Friday, July 11, 2008

Inspections When Ship At Dry Dock

There are a few areas that need to be inspected when ship going dry dock as there are some inspections that are impossible to be carried out when the ship is in service or afloat.

First thing first is to inspect the underwater bottom plate for any deformity. Should there be serious buckle or deformity, the concerned area need to be cut and renewed with new steel plate.

Bilge keel also to be inspected for any serious buckle. Here, the bilge keel is a bit buckle and need to be repaired. A bilge keel function is to assist in stabilizing the ship when sailing.

Side shell plating will also need to be inspected for serious damage or buckle. Side shell and the underwater bottom plate is a huge area and need good observation to spot any defects.

Wasted welding seam should be repaired and welded back

Bulbous bow is another area that need attention as this is the area most susceptible to damage

Check the stern tube bush (inboard and outboard) clearance. The zinc anode around the hub should also be replaced. Slack bushes are to be replaced

Propeller blades should be inspected for damage (light damage can still be repaired). Heavily damaged propeller should be replaced. The rudder bushes (upper and lower) should also have the clearance measured and replaced if the clearance exceed the specification.

Sea chest to be opened up and cleaned. Zinc anode inside the sea chest should be replaced. The sea chest shoul also be inspected for any damage

Anchor hub to be inspected for any hole or serious deformity caused by the constant hammering by the anchor

Anchor chain to be lowered down and gauged. 12% diminution anchor chain to be replaced with new one (let say the original thickness is 40mm, anything less than 35.2mm need to be replaced)

Anchor shackle, swivel and the anchor in general to be inspected for any wastage or thinned down.

Chain locker room to be cleaned and inspected for damage. Wonder how to get into it? See the semi circular holes? That where one be putting their feet and grip it when entering it. Always a scary experience.

Sea chest valves to be opened up to be inspected and lapped. Badly damaged valves should be replaced
Anchor hawse pipe and wash pipe to be inspected for any hole or leak.

Here comes the fun part. Into the ballast tank for inspection. All the longitudinal stiffeners, structure, brackets, frames as well as bottom plate to be inspected for damage, buckle or thinned down.

Cargo hold frames, brackets and flange to be inspected for wastage and buckle. Close up inspection is required here.

One of the most common defect at the cargo hold (even with the one with tween deck) is at the edge, in way of side shell. This area usually is badly pitted and thinned down into the side shell. The best repair when it is no do badly thinned down is to re-weld the groove. If the groove is too deep, the side shell need to be cropped together with the deck concerned.

Depending on the type of hatch cover for individual ship, it is likely that the hatch cover will sustain some damage after years in service.

The hatch cover rail/runner might also sustain some damage.

Hatch coaming stiffeners are also subject to high stress and wastage is likely in this area

Hatch cover winch foundation is a stress point and likely to be holed as shown

Anchor windlass structure and windlass will also likely to turn out to be like this. Multiple defects can be spotted.

Bulwark stiffeners and flange around the main deck will also suffer wastage

Defective and buckled railing around the open deck area will also need to be repaired

Load line items such as mushroom air vent, air vent head and goose neck air vent are also subjected for further repair or renewal.

Another annoying thing when going dry dock is when there is an annoying surveyor. Not all surveyors are annoying, only certain surveyors (usually the young and inexperienced) that tend to show off and create a lot of condition of class for ship owners. Sometime they will find some petty issues for the owners to resolve.

There are many more inspections to be carried out but that are pretty much the basic to it. It is not an easy job. Wish I could have an easier job.


shawnn loo said...

Wow... what ship is it..?

Borneo Falcon said...

This is cargo ship

Petite Lass said...

Hey, interesting and informative post! Thanks for sharing. I work in the shipping line and I really appreciate the information shared. Have yet to board on a vessel yet.

Anyway, keep on posting ;)