weights to make snorkel less buoyant

[agilis]

Try tossing your snorkel in the water. If it sinks (give it a few seconds if it's one of those ridiculous types with all sorts of frou-frou bulbs, bulges, and passage ways), it's not buoyant. If it floats, then you are correct, and I am wrong. If that's the case, I suggest getting some metal pipe of appropriate diameter, about 3/4 inch. One straight section about 14 inches long, threaded on the bottom, and another 3 inch section, also threaded at one end. You will need two right angle angle sections with female threads that you will connect with a threated nipple, creating a 'U' section. Thread the 14" (approx) section to one end of the U section, and the shorter 3 inch section to the other end. Attach a mouthpiece to the shorter open end, and you are in business. Remember to use pipe tape on the threads to create a leak froof non-buoyant snorkel. You may have to strap it to your head to prevent the mask from being displaced.

 

[ballastbelly]

a snorkel is not buoyant if full of water. but when it is being used at the surface (i.e. it contains air) then its displacement makes it positively buoyant.
Through measurement i found my (common J type,not dry) snorkel can support .5lb of wieght tied to it before sinking, if i seal both ends for the purpose of this measurement.

half a pound is not insignificant. from agilis attempt at humor at my expense (my teeth do hurt after a dive), i did manage to get an idea. i cut a length of non corroding pipe, smaller in diameter than the snorkle, and used it to line the inside of the straight part of the snorkle. enough wieght to balance out the displacement but at the same time asthetically neat & only plastic will contact my head if bumped.

i will look into the alternative mouthpiece as well to improve comfort.

 

[james croft]

I would not work on your own snorkel unless you are properly certified. You will die.

 

[agilis]

At your expense? I'm sorry you feel that way. I apologize for any distress I may have caused. In any case, sealing the snorkel at both ends changes its buoyancy substantially. It also is no longer a snorkel. You have in essence created a plastic float.

When you are employing a snorkel in the usual manner it has no significant buoyancy because it is open on one end. Try sealing the mouthpiece end and submerging it to the depth it would normally be when attached to your mask while you are on the surface. You will find that it is not buoyant. When you submerge it fills with water, again maintaining essentially neutral or even very slightly negative buoyancy. Your problem is almost certainly the manner in which you have attached the snorkel to the mask. Try using the snorkel without any attachment. I think you will see what I mean.

I would not blithly dismiss the warning from James Croft regarding the possible consequences of modifying your snorkel if you do not have a Snorkel Modification C-card.

 

[Arubandi07]

a snorkel is not buoyant if full of water. but when it is being used at the surface (i.e. it contains air) then its displacement makes it positively buoyant.
Through measurement i found my (common J type,not dry) snorkel can support .5lb of wieght tied to it before sinking, if i seal both ends for the purpose of this measurement....

Would you care to explain why, by sealing both ends of your snorkel, you would intentionally create a setup which doesn't replicate actual dive conditions, and use that in support of your argument?? Might as well tie a balloon to your snorkel, and voila, it may be able to support 2, 3, no..., maybe even 4 pounds of weight, before haplessly sinking to the bottom of the ocean ...

Seriously now, as Diver0001 stated way back in post #4, your problem is related to misalignment of the snorkel/mask-strap setting, not buoyancy. Actually went through the trouble of talking to my dentist(fellow snork-diver) about this, and his 2c were, that you're most likely are setting the retainer a bit 'short', causing the mouthpiece to pull against your teeth, and in reaction to that, biting down to hard.
Anyway, I'm sure others with a bit more expertise have weighed in on this subject ... gonna be interesting to see where this one goes ...

 

[Belmont]

I sympathize with you Ballastbelly.
I understand what you mean by the buoyancy of your air filled snorkel and the
way you experimented with it to determine the value of that buoyancy.
Many here have been off track and did not deem to understand plain English.
Tape some fishing lead weights on the outside of your snorkel to see if it helps.
Easily done and not a permanent modification. After that, if it's conclusive, find a more
permanent way to weigh it down.

Ask your dentist if your teeth are over sensitive. One would think the jaw muscles would cramp up
before healthy teeth would feel any pain.

You might find more enlightened answers on some freediving forum

 

[vladimir]

Wow, guys, a rowboat is open at the top and it is buoyant. Why can't the OP's snorkel be buoyant?

 

[Diver0001]

I sympathize with you Ballastbelly.
I understand what you mean by the buoyancy of your air filled snorkel and the
way you experimented with it to determine the value of that buoyancy.

Well... he calculated about 225 grams of positive buoyancy but for the bit of the snorkel that's actually in the water on the surface, the actually pressure it's exerting will be about a 1/4 of that. I just did a little experiment with my own snorkel and assuming he has the same big-ass version I do then the displacement of the bit that would be in the water is between 30 and 50 grams.

The bite of an average human male in the bicuspid area is just shy of 100 kg. That's 100,000 grams or 2000 *times* the amount of upward pressure that the snorkel would create. So even if he is just *lightly* clenching on the mouthpiece, he's guaranteed to be generating a great deal more pressure on his teeth than the upward force of the snorkel could do.

But he ignored that and decided that the snorkel itself, and not the possibility that he could be clenching on the mouthpiece, is the big problem. Apparently you agree with him but I would personally double down on the bet that he's biting on the mouthpiece even if he's not fully aware of it. Moreover, given the amount of pressure normally exerted on our teeth by chewing things or even just keeping your mouth shut normally, I would be willing to bet that 50 grams of pressure would be virtually imperceptible to most people, let alone enough to cause pain.

Either way, I *do* hope that the OP reports back about his findings. I've been wrong about things before when I was quite sure of myself so I'm very curious if he can fix his problem with weights. My bet, though, is that he'll try it, it won't work and he'll revisit this thread to review the other advice he got and not say anything and we will never know.

R..

 

[Belmont]

Well... he calculated about 225 grams of positive buoyancy but for the bit of the snorkel that's actually in the water on the surface, the actually pressure it's exerting will be about a 1/4 of that. I just did a little experiment with my own snorkel and assuming he has the same big-ass version I do then the displacement of the bit that would be in the water is between 30 and 50 grams.

The bite of an average human male in the bicuspid area is just shy of 100 kg. That's 100,000 grams or 2000 *times* the amount of upward pressure that the snorkel would create. So even if he is just *lightly* clenching on the mouthpiece, he's guaranteed to be generating a great deal more pressure on his teeth than the upward force of the snorkel could do.

But he ignored that and decided that the snorkel itself, and not the possibility that he could be clenching on the mouthpiece, is the big problem. Apparently you agree with him but I would personally double down on the bet that he's biting on the mouthpiece even if he's not fully aware of it. Moreover, given the amount of pressure normally exerted on our teeth by chewing things or even just keeping your mouth shut normally, I would be willing to bet that 50 grams of pressure would be virtually imperceptible to most people, let alone enough to cause pain.

Either way, I *do* hope that the OP reports back about his findings. I've been wrong about things before when I was quite sure of myself so I'm very curious if he can fix his problem with weights. My bet, though, is that he'll try it, it won't work and he'll revisit this thread to review the other advice he got and not say anything and we will never know.

R..

This is most likely what will happen.

I did not say I agreed with him, simply that many here did not understand the thought process he was going through.

Clenching is a strong possibility, dental problem most likely the aggravating problem.

 

[agilis]

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.