On Wed, 24 Nov 2010 19:50:37 -0600, Vic Smith
wrote:

On Thu, 25 Nov 2010 07:50:21 +0700, Bruce
wrote:

On Wed, 24 Nov 2010 06:12:11 -0800 (PST), Joe
wrote:


If the hull speed is 11 kts ..it's eleven knots even with a bobulious
bow.
So lets say you have a 15% drag, you hoist 20% more canvas.

Joe

Do you really not understand what is written or is it deliberate.

I didn't say that the bulb bow increases speed, I said that it
decreased drag. Damn, it is even right up at the top of the part of my
message that you have included.

However, if you don't understand here is a quote from the Wiki, which
I might add, is freely available to anyone that cares to look.

A bulbous bow is a protruding bulb at the bow (or front) of a ship
just below the waterline. The bulb modifies the way the water flows
around the hull, reducing drag and thus increasing speed, range, fuel
efficiency, and stability. Large ships with bulbous bows generally
have a 12 to 15 percent better fuel efficiency than similar vessels
without them.
Bulbous bows have been found to be most effective under the following
conditions:
when used on hulls with waterline lengths of more than about 15 m (50
ft)
when used on long, narrow hulls
when used at speeds close to the vessel's maximum speed
These points make them a standard feature for cargo ships, naval
vessels and passenger ships, all of which are large, narrow and
usually operate within a small range of speeds close to their top
speed. On the other hand, they are virtually unknown in recreational
craft like yachts, especially sailing vessels and powerboats.
Contents [hide]


Cheers,

Brice

I think what Joe was saying is that if hull speed is reached under
less than full sail, more sail can compensate for any generator drag
so hull speed is still maintained.
Basically excess and wasted wind is utilized to generate power.
I don't know how common or what percentage of time a sail boat moves
at hull speed with less than full sail, but it seems a good point to
make.
Bulbous bows have nothing to do with that.

--Vic

Certainly. However what portion of the time does the boat move at less
then hull speed with all the sails up?

And yes, I've seen boats built with more sail area then one might
think logical, usually because the owner wanted thicker (and thus
heavier) hull plating.

But there is another problem with having all that top hamper. What do
you do if it comes up a real blow? The square riggers sent down their
topmasts in a blow but it is hardly feasible on a single handed yacht.
The weight of the mast and rigging does have an effect on the boat's
righting moment.

Cheers,

Brice

On Nov 25, 4:56*am, Bruce wrote:
On Wed, 24 Nov 2010 19:50:37 -0600, Vic Smith





wrote:
On Thu, 25 Nov 2010 07:50:21 +0700, Bruce
wrote:

On Wed, 24 Nov 2010 06:12:11 -0800 (PST), Joe
wrote:

If the hull speed is 11 kts ..it's eleven knots even with a bobulious
bow.
So lets say you have a 15% drag, you hoist 20% more canvas.

Joe

Do you really not understand what is written or is it deliberate.

I didn't say that the bulb bow increases speed, I said that it
decreased drag. Damn, it is even right up at the top of the part of my
message that you have included.

However, if you don't understand here is a quote from the Wiki, which
I might add, is freely available to anyone that cares to look.

A bulbous bow is a protruding bulb at the bow (or front) of a ship
just below the waterline. The bulb modifies the way the water flows
around the hull, reducing drag and thus increasing speed, range, fuel
efficiency, and stability. Large ships with bulbous bows generally
have a 12 to 15 percent better fuel efficiency than similar vessels
without them.
Bulbous bows have been found to be most effective under the following
conditions:
when used on hulls with waterline lengths of more than about 15 m (50
ft)
when used on long, narrow hulls
when used at speeds close to the vessel's maximum speed
These points make them a standard feature for cargo ships, naval
vessels and passenger ships, all of which are large, narrow and
usually operate within a small range of speeds close to their top
speed. On the other hand, they are virtually unknown in recreational
craft like yachts, especially sailing vessels and powerboats.
Contents [hide]

Cheers,

Brice

I think what Joe was saying is that if hull speed is reached under
less than full sail, more sail can compensate for any generator drag
so hull speed is still maintained.
Basically excess and wasted wind is utilized to generate power.
I don't know how common or what percentage of time a sail boat moves
at hull speed with less than full sail, but it seems a good point to
make.
Bulbous bows have nothing to do with that.

--Vic

Certainly. However what portion of the time does the boat move at less
then hull speed with all the sails up?

Ohh so if you are not at hull speed then you can not compensate for
the drag using more sail even if you are sailing slower than hull
speed


And yes, I've seen boats built with more sail area then one might
think logical, usually because the owner wanted thicker (and thus
heavier) hull plating.

So he used more sail to compensate for the increased drag/load....what
a crazy ideal.


But there is another problem with having all that top hamper. What do
you do if it comes up a real blow?

Geeeze, reef and furl..They even have these new fangled things that
can just roll up the sails.


The square riggers sent down their
topmasts in a blow but it is hardly feasible on a single handed yacht.

The Maltise facon, the largest private sailing yacht in the world has
it sails furled by one person pushing a button.

The weight of the mast and rigging does have an effect on the boat's
righting moment.


Ever hear of that stuff called ballast?
Are batteries heavy?

Joe

Cheers,

Brice- Hide quoted text -

- Show quoted text -