Who has a balanced 230mm dome?

I've been shooting a 230mm dome port (D810, D850 and Z9), and while I have finally got the whole rig very neutrally buoyant, it still wants to twist upward because the dome is so floaty.

So the suggestion has been made to add some tire weights to the dome, and I'm just looking for details there.

Specifically how much weight, and perhaps mounting locations (I assume bottom front). (Pics would help).

Currently, with Z9/D850, dual YS-D1's and a focus light, six Stix floats have the rig extremely neutral. 

Hi Craig

I'd suggest it's one of those things that you play around with until you are happy.

The weights are inexpensive and a bulk buy is easy. You can stick them on, pull them off until you have the result you are looking for. If you have a pool - or even a bath tub - handy you could just stick the weights on with, say, BluTack, as a temporary hold until you have them in the right place then stick them on properly.

They are easy to remove as and when necessary. Hours of fun!

Here's an example of some:

https://www.amazon.com/Pit-Posse-Balancing-Weights-Adhesive/dp/B00OQWS98S/ref=sr_1_3?keywords=car%2Btire%2Bbalance%2Bweights&qid=1665863580&qu=eyJxc2MiOiIxLjU2IiwicXNhIjoiMS4wMCIsInFzcCI6IjAuMDAifQ%3D%3D&sprefix=car%2Btire%2Bweights%2Caps%2C342&sr=8-3&th=1

2 hours ago, TimG said:

Hi Craig

 

Here's an example of some:

https://www.amazon.com/Pit-Posse-Balancing-Weights-Adhesive/dp/B00OQWS98S/ref=sr_1_3?keywords=car%2Btire%2Bbalance%2Bweights&qid=1665863580&qu=eyJxc2MiOiIxLjU2IiwicXNhIjoiMS4wMCIsInFzcCI6IjAuMDAifQ%3D%3D&sprefix=car%2Btire%2Bweights%2Caps%2C342&sr=8-3&th=1

I didn't think they were easy to remove, or at least not without leaving stuff behind.  I've had numerous times where I was trying to clean car or motorcycle rims and could barely get the glue residue off.

I ordered the above as it was just too convenient not to!   How much weight are people using though?

1 hour ago, phxazcraig said:

I didn't think they were easy to remove, or at least not without leaving stuff behind.  I've had numerous times where I was trying to clean car or motorcycle rims and could barely get the glue residue off.

I have used lighter fluid as a solvent to remove the glue residue.

6 hours ago, TimG said:

The weights are inexpensive and a bulk buy is easy. You can stick them on, pull them off until you have the result you are looking for. If you have a pool - or even a bath tub - handy you could just stick the weights on with, say, BluTack, as a temporary hold until you have them in the right place then stick them on properly.

I did exactly what Tim suggested. I bought some black tire weights on Amazon and balanced the dome by adding weight, testing in a pool, adding more, … until the rig was perfectly balanced. I stuck the weights to the bottom of the dome shade so they would be inconspicuous. The weights also protect the bottom dome shade if it is set on concrete or another hard surface. I have not tried to remove them.

I actually applied some self adhesive velcro to the base of the dome and then to some wheel balancing weights. 

I can add or remove weights as required! 

You could also try this:

https://www.ikelite.com/products/trim-weight-system-for-dslr-mirrorless-housings

Or make up something similar - you adjust the balance by moving the weight back and forth and no adhesive to worry about.

6 hours ago, ChrisRoss said:

You could also try this:

https://www.ikelite.com/products/trim-weight-system-for-dslr-mirrorless-housings

Or make up something similar - you adjust the balance by moving the weight back and forth and no adhesive to worry about.

 

At first I thought it was just too big and ... too much.  But, given that you don't have to fly with the weights, maybe not a bad idea.  Certainly the adjustment can be easily tuned.   Still, I never thought I would need that much weight, which is why I've been trying to get any kind of feel for just how much weight is being added.   I thought maybe a few ounces, but if it is pounds than I think I'd rather go with this solution than carry even more weight in luggage or carryon.

I used the Ikelite solution with an Ike housing and the large eight inch dome on a review trip to Mexico. It packed very well and as has been pointed out you can just grab weights from your dive operator and avoid the weight during travel. It can be installed and removed quickly. It is a bit awkward when you try to set it on a level surface. 

5 hours ago, phxazcraig said:

At first I thought it was just too big and ... too much.  But, given that you don't have to fly with the weights, maybe not a bad idea.  Certainly the adjustment can be easily tuned.   Still, I never thought I would need that much weight, which is why I've been trying to get any kind of feel for just how much weight is being added.   I thought maybe a few ounces, but if it is pounds than I think I'd rather go with this solution than carry even more weight in luggage or carryon.

It's sold for acrylic ports which are more buoyant - I would think a standard 3lb dive weight might be a bit too much for a glass port and you'd be looking for a smaller dive weight.

I mounted my focus light on a 5" arm cantilevered straight forward so the front of the light is about even with the top of the dome hood.  Moving the focus light weight forward balances my 230mm dome quite well.

2 hours ago, JayceeB said:

I mounted my focus light on a 5" arm cantilevered straight forward so the front of the light is about even with the top of the dome hood.  Moving the focus light weight forward balances my 230mm dome quite well.

I like this simple idea!

See if it works for you.  Not only does it remove weight from the center of the kit, but it moves weight to the far front.  The further forward you can cantilever weight, the less weight you need to add in total.  And since you're already traveling with the focus light, you wouldn't be traveling with any additional weight (except the additional arm and clamp).

On 10/17/2022 at 10:36 PM, JayceeB said:

See if it works for you.  Not only does it remove weight from the center of the kit, but it moves weight to the far front.  The further forward you can cantilever weight, the less weight you need to add in total.  And since you're already traveling with the focus light, you wouldn't be traveling with any additional weight (except the additional arm and clamp).

Since I already changed strobe arms from a 5/8" combo to a 8/8", I have a pair of extra 5-inch arms I can use.   And since I replaced two strobe arm clamps with ones with rings (for clipping a handle to), I have a pair of extra clamps too.   So I will try this technique and supplement it, if needed, with the tire weights.

The weights came a couple of days ago.   Now I'm wondering about the viability of trying to balance the rig in fresh water.  I could get into a pool here - except now they are all cold!   Anyway, I'm wondering this - if I got the dome to be perfectly trimmed via weights and/or placement of focus light in a pool, should I expect it to still be balanced as well in salt water?

My next dive trip may not happen until March when I go to Truk/Chuuk.   It would be nice not to have to fiddle with the equipment there.  I'm only there for 10 days and 20 dives.

I wouldn't expect it would change much in fresh vs Salt, the density difference is only 3%, my educated guess is that it would be within the tolerance of how accurately you can balance out the buoyancy.  If you make it so it tip slightly forward that should be unnoticeable in use.

I tried an 8" arm with YS mount on the light, and a ball mount on the housing today.  My focus light is fairly small, but it trimmed the 230mm dome very well.  A larger focus light might be cantilevered out too far with an 8" arm and would probably pair better with a 5" arm.