Jim, thank you for your posting.
What you have between Fr. 2-6 and Fr. 41-45 is sort of fore peak and after
peak tank, which
as far as I understand the effect is to make a pure displacement vessel even
heavier/deeper or
to change the trim. (this possibility was reduced since you converted the
fore peak to a bow thruster
compartment.
Indeed, what I am talking about is a different thing.
I take for granted (if I am wrong please correct me) that
A deep V sails better through heavy seas, but you have to be prepared to
spent more
energy to make her push the water aside and make her way through it
A planing or semi-planning hull needs less power and is faster, provided
the sea is
calm. Once the sea gets rough, this advantage less power/speed is lost,
you have to slow down
to reduce the pounding and, if things get worse, then you probably think
that your choice of a semi or planing hull was not right.
If we place the displacement hull on a scale on zero and the lightest
planing hull on ten, any hull
you find on the market will cover two points one the scale. No more. Your
mv Fintry is 0-1, a
low powered Hatteras goes 3-4, a Sealine goes 6-7 and a Baja sport boat goes
8-9 and competition boats go to 10. A prospectvie buyer will make his
choice according to his needs.
And the manufacturers of mass production try to make the best hull form for
each (narrow) range.
What I want to do is to ample the range for a hull (lets say from 3 to 6 or
7) and I am prepared
to pay the price, which to my understanding is that I will have to be
overpowered and give the engines more fuel than that of the Sealine and I
wil never peform like a Sealine in calm seas. Neither like a Hatteras in
rough seas. In evey case I will be spenting more fuel/mile.
Of course I will lose space for bigger engines and the ballast tank(s) let
alone I will need good
tranfer pumps which are heavy and additional manhours and cost to make
transverse and longitudinal separations to reduce the free surface inertia.
I will probably need Gear Box of two ratios (I have heard that ZF started
producing something like that)
To cut a long story short, I want to be fast in calm seas and not to start
praying in heavy seas. I will slow down, ballast and be closer to the zero
on the "scale" I described you earlier. I would sail
not exactly like a Hatteras or a Bertram, but closer to them
I do not think that I have invented (or re-invented) the wheel. The fact
that manufactures of those
moving on the water machines have not made the slightset effort to ample the
range using ballast/extra horsepower etc make me think (1) my concept is
wrong (2) my concept is right but
only few prospective buyers would make such choice- so no target group.
What makes me post this is my hope that somebody will reply and tell me I am
wrong because this
and that or will tell me : you maybe right but you are "minority"- most
people do not like it, or whatever..
I havent found any boat plans with ballast tank on the net.
Is my dream to build such a ballasted/deballasted boat an " utopia"?
Thanks for giving me your time to read this. Somebody has something to say?
Regards
AP
"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