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Discussion Starter #1
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.

 

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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)
 

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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!
 

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

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Discussion Starter #5
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?
 

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

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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
 

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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.
 

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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..
 

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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)
Ive seen it done on 3 separate occasions on early 1970s Fedships. I honestly cannot remember the reason behind it, but Im fairly sure that the blocks on these engines would not fit out through the existing access. I also recall it having to be done for the generator on one occasion....
 

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Ive seen it done on 3 separate occasions on early 1970s Fedships. I honestly cannot remember the reason behind it, but Im fairly sure that the blocks on these engines would not fit out through the existing access. I also recall it having to be done for the generator on one occasion....
Generator I could understand, being that they are typically against the bulkhead and removal of the engines would be first on the list of getting it out of there! But unless the block was cracked, I dont know why they'd want to pull the motor out the side... Steel being much easier to fix than fiberglass, it may make more sense.. I'm not terribly familiar with single steel hulls, I slept through that class, knowing I wouldnt be working in that field....:whistle:
 

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As I said, it MAY have been the generators on at least one occasion...
 

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I'm working on a few projects right now---70' Aluminum Passagemaker, they are building the boat, and then once the customer has made up his mind as to power, they'll just cut the port side of the the hull open and weld it shut when the engine is in.
During the build of a larger, 90' and 141' by the same builder, they left sections of the hull open so that the trades didnt have to go up and down and all through the yacht to get to areas in the hull, or up at the bow.
On one of my customer's yachts, after they did a major refit, a mechanic discovered that the crank in the engine (a 16 cylinder locomotive engine) was bad. They had to jack the engine up, drop the pan, and pull this crank out.... makes me sweat thinking about it...
All of these are built to Lloyds, or DNV standards, so when a panel is properly welded back in, the welds are not dressed or ground down. The fairing compound is built up to the weld, so no compromise in strength.

I always enjoy the tours of the engine rooms, and all of the mechanical goings on...
 

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Where did the resident yacht builder go off to...his name is escaping me at the moment.
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Me you talking about?
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Yes the engines can be replaced without a problem, though not common. Like it was mentioned above, the structure of the deck is designed with space large enough for the engines to be pulled out from. Of course the engine needs to be totally stripped of all accessories before hand cause the space is not all that large.
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Some yachts have the cutout visible, while others laminate everything and makes it invisible (for asthetics). When the time comes, all you have to do is removed the fiberglass deck (or cut out "along the dotted lines"), overhaul the engine and then re-laminate.
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I have come across some yachts that dont have that at all, and we have had to literally chop it to get the the engines.
However, all our designs are out of aluminum so it facilitates this event for the owner, should it arise.
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Heres a pic of an aluminum hull that didn't have the cutouts. Obviously we didn't cut it in half just to get to the engines. We needed to pull the engines out to replace with larger ones because the hull was going to be modified.
 

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Good to see you back, bro!
 
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