well we calculated last weekend. Depending on how much trimix dives you do, The price of helium still hasn't reach the point where a rebreather is cheaper here.
a 2x12 filled here is around 200eur. more or less. And most of our dives are well in 66m, so no point of still going for a rebreather if you're going to do one or two dives in a year.
Have about 20 deep dives of 60m/200ft and more booked for this year. A week's diving can be done with 2 full diluent tanks and 2 full oxygen tanks with plenty left over.
Checking my logs for dives over 60m/200ft (use AI for pressure monitoring and logging), it's less than 50 bar gas use for both oxygen and diluent. Use 3 litre tanks, so that's 3 x 50 = 150 litres of gas consumed per dive. Assume 50% helium, that'll be 75 litres/dive; I pay 5p/6c per litre, so under £4/$5 per dive for helium, plus 150 litres of oxygen at 1.5p/2c = £2.25/$3 so £6.25/$8 per dive for the gas.
Add another £6/$8 for 1.3kg of lime (Revo - only need 1 scrubber cannister).
With a catheter for the pee valve, that's less than £20/$25 dive.
The 20 dives would be £400/$500. About 2 OC fills.
The killer for OC -- and I know this as it happened to me -- is that if you're on a boat for 3 days, it's really easy for CCR as you just bring two spare 3 litre cylinders (one oxygen, one diluent). For those dives you'd need two decent fills on two ali80s. Plus the rebreather. Oh, a small cannister of lime.
On OC, you'd need to bring 3 twinsets and 6 deco stages (50% + 80%) plus any bottom stages if you want to do a decent runtime. That is a killer to transport from the boat to the car even with a marina trolley. The boat skipper hates you for taking up so much space.
