Visual reference on anchor line

[Nick_Radov]

What are you calling 'rough seas'? The waves don't have to very high to make it very hard to see small smbs, especially in overcast conditions.

I guess the definition of "rough seas" is subjective but boat crews have no trouble spotting small SMBs in 8ft+ swells with wind chop. The boat remains over the dive site with engines running during the bottom time and then divers launch their SMBs as they start their ascent so the SMBs pop up near the boat. Most of us use something like this (doesn't have to be this exact model, just something similar).

Halcyon Dive Systems

Halcyon began as a group of divers who knew exactly what they wanted, but could not find it in any dive store. Our passion for diving led us to designing wings and lights to satisfy ourselves.

halcyon.net

 

[Nick_Radov]

I actually agree with wibble here, the small smbs are useless in the sea. I doubt that Nick has actually tested it or has seen any conditions that you would consider 'rough seas' in northern Europe. Only 3 feet waves will make it incredible hard to see a smb that 3 or 4 feet out of the water. And you only see it for a second. And 3 feet waves are not 'rough seas' by any means.

Nope. We have done comparisons in rough seas with swells much larger than 4ft. Conditions can be plenty rough in the open Northeast Pacific Ocean off of the Big Sur coast. Boat crews reported that the small SMBs were easier to see than large ones because the small ones tend to stand up straighter. Small SMBs are also faster and easier to fully inflate; with large ones there's more of a risk that divers fail to inflate them fully and then they end up kind of flopping around on the surface. And, as I mentioned in my previous comment, regardless of what size SMB you use the key is to launch it as soon as you leave the bottom so that it pops up close to the boat (one time I actually hit the boat).

If you're comfortable dealing with the large SMB and can manage to keep enough tension on the line to stand it up without exerting yourself during deco then go ahead and use it if you like. But it practice it doesn't seem to offer any safety advantage.

 

[Wibble]

If an SMB is a full sized one,

Longer mean >2h? >3h? or what?

Longer meaning the time at deco. If you're diving a wreck -- and you don't fall off it! -- then the skipper knows where your bag (SMB) will appear. All the time at deco means you and your bag will drift away from the wreck.

Interestingly with deeper dives where the bottom time is limited by the max dive time, the divers will bag off within 15 mins of each other. The SMBs then all drift downstream together in the "field of SMBs".

I assume rough sea is F3 or F4 given your previous post, right?

F4 is OK as long as it's not forecast to be rising. A F4 to F5 probably would be abandoned.

(Obvs. down to the specifics of the dive, the site, steaming distance and bearing, direction of wind + current, etc.) A wind against tide will build up the sea to short chops. Wind with tide will tend to have longer and lower waves.

Nope. We have done comparisons in rough seas with swells much larger than 4ft. Conditions can be plenty rough in the open Northeast Pacific Ocean off of the Big Sur coast. Boat crews reported that the small SMBs were easier to see than large ones because the small ones tend to stand up straighter. Small SMBs are also faster and easier to fully inflate; with large ones there's more of a risk that divers fail to inflate them fully and then they end up kind of flopping around on the surface. And, as I mentioned in my previous comment, regardless of what size SMB you use the key is to launch it as soon as you leave the bottom so that it pops up close to the boat (one time I actually hit the boat).

I think there's an interesting point here...

Ocean swells are gentle long-wavelength waves of the order of many seconds, say 15s or more, originating far out at sea. These waves can be quite high but are quite gentle lifting the boat gently up and lowering it -- remember sailing "off soundings" and this really long but gentle swell of 6m/20ft meant seeing for miles one minute and a wall of water the next (that was obviously the low far out in the Atlantic that battered the boat a day or two later with F9 winds, eventually leading to the rudder failing!)

"Waves" are short wavelength and driven primarily by the local wind (and affected by current). These are lower, but really rock the boat around.

If the seas are calm but with a swell, you can see a fair way when the boat is on a crest, and see hardly any distance when the boat's in a trough. But, if the SMB's say 400m/400yds away, there's a possibility that the SMB might be up when the boat's down and vice versa. A larger SMB will be visible for a little longer. Also, when the diver's up, you can hold the SMB vertical. Bigger is best then!

In tidal coastal waters, such as the English Channel or estuaries, the issue isn't swell, unless at the Western end, the challenge is wind and tide. The prevailing wind is south easterly and there's a long fetch to build up the waves. These short wavelength waves of the order of a few seconds rock the boat around, make diver recovery difficult and make steaming/motoring miserable for those prone to seasickness.


Personally, I wouldn't even think of using a training/small SMB for diving in the sea unless it's really sheltered -- even then it's the big SMB, 'cos that's all I would bring!

 

[berndo]

I guess the definition of "rough seas" is subjective but boat crews have no trouble spotting small SMBs in 8ft+ swells with wind chop. The boat remains over the dive site with engines running during the bottom time and then divers launch their SMBs as they start their ascent so the SMBs pop up near the boat. Most of us use something like this (doesn't have to be this exact model, just something similar).

So the crew was able to see the SMBs that popped near the boat? That's not a great test.
Trying to spot an little tiny 3 foot SMB that's maybe 2 feet out of the water in 8 ft swells is extremely difficult unless they're popping up right by the boat or know exactly where to look.

 

[ginti]

I think there's an interesting point here...

Ocean swells are gentle long-wavelength waves of the order of many seconds, say 15s or more, originating far out at sea. These can be quite high but are quite gentle lifting the boat gently up and lowering it. "Waves" are short wavelength and driven primarily by the wind (and affected by current)

If the seas are calm but with a swell, you can see a fair way when the boat is on a crest, and see hardly any distance when the boat's in a trough. BUT if the SMB's say 400m/400yds away, there's a possibility that the SMB might be up when the boat's down and vice versa. A larger SMB will be visible for a little longer.

In tidal coastal waters, such as the English Channel or estuaries, the issue isn't swell, unless at the Western end, but it's wind and tide. The prevailing wind is SE and there's a long fetch to build up the waves. These short wavelength waves of the order of a few seconds rock the boat around, make diver recovery difficult and make steaming/motoring miserable for those prone to seasickness.


Personally, I wouldn't even think of using a training/small SMB for diving in the sea unless it's really sheltered -- even then it's the big SMB, 'cos that's all I would bring!

This is what I meant when I said "conditions out of the sea." Many thanks

 

[Nick_Radov]

So the crew was able to see the SMBs that popped near the boat? That's not a great test.

Why would the SMBs not pop up near the boat? Even with scooters, the divers don't venture very far from the initial descent point. The captain has the GPS coordinates marked and remains there until the crew sees the SMBs.

To be clear, I am describing protocols for ocean tech diving in strong currents on a single wreck or reef site followed by a drifting ascent. If you're planning a long drift or one-way scooter run during the bottom time then obviously different protocols apply and you need to tow a float during the entire dive so that the boat crew can track you from the start.

Trying to spot an little tiny 3 foot SMB that's maybe 2 feet out of the water in 8 ft swells is extremely difficult unless they're popping up right by the boat or know exactly where to look.

It's really not difficult. On some occasions I have skipped dives and stayed on the boat. I had no trouble spotting tiny SMBs. And if the crew fails to spot one they know it has to be either up current or down current; it can't be miles away in some other random direction.

 

[Celt]

I’m starting to wonder have some of the posters ever been at sea. To say that a smaller SMB is easier to see than a larger version is so wrong. A flat earther wouldn’t deny that something standing 4 feet out of the water is easier to see than 2 feet. Why do people think fishing boats use dan flags on long poles to mark fishing gear. The earth is round.

 

[Nick_Radov]

I’m starting to wonder have some of the posters ever been at sea. To say that a smaller SMB is easier to see than a larger version is so wrong. A flat earther wouldn’t deny that something standing 4 feet out of the water is easier to see than 2 feet. Why do people think fishing boats use dan flags on long poles to mark fishing gear. The earth is round.

You're really missing the point. A large SMB is easier to see than a small one if both are standing up vertically. In practice we have found that the large ones don't actually stand up as well because it's awkward to maintain sufficient tension on the line during deco stops, or the wind knocks them over, or divers launch them without enough inflation gas to keep them rigid.

 

[berndo]

Small SMBs are also faster and easier to fully inflate; with large ones there's more of a risk that divers fail to inflate them fully and then they end up kind of flopping around on the surface.

Trying to fix a skill issue with gear. Cool.

It's really not difficult. On some occasions I have skipped dives and stayed on the boat. I had no trouble spotting tiny SMBs.

I'm not buying this story. Spotting a 3 foot smb in 8 feet waves might be easy when it's right by the boat. From 50 yards or more from a rocking boat it's very hard to spot anything that tiny. Add overcast and it's get even harder.

Why would the SMBs not pop up near the boat?

Really?

 

[berndo]

In practice we have found that the large ones don't actually stand up as well because it's awkward to maintain sufficient tension on the line during deco stops, or the wind knocks them over, or divers launch them without enough inflation gas to keep them rigid.

That's a skill issue.

I’m starting to wonder have some of the posters ever been at sea.

Yeah, that's what I'm wondering too.