Stay tuned ...on a much smaller boat, there was one produced that did all
these things. I think the concept and how the boat worked were up to snuff,
but the company built cheaply (or something) and ended up going out of
business, or something like that. Anyway, to make a long story short, a
friend of mine told me about a boat that could be used for planing (w/o
ballast), or sailing (w/ballast), or motoring in rough seas (w/ballast). He
had pictures. I'll dig up a reference and post it here... it was
interesting.

Brian

"Jim Woodward" jameslwoodward at attbi dot com wrote in message
...
Broadly speaking, it's done all the time in larger vessels.

Fintry was built with tanks for 50,000 pounds of seawater ballast. We' re
putting a bow thruster in the forward one, so we'll replace the weight
there
with lead, but the aft pair (14,000 pounds each, p&s) allow us to get her
up
to a draft of less than seven feet for sheltered waters or down to over
eight feet at sea.

Actually doing it in a boat that will go between planing and displacement,
is another thing. The hull forms are quite different and it might prove
to
be a challenge. And, of course, you're talking about a lot of water --
you
might not like what it does to the interior in a 46 foot boat. You can
see
Fintry's tanks between frames 2-6 and 41-45 at
http://www.mvfintry.com/details.htm -- the scale on all the drawings
shows
frame spacing, which are 20" apart.

--
Jim Woodward
www.mvFintry.com

"AP" wrote in message
...
I want to build a cruiser with the following characteristics
46 foot with very deep V foreward. 25-28 degrees deadrise at transom
Overpowered.
And I want to have a " ballast tank."
The idea is :
If the sea is calm I will have the ballast tank empty and I will make
her
plan using my extra horsepower.
If the sea is rough (or I meet heavy weather on the way) I will ballast
my
tank, increase the displacement, will slow down the engines and I will
be
sailing like a deep V boat, good for
rough weather.
Does that make sense??
Comments/suggestions are kindly invited.
Regards
AP