Is a 5lbs backplate overkill for warm water with no wetsuit?

[Mtbr]

Hi there,

I dive cold water using 3lbs of lead, a 5lbs plate, X7 HP100, and a 7mm suit.

I'm leaving for Belize next month, and I'm deciding if I it's worthwhile to buy a travel (aluminum) plate just to use it for a week.

Will my 5lb plate be overkill if I take it with me? I'll be diving warm water using Aluminum 80 and with no wetsuit?

 

[Gombessa]

Hi there,

I dive cold water using 3lbs of lead, a 5lbs plate, X7 HP100, and a 7mm suit.

I'm leaving for Belize next month, and I'm deciding if I it's worthwhile to buy a travel (aluminum) plate just to use it for a week.

Will my 5lb plate be overkill if I take it with me? I'll be diving warm water using Aluminum 80 and with no wetsuit?

There are plenty of people here who do just that - steel backplate, AL tanks, no weights (the ones I know personally use 3mm suits/shorties though).

Without doing the math, I'm assuming you're a tad buoyant in salt water with lungs filled. You're looking at roughly -6lb with a plate and harness, -2lb at the beginning of the dive with an AL80, maybe another -2-5lb counting regulators, negatively buoyant fins, miscellany. Can you swim up 10-13 pounds? If so, that may be enough. I'm sure someone with more precise numbers/measurements will come by.

Btw, your cold water weighting looks way off to me. You use 3lb, I need *30lb* with a steel tank (12lb of which is bp+sta).

 

[halocline]

3lbs lead, 5lbs BP, say 3lbs for a near empty HP100, 2lbs reg, that's only 13lbs of ballast for a 7mil suit? Impressive if it's accurate! How you can sink a 7 mil suit with 13 lbs ballast I don't know. I thought a typical 7 mil suit was about 20lbs positive at least. I know with a full tank you'll add 7 lbs of ballast, but I'm surprised you're not floating like a cork at the end of your dive.

Add 4lbs for salt water (a guess), about 7 lbs for the AL80 (+4.5 vs-2.5 empty), and you're looking at somewhere around 11lbs of increased positive buoyancy going to your tropical set up. Removing the wetsuit is going to more than offset that, so if your numbers are accurate, you'll probably be fairly negative with just the steel plate.

Look at it this way, no matter what, you need to offset 4 lbs of positive buoyancy for the AL80. Are you that much of a sinker?

 

[Nemrod]

That plate will be fine with an aluminum 80.

N

 

[nereas]

Hi there,

I dive cold water using 3lbs of lead, a 5lbs plate, X7 HP100, and a 7mm suit.

I'm leaving for Belize next month, and I'm deciding if I it's worthwhile to buy a travel (aluminum) plate just to use it for a week.

Will my 5lb plate be overkill if I take it with me? I'll be diving warm water using Aluminum 80 and with no wetsuit?

The SS plate should almost exactly offset the aluminum tank to perfect -0- buoyancy when almost empty. That is a good combo, as far as equipment goes.

If you are thin and boney, and thus a "sinker", you would need to "swim up" yourself if you your wing failed, but that should be easily do-able with a neutral rig.

 

[Mtbr]

that's only 13lbs of ballast for a 7mil suit? Impressive if it's accurate! How you can sink a 7 mil suit with 13 lbs ballast I don't know. I thought a typical 7 mil suit was about 20lbs positive at least. I know with a full tank you'll add 7 lbs of ballast, but I'm surprised you're not floating like a cork at the end of your dive.

Look at it this way, no matter what, you need to offset 4 lbs of positive buoyancy for the AL80. Are you that much of a sinker?

I'm one of those lean sinkers. I can't float in salt water without teading water. Nonetheless, my setup has 2 extra D rings on my harness - six all together, 2 small steel snap bolts, + an Oxycheq Raider light. So! that probably adds another -1lbs.
With this setup in cold salt water, I can still maintain neutral at 15' with 500 psi.

 

[DeepSeaExplorer]

There are plenty of people here who do just that - steel backplate, AL tanks, no weights (the ones I know personally use 3mm suits/shorties though).

I personnally use that combination and it's perfectly balanced.

 

[halocline]

I have done plenty of tropical dives with an AL plate, AL80, and no lead. Not so much by choice; I usually started off with 4-6 lbs on my waistbelt but would give those weights to divers in my group when I was DM-interning. It was okay, occasionally a little light towards the end of the dive. For me, the steel plate is better when wearing a 3 mil suit; with a skin only I like to use the AL plate.

If you were talking about 3 lbs with a 7mil in salt water, I think you're going to be pretty heavy with no suit and the same plate. You could, if you wanted, measure the buoyancy of your suit, just put it in a mesh bag and add lead until it sinks. If it's a typical 7 mil suit, I think it's going to take 15 lbs at least to sink it.

So, you could get an AL plate, maybe try a couple of lbs on cam straps. The steel plate will also work fine, but you'll probably have more air in your wing. My trim is better with the steel plate even if I'm a little overweighted, so you might consider that.

 

[fdog]

That plate will be fine with an aluminum 80.

N

Succinct and absolutely correct.

I'd take my SS plate on tropical trips if it wasn't for the baggage weight restrictions. Instead, I take a Kydex plate and add 6 lbs of lead to it.


All the best, James

 

[Mr. Sunday]

I think an SS plate is just about ideal. It is just a pain to lug it down with you on the plane. The weight on while traveling is the only reason I would ever choose an aluminum over my SS.