weights to make snorkel less buoyant

[Diver0001]

Unlike boats, snorkels are open at both ends. Even when held in the mouth, they are not a sealed tube. I wonder why, following the buoyant snorkel logic, facemasks do not pull themselves free, or push the wearer's head toward the surface? After all, masks hold a sealed air bubble and snorkels do not.

when it's in you mouth it is no longer open on both ends. It will, in fact create a miniscule amount of upwards force.

R..

 

[vladimir]

Unlike boats, snorkels are open at both ends. Even when held in the mouth, they are not a sealed tube.

Nor is a boat a sealed tube, yet it is buoyant. It's just a question of whether it displaces enough water to offset its weight.

I wonder why, following the buoyant snorkel logic, facemasks do not pull themselves free, or push the wearer's head toward the surface? After all, masks hold a sealed air bubble and snorkels do not.

First, we would have to know the weight of the mask and the weight of the water it displaces. If the weight of the water it displaces is more than the mask's weight, it is buoyant while in place, and it is subject to an upward force, however slight.

Second—and you seem to be having a hard time grasping this—when the snorkeler is on the surface, it doesn't matter whether the snorkel is sealed or not. If it is displacing water it is just a question of whether that water weighs more than the snorkel itself. Without knowing the weight of the snorkel and the water it displaces we can't say whether it is buoyant or not, but it certainly could be.

 

[agilis]

Alas, it's true that I have difficulty grasping many things. Still, it seems to me that when a snorkel is being employed at the surface, it is being breathed through, and consequently is not sealed at one end. It is connected to the snorkeler's respiratory system. Consequently, the only water being displaced is that displaced by the insignificant amount of solid material from which the tube itself is constructed. Another element to be considered is the portion of the snorkel that is above the surface. It would obviously be exerting a downward force, however miniscule.

This is all rather ridiculous. Detach a snorkel from the mask while using it at the surface and hold it in position with a finger. You will find it tends to sink, not float.

 

[vladimir]

Alas, it's true that I have difficulty grasping many things. Still, it seems to me that when a snorkel is being employed at the surface, it is being breathed through, and consequently is not sealed at one end. It is connected to the snorkeler's respiratory system. Consequently, the only water being displaced is that displaced by the insignificant amount of solid material from which the tube itself is constructed.

That is wrong. Whether or not air is passing through the tube has no effect on the amount of water it displaces. Whether or not it is connected to the snorkeler's respiratory system has no effect on the amount of water it displaces. Whether or not it is sealed at one end has no effect on the amount of water it displaces, as long as water is not entering.

If the snorkel was filled with water, then the only water it would displace would be by the insignificant amount of solid material from which the tube itself is constructed. The OP specified that he was talking about snorkeling on the surface, when the snorkel was filled with air.

You should review Archimedes' Principle; it is fundamental to a proper understanding of simple diving physics.

 

[agilis]

With all due respect to Archimedes, try the acid test I mentioned- operational reality, not possibly misapplied theory. Free of any connection to the mask the snorkel will tend to sink, not float. This can be perceived with the unsupported snorkel held lightly in the snorkeler's mouth. I will certainly follow your recommendation and review Archimedes' principle, particularly as it applies to the density of material and its effect on water displacement. It might help to determine what is the better snorkel construction material- gold or wood.

 

[vladimir]

Because the snorkel is open on top it exerts no upward pull.

Wrong. It may or may not be buoyant, but the open top has nothing to do with it.

In any case, sealing the snorkel at both ends changes its buoyancy substantially.

Wrong. Sealing it does not change its buoyancy at all, assuming it is displacing the same amount of water (ie, submerged to the same extent and still excluding water).

When you are employing a snorkel in the usual manner it has no significant buoyancy because it is open on one end.

Again, wrong. It might have no significant buoyancy, but the open end has nothing to do with it.

Unlike boats, snorkels are open at both ends. Even when held in the mouth, they are not a sealed tube. I wonder why, following the buoyant snorkel logic, facemasks do not pull themselves free, or push the wearer's head toward the surface? After all, masks hold a sealed air bubble and snorkels do not.

Wrong, as noted above.

Still, it seems to me that when a snorkel is being employed at the surface, it is being breathed through, and consequently is not sealed at one end. It is connected to the snorkeler's respiratory system. Consequently, the only water being displaced is that displaced by the insignificant amount of solid material from which the tube itself is constructed. Another element to be considered is the portion of the snorkel that is above the surface. It would obviously be exerting a downward force, however miniscule.

Wrong, as noted above.

This is all rather ridiculous. Detach a snorkel from the mask while using it at the surface and hold it in position with a finger. You will find it tends to sink, not float.

This might or might not be true, depending on the density of the material it is made from and the amount of water it displaces.

With all due respect to Archimedes, try the acid test I mentioned- operational reality, not possibly misapplied theory. Free of any connection to the mask the snorkel will tend to sink, not float. This can be perceived with the unsupported snorkel held lightly in the snorkeler's mouth.

Yes, again, this might be true, but all of your reasoning above is flawed.

I will certainly follow your recommendation and review Archimedes' principle, particularly as it applies to the density of material and its effect on water displacement. It might help to determine what is the better snorkel construction material- gold or wood.

Good; when you read Archimedes' Principle you will see that it covers that, and you have some intuitive understanding of it. Yes, it is certainly possible to construct a snorkel that sinks, as well as one that floats. The weight of the snorkel and the amount of water it displaces will determine which. Whether the top is sealed or not will not be a factor in its buoyancy, though it will affect its utility.

 

[agilis]

Thanks for clearing things up for me. Something beyond 'wrong' would have been helpful, but the absolute certainty of your tone carries great weight. Or is it density? In any case, your disclaimer "Everything I post is an opinion; I do not pretend to have any facts to offer" puts your comments into proper perspective, and your use of a semi-colon is most impressive.

Your kind approval ("Good...") and generous observation regarding my intuitive but flawed understanding has given me some small hope and done wonders for my self-esteem.

 

[Diver0001]

Your kind approval ("Good...") and generous observation regarding my intuitive but flawed understanding has given me some small hope and done wonders for my self-esteem.

I'll give that my vote for funniest come-back I've read all week

R..

 

[HBDiveGirl]

I'll give that my vote for funniest come-back I've read all week

R..

+1.
And I'll raise that to "Best of Year."



"If you can't explain it simply, you don't understand it well enough."
--Albert Einstein

 

[vladimir]

the absolute certainty of your tone carries great weight.

If that were a good way to evaluate posts a reader might still be undecided between yours and mine.