Arm Floats

Attached are images of the arm floats I made.

Each float is 6" long and 1.5" square.

A groove 0.375" wide and 0.5" deep runs the length.

The 45* bevels are to clear the clamp.

They are temporarily mounted on 8" Ultra lite arms using tie wraps.

I now plan to glue them in place using silicone glue and then cover with a thin layer of fiber glass with black pigment in the matrix

These are made from 6 lb/ft3 closed cell PVC (divinylcell). Closed cell 9 lb/ft3 polyethylene will also work. Neither will compress at 100'.

They can be made wider, but at 1.5" thick, the arms will fold flat.I may glue 1/4'" strips on the edges for a little more buoyancy,

All work was done on a table saw.

The results are in fresh water: salt water will be a little better

Subal/Nikon D-200 with Subal port and camera & lens and two Inon 240 with rechargeable batteries installed

60 mm: very slightly negative

105 mm very slightly negative, tends to float port up about 15*

8" glass dome very, very slightly negative, floats horizontal.

Comments, questions ?

Wow - Popeye's camera arms.

Alex

Thanks for posting. Nice to see different ways to add buoyancy to systems.

Where do you buy divinylcell?

Since you're not getting paid by the hour ..........

Inside the "sandwiched" area of the ULCS arm, I suggest adding some scrap pieces of Divinycell, cut with a matt knife, to the shape of the voids designed in the original strobe arm.

The 3" face of the buoyancy system may create some interesting hydrodynamics in areas of current......................yet another "force" to consider........

btw, i assume divinycell and not divinylcell as written by the o.p.

One of the drawbacks of permanent attachment (other than potential travel damage) is that the arms may develop a smell. Hopefully not as long as they are rinsed well.

When a friend on mine did this exact same mod, she used plastic bolts and flipped the arms 90 degrees from yours. That enabled her to disassemble for travel.

if okuma is using Divinycell, manufactured by Diab:

http://www.diabgroup.com/americas/u_opening/u_home.html

then here is possibly some supporting technical data:

http://www.diabgroup.com/americas/u_litera..._pdf/H_DS_U.pdf

Also, from the dimensions and images supplied, it appears that with 8 sections "installed", around 90 cubic inches of water will be displaced. Since salt water weighs 0.037 pounds per cubic inch, that translates to roughly 3.3 pounds of lift.............acknowledging that the actual dry weight of divinycell along with any attachment devices (adhesives, cable ties or plastic bolts) must still be considered.

Here is the material I used http://tinyurl.com/9tgjc

I looked at 'Last A Foam', but it lacked edge strength. Thats why I'm going to fiber glass the out side.

And yes there is a fair amount of drag unless you turn the edges forward.

As for the smell potential - a treat for customs!

Here is the material I used http://tinyurl.com/9tgjc

I looked at 'Last A Foam', but it lacked edge strength. Thats why I'm going to fiber glass the out side.

 

And yes there is a fair amount of drag unless you turn the edges forward.

 

As for the smell potential - a treat for customs!

Looks good Okuma, very neatly done job.

I think the attached floats will dry OK if you incorporate some way to drain that won't affect buoyancy too much? I had/have a little corecell foam attached to my arms, it is thinner than yours but I've never had a problem with "smell" (at least as far as camera gear is concerned.... , ha ha....)

I think it is funny that people tend to harp on buoyancy solutions and say "too much drag", when the drag caused my those things on your arms is so miniscule compared to the drag caused by the dome port, housing, or our very own bodies with tank and BC attached for that matter. I like your arms better than longer ones - looks more manageable. Yup that is how I handle the drag on my setup/buoyancy devices, turn them sideways or turn the whole housing sideways or swim it under or behind you if possible.

Anyway looks well-done and manageable.

Best, Carol

Oh, Oh, Oh......

Have to fight the urge to not post this, but I must (Tee Hee......)

Being 110% biased to Ikelite I find this "engineering" to solve problems sadly amusing.....

Even with dual DS125 strobes and Ikelite's 8" dome port my Ikelite rig is barely 1-2 lbs. negative underwater....

It does vary depending on the actual camera in their SLR-DC style housing. A Canon 20D / 30D / 5D or Nikon D80 or especially Nikon D200 are heavier. But not to the extent of needing to ADD buoyancy! Arrgghh!!!!!!

(OK, rant over, I'm happy now....)

When using the light, super capable Canon Rebel XT or XTi cameras (and likely the new Nikon D40X!) with a single DS125 and any port / lens my system can be practically neutral! Meaning I can toss it up in the water column to adjust a BC strap, etc.

For those not choosing Ikelite I sure hope the metal mfrs. sort out the buoyancy of particlualr models as they're machining the innards of their housings......

Swimming around with cinder block certainly isn't fun......

YMMV

dhaas

Oh, Oh, Oh......

 

Have to fight the urge to not post this, but I must (Tee Hee......)

 

Being 110% biased to Ikelite I find this "engineering" to solve problems sadly amusing.....

 

 

For those not choosing Ikelite I sure hope the metal mfrs. sort out the buoyancy of particlualr models as they're machining the innards of their housings......

 

Swimming around with cinder block certainly isn't fun......

Didn't Archimedes say something about that. Small vs bouyant seems to be the choice.

Bill