why more than 60-100' of line for a DSMB?

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Edward3c

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Confused by some of the comments. When people say "open bottom" and that being a bad thing, are they referring to literally an open bottom? Or are they also including the "semi closed" style that will allow exhaust from the regulator to inflate from below and it has a self sealing one way inlet that supposedly does not allow air out after inflated?
Open bottom is just that. I used fishing weights on mine to keep it below the surface.
 

Joris Vd

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Anyone else recommend a close bottom vs duck bill type device?
As long as it's not an open type, I'd go for a duck bill tbh. You always have the option to inflate with your reg might the need arise.

Especially if you need dsmb's for sea diving (North Sea etc) where you are expected to have a dsmb that's 1m80 - 2m minimum. Good luck inflating that orally.

My small dsmb's are all closed, oral inflate only, but the bigger ones I always go for a duckbill just to make sure I have both options.
 

Nemrod

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It depends upon how you intend to inflate it? If you are going to use your regulator then you need an open bottom. If you are going to orally inflate or use a fitting off your LP inflator hose then a close bottom.

I have multiple spools and dsmbs from 3 feet to gargantuan. I prefer a 4 foot, closed bottom with an oral inflator I can use off my LP hose on a small reel with 60 to 80 feet of line. At safety stops of 20 feet, you do not need a lot of line as the scope will not be the issue it is if you shoot the thing from 120 feet.

I can inflate from my LP hose using a Y fitting:





Pssst, zoom, away the sausage goes. That spool has 60ish feet of line on it and a 4 foot sausage, closed bottom with OPV, that is all you need for your purpose. I carry it pre-rigged to the dsmb, spool goes in an XS weight pouch pushed down to the plate on my right shoulder strap with the dsmb hanging out.

For drift diving in the Jupiter area where groups can be far apart and shore too far to swim too, lol, I may use this giant 6 feet one here, bungee loop on the right side of my plate and 100 feet of cave line on a spool:



James
 

MAKO Spearguns

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I've never used a DSMB and feel I need one for the equipment setup I'm putting together. I would be using it for recreational diving for now and want to keep things simple and minimal on my kit. I assume I can rig up a couple bungee loops on the side of my BP and stuff the rolled up device in there for storage.

On the topic of spool vs reel, is there a small and user friendly reel that I could use for this but also use for basic wreck dives as well and not carry two devices? Or would you recommend a compact spool solely for the DSMB for most of my dives and if I know I'm diving on a wreck, bring an extra reel for that?

Seems the color standards vary depending on location, but is it safe to say a solid orange one will be considered a standard, non emergency marker for most common situations?

What would be a sweet spot between being large enough to see on the surface but not be to much bulk on a streamlined gear setup? I'm guessing 1.5 meters?

I see most have a dual purpose valve for your inflator or oral inflation. Any pluses and minuses for the ones that have the open end with a "duck bill"? I assume that would be for exhaling into from your regulator exhaust?

I see they have an over pressure valve in case you get over zealous with inflating them. Depending on the depth of inflation, this thing is going to try and expand considerably. Is it normal for that excess air to bleed out of the over pressure valve on the way up, by design, or is the diver underinflating it at depth, anticipating expansion on ascent?

Any preference on color of line?



I think these might work well for your application, however the smb does not have an OP valve,, so you want to consider expansion of air from whatever depth you deploy from.
 

BoundForElsewhere

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Girth matters as much as length.

Bwahahahahahahahahahaha. Gasp...
Hahaha hahaha hahaha. Sigh...

Though he may be small, he is mighty! And stays erect on the surface while a lot of those magnum sized units just seem to flop around. Just sayin'.
 

KenGordon

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It depends upon how you intend to inflate it? If you are going to use your regulator then you need an open bottom. If you are going to orally inflate or use a fitting off your LP inflator hose then a close bottom.

These are “self sealing” - they can be filled with a regulator or via an inflator hose. The opening at the bottom is shaped such that there is a non return valve a little way up the tube.

These, or the version without the inflator hose option, is the default in the U.K.
 

RobPNW

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Bwahahahahahahahahahaha. Gasp...
Hahaha hahaha hahaha. Sigh...

Though he may be small, he is mighty! And stays erect on the surface while a lot of those magnum sized units just seem to flop around. Just sayin'.
Like when my mom took me as a kid to the clothing store and said he'll need a "husky" lmao.
 

RobPNW

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It depends upon how you intend to inflate it? If you are going to use your regulator then you need an open bottom. If you are going to orally inflate or use a fitting off your LP inflator hose then a close bottom.
This is kind of where I was going on my last question. Seems having more option available and to practice, would be better for me. But some folks were basically implying the "open bottom" ones suck for various reasons. I just don't know if they were including the "semi closed" duck bill style ones in their definition of "open bottom". If those are also problematic for some reason, I would rather have one less option and have the device be more reliable. If they work fine, I'd rather have the additional inflation option. Make sense?
 

Nemrod

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These are “self sealing” - they can be filled with a regulator or via an inflator hose. The opening at the bottom is shaped such that there is a non return valve a little way up the tube.

These, or the version without the inflator hose option, is the default in the U.K.
The dsmb I showed has the no-notch adapter for filling from a LP hose, which I do.



I have not had good luck with the open bottom types with the internal duckbill. Maybe they have improved. I prefer a closed bottom with an OPV. Those giant dsmb, and I have a couple, I do think the open bottom is a good thing as they take too long to fill from the inflator and orally inflating is impossible.

James
 

drk5036

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This is kind of where I was going on my last question. Seems having more option available and to practice, would be better for me. But some folks were basically implying the "open bottom" ones suck for various reasons. I just don't know if they were including the "semi closed" duck bill style ones in their definition of "open bottom". If those are also problematic for some reason, I would rather have one less option and have the device be more reliable. If they work fine, I'd rather have the additional inflation option. Make sense?
The duckbill style works fine. It completely seals and stays fully inflated on the surface even if it falls over.
 
https://www.shearwater.com/products/teric/

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