human buoyancy question.

[vash]

i was reading the specs to my PFD. it provides 16.5 lbs of buoyancy lift. at first glance that isnt much, right?

i dont naturally float all that well.

help me work this through. haha. the PFD manufacturers come up with this 16.5lbs. that just covers a wide range of body types? a super lean, heavily muscled guy would need more right? i'm surprised i dont float like a slice of bacon..or a fake hotdog.

i did learn early on, that crappy moldy smelling PFD they hand you in one of those big tourist boats..in a big accident, i bet that is all they find. a bunch of floating vest. they dont fit people, not the way we just toss them over our heads. that one under the airplane seat..yea. two arm straps.

[Eric Hahl]

Buoyancy. Ya need some extra.

[flatbutt]

https://www.lifejacketassociation.org/resources/faqs/

Most people will naturally float in water, especially if they fill their lungs with air. Most require only about 11 pounds of extra buoyancy to keep their heads out of water. That is why a PFD with just 15-1/2 pounds of buoyancy can provide flotation for an adult— even a large person. PFDs with 22 – 34 pounds of buoyancy can provide superior performance in rough, off shore type of conditions.

[GH85Carrera]

As a boy scout I was a very skinny very active kid. I bet my body fat was minimal.

At Boy Scout summer camp (Camp Tukabatchee) in Alabama, they were teaching the boys all the typical camp activities. I could swim like a fish having grown up in Hawaii. One activity was treading water, which was easy for me. Then they moved to just floating on your back. I just sank like a piece of waterlogged wood. I had the three top swim teachers hold me at the surface and tell me to just relax, but keep my back straight. They would let go, and I just went down. They all agreed I was too skinny to float. Now I have lots of excess fat and likely could float like a cork.

A good life jacket is always a good idea if you are on the water.

[vash]

Originally Posted by Eric Hahl

Buoyancy. Ya need some extra.

hahhaha...with those i wouldnt have time to be in water. i would be doing jumping-jacks in front of a mirror all the time.

[911 Rod]

Originally Posted by vash

hahhaha...with those i wouldnt have time to be in water. i would be doing jumping-jacks in front of a mirror all the time.

Now I can't get this image of you out of my head!

[porsche4life]

Originally Posted by GH85Carrera

As a boy scout I was a very skinny very active kid. I bet my body fat was minimal.

At Boy Scout summer camp (Camp Tukabatchee) in Alabama, they were teaching the boys all the typical camp activities. I could swim like a fish having grown up in Hawaii. One activity was treading water, which was easy for me. Then they moved to just floating on your back. I just sank like a piece of waterlogged wood. I had the three top swim teachers hold me at the surface and tell me to just relax, but keep my back straight. They would let go, and I just went down. They all agreed I was too skinny to float. Now I have lots of excess fat and likely could float like a cork.

A good life jacket is always a good idea if you are on the water.

I had that problem when I was younger. Now I’ve put on a little weight and float fine.

After scuba diving I learned to regulate my breathing and buoyancy. I float around our pool all the time with no floaty. The kids think I’m weird. 🤣


But to the OPs question how buoyant you are all depends on your body type for sure. If you feel like the best you have doesn’t float you where you want, get one that has some more foam.


I really like the neoprene covered vests. Seems like they fit better and stay in place better. They also offer the same buoyancy in a thinner package usually.

[Seahawk]

Sterns was the gold standard when I was heavily involved in WW.

They used to have customizable gear for "aqua rocks".

https://www.stearnsflotation.com/

[Cajundaddy]

As a college athlete my body fat was measured at 11% (very low). Even with full lungs I did not float except the top of my head. The legs were sinkers. Any water sport life jacket designed for kayaking or water skiing was plenty to keep my head above water. It does need to fit right so it will not rise up.

[masraum]

Originally Posted by GH85Carrera

As a boy scout I was a very skinny very active kid. I bet my body fat was minimal.

At Boy Scout summer camp (Camp Tukabatchee) in Alabama, they were teaching the boys all the typical camp activities. I could swim like a fish having grown up in Hawaii. One activity was treading water, which was easy for me. Then they moved to just floating on your back. I just sank like a piece of waterlogged wood. I had the three top swim teachers hold me at the surface and tell me to just relax, but keep my back straight. They would let go, and I just went down. They all agreed I was too skinny to float. Now I have lots of excess fat and likely could float like a cork.

A good life jacket is always a good idea if you are on the water.

Yep, I've never been able to float. I still don't float that well in fresh water, but the ocean or a salt water I float pretty well.

[Tobra]

Muscle sinks, fat floats. When I did a lot of cycling and had the super low body fat, sank like a stone.

[vash]

Originally Posted by 911 Rod

Now I can't get this image of you out of my head!

damn..me neither. sorry. i owe you a beer mind cleanse.

[GH85Carrera]

Originally Posted by 911 Rod

Now I can't get this image of you out of my head!

OK, focus on this.

Focus focus focus!

[BK911]

Buoyancy is basically the weight of the water being displaced minus the weight of the displacee.
So for equal volume dudes, whoever weighs more will sink more.
For equal weight dudes, whoever takes up the most volume will be more buoyant.
Fill your lungs up with air? More volume displaced, same weight, more buoyant.

[Captain Ahab Jr]

I used do a bit of free diving at a certain depth I'd become negatively buoyant without a lead belt and sink like a stone

[RWebb]

I used to date a world champion athlete* - she marched next to Ahnald Schw. at one of the World Games things. She had low body fat and was very muscular, but not ripped looking at all. She could not swim a stroke and just sank (quickly) in water, despite having well-developed "flotation devices" and a curvy appearance.


* fly-casting (seems odd for a world sport...)

[RWebb]

Originally Posted by Captain Ahab Jr

I used do a bit of free diving at a certain depth I'd become negatively buoyant without a lead belt and sink like a stone

deep enough to compress your chest?

[cabmandone]

I sink like a damn rock. I almost failed the cub scout swim test as an adult troop leader because I couldn't float. I could swim the length of the pool back and forth under water but damned near drown when asked to float.

[Captain Ahab Jr]

Originally Posted by RWebb

deep enough to compress your chest?

Yes, I spent my childhood under water, back then it was called snorkeling

Wasn't until I was 40yrs old I really found out what negative buoyancy could feel like when I had a fun weekend on a free diving course at a 10 story tall Naval submarine escape training tower





Was slightly disconcerting sinking towards the bottom on the 1st go, would glide the last 25ft and then start the long 100ft swim back up

Sea off the UK is too cold and dark to have make it enjoyable, would have loved to have had the chance to push it further but....

not to this extreme
https://www.youtube.com/watch?v=uQITWbAaDx0

[RWebb]

pretty exciting

seals have a LOT of blubber but they can do it deep...

7,835 ft is the record