Thread: Question about megayachts, superyachts. Can you change the engine if it goes bad?

Really random I know, but I was thinking if a engine in a huge yacht goes out what do you do? I can't see how you can "swap out" the engine. A engine in a boat like this one below.

yea you can

often times they need to be overhauled after a certain number of hours anyways

basically parts of the deck that sit above the engine come off, of course they are made to look like they can't off but they can (some are more obvious than others)

Actually, in many cases, the boat is taken out of the water (Dry Dock) and a HOLE is cut in the side of the hull (Steel Hull) the engines are then replaced, and the hole is welded shut!

Where did the resident yacht builder go off to...his name is escaping me at the moment.

Originally Posted by PBR ME

Actually, in many cases, the boat is taken out of the water (Dry Dock) and a HOLE is cut in the side of the hull (Steel Hull) the engines are then replaced, and the hole is welded shut!

Noob question, but wouldn't that made the hull weak?

As with every weld, the weld is usually stronger than the material being welded.

Originally Posted by Forfend

As with every weld, the weld is usually stronger than the material being welded.

Did not know this. Thank you.

The majority of the engines in the larger yachts are rebuilt while still in the hull.. no reason to take it out, its disassembled and carried out for machine shop work. The blocks are bored and machined while still in the hull.

Ive never seen one taken out thru the side of a steel hull, if it was large enough to be a steel boat, the motors would be rather large and have the ability to be rebuilt while on-board (not saying they DONT do it, Ive just never seen that before)

EDIT: in cruise ships and tankers they go through the side but its a rarity because the engines are built to live for as long as the hull, as far as passenger vessels, they usually wont go through the side because the engines are generally half draft and thats a pretty sensitive area to cut and weld.

Cruise ship/fleet tankers/ cargo ships are all rebuilt while in motion, they are so short rpm'ed motors that they can rebuild one cylinder at a time while its still under way.

But the yachts you see on the great lakes and the bays sometimes do have to have the floor of the salon cut out and the back windows removed (aft cabin style) to have the engines pulled, especially if they are under warranty and manufacturer requiring they be in one piece for warranty replacement.

Heres a quick vid on cruise ship engines:

http://www.youtube.com/watch?v=rdAQeg5-SZM

Big diesels are designed to be overhauled/rebuilt with the block in place. You can generally replace the sleeves/piston/rods/head without too much headache.

Those things should go for thousands and thousands of hours anyway, so it isn't really a regular problem.

Anon is correct.. They rarely "wear out", but stuff does break at times and can usually be fixed while its still in operation.. The QE2 has over 6 million nautical miles on it, something like 800 transatlantic voyages and still on the original mechanical diesels.. And those are 1960s technology..