actually, that hull shape would make you run into problems. your shading also does not really represent it as such. may I represent taking a look here:
https://dl.dropboxusercontent.com/u/632 ... le%203.png
as for why you would run into problems.
- the boat you linked has a draft which is about the same size as your beam. that means that the draft of your vessels with such a hull shape would need to be 3 times what you have now to have those guns on board.
Fishing boat?
- boilers take quite a lot of your in-hull volume. however, in this hull shape they could not go all the way to the lower decks (as the hull has a bit of a V shape at the bottom and is round higher up) meaning you have the boilers starting about 2-3 meters above the keel. this means more weight up top and thus less stability (which you can best increase by adding to the beam)
Do you mean taking the Vee out and bulging the hull amidships?
- if you look at the hull of that small boat, you see how high the bow and stern go up. this shows what kind of waves that hull can expect when sailing....... the bow is quite round, as the hull is not made for relatively high speeds (it is actually a hull very close to that of sailing ships) so the bow wave will be large.
With a lot of parasitic drag implied from the bows on. More about that factor (thanks for pointing that mistake out to me.) when we discuss aircraft below.
- note that on the small boat on the picture, the hull is actually not stern heavy, there is only a big keel which holds the rudder and propeller, which adds very little to the volume but protects these 2 parts.
Okay.
in other words, have you any grounded reason why you think this is a suitable hull shape for ships like this? because the ones I can think of all go back to the sailing ships.
Topheavy sailing ships which needed deep keels, if I am following you properly.
Got it; area rule for boats applies to buoyancy. Not the same as aircraft, but I understand the sausage segments rule.
what? area rule? the area rule is a rule about an object going near supersonic speeds, something you are not going to do with an boat! (especially since the speed of sound in water is actually higher IIRC) I am talking about stability.[/quote]
I see what you mean in the example boat.
Further, you're right about keel strikes. I get that a propeller strike in a steep gradient is very common, but the harbors I describe have nasty shallow gradients, even for the bars and reefs. I think the bow might hit first and reverse hog the ship (snap the keel), like that US cruiser did, that grounded and was ruined a few months back at Pearl Harbor. She'll be back in 2017. Lots of money wasted.
actually, the reverse. in steep gradients the part that comes first will hit first. in a shallow one, the deepest point will hit first. the line between those 2 is the angle of the keel: if the keel is more horizontal then the gradient the most forward part will hit first, if it is more vertical then the bottom gradient the deepest part will hit first.[/quote]
Wouldn't that depend on the angle of difference in the two slopes?
The Americans started with monitors and lost about a dozen of them to swamping and waves. Those things tended to take the whole crew when they went. Not a lot of reserve buoyancy. I just thought that Mister Robeson would have lied to the American congress about what he was building (That congress loved monitors. Those were cheap. Battleships and seagoing armored cruisers were expansive.) or planning in the AU. Even at that the Baltimore is kind of monitorish. Small, short ranged and with a low freeboard. The illustration is labeled (I hope) correctly.
Even at that, the old Baltimore has a freeboard I wouldn't trust in blue water. Not in those days where hatch and manhole seals were no good. In the real time line, I
shudder when I read the accounts of the USS Oregon's speed run. That was supposed to be an ocean going battleship.
of course, monitors were not meant to be oceangoing ships. IIRC they did a few ocean crossings with them, after the addition of breastwork to keep waves from going over the deck! however, the problem is that your ships would have been expensive, even when called monitors. [/quote]
It was those ocean crossings where the sinkings occurred.
The reason the monitors were expensive for the Americans to build has more to do with the half decade or more lag in their technology viv a vis the Europeans (specifically France and Britain who were in an arms race of sorts at the time. The Americans started and stopped work on Amphitrite and her sisters about a half dozen times. Shipyards went bankrupt on canceled contracts or revised requirements. Every time the Americans thought they had a handle on the problems, the British or the French or they, themselves, would invent something new that caused a work stoppage until they either incorporated the new idea or tech and revised the ships accordingly.
An example of this backwardness is the question of naval artillery. Many US ships still used brown and black powders when the French and British moved to nitrocellulose propellants. You can see it in the short caliber guns and larger bores the Americans were using compared to their European counterparts. Breech design was another issue. And then there were the gun houses and barbettes, ammunition stowage and hoists, rammers, the slue and elevate gears, etc. Just in those areas alone, when you look at ships like the Texas and the Indiana, you realize that those vessels actually look primitive or somewhat behind their British and French opposites. It's not until the turn of the century until the Americans finally catch up.
if I were you, I'd look into the wonderful world of ship stability before drawing all your ships and finding out they would float..... upside down. (which is the impression I get from your last 2 drawings as well)
Topheavy?
Revisions.
The drafts are deeper, the hulls are bulged and I hope that corrects the topheaviness.
Oh, yeah,
I almost forgot.
The underwater cross section shape is defined by dimensionless shape parameters that control the beam/depth ratio, the angle of the sides near the waterline, and the slackness of the bilge. I vary these parameters smoothly along the length of the hull to produce a fair shape. The wetted area is the biggest influence on the hull's low speed resistance, and this is largely determined by the cross sectional shape. The wave drag is also influenced by the cross sectional shape, but this is not as strong an influence as the manner in which the area of each cross section changes along the length of the hull - the cross sectional area distribution.
Drag is drag, whether plane or boat and the term 'area rule for wetted surface' applies. The difference is that in a plane, lift (vacuum generated over the top of the shape as the air flows past a more curved (camber) surface is the 'float' component, while the volume of water displaced by the air bubble in the hull is the float component for the ship. So with the ship the area rule has a constant volume cross section component for that water displacement as the major factor, while the aircraft is more concerned with pure drag caused by the slipstream. Another difference is that the ship from a gravity standpoint is a continuous supported beam, while the plane is fundamentally a single point bridge load suspended by the main wing.
Similar constant area cross section sausage segment rule, different forces and attributes ratios involved.