Exhaust system

A typical system on a generator will have a lift muffler and then a water separator muffler. The exhaust gases exit above waterline while the water exits below. For the mains, most European builders like to use a dry muffler and then cool the gases. American builders for the most part like to cool the gases and then use a good wet muffler on the bypass. I have seen as many different systems as there are boats floating around. Most do what they need to as long as there is some good engineering behind it. Unfortunately, a few builders see at as just "stainless plumbing" and then they find out they have issues during sea trials. Let me know if you have any other questions.

If you have been at this work for 3 months is there not someone where you work who can advise you as to what is the best and why? I would personally be very dubious about anything designed for a megayacht in the way of the systems you mention by someone with 3 months in the marine world asking for advice on the internet.

There are many rules for the design of most systems on a megayacht and these change as the size of the vessel increases, start reading LY3 and SOLAS where applicable, your IACS Surveyors should be able to tell you if what you have desigedn is any good at the plan approval stage.

There is no problem with it as such as long as you have enough of an understanding to sort fact from fiction - even well intentioned fiction ( I not saying that anything posted here so far is fiction)

Maybe it is the way you described your position that got my attention, I have done a number of builds over 50m and sailed on them all as Chief Engineer. I am yet to see a yard where junior designers ask Project Managers for advice on what to use in a system.

The system should be specified to do whatever it is required to do, drawings showing the system should be produced, not so detailed at first while general dimensions are checked and comments made, then ones it can be made from come next.

The sub contractor is then engaged to build and sometimes fit/ install it. There will also often be a FAT ( Factory Acceptance Test) where the equipment is demonstrated to work correctly at the manufacturers facility and an acceptance can be offered with any points noted on a punch list to be corrected prior to final acceptance if only minor and not affecting function as such.

There are other companies who do more than just design and route the system. They can fabricate the exhaust to class requirements and also recommend the sizing and do preliminary backpressure calculations.