DSMB - SMB the definitive post... well maybe

[Ulfhedinn]

I have seen posts covering some aspects of SMB's but none have answered what I need to know either that or I have missed it somewhere in the mix.

1. Does one need to have two SMB's on them when diving. I have noticed posts of people saying the keep a "standard" SMB in the left pocket attached to a spool. Then a 2nd "smaller" SMB in the right pocket attached to a backup "smaller" spool.

2. What do you carry and why?

I guess what I'm missing is.. if your doing a blue water and\or night dive off a boat should you be packing both. Is this mandated by any organizations? GUE\IANTD as examples.

I have noticed that they sell SMB from 4' to 10' and I'm not sure what I should be packing when I shore dive, boat dive, night dive, deco dive, etc.

[Charlie99]

1. Does one need to have two SMB's on them when diving.

Not all dive environments are the same, so there isn't a universal rule.

I always have a Trident FM36 "orange garbage bag" surface signalling sausage. Heavy plastic, 88" x 6" diameter. It is simply a long plastic cylinder, without any valve, and can only be used on the surface. I encase it inside a length of bicycle innertube and it permanently resides in my BCD pocket -- I don't even take it out when rinsing the BCD. This is a good piece of emergency gear to carry at all times.

I often carry a second sausage, simiar to the Trident FM35, with 25' of 2mm cord wrapped around it. This I can send up from a 15' safety stop. Only about 45" x 5" diameter, it is not good for long distance signalling. It's purpose to to let a boat know where I am for pickup at the end of a drift dive, and also works as a "don't run me over" signal.

Were I diving in open ocean with deco obligations, then I would add a much larger sausage or bag, along with a reel for use as a DSMB, but since I don't incur large deco obligations, I find it unnecessary.

Don't forget that the worlds greatest DSMB doesn't do you any good if it is too big and awkward, and you left it back on the boat the day you need it.

Charlie

[Peter_C]

Many of the people I dive with, including myself, carry around a 3 ft DSMB, pre-rigged on a spool, kept in the left pocket. The only difference between the two types of surface marker buoys is one has an over pressure valve to let air out as it expands headed for the surface.

The smaller (D)SMB allows a small breath to be put in it, then get everything squared away under water, followed by putting everything you got in your lungs right before you send it to the surface. Since your lungs are now empty the buoyancy change is non existent. A larger SMB will require more air to stand up at the surface therefore causing a larger buoyancy swing. Often they have an open bottom or a flapper that allows them to be filled with a second stage. The issue is they can also spill the precious air once at the surface (Even duck bills let some air back out). The smaller SMB will also stand upright at the surface, with minimal line tension. Once at the surface a larger one will be more visible, but few I know carry anything that large.

Having tried it I really don't recommend wrapping line around the SMB as it can easily create an entanglement hazard.

The spool used it typically a 100 ft, and made of delrin (I use a stainless spool, but it is negatively buoyant). You then need to remove about 25 ft of the line in order to get the double ender into the holes. I prefer a spool with a larger center that allows my thick gloves to enter the center. We are cold water divers after all.

We often launch SMB's for practice and also in case there is a boat overhead. Lets them know where we are coming up.

With technology going the way it is if Drifting Dan had a Nautilus Lifeline he probably would have been picked up within half an hour, and wouldn't have just won a huge lawsuit, there in SoCal.

[TSandM]

I almost always carry a 3' SMB attached to a 100 foot spool in my drysuit pocket. The only exception would be shallow shore dives in places restricted from boat traffic.

But I have read articles reviewing the visibility of such items at distance in open ocean, and if one is going to dive in an area with significant swell and/or strong currents, something larger is almost certainly better. And something you can deploy immediately, when you realize you are off course, is better than something you can't fill until you are on the surface, which may be a long way from the boat. A 6' SMB does not easily fit in a pocket, so requires to be stowed behind the back or elsewhere.

[dbulmer]

As Charlie99 pointed out, what and how many blobs you carry is determined by the conditions that you dive in.

The majority of my diving is UK diving where practically every sea dive requires deployment of a DSMB because of our local sea conditions and heavy boat traffic.

Because it is required, I carry 2 DSMBS just in case I lose a DSMB - I don't normally mess up deployment but it can happen so I like having a second just in case. Bear in mind that you also have a buddy and for those with team diving in mind the DSMB carried by your buddy is an extra resource.

Since the DSMB allows the diver to be seen. it makes sense that a blob of an appropriate size is chosen. I use a 4.5 foot - it's big enough to be seen in heavy seas and small enough to fit inside a decent drysuit pocket. I am not a fan of the 6 foot blob personally - if I think my blob could not be seen by the skipper I probably won't dive as I'm likely to be sea sick in really heavy seas so I'd rather be sat in a pub drinking beer if I'm honest.

For warm water dives in the Caribbean I just carry the one - I think of it as an emergency blob but I suspect I'd carry 2 if heavy currents were the norm in the area I was visiting.