Removing Submerged Navigation Hazards

[TomC]

Originally Posted by Yankee

Dave,

Why would the rock weigh less under water than above it?

terms which people tend to use interchangeably, but they do not mean the same thing...

[SIKSUKR]

I know what you mean Seaplane,I've seen the damage done at your Dockham Shore property.

[Dave R]

Any chance you can just mark the rocks well and leave them alone? I see plenty of privately maintained navigational aids on the lake. I can't imagine why marking would be a problem. Of course, being denied the option of moving them seems utterly silly to me. Love to hear a good reason why the rocks should stay.

[John A. Birdsall]

Originally Posted by Dave R

Any chance you can just mark the rocks well and leave them alone? I see plenty of privately maintained navigational aids on the lake. I can't imagine why marking would be a problem. Of course, being denied the option of moving them seems utterly silly to me. Love to hear a good reason why the rocks should stay.

I think I can see a reason why rocks should stay, specifically only along the shore line which is what I think they are talking about. and that is too stop the errosion of the beaches or land. I say that cause they said to "move the dock" why not find a way to anchor your dock on the rock. My dad often says that an old timer stated sonny if you find anything that can stay in that lake you will make your first million. Well boulders do stay put. Even when hit by boats or propellars.

[Pineedles]

Just blow the damn thing up and take the consequences if any.

[jrc]

Originally Posted by Yankee

I asked the question because I was curious about the answers that I’d get. Let me give you a brief high school level primer:

....

Don't be so pedantic, we answered the question how it was asked. We explained "Weigh" as an English word on a freindly website, not the formal scientific meaning.

[jrc]

Originally Posted by Yankee

....

jrc, excuse me! We? Do you have a mouse in your pocket or what? Jeesh! For what it's worth, I'd rather be pedantic in a post than haughty, like you....


Not too much time, just an engineer by trade, and a geek at heart!!

I guess, my point was that there are several engineer/geek people on the board that are well qualified to give you a scientific explanation. But since I didn't know a geek was asking, I gave a real world example. I am brusque and rude, but am I really haughty?

[ITD]

Mass, you people are talking about the mass of an object, which doesn't change. Weight is generally a measure of force exerted by an object due to gravity. Weight generally falls under the auspices of f=ma where f equals the force measured (weight in this case), m equals the mass of an object and a equals the acceleration due to gravity. Weight (the measure of force) is also influenced by the medium in which an object is weighed, even air has an effect. Also, although we generally consider the acceleration of gravity to be a constant, it does vary dependant upon your location on the earth. This variation is very small fortunately. The mass of an object is constant no matter where an object is weighed.

A rock, however, will weigh less in the water than on land.

[SteveA]

Maybe David Copperfield could make it disappear... worked for a 747 in 1981.

Another thought, maybe someone could go down to the dock and read this entire thread to the rock.... it may just leave on its' own. Considering that it has been suggested to tow it, drill it and even blow it up..

PS... I'd feel better if someone would admit to having had to look up the word pedantic like I did.

[GWC...]

Originally Posted by SteveA

PS... I'd feel better if someone would admit to having had to look up the word pedantic like I did.

Okay, just to make your day, since you did such a great job with FFIII - I did, too.

Actually, reading the second definition made it seem an apposite choice.

For those less likely to exert the effort, here's the definition:
pedantic
One entry found for pedantic.

Main Entry: pe·dan·tic
Pronunciation: pi-'dan-tik
Function: adjective
1 : of, relating to, or being a pedant
2 : narrowly, stodgily, and often ostentatiously learned
http://www.m-w.com/dictionary/pedantic

[Weirs guy]

As a half-an-engineer, I think the real question all of us geeks at heart should be asking is this:

When do we get to blow up the rock, and how much explosives do we get to play with?

[Airwaves]

J.A.B wrote
"move the dock" why not find a way to anchor your dock on the rock.

Actually that is a very good idea. If the rock is close enough to do damage to the boat when you come into the dock or leave it, why not look at using the rock as an anchor to the dock, or extending/moving the dock so that it covers the rock? I remember when we had a place on Dockham Shore there was a huge rock just off our dock. It didn't cause us any problem to our boats (I actually named it Big Bertha!) but if it had we certainly could have covered it with the dock itself.

[Mee-n-Mac]

Originally Posted by Weirs guy

As a half-an-engineer, I think the real question all of us geeks at heart should be asking is this:

When do we get to blow up the rock, and how much explosives do we get to play with?

Sadly the answer is probably not as much as you'd like. A few bore holes and just a tiny bit would no doubt do the job. Wasn't there a MythBuster's episode where they re-created the water-in-a-safe + explosives to "crack" it ? I'm thinking T.H.E. Binz might be better off enlisted a squad of UDE rock bass. I mean they must be called rock bass for a reason !? Perhaps they could be enlisted to peck away at the rocks Then it's all due to "nature" and he couldn't be blamed. Until then I' thinking the old Chlorox bottle(s) on a string is a legal alternative.

[ITD]

A series of holes with wedges tapped in could also be done, has worked for hundreds (thousands???) of years. Probably a little tougher to do underwater though.

[Pineedles]

Exactly, a few wedges and in a couple million years the rock will split. Problem solved.

[fpartri497]

Originally Posted by Yankee

I asked the question because I was curious about the answers that I’d get. Let me give you a brief high school level primer:

Specific gravity also known as relative density is the ratio of of an objects density (mass/volume) to a reference density, which is usually water but also can be a gas or any other form of matter. It has absolutely nothing to do with the weight of an object, in this case the aforementioned rock.

Weight is the force enacted upon a body (of a certain mass) when exposed to a gravitational field. This is why a person would weigh less on the moon than the Earth, but he would also maintain his same mass. It’s suffice to say, whether the rock is under or above the water, it will have the same mass and since the Earth’s gravitational field is constant, it will have the same weight. So it will be just as heavy no matter where on the Earth that it resides.

You got way to much time on your hands!!!!!!!!

[Dave R]

Originally Posted by Yankee

I asked the question because I was curious about the answers that I’d get. Let me give you a brief high school level primer:

Specific gravity also known as relative density is the ratio of of an objects density (mass/volume) to a reference density, which is usually water but also can be a gas or any other form of matter. It has absolutely nothing to do with the weight of an object, in this case the aforementioned rock.

Weight is the force enacted upon a body (of a certain mass) when exposed to a gravitational field. This is why a person would weigh less on the moon than the Earth, but he would also maintain his same mass. It’s suffice to say, whether the rock is under or above the water, it will have the same mass and since the Earth’s gravitational field is constant, it will have the same weight. So it will be just as heavy no matter where on the Earth that it resides.

OK, what would happen if we were to hang the rock on a scale while it's in the water and while it's out? Would the scale read the same weight or not? That was my point. I realize the rock's mass never changed.