Retardation of an object through water

[Parsnip]

I wonder if any one can help. I need to find out how far a cyclindrical object will descend in to the ocean if it has been dropped from a certain height (40 - 5000m) above the surface. The object weighs about 10kg and will be retarded to approx 30 m/s by a parachute which will still be attached when it descends through the water. I don't need to be very accurate but a way of calculating a ball park figure would be good.
Cheers in advance

 

[kenvlach]

A large diameter Styrofoam® cylinder might stop in 2 feet; one of depleted uranium might go to the bottom and beyond, through any silt.
Please define your parameters:
Closed cylinder?
Length?
Diameter?
It’s logical to assume a closed cylinder (otherwise, no payload) that floats, but I’ve already made too many assumptions in my life!
Ken

 

[Parsnip]

kenvlach,
True I probably wasn't that specific. The cylinder is about 0.5m in length and 0.12m in diameter. It is closed but has holes for flooding the interior. The cofg would be located about 0.1/0.15 m up from the end entering the water. It should enter vertically. As I said mass of about 10kg and impact velocity of approx 30 m/s.
Any advice on this would be much appreciated.
Cheers
Parsnip

 

[IRstuff]

The object itself may be irrelevant compared to the parachute. The drag from the parachute will vary wildly, depending on whether it collapses and stays collapsed, versus reopening

TTFN