OK I'll just give you my 2 cents on the clump weight idea then.
Considering the size of vehicle you are talking about the tether will be small and malleable.
The primary reason I would consider using a clump weight is to divert away from a thruster or obstruction but I would only do this if I had no other choice. I would seriously question the necessity of putting my system in that position in the first place...
It's a double edge knife. the idea seems great and has been done before but there is no way to ensure the tether will not build up above the clump weight causing an excess amount to float around shallow increasing the chances of entanglement with structures, thrusters, etc.
The tether can build up there because your ROV is not pulling fast enough VS the surface winch paying out, you have slack tether and the current is pushing it, etc... Note that current is usually stronger at surface... This will be worst if your tether is neutral or buoyant.
If you do want to try it out. You should consider buying some plastic rods (acetale preferably) drill in the center, put ss pipe in and mount 4 rollers in a square shape. The rollers and "hole for the tether" should be as big as reasonably practical but the rollers should be close vertically to prevent damage to your tether. (check your tether specification for the minimum bend radius) You can build a simple frame with aluminium and use scuba diver weights to mount below the rollers. Put an eye bolt on the side and use whatever rope you fancy. The rope has to be offset to one side else you will have it entangling with your tether.
I'm sure different folks have different opinions the truth is the requirements and results vary depending on the working conditions and scenarios.
Rule of thumb is your tether is best underwater/on the seabed where you have some control versus on the surface where you have none. Therefore, free flying is definitely better with a slightly negative tether. I would use floats near the ROV to compensate the weight and keep the tether off the seabed only if the seabed is soft to keep it from destroying the visibility. Else I would let it be because it is easier to manage.
Bottom line is don't "add" complications unless their is a need. IE don't put a clump weight cause it seems like a good idea...
Hope this helps.
Cheers,
E.
Considering the size of vehicle you are talking about the tether will be small and malleable.
The primary reason I would consider using a clump weight is to divert away from a thruster or obstruction but I would only do this if I had no other choice. I would seriously question the necessity of putting my system in that position in the first place...
It's a double edge knife. the idea seems great and has been done before but there is no way to ensure the tether will not build up above the clump weight causing an excess amount to float around shallow increasing the chances of entanglement with structures, thrusters, etc.
The tether can build up there because your ROV is not pulling fast enough VS the surface winch paying out, you have slack tether and the current is pushing it, etc... Note that current is usually stronger at surface... This will be worst if your tether is neutral or buoyant.
If you do want to try it out. You should consider buying some plastic rods (acetale preferably) drill in the center, put ss pipe in and mount 4 rollers in a square shape. The rollers and "hole for the tether" should be as big as reasonably practical but the rollers should be close vertically to prevent damage to your tether. (check your tether specification for the minimum bend radius) You can build a simple frame with aluminium and use scuba diver weights to mount below the rollers. Put an eye bolt on the side and use whatever rope you fancy. The rope has to be offset to one side else you will have it entangling with your tether.
I'm sure different folks have different opinions the truth is the requirements and results vary depending on the working conditions and scenarios.
Rule of thumb is your tether is best underwater/on the seabed where you have some control versus on the surface where you have none. Therefore, free flying is definitely better with a slightly negative tether. I would use floats near the ROV to compensate the weight and keep the tether off the seabed only if the seabed is soft to keep it from destroying the visibility. Else I would let it be because it is easier to manage.
Bottom line is don't "add" complications unless their is a need. IE don't put a clump weight cause it seems like a good idea...
Hope this helps.
Cheers,
E.