Full Question
Normally, we allow 6 weeks to deliver to Sydney on Sea Freight from the date of "Shipped on Board" in the B/L. If it takes some times more than 2 months, who is responsible for this delay ? Can we question the manufacturer who is also the shipper using their Freight forwarder, can we ask them to compensate for this delay.

Answer
If you are shipping out of China and the B/L is being provided as the goods are about to ship out, then 6 weeks does sound like a very long time to wait, even if the 6 weeks includes clearing inbound customs in Australia.
In the effort to fight corruption and enforce safety/quality standards, in 2013/2014 I have noticed that shipments with values over 100K USD are being inspected by the port authority in much more detail in the past. This inspection can hold up the shipment for weeks. While the inspections are random, if you are on a blacklist or if you have a value of over 100K USD, you may find “random” inspections are the norm, not the exception.

You ask who is responsible for that delay. The answer depends on the terms of your contract. For example, once I started putting in penalty terms for late delivery, my suppliers “magically” starting hitting the delivery dates. (read more here: 7 items you probably forgot to put in your contract with the factory.). Unless you have clear terms in your contract the freight forwarder will blame the supplier and the supplier will blame the freight forwarder, when shipments are late.

Related content:

Why would a supplier break the terms of your contract/PO?

How to get my suppliers to respect the agreed terms and conditions of our contract/purchase order?