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Joe,
I think your best approach would be to determine
what you consider a weight you can haul on a trailer and then use that weight
for your sub's displacement. You'll quickly see that what your designing
is way to large for anything other then a tractor and semi trailer.
Water weighs nothing in water! If your
planning to trailer a light sub and later take on water to make your sub heavy
enough to dive, your just building a big tank attached to your sub to take down
with you. The only way that water ballast is effective is if it's
contained within your existing hull's displacement. Adding on ballast
tanks to make a large sub heavy enough to dive is futile. The only way to
make a sub heavier with water is to increase your weight without
increasing the displacement. That is, reduce your sub's interior
space with water tanks.
You have to trailer all the weight with you,
either in or on your sub, to dive it when your ready to launch.
If your sub displaces 28,637 lbs you must have your sub weigh that much with your hard
tank full of water or you aren't going down. Your trailer must
be capable of hauling that much weight minus the water your hard tank
holds.
As Carsten advised, your hard tank volume
is only a small percentage of your subs total weight. It's
for adjusting buoyancy and not practical to add significant weight to an under
weighted sub.
You have several options, A smaller sub
(less displacement), and less to trailer.
A
large sub with a lot of fixed lead weight either inside or outside of the hull
(if
outside, you have to consider the water it displaces also).
Make your sub out of heavier or thicker material and let the weight of that
extra material
do
some work for you by allowing you to dive
deeper.
No matter how you cut it, you have to trailer the
subs displacement weight to the launch ramp or your sub will be a
surface boat..
I think you'll find that 5000 to 7000 pounds is
about the upper practical limit. One additional reason not to get
to large is, most boat ramps aren't deep enough to launch a large diameter
sub from a trailer.
Dan H.
----- Original Message -----
Sent: Saturday, November 12, 2005 5:45
PM
Subject: [PSUBS-MAILIST] Variable Ballast
Calculations
Carsten,
Yes you did understand me correctly, the soft water ballast
ratio is indeed high in this example. However, the response indicates to me
that I understand the principles much better than when I started out. The
target range you mention of 20 to 30% of dry weight for a sea boat is
extremely helpful, thank you. I am still learning, with help from those such
as yourself, what is and what is not possible.
I am trying to work the numbers for a dry ambient boat that
would be large but still be trailer able. It will take me months but if I
will post schematics when I have what I believe to be a practical
solution. See the link below to follow my train of thought.
Thank you
Joe Perkel
Miami, Florida
Rick,
Same as above, the numbers represent a new upslope in the
learning curve for me. They are indeed lopsided as you and Carsten point out,
but they are in the theoretical ballpark if not a practical one. Exomos (see
the link) has a submersible "surface" yacht (Proteus) that has a displacement
of 45 tons. They do not specify if this is submerged or not but the thing does
25 knots on the surface.
I don't want to go 25 knots, but I suspect that the dry weight
to ballast numbers look something "like" my example in order for it to plane
at that speed.
To answer your question about size, whatever is possible for a
crew of three in relative comfort?
Thank
you as well.
Myles,
Dry
weight and displacement are not the same thing. I appreciate the effort
however.
Thanks
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