Holy shi** g

--Mike

"Gregory Hall" wrote in message
...

"David" dh@. wrote in message
...
I've got an old boat very much like this one:

http://www.warnersdock.com/images/Fr...fores15yel.JPG


snip

THIS is top-heavy:
http://images.thebiggestbreasts.com/...fake_boobs.jpg

Caution: nudity. Adults only please.

--
Gregory Hall

David,
Get a book on Naval Architecture and read about GM.
Every boat has the center of gravity above the center of buoyancy.
Weight added alone might not keep it upright.
Matt Colie


David wrote:
I've got an old boat very much like this one:

http://www.warnersdock.com/images/Fr...fores15yel.JPG

that I'm trying to make into a mini-houseboat,
sort of like a camper. I only expect to have
about 200-300 pounds in the roof and walls,
and the roof will only be about 48" above
the gunwale. The hull will weigh a *lot* more
than what is added, so shouldn't that alone
be enough to keep it from being top heavy
and flipping over? If I add weight, like a
couple hundred pound bags of sand down
in the hull to counterbalance, shouldn't
that take care of it? If so, should they
be placed on the sides, or in the center?

"Mike" wrote in message
...
Holy shi** g

--Mike

"Gregory Hall" wrote in message
...

"David" dh@. wrote in message
...
I've got an old boat very much like this one:

http://www.warnersdock.com/images/Fr...fores15yel.JPG


snip

THIS is top-heavy:
http://images.thebiggestbreasts.com/...fake_boobs.jpg

Caution: nudity. Adults only please.

--
Gregory Hall




LOL, is that a look of pain on her face

On Thu, 03 Jul 2008 14:34:39 -0100, David dh@. wrote:

I've got an old boat very much like this one:

http://www.warnersdock.com/images/Fr...fores15yel.JPG

that I'm trying to make into a mini-houseboat,
sort of like a camper. I only expect to have
about 200-300 pounds in the roof and walls,
and the roof will only be about 48" above
the gunwale. The hull will weigh a *lot* more
than what is added, so shouldn't that alone
be enough to keep it from being top heavy
and flipping over? If I add weight, like a
couple hundred pound bags of sand down
in the hull to counterballance, shouldn't
that take care of it? If so, should they
be placed on the sides, or in the center?


You probably want to go over to the rec.boats.cruising group and give
Roger Long a shout. I doubt that he will be prepared to tell you
whether your boat is a camper but he probably would get you a
reference to some rough and ready "righting moment" calculations which
you could use to figure out the answer to your question.


Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Mike wrote:

Holy shi** g

Yes indeed! Amazing what they can with modern plastics ;-)


THIS is top-heavy:

http://images.thebiggestbreasts.com/...fake_boobs.jpg

Caution: nudity. Adults only please.

David wrote:

I've got an old boat very much like this one:

http://www.warnersdock.com/images/Fr...fores15yel.JPG

that I'm trying to make into a mini-houseboat,
sort of like a camper. I only expect to have
about 200-300 pounds in the roof and walls,
and the roof will only be about 48" above
the gunwale. The hull will weigh a *lot* more
than what is added, so shouldn't that alone
be enough to keep it from being top heavy
and flipping over? If I add weight, like a
couple hundred pound bags of sand down
in the hull to counterballance, shouldn't
that take care of it? If so, should they
be placed on the sides, or in the center?


Well, boat stability is a complex subject. Here
some loose thoughts (before my first cup of coffee,
so no guarantees that I get all things right. I'm
sure others will jump on the chance to correct my
worst blunders - maybe I can learn something too!)

I would recommend you read a bit more about it. The
"Nature of Boats" by Dave Gerr is a good all-around
introduction, and doesn't get too technical. Many
other books work as well.

When you add weight and windage high up, you reduce
the stability. That increases the risk that your boat
will capsize in high seas (or even in flat water). It
also changes the way the boat rolls in seas, which may
make it more or less comfortable to be inside.

You are right, you can compensate by adding weight (as
low as possible!). This will make the boat sit deeper
in the water. Maybe too deep.

It all depends what you are going to use the boat for.
With a solid house on it, and enough ballast to keep her
upright, she will not want to plane. If you can live with
moving her at hull speed (a few knots), you can make do
with *much* smaller engine, and use the weight difference
as ballast. If you do not plan to move her around much at
all, then you can afford to load he a bit deeper, as the
sailing characteristics won't matter.

You can probably get an idea of the stability by doing a
simple roll period test. Rock the boat sideways, it will
settle on some speed of rolling from side to side. If
this roll time (in seconds) is the same as your overall
beam (in meters), (or 10% more), you have what Gerr
describes a good initial stability. If the boar rolls
much faster, you have more (initial) stability for
good comfort - that would be good news for you. If,
after all the construction, your boat rolls slower than
this, you may want to add some ballast.

In any case, keep the structure as low as you can manage,
and build it light! It looks like a small boat to begin
with, so don't even try to build a large house on her.
Keep it small and simple, and might work well.

Remember that a boat is always a compromise. A heavily
modified boat is a compromise between the original
compromiseand a your new ideas. It is your own boat,
and it is you who will have to live with it. Don't let
us naysayers put you completely off. But watch out, it
is also your own life you are risking, and possibly your
dear ones as well!

Good luck!

-Heikki

Matt,

Haven't heard from you in a while. Nice to have you back.

I remember that you knew my boat in her previous life. Take a look at her
now

http://home.maine.rr.com/rlma/Boat.htm

Have you heard anything about the previous owners? Last I talked to them,
one was having some medical issues and they weren't sure if they were going
to be able to go cruising. I've now lost contact.

Container ships sometimes have a slight negative GM, or used to 30 years ago
when we would watch them come down the harbor with a slight list, make the
turn, flop over, and continue on to sea with a slight list the other way.
They have enough freeboard and flare in the ends that the righting arms
would go positive after a couple degrees of heel. This loading made for
minimal rolling and least strain on the upper layers of boxes. You can only
get away with this in a very large ship though.

The mini houseboat fellow won't get very far trying to apply what he reads
about GM in a standard textbook to his problem. He should weight a sheet of
plywood or get it's weight, calculate how much he needs to make the cabin,
add about 50% for framing and other stuff, and then add the estimated weight
of anything else he plans to put on board. Next put a table on board with
the legs propped up a bit to get the top to about 75% of the cabin height.
Pile the table with the estimated weight and go aboard. If the motion feels
drunken and sluggish with very slow rools, the boat will probably be
uncomfortable as well as dangerous. Keep removing weight from the table
until a couple of people can walk around with the boat feeling solid and the
rail getting close to the water. Then figure if he can build a cabin
within that weight allowance.

Strong winds are another issue but it sounds like this is a lake boat to
spend most of its time on a mooring.

--
Roger Long

Roger,

I like both your practical answer and your pictures.

You're cruising my old stomping (sailing) ground. I do miss the coast.

Tom had recovered well and was looking good last time I spoke to him.
I'll send him the URL to your pictures.

I was kind of hoping that this guy would get the plan that there is a
whole lot to know before his question could be answered effectively.

A tanker I was 2AE on had a negative GM and a slight port on the way
out. Every wave made it snap to Stbd, stall a couple of seconds and
snap back. It was all a guy could do to stay on his feet. We did lose
the fire in one boiler, but the FM lit it off the bricks. My chief
called the bridge and told them if they tried to make for sea this way,
he would shut them down. - They believed him, but he still had to
listen to a bunch of griping because we lost two hours while they
finished correcting the ballast.

Matt

On Jul 4, 10:46*am, Matt Colie wrote:
Roger,

I like both your practical answer and your pictures.

You're cruising my old stomping (sailing) ground. *I do miss the coast.

Tom had recovered well and was looking good last time I spoke to him.
I'll send him the URL to your pictures.

I was kind of hoping that this guy would get the plan that there is a
whole lot to know before his question could be answered effectively.

A tanker I was 2AE on had a negative GM and a slight port on the way
out. *Every wave made it snap to Stbd, stall a couple of seconds and
snap back. *It was all a guy could do to stay on his feet. *We did lose
the fire in one boiler, but the FM lit it off the bricks. *My chief
called the bridge and told them if they tried to make for sea this way,
he would shut them down. *- They believed him, but he still had to
listen to a bunch of griping because we lost two hours while they
finished correcting the ballast.

Matt

Well, at the risk of being simple. I still suggest it's the wrong boat
for the job. He just needs to start with the right boat. He can
justify, defend, and make any excuses he wants.. Still water,
whatever.. But once you leave the dock, things can change quickly to
something you have never seen before.
Anyway. Have a great fourth, go out in your boats for me Scotty

On Thu, 03 Jul 2008 22:27:51 -0400, Matt Colie
wrote:

Every boat has the center of gravity above the center of buoyancy.

Why? Ever hear of heavy ballast keels? If the superstructure is heavy
that's one thing, but it doesn't have to be.

Casady