Doubles bolts are too short – what do I do?

[nairn_diver]

Hi all,

I have a question that maybe someone can help me out with. I have a set of doubles that I have been diving for the last year (E7 HP100s, Highland bands, 11lb V-weight, halcyon wing, and SS backplate). The doubles were set up when I bought them used and I recently took them apart (with assistance) for them to get their first hydro test.

My tanks just got back from a hydro test and were re-assembled back into doubles (with help from a local dive shop). The problem is that my bolts are now too short for the wing nuts to be tightened enough to hold my backplate (the lower bolt can be tightened a little but I cannot get the wing nut on the upper bolt). As far as I can tell they are set up exactly the same as how I was diving them over the last year. The only change is that the dive shop put rubber inner tubes under the bands this time.

My question: are the rubber inner tubes causing the bolts to now be too short? What do I need to do about this? Get longer bolts? Take out one of the locking washers?

This is my hardware order:
End of 3/8 bolt (fixed) + band + band + locking washer + nut + V-weight + wing + backplate + washer + locking washer + wing nut

Thanks in advance for assistance.

Cheers

 

[Thalassamania]

Go to the hardware store and get bolts that are a 1/4 longer.

 

[Scott L]

Are rubber inner tubes under bands SOP these days?

 

[firemedic1015]

Get rid of the inner tubes. They belong on your car not your doubles.

 

[nairn_diver]

It looks like picking up longer bolts would solve the problem. Are all SS bolts from the hardware store created equal?

I am glad that the topic of putting rubber inner tubes under the bands has come up. When I acquired my doubles I learned that the rubber was not necessary as the metals were similar (bands and tank are both steel) and would not corrode. When I looked under the bands after one year of diving, there was lots of the white discolouration on the tanks. I decided that I would put rubber under the bands to prevent any further discolouration.

Why would rubber inner tubes under the bands not be necessary or be a bad idea?

Cheers

 

[Thalassamania]

Get real stainless bolts from a chandler.

 

[Indian Valley Scuba]

A chandler? Fastener supply houses don't cut it? Any decent alloy of stainless will do the job, 316 being an excellent choice. If you have difficulty locating that locally, try www.McMaster-Carr.com And while some use 'bolts', as defined by a headed fastener, you may also consider using threaded studs (no heads) which give you plenty of ability to adjust them in or out as needed.

You might also consider using bronze nuts in lieu of stainless nuts to avoid galling on the threads.

Hope this helps.

 

[Thalassamania]

Obviously you have more options on the mainland.

 

[Indian Valley Scuba]

McMaster Carr ships to Hawaii daily, am I correct in assuming that is where you are? i apologize if I am incorrect.

 

[Thalassamania]

Most people don't want to wait a week and change. FedX overnight takes 3 days.