520 Sedan Bridge fuel burn rates (GPH)

Mike71

Mike71

New Member
Aug 17, 2021
9
Melbourne, FL
Boat Info
2012 450 Sundancer
Engines
Cummins QSB 480HP
Looking to get away from my pod boat. Thinking about moving up to a 520 Sedan Bridge boat with cummins QSM11 engines. Does anyone know what the fuel burn rates are? Looking for how much fuel I would burn running around 27-29 mph in this 51,000 LBS boat. I'm coming out of a 30,000 boat that burns 31-32 gallons at 30 mph.
 
Last edited:
If I understand it correctly, you want the QSM-11s to burn 20 GPH at your cruise RPM. This keeps them from overheating the exhaust manifold and causing issues. Your control this by adjusting the prop pitch. I understand that many of larger Sea Rays are “over propped”. There is a guy on the west coast, Tony, who is a Cummins guru and can explain this much better than I can.
 
If memory serves me correct, I burned about 44-45gpm at cruise speed (the range you asked about). That’s about 1900-1950 rpm.
 
tc410 said:
If memory serves me correct, I burned about 44-45gpm at cruise speed (the range you asked about). That’s about 1900-1950 rpm.
Click to expand...
Gallons per minute? Exactly how large are your fuel tanks???
 
Steve S said:
Gallons per minute? Exactly how large are your fuel tanks???
Click to expand...
LOL my head knew what to type, my fingers didn’t! Please excuse me, gpH!!! Although sometimes it felt like fuel burned like that per minute!
 
Here is the link to the website I was referring to https://www.sbmar.com

Tony has a wealth of info there about Cummins diesels, and the manifold issues of the QSM-11’s. He will have the info you are looking for.
 
As stated above with the QSM11s you want to keep the fuel burn to about 20gph at 2000rpms to avoid having issue with the manifolds and turbos. That being said I hVe tweaked my props a few times and got to about 21gph at 2000rpms and that is cruising at 24mph or about 21knots. 30mph is almost top speed and wouldn’t be sustainable for long period of time.
 
  • Like
Reactions: RBB
40GPH at cruise for a boat that size is pretty good if you ask me. I was expecting more in the 48-56gph range.
 
Reading posts above it sounds like cruising at 27-29 is not recommend with the Cummins QSM11. Can this speed be acheived with the Man R6 800hp?
 
Guessing you would get a few more MPH out of the MAN's but I think you need to decide if you really need to run that fast in a boat this big.

A 21-23 kt cruise is quite normal for a 50+ footer.

The MAN option in the 52 seemed pretty rare. When we were looking we only saw a few for sale compared to dozens of QSM powered boats.
 
swaterhouse said:
Guessing you would get a few more MPH out of the MAN's but I think you need to decide if you really need to run that fast in a boat this big.

A 21-23 kt cruise is quite normal for a 50+ footer.

The MAN option in the 52 seemed pretty rare. When we were looking we only saw a few for sale compared to dozens of QSM powered boats.
Click to expand...


Your might be right. I currently have a 450 Sundancer with the 5.9L 480 hp with zeus pods. This past June we broke a prop on one of the pods. That caused so much more damage. I have am having to rebuild the entire pod. MarineMax is up to $42,000 and should finally be finished in the next week. The Prop that broke is not going be available till March 2022. I am still open to what the next boat be I just know it won't be a pod boat especially Zeus. I am looking at any boat in 46-58ft range that doe's not have pods. The 55/58 Sundancer caught my eye. I can't decide whether the Sedan Bridge boats or Sundancer.
 
I have a 320 Sundancer. I am looking to upgrade to 48 or 520 Sedan Bridge. Any comparison fo the 2 would be greatly appreciated. There are some things I like about the 520 but not sure the price difference is worth it.
Thanks in advance.
 
Mike71 said:
Your might be right. I currently have a 450 Sundancer with the 5.9L 480 hp with zeus pods. This past June we broke a prop on one of the pods. That caused so much more damage. I have am having to rebuild the entire pod. MarineMax is up to $42,000 and should finally be finished in the next week. The Prop that broke is not going be available till March 2022. I am still open to what the next boat be I just know it won't be a pod boat especially Zeus. I am looking at any boat in 46-58ft range that doe's not have pods. The 55/58 Sundancer caught my eye. I can't decide whether the Sedan Bridge boats or Sundancer.
Click to expand...

I didn't mention anything about the 58 Sedan Bridge because I wasn't sure how big of a jump you were willing to take, but if your willing to go up to that size I can say its a great boat. We just got ours this year and very happy we chose the 58 over the 52. First the full beam master is fantastic. Yes I wish it had full height headroom all the way across but honestly its been a non issue, I am 6'1", and its way better being able to walk all the way around the bed than to climb up into the vberth on the 52. The amount of room on the bridge is awesome and its got a ton of interior storage. The only downside is there is nearly zero room in the engine room and lazaret. I don't regret at all we chose the 58 over the 52. The only thing I wish the 58 had that the 52 has is the space in the lazaret.

The 58 will however happily cruise at 25kts - very close to your desired speed. Fuel consumption at that speed will be close to 60gal/hr, but in reality the mile/gal is extremely flat from about 15kts all the way to 26kts. The 58 is a beast, we were out yesterday in square shaped super short period very confused 6-8' seas, and it ran through that mess at 16kts relatively comfortably and no pounding. Yes we got spray up and over the hard top but that was the worst of it.

You already dipped your toes into thinking about the MAN's on the 52. Despite what a lot of people who have never owned a MAN say, they are fantastic engines if they have been and are maintained well. They do need a major maintenance every 2-4 years depending on location and use to maintain the seawater cooling system. This service will vary depending on location, but I called three different areas for quotes on this service (MA, FL and TX) and they were all with a thousand dollars of each other. There is a great couple of posts on this subject in the 58Db thread by @bmac and @carterchapman. I will say the quotes I received were right in the same ballpark.

Having come from a Sundancer to a Sedan Bridge, there is no comparison. We live on our boat every weekend plus about 3 weeks from early May to Late October. On cool or rainy days its so nice to sit inside a dry warm (or cool depending on weather) and be able to see out all around you. You cant get that in a Sundancer. Also the visibility from the helm is so much better.
 
Mike Gillies said:
I have a 320 Sundancer. I am looking to upgrade to 48 or 520 Sedan Bridge. Any comparison fo the 2 would be greatly appreciated. There are some things I like about the 520 but not sure the price difference is worth it.
Thanks in advance.
Click to expand...

The 48 was made until 2004. I think the 2003 and 2004's were offered with QSM's, otherwise I believe they were CAT powered.

The 500 was the first year of the redesign in 2005. The major changes were in the interior layout, the bridge got bigger and taller, and a molded swim platform was added.

The 52 was from 2006 until 2008?, and is identical in nearly every way to the 500.

The 520 was from 2009? to 2013. This model has a larger cockpit with an optional summer kitchen layout, and there is some small improvements in the interior most notably easier access to the "basement" and the bunk beds are slightly longer.

I might be a bit off in the year transition from 52 to 520, hence the question marks.

From 2005 on the QSM11 was standard, the MAN R600 were optional.
 
swaterhouse said:
I didn't mention anything about the 58 Sedan Bridge because I wasn't sure how big of a jump you were willing to take, but if your willing to go up to that size I can say its a great boat. We just got ours this year and very happy we chose the 58 over the 52. First the full beam master is fantastic. Yes I wish it had full height headroom all the way across but honestly its been a non issue, I am 6'1", and its way better being able to walk all the way around the bed than to climb up into the vberth on the 52. The amount of room on the bridge is awesome and its got a ton of interior storage. The only downside is there is nearly zero room in the engine room and lazaret. I don't regret at all we chose the 58 over the 52. The only thing I wish the 58 had that the 52 has is the space in the lazaret.

The 58 will however happily cruise at 25kts - very close to your desired speed. Fuel consumption at that speed will be close to 60gal/hr, but in reality the mile/gal is extremely flat from about 15kts all the way to 26kts. The 58 is a beast, we were out yesterday in square shaped super short period very confused 6-8' seas, and it ran through that mess at 16kts relatively comfortably and no pounding. Yes we got spray up and over the hard top but that was the worst of it.

You already dipped your toes into thinking about the MAN's on the 52. Despite what a lot of people who have never owned a MAN say, they are fantastic engines if they have been and are maintained well. They do need a major maintenance every 2-4 years depending on location and use to maintain the seawater cooling system. This service will vary depending on location, but I called three different areas for quotes on this service (MA, FL and TX) and they were all with a thousand dollars of each other. There is a great couple of posts on this subject in the 58Db thread by @bmac and @carterchapman. I will say the quotes I received were right in the same ballpark.

Having come from a Sundancer to a Sedan Bridge, there is no comparison. We live on our boat every weekend plus about 3 weeks from early May to Late October. On cool or rainy days its so nice to sit inside a dry warm (or cool depending on weather) and be able to see out all around you. You cant get that in a Sundancer. Also the visibility from the helm is so much better.
Click to expand...


This is the info I'm looking for. I spent all day today looking up info on the 58 sedan bridge and the 580 Sundancer.
I looked at 510 on yachtworld that had straight shafts , NO pods. But I'm thinking with wanting to move up from a 450 Sundancer to a 51' boat is not enough of a jump. I am in Central Florida on the East Coast. There is Man dealer just south of us in Vero Beach.
 
Mike71 said:
This is the info I'm looking for. I spent all day today looking up info on the 58 sedan bridge and the 580 Sundancer.
I looked at 510 on yachtworld that had straight shafts , NO pods. But I'm thinking with wanting to move up from a 450 Sundancer to a 51' boat is not enough of a jump. I am in Central Florida on the East Coast. There is Man dealer just south of us in Vero Beach.
Click to expand...
If the 58 is even remotely close to your budget - extend a bit. I’ve had the 50/52 sedan bridge and now the 55/58 sedan bridge. You will be happy for a long time in the 58. We’ve had ours for 6 years now. My wife got the itch to look at 61 sundancers this summer. We were on for about 15 minutes in July and she made me promise to keep our 58 until the right 65 DB comes on the market.

Little things like standing in the galley washing dishes while having a beautiful wide open view of the outside mean so much. The full beam master aft with all its comfort and privacy allow for sleeping in and watching Netflix on a dreary day. The bridge - or man cave as my guy friends call it is the best view in the marina.

Having had and/or been on many sea ray sundancers and sedan bridges, I can say that the 58 is the best boat for the price in the current lineup. The 65 is probably a bit nicer, but they need a few more years of depreciation to offer the value of the current 58.

PM any of us in the 58 group for any further comments, questions, or conversations.
 
tc410 said:
If the 58 is even remotely close to your budget - extend a bit. I’ve had the 50/52 sedan bridge and now the 55/58 sedan bridge. You will be happy for a long time in the 58. We’ve had ours for 6 years now. My wife got the itch to look at 61 sundancers this summer. We were on for about 15 minutes in July and she made me promise to keep our 58 until the right 65 DB comes on the market.

Little things like standing in the galley washing dishes while having a beautiful wide open view of the outside mean so much. The full beam master aft with all its comfort and privacy allow for sleeping in and watching Netflix on a dreary day. The bridge - or man cave as my guy friends call it is the best view in the marina.

Having had and/or been on many sea ray sundancers and sedan bridges, I can say that the 58 is the best boat for the price in the current lineup. The 65 is probably a bit nicer, but they need a few more years of depreciation to offer the value of the current 58.

PM any of us in the 58 group for any further comments, questions, or conversations.
Click to expand...


My budget does support a 58 sedan bridge. I curious how much head room is the engine compartment and if you get down both sides of the engines for services on the 58 SB.
 
At 5’9” I have to bend over slightly to make it through the engine room between the engines. There is not room to walk around the outboard side of the motors, but my MAN mechanic can service the outboard components (valve clearances, valve covers/gaskets, oil cooler gasket, etc.). The salon floor is removable if there’s ever a need to lift a motor, or do a major in-frame service on the top side of the motor.

All annual service is easily accessible on the motors due to placement of the oil filters, fuel filters, water pump impellers etc.
 
Essentially the 50/52 sedan was an updated or restyled version of the 48 Sedan. There are many similarities and differences between the 48 and 50/52 Sedan Bridge models. For example, the 3rd stateroom in the 48 is an “L” shape with the washer/dryer combo located in that stateroom vs bunks in the 3rd stateroom on the 50/52. The 48 has more of a “booth” style dinette and the galley is on the same level as the dinette. 50/52 have a galley that is a step down from the salon and two steps down from the dinette. The 50/52 has a “ basement” compartment under the galley which is where the washing machine is located. The 50/52 have a molded swim platform and the hulls are solid fiberglass with no balsa coring below the rubrail.

We burn approximately 21 gph per engine with the QSM 11’s cruising about 21-22 knots. Similar to others who have the QSM’s we cut the props to reduce the fuel consumption/load. We are finishing our 7th season with our boat and the QSM’s have been super reliable. We are extremely happy with boat and engines.

Feel free to private message me if you would like to know more.
 
You must log in or register to reply here.

Forum statistics

Threads
113,153
Messages
1,427,324
Members
61,060
Latest member
Danileo
Back
Top