternator will rise. While
the rectifier diodes can handle higher than normal amperage for short
periods they cannot tolerate voltages significantly over their rating
for even an instant. Therefore if this voltage rise is not checked


Sounds like they need to make them properly, with higher voltage diodes.

greg

Read an application note from the load dump protector
manufacturer (when still called SGS Thompson) about 1996.
It's more than just putting a suppressor diode on output or
using larger components. As they noted:
The protection at the alternator level is a quite new concept and
all the technical problems do not seem to be completely solved.

The problem has long been known and has long created
problems. Solutions have been installed for decades. Still an
adaquate design has not been perfected. My first experience
was in early 1960s when alternators used germanium diodes.
The problem has been understood that long. Thompson
Electronics does make load dump suppressors and are a major
electronic supplier to GM. However I don't know if GM uses
the parts (model numbers provided in the previous post) from
Thompson.

As Glenn Ashmore has so accurately noted, load dump is a
serious electrical threat even to powered electronics. Simply
look at the voltages that can exist on a 12 volts system
(which is why electronics whose specifications specifically
state load dump protection cost more). Especially susceptible
are boat power systems. Master battery switch must be
designed 'make before break'. IOW during battery switchover,
a battery must be always connected to alternator. Better
designs even transition the switchover to soften the 'change
of load'. Cars typically don't suffer as easily BUT will be
more susceptible as more functions become electrical (ie
steering) and voltage is raise from 12 volts to the new 42
volt standards.

Glenn Ashmore wrote:
GregS wrote:
Sounds like they need to make them properly, with higher voltage
diodes.

It is a matter of size and economics. Diodes capable of handling
high voltages and high amperages are large and expensive.
Leece-Neville makes such a rectifier for heavy EMT and construction
equipment but it is a box separate from the alternator and cost more
than any of us would want to pay.

99% of the alternator installations are automotive and do not have
master battery disconnects. Also automotive alternators seldom run
at a significant percentage of rated capacity for very long. The
major load last for only a few minutes to replenish the cranking
power.

Boats with house banks on the other hand usually do have master
switches and either the switch must have a capability to disconnect
the field current before opening the battery circuit or a bypass
diode of some kind on the alternator. To do otherwise is a pretty
good bet that eventually you will fry the rectifier diodes.
Unfortunately boats make up a microscopic percentage of the
alternator market so this type of protection is not provide for.
...

"Glenn Ashmore" wrote in message
...

Ed Price wrote:

Well, pardon me for asking you to address my question. In case you
didn't
remember, since it always seems to slip your attention during your
posts, I
wanted to know why the suppression is applied to the LOAD side of the
alternator diodes. Perhaps you two could stop slapping each others butts
long enough to try to answer that question.

True, there are none so ignorant as those who refuse to learn. Now that
we're even on stupid witticisms, can you try for a technical answer?

OK, I am going to try one more time. What I am about to say was
verified yesterday afternoon by Randy Johnson, formerly of Cruising
Equipment and developer of the Zap-Stop and confirmed by the tech
support people at Balmar and Leece-Neville.

When an alternator is producing a significant percentage of its capacity
to a load, be it a battery, motor or other device and that load is
suddenly removed the output voltage of the alternator will rise. While
the rectifier diodes can handle higher than normal amperage for short
periods they cannot tolerate voltages significantly over their rating
for even an instant. Therefore if this voltage rise is not checked
there is a very good possibility that the alternator rectifier diodes
will be damaged.

The physical law of conservation of energy says that the amount of
energy output by a device must equal the amount supplied to it. The
power output of an alternator is determined by the amount of energy
being supplied by the engine. The amount supplied is a function of RPM
and torque. The torque is governed by the intensity of the magnetic
field. As the engine speed cannot normally be adjusted quickly the
regulator is used to control the magnetic field. This control is fast
but it is not instantaneous. As the field collapses, a back EMF is
inducted in the field coil slowing the process. Therefore there is a
lag in reducing the total power being produced. FOR AN INSTANT TOTAL
POWER REMAINS THE SAME. Power is volts times amps. As there is no
demand for the amps basic math says that the voltage must rise.

The current practice for preventing damage to the regulator diodes is to
place a sacrificial diode between the alternator output and ground to
provide an alternate path for the energy. Both of the alternator
manufacturers I talked to strongly recommend the installation of one of
these diodes whenever there is a possibility that a heavy load might be
suddenly dropped.

This diode will not conduct until the voltage exceeds a certain preset
limit determined by its construction. It has only one function: To
provide a way for the alternator to shed the surplus current so that the
voltage will not rise to a damaging level. The rectifier sees only a
slight drop in current demand and a slight rise in voltage. It does not
know anything about whether it is supplying the original load or the
protecting diode.

The protecting diode however has to bite the bullet and very often gives
its life in the process but it will last long enough to handle the surge
for the fraction of a second required to get the power output below a
damaging level.

That is about as simple as I can get it. If that is not satisfactory,
go talk to JAX. He is more on your level.

--
Glenn Ashmore


Thanks for the more lucid explanation, despite the several gratuitous
insults. After reading your new information, I'll even go so far as to
retract my quip of a totally bogus explanation of energy within the
alternator; I now realize you were being more condescending than obscure. To
me, fast is microseconds or nanoseconds, and I guess you just live in a
slower world.

It further helps to hear that the Zap-stop only conducts a current similar
to the original load, and that for only a few hundred milliseconds. That's
probably why connecting the protection to the output of the alternator
doesn't kill the alternator diodes.

But that leads to another issue. You said the protection diode often fails!!

Question 1.: Why does the protection diode "often fail" if it's drawing the
same load as the alternator diodes?

Question 2.: You assert that the protection diode "will last long enough."
Is this some kind of smart silicon, in that it knows when it's OK to die?
Again, I'm not familiar with your world, but devices that I have seen in
which there is a failure under load usually fail under full load, or at
least not when most of the load has gone away. Whenever I cook off a diode,
it usually dies a lot faster than a couple of hundred milliseconds.

I would think that the protection diode would be sized so that it rarely
fails. After all, isn't a protection diode failure just another way of
describing load shedding? IIRC, you said that diodes that could handle
typical alternator currents could be had at Digikey for under a buck. Maybe
you should refer Xentrex, too.


Ed

The tone of the debate was set by you. I was only responding.

The field coil is a gigantic inductor compared to the inductors used in
high speed electronics like computers and radio frequency equipment.
When the field current is removed the time it takes for the magnetic
field to collapse is related to the strength of the field and the number
and centerline spacing of the turns. Strong fields take a lot of time
to collapse through a lot of turns of relatively thick tightly wound
wire so we are talking about milliseconds rather than micro or nanoseconds.

Diodes are rated by the voltage and amperage they can take and how long
they can take the power. The larger the combination gets the more
expensive and larger the diode gets. We are facing the limits of size
and economics. The Zap Stop is sized to "do the job" without pricing
itself out of the market. In most cases it will rarely fail but the
potential is still there. Probably the worst case would be dropping the
load on a large cold alternator bulk charging at full power. All that
power that was going through a 4/0 cable now flows through a few inches
of #14 wire and a fraction of an inch of diode material. That can
generate a lot of heat very quickly. The newer Zap Stops have a fuse in
series with the diode. The idea being that in the time it takes for the
fuse to blow the field strength drops below the damaging level.

It would be nice however if they added a little circuitry and an LED to
indicate when the diode had been fried. Right now the only way to know
that your alternator is protected is to periodically test it with a
multimeter.

The diode that the Zap Stop uses probably only cost a dollar or two but
the case probably cost another couple of bucks and it might take 5
minutes worth of labor to put it together and stick it in a box. Total
manufacturing cost is probably under 5 bucks. BUT, a general rule of
thumb is that manufacturing cost of any item should be no more than 25%
of retail price. If you put the word "marine" in the description it can
drop to 20%.


Ed Price wrote:


Thanks for the more lucid explanation, despite the several gratuitous
insults. After reading your new information, I'll even go so far as to
retract my quip of a totally bogus explanation of energy within the
alternator; I now realize you were being more condescending than obscure. To
me, fast is microseconds or nanoseconds, and I guess you just live in a
slower world.

It further helps to hear that the Zap-stop only conducts a current similar
to the original load, and that for only a few hundred milliseconds. That's
probably why connecting the protection to the output of the alternator
doesn't kill the alternator diodes.

But that leads to another issue. You said the protection diode often fails!!

Question 1.: Why does the protection diode "often fail" if it's drawing the
same load as the alternator diodes?

Question 2.: You assert that the protection diode "will last long enough."
Is this some kind of smart silicon, in that it knows when it's OK to die?
Again, I'm not familiar with your world, but devices that I have seen in
which there is a failure under load usually fail under full load, or at
least not when most of the load has gone away. Whenever I cook off a diode,
it usually dies a lot faster than a couple of hundred milliseconds.

I would think that the protection diode would be sized so that it rarely
fails. After all, isn't a protection diode failure just another way of
describing load shedding? IIRC, you said that diodes that could handle
typical alternator currents could be had at Digikey for under a buck. Maybe
you should refer Xentrex, too.


Ed



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

don't be upset, Ed trolls to test your conviction and real understanding.

"Glenn Ashmore" wrote in message
...
The tone of the debate was set by you. I was only responding.

The field coil is a gigantic inductor compared to the inductors used in
high speed electronics like computers and radio frequency equipment.
When the field current is removed the time it takes for the magnetic
field to collapse is related to the strength of the field and the number
and centerline spacing of the turns. Strong fields take a lot of time
to collapse through a lot of turns of relatively thick tightly wound
wire so we are talking about milliseconds rather than micro or
nanoseconds.

Diodes are rated by the voltage and amperage they can take and how long
they can take the power. The larger the combination gets the more
expensive and larger the diode gets. We are facing the limits of size
and economics. The Zap Stop is sized to "do the job" without pricing
itself out of the market. In most cases it will rarely fail but the
potential is still there. Probably the worst case would be dropping the
load on a large cold alternator bulk charging at full power. All that
power that was going through a 4/0 cable now flows through a few inches
of #14 wire and a fraction of an inch of diode material. That can
generate a lot of heat very quickly. The newer Zap Stops have a fuse in
series with the diode. The idea being that in the time it takes for the
fuse to blow the field strength drops below the damaging level.

It would be nice however if they added a little circuitry and an LED to
indicate when the diode had been fried. Right now the only way to know
that your alternator is protected is to periodically test it with a
multimeter.

The diode that the Zap Stop uses probably only cost a dollar or two but
the case probably cost another couple of bucks and it might take 5
minutes worth of labor to put it together and stick it in a box. Total
manufacturing cost is probably under 5 bucks. BUT, a general rule of
thumb is that manufacturing cost of any item should be no more than 25%
of retail price. If you put the word "marine" in the description it can
drop to 20%.


Ed Price wrote:


Thanks for the more lucid explanation, despite the several gratuitous
insults. After reading your new information, I'll even go so far as to
retract my quip of a totally bogus explanation of energy within the
alternator; I now realize you were being more condescending than
obscure. To
me, fast is microseconds or nanoseconds, and I guess you just live in a
slower world.

It further helps to hear that the Zap-stop only conducts a current
similar
to the original load, and that for only a few hundred milliseconds.
That's
probably why connecting the protection to the output of the alternator
doesn't kill the alternator diodes.

But that leads to another issue. You said the protection diode often
fails!!

Question 1.: Why does the protection diode "often fail" if it's drawing
the
same load as the alternator diodes?

Question 2.: You assert that the protection diode "will last long
enough."
Is this some kind of smart silicon, in that it knows when it's OK to
die?
Again, I'm not familiar with your world, but devices that I have seen in
which there is a failure under load usually fail under full load, or at
least not when most of the load has gone away. Whenever I cook off a
diode,
it usually dies a lot faster than a couple of hundred milliseconds.

I would think that the protection diode would be sized so that it rarely
fails. After all, isn't a protection diode failure just another way of
describing load shedding? IIRC, you said that diodes that could handle
typical alternator currents could be had at Digikey for under a buck.
Maybe
you should refer Xentrex, too.


Ed



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"phil" wrote in message
et...
don't be upset, Ed trolls to test your conviction and real understanding.

"Glenn Ashmore" wrote in message
...
The tone of the debate was set by you. I was only responding.

The field coil is a gigantic inductor


And thank YOU, Phil, for your cogent contributions to this discussion.

The definition of a troll is not someone who poses a question which confuses
you. The best trolls usually reply to any reasonable answer with a new set
of conditions which defeat the original answer. If they are fast enough,
they can keep sliding out from under your logical hammer.

I will admit that I'm quite skeptical of the claims of almost any marketer.
When someone tells me that I need their latest gadget to protect a system
that is not known for failure, then the little BS flag starts to wiggle.

At the beginning of this thread, I went to the Xentrex site, and found
market hype, not engineering data. No schematics, no info on joules ratings,
no waveforms of with and without a Zap-stop. It took several exchanges just
to understand what this thing really does.

There are a vast number of auto owners, with alternator systems, who will
NEVER experience 60-amp load dumps. And there are many, many small boat
owners whose electrical systems are close copies of automotive systems, and
they also operate under nearly the same conditions as a car. So that's
another whole cohort that will NEVER see those 60-amp load dumps.

So who does experience these load dump conditions? How often will Glenn, in
his cruiser, be pumping 60 amps back into his battery bank? And for how
long? And with what probability that he will do a trick with the battery
changeover switch during that short period of exposure?

So help me out here, Phil; what class of vessel often sees 60-amp charging
currents? Does that class of vessel usually have switch-twiddling idiots
running the below-decks division?

It seems to me that the Zap-stop is being hyped as needed for everyone with
an alternator, while the conditions of 60-amp load dumps are experienced by
only a small slice of small boat owners.

Or maybe I'm just a troll.


Ed

I will be pumping over 200 amps for as long as an hour every day while
cruising. I had to go back and look at some of your previous posts to
figure out why you are thinking the way you are. Then I found the post
about having a 0-75 MPH speedo and realized that you are a hot rod ski
boater with no idea of how a cruising boat works.

A typical 35' to 50' cruising boat with a well balanced electrical
system will have anywhere from 350 to 1200 amp hours of battery bank and
will regularly draw it from 75% to 50% to keep the charging cycle in the
bulk current range. They will have an alternator capable of outputting
20 to 25% of the bank's capacity per hour and run it once or twice a day
for up to an hour at as close to full capacity as possible. That is
what those fancy three stage regulators with temperature sensors and
recombinant caps are for.

As an example, my boat will have a pretty heavy duty system but it is
not as large as some in that size range and not all that much larger
than most. It is 800 amp hours in four L16HC batteries charged by a 250
amp brushless Niehoff fire truck alternator with an external three stage
regulator and external rectifier. The energy budget calls for charging
and making water for 45 minutes to an hour every day while cruising.
Should a guest unknowingly turn the master battery switch during that
time I could be out about $1,000. In this situation, which is not
unusual for a cruiser, a $25 investment in a Zap Stop is a no brainer.

The single most common reason for failures in cruising boat alternators
is load dump spikes with bearing failures a distant second. OTOH, a ski
boat with only a cranking battery, no master battery switch and a stock
60 amp alternator would never have to worry.

Ed Price wrote:

snip

There are a vast number of auto owners, with alternator systems, who will
NEVER experience 60-amp load dumps. And there are many, many small boat
owners whose electrical systems are close copies of automotive systems, and
they also operate under nearly the same conditions as a car. So that's
another whole cohort that will NEVER see those 60-amp load dumps.

So who does experience these load dump conditions? How often will Glenn, in
his cruiser, be pumping 60 amps back into his battery bank? And for how
long? And with what probability that he will do a trick with the battery
changeover switch during that short period of exposure?

So help me out here, Phil; what class of vessel often sees 60-amp charging
currents? Does that class of vessel usually have switch-twiddling idiots
running the below-decks division?

It seems to me that the Zap-stop is being hyped as needed for everyone with
an alternator, while the conditions of 60-amp load dumps are experienced by
only a small slice of small boat owners.

Or maybe I'm just a troll.


Ed



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

So Ed....

Again, I will ask you just like I did during our EMC discussion, what
percentage of boaters have an engineering degree and would understand
joules, ohms, volts, ohms law, etc. to even have an inkling of what the
information meant if it were indeed included on the web page? Even if it
were included, how would it relavent unless the matching information were
provided by the alternator manufacturer under load dump conditions?

I find it interesting that most people don't have a clue how electricity
works and couldn't troubleshoot a light switch, much less understand
alternator load dump waveforms versus load and rpm, joules dumped, whether
their alternator diodes were damaged, and on and on. How many people come
on here and ask "I have no spark and I replaced everything such as the coil,
plug wires, plugs, coil driver components (mechanical or electronic), and
there still is no spark".

I would suggest most people would just get a protector and just feel good
that there was some additional protection from battery disconnects.

To me, load dump is not mysterious, I deal with it all the time in my job
(don't ask cause I won't tell you).

Phil



"Ed Price" wrote in message
news:IGmSa.1006$Ye.415@fed1read02...

"phil" wrote in message
et...
don't be upset, Ed trolls to test your conviction and real
understanding.

"Glenn Ashmore" wrote in message
...
The tone of the debate was set by you. I was only responding.

The field coil is a gigantic inductor


And thank YOU, Phil, for your cogent contributions to this discussion.

The definition of a troll is not someone who poses a question which
confuses
you. The best trolls usually reply to any reasonable answer with a new set
of conditions which defeat the original answer. If they are fast enough,
they can keep sliding out from under your logical hammer.

I will admit that I'm quite skeptical of the claims of almost any
marketer.
When someone tells me that I need their latest gadget to protect a system
that is not known for failure, then the little BS flag starts to wiggle.

At the beginning of this thread, I went to the Xentrex site, and found
market hype, not engineering data. No schematics, no info on joules
ratings,
no waveforms of with and without a Zap-stop. It took several exchanges
just
to understand what this thing really does.

There are a vast number of auto owners, with alternator systems, who will
NEVER experience 60-amp load dumps. And there are many, many small boat
owners whose electrical systems are close copies of automotive systems,
and
they also operate under nearly the same conditions as a car. So that's
another whole cohort that will NEVER see those 60-amp load dumps.

So who does experience these load dump conditions? How often will Glenn,
in
his cruiser, be pumping 60 amps back into his battery bank? And for how
long? And with what probability that he will do a trick with the battery
changeover switch during that short period of exposure?

So help me out here, Phil; what class of vessel often sees 60-amp charging
currents? Does that class of vessel usually have switch-twiddling idiots
running the below-decks division?

It seems to me that the Zap-stop is being hyped as needed for everyone
with
an alternator, while the conditions of 60-amp load dumps are experienced
by
only a small slice of small boat owners.

Or maybe I'm just a troll.


Ed

You're just a troll.

The cruisers that buy other Xantrex products, like the Link 2000R monitor/regulator are
the people that frequently charge over 60 Amps at a time. If I'm at anchor for an
extended period, I'll likely be running an engine an hour a day, charging at about 85
Amps.

Although many new cruising boats don't have the "Big Red Switch," almost all older boats
have one, just waiting for the mischievous nephew, or helpful brother-in-law to flip. I
know of one case where a friend, and experienced oat owner, had a brain stall and flipped
the switch, killing a GPS and sounder.

"Ed Price" wrote in message news:IGmSa.1006$Ye.415@fed1read02...

"phil" wrote in message
et...
don't be upset, Ed trolls to test your conviction and real understanding.

"Glenn Ashmore" wrote in message
...
The tone of the debate was set by you. I was only responding.

The field coil is a gigantic inductor


And thank YOU, Phil, for your cogent contributions to this discussion.

The definition of a troll is not someone who poses a question which confuses
you. The best trolls usually reply to any reasonable answer with a new set
of conditions which defeat the original answer. If they are fast enough,
they can keep sliding out from under your logical hammer.

I will admit that I'm quite skeptical of the claims of almost any marketer.
When someone tells me that I need their latest gadget to protect a system
that is not known for failure, then the little BS flag starts to wiggle.

At the beginning of this thread, I went to the Xentrex site, and found
market hype, not engineering data. No schematics, no info on joules ratings,
no waveforms of with and without a Zap-stop. It took several exchanges just
to understand what this thing really does.

There are a vast number of auto owners, with alternator systems, who will
NEVER experience 60-amp load dumps. And there are many, many small boat
owners whose electrical systems are close copies of automotive systems, and
they also operate under nearly the same conditions as a car. So that's
another whole cohort that will NEVER see those 60-amp load dumps.

So who does experience these load dump conditions? How often will Glenn, in
his cruiser, be pumping 60 amps back into his battery bank? And for how
long? And with what probability that he will do a trick with the battery
changeover switch during that short period of exposure?

So help me out here, Phil; what class of vessel often sees 60-amp charging
currents? Does that class of vessel usually have switch-twiddling idiots
running the below-decks division?

It seems to me that the Zap-stop is being hyped as needed for everyone with
an alternator, while the conditions of 60-amp load dumps are experienced by
only a small slice of small boat owners.

Or maybe I'm just a troll.


Ed