With the congestion in Nigeria ports that has turned an otherwise three weeks shipping period to three or four months affair and considering the saline (salty) nature of sea water, I want to ask what effect the long period that vehicles have to stay on the RORO ship has on such vehicles especially on
Body – metal work and paint work
Electrical - ECM
Mechanical – engine (no driving for the whole period)
Tyres – stationary for the whole period

Is there any proactive measure the ‘potential’ owners can take on delivery of such vehicles to minimise or mitigate short or long term adverse effect if any? Must the engine oil be changed even if it was newly put before exportation since it would be over 4 months though unused.

Is the effect (if any) different on roro or containerised vehicle

no effect. Its not different from you parking your car in the house without driving for a long time.

What is the shipping cost of a porche 911 from either UK or US? Pls

promise72:

no effect. Its not different from you parking your car in the house without driving for a long time.

Why then do they advise special comprehensive washing and waxing if you live near the sea? or is it just a hoax?

Of course there are negative effects.

1) Tyres: May harden and perish.
2) Wheel bearings: Races get pitted, due to weight concentrated in one spot, will be noisy later.
3)  Brakes:  Especially parking brakes may seize in place.
4) Clutch: If there's enough moisture, clutch friction disc can seize to pressure place.
5) Clutch: Hydraulic clutch master / slave cylinders may corrode internally. So the first time the pedal's depressed, the rubber seals scrub the rust, the fine lips are damaged, then they begin to leak.
6) Engines: No negative effects.
7) Transmission: No negative effects.
Suspension: Springs may lose strength, and become too soft, car may sag. On cars with rear torsion bars (most French cars) these may seize.
9) Battery: May be completely flat.
10) Paintwork / bodywork may degrade.

Solution to the above:

1) Make sure tyre pressures are way above the recommended amount - about 50psi, that way, the tyres can't crease.
2) If the car can be moved, backwards and forwards once weekly will help prevent concentrated weight / pitting.
3) If practical, leave parking brake off, and leave transmission in first, or park for autos. May not be adviceable though, given rough seas.
4) If access can be gained to the car, at least once weekly, it's a good idea to pump the clutch a few times, to prevent plate and disc sticking.
5) As above, to keep the clutch master and slave cylinder bores lubricated.
If practical, have suspension transit blocks fitted before car is put on ship - these are blocks designed to raise the car, and keep the weight off the springs.
9) Make sure battery is fully charged before car is put on ship - you can also help preserve life by buying a small solar-powered trickle charger. It plugs into the cigarette lighter, and is placed where it can catch some sun / daylight at least a couple of hours daily.
10) Smear grease generously all over the car's bodywork. Pay particular attention to wheel arches and underbody. Unpleasant and messy yes, but beats conventional car waxes, especially if exposed to saline environment long term.

Flat batteries can be a source of electrical gremlins:

1) Loss of radio code, a pain if you don't know what it is.
2) Intermittent immobiliser issues.
3) Loss of throttle body basic settings - most modern cars rely on constant power to retain memory settings for the ECU and throttle body / throttle potentiometer. Sure the car will still start, but it'll either fail to idle, fluctuate between 500 and 3,000rpm, or just remain at a fixed 3,000 rpm.

The car will of course develop an insatiable appetite for fuel, and be a dog to drive at anything other than full-bore throttle.

If this happens, the easiest way to rectify, and restore basic map settings, would be to drive the car under different load conditions, and hopefully, your car may have a "learning" facility, whereby the ECU will find its original settings.

If not, you'll have to get the basic settings restored via the OBD / OBD II / EOBD ports with a diagnostic device that's capable of communicating with your make of car's ECU, take it to a dealership, or get bent over by a money-grabbing Mr Bodge-It-And-Scarper merchant masquerading as a qualified technician.

@Siena
This is the comprehensive answer I expect and I think the poster expected also.

But Siena, within what time frame will these negative effects happen? If the car stay 2, 3 or 6 months on the ship/in the port? Dont think that 6 months is far-fetched. This is naija

I'd say anything up to, and over 3 months.