Sea Ray 400 Sedan Bridge Fuel Burn (Gas)?

Nepenthe

Active Member
Aug 29, 2011
148
Fontana on Geneva Lake, Wisconsin
Boat Info
400 Sedan Bridge
Engines
7.4L Mercruiser
Hello all -

I have a Sea Ray 400 DB with gas engines (454 MPI - 380 HP). I have read all of the threads that mention this boat, but most contain information about diesel engines.

I am just curious as to whether anybody has a fuel burn curve or any idea of the most efficient cruising speed on this boat. We are on an inland lake, so cruising fast is not a concern...

Thank you for the help and best regards.
 
I don't have data for you, but I can tell you that after installing meters, I learned not to believe anyone else's data anyway. So many factors have an impact on fuel burn and performance, that imo, meters are the only way to go.

I found them worthwhile and enlightening even after doing without for more than a decade. If the boat is new to you, all the more reason to have factual info asap.
 
I would not worry about fuel consumption on lake Geneva. I think you would have a hard time burning through a full tank of fuel on that lake during a season.

I would guess that 3400-3600 RPM would be your best cruise.
 
I had a 2000 400DB with same engines for about 5 years. We really enjoyed the boat--great layout, ton of room and a fantastic bridge--but it is definitely not a lean, mean cruising machine. I remember around .6-.65 mpg at 20-21mph. Seems like she did a tad better cruising below 20 (never much better than .7) but I just can't stand moving at that speed.
 
Thank you all very much for the quick replies! I appreciate the idea of installing flow meters. As Andy K said, Lake Geneva is not that large so it is more of a curiosity than anything. We do, however, use roughly 3-4 full tanks of fuel per year while boating every weekend in the summer.
 
I had a 2000 400DB with same engines for about 5 years. We really enjoyed the boat--great layout, ton of room and a fantastic bridge--but it is definitely not a lean, mean cruising machine. I remember around .6-.65 mpg at 20-21mph. Seems like she did a tad better cruising below 20 (never much better than .7) but I just can't stand moving at that speed.

I wonder what was her cruising range with gas engines (I'm guessing the same 350 gal of fuel)?

Interesting move from 400DB to 480DB. What were your primary selling points (I take it diesels was #1)?
 
I wonder what was her cruising range with gas engines (I'm guessing the same 350 gal of fuel)?

Interesting move from 400DB to 480DB. What were your primary selling points (I take it diesels was #1)?

Yes, 350 gals. Pretty close to 200 miles range. Made several trips to Nashville, TN from our place and its right at 175 miles. I'd be nervous until I saw the skyline.

I did the 480db vs. 420/44db debate for 2 years. Wife wanted the 44DB initially but moving laterally wasn't sitting well with me. I'm a firm believer that if you can go bigger, do it. I'd been around and all over the 480 for at least 6-7 years (a boating pal had one) so I knew it about as well as my boat. Always felt (just like Gary has said a time or two) it was/is one of if not the best boat SR has ever made. Regardless of the size, the next boat was going to have diesels, a lift, tracvision, bridge AC and have a hardtop, period, end of report. Less canvas the better. We wanted the extra room and the 3rd stateroom was a big factor. About the only thing she doesnt like about the 480 is the galley storage, the 400db had the pantry and the under galley sole storage. The 480 is lacking when it comes to ample galley storage. Both boats have great bridges, but I'd give the 480 the edge due to the stern visibility. But, probably the thing I dreamt about most was the way the boat (my buddies 480) would throw you back in your seat when the turbos kicked in. You would have to hold on or be ready for it or else you would be moving backwards. The first time I experienced it I knew I had to have one. I still get a kick out of it today.

With all that being said, we really liked the 400db alot...but I suppose I can say the same for the 400EC, 310DA, 280DA, 268DA and all the ones that came before too. Guess it's all good, huh...
 
When I checked ours with the same motors it was around .7 and thinking it was mid 30's per hour on the burn running 31-3,200 rpm. Our boat specs at 22,500lbs which is lighter than a DB. The other poster is right about guages. I'm sure thats the only way to really know since there are so many variables. One of those things that ya'd want/don't wanna know!
Kinda off topic but I know boat engines are constantly under load while running. It's been compared to driving your car constantly uphill. My question is what kind of load % do you think they are really under once the boat achieves planing speeds? A fuel flow meter might give you an idea based on usage and speed achieved. Lowest fuel consumption at highest speed might indicate lowest load?
 
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...Our boat specs at 22,500lbs which is lighter than a DB. ...

You'll be surprised. 400DB is 22,000LBs according to the specs. But, I guess it's safe to assume that we can't expect much better than .5-.6MPG out of it with gas engines. According to searay40dad's report 200 miles range on the 350gal tank gives you .57MPG, which is still not too bad.
 
I'm sure thats the only way to really know since there are so many variables. One of those things that ya'd want/don't wanna know!

From your past posts Skuza, I gather that your boat performs as well as mine does. Even so, I'd like to get you onto the meter bandwagon. I tracked data manually for years, but the difference in trim and load makes such a difference that you can never really make assumptions. For example, I can get better economy at 3,000 (which FEELS miserable) and at 3,400 AND at 3,600 than I do at 3,200!

Some of my other surprises included just how limited the "speed penalty" is - these boats like to run after all, and how much difference loading makes. With accurate tankage information, I now try to carry much less fuel and water, which lets me run faster and leaner than I ever thought I could.

If you're at all considering a Nav system upgrade, this could help pave the way with a metering project. Tying meters into Nav displays and the NMEA2000 network offsets a lot of the cost.
 
We have fuel flow meters on both engines.
At 5 to 6 knots 3 gallons per engine 1200 RPM
At 18 knots 22 gallons per engine 3800 RPM
At 10 knots 7 to 8 gallons per engine 1800 RPM
Boat weight is 20,000 we have added house batteries and a water maker that all added about 2,000 pounds
LWL 38 beam 13'11"
We mostly travel at 6 knots as we we go far and have the time to get there.
At fill up we have determined the fuel fill gauges are correct.
 
You'll be surprised. 400DB is 22,000LBs according to the specs. But, I guess it's safe to assume that we can't expect much better than .5-.6MPG out of it with gas engines. According to searay40dad's report 200 miles range on the 350gal tank gives you .57MPG, which is still not too bad.

When a friend of mine was looking at 400DBs a couple years ago I told him to to expect .55-.65 as a range. He ended up buying a cherry of a 2000. After he had the boat for a year he said my projection was right on the mark, then said he'd wished he would have listened to me. I had a '96 400EC with 7.4MPIs and its cruise was similar, 18-19 knots, and she was about .7.
 
You'll be surprised. 400DB is 22,000LBs according to the specs. But, I guess it's safe to assume that we can't expect much better than .5-.6MPG out of it with gas engines. According to searay40dad's report 200 miles range on the 350gal tank gives you .57MPG, which is still not too bad.

Btw, I never believed this...that the 400db was 22,000lbs. It has 6-7 inches of beam over the 400 dancer and a bridge/cap structure that has a buttload of fiberglass--and it's 500lbs LESS?? The dancers V-drives can't make up that much difference. And, the 400db beam is the same as a 420/44db and nearly same loa, except for the integrated platform and the 420/44db comes in at 28000+?? 6,000lbs difference?...I can see the diesels adding a some extra weight, maybe a ton more, but the numbers always seemed off to me. Maybe the 400db hull was made out of the same stuff those little Easter chicken things are made out of...peeps or something.
 
Btw, I never believed this...that the 400db was 22,000lbs. It has 6-7 inches of beam over the 400 dancer and a bridge/cap structure that has a buttload of fiberglass--and it's 500lbs LESS?? The dancers V-drives can't make up that much difference. And, the 400db beam is the same as a 420/44db and nearly same loa, except for the integrated platform and the 420/44db comes in at 28000+?? 6,000lbs difference?...I can see the diesels adding a some extra weight, maybe a ton more, but the numbers always seemed off to me. Maybe the 400db hull was made out of the same stuff those little Easter chicken things are made out of...peeps or something.

I understand your point, but every spec I've looked at had 22,000LBs for 400DB.

.... Maybe the 400db hull was made out of the same stuff those little Easter chicken things are made out of...peeps or something.

I have nothing bad to say about the boat, but the fact that at least models prior to 2001 have cored hulls, which I'm sure add good amount of weight. In any event, I'm just going by SR specs. BTW, when I was in the process of upgrading and surveyed 2002 400DB I've raised a question on CSR with similar thoughts but more geared toward the performance. I was surprised to find out that the same engines (Cummins 450Cs) moved 420DB (28,000LBs) with the same results as it did 400DB (22,000LBs). The conclusion to my question was an art of engineering putting together the hull, engines, transmissions gear ratio and running gear.

Did SR posted misleading info for several years and they're off by 6,000LBs on 400DB? I'd like to hear the answer to this one. I've experienced where SR's prop chart was off (e.g. they posted 26" dia. props while in reality they were 23" dia., at least on the boats of my interest), but being off by 6,000LBs would be too much.
 
Yes, I've seen the specs...they are what you say. If you compare gas 400db to gas 400da, or diesel to diesel for that matter, same year...appples to apples...and the dancer weighs more....hmmmm. My vote is the 400db weight is understated. I've seen loa's and other details off before so I'm not sure it's that unusual of an occurrence.
 
My boat is (and has always) been 32000 plus or minus a few hundred pounds. I believe the posted weight is inaccurate. My boat has tons of gear (literally), multiple batteries, safety equip etc that adds up to just over 4150 pounds.
 
My boat is (and has always) been 32000 plus or minus a few hundred pounds. I believe the posted weight is inaccurate. My boat has tons of gear (literally), multiple batteries, safety equip etc that adds up to just over 4150 pounds.

One thing that clearly doesn't make any sense is the specs for 2001 and newer. Your boat is 2003 and from I've learned should have solid fiberglass hull. There's no way it could have the same weight as the ones with cored hulls.

Yes, I've seen the specs...they are what you say. If you compare gas 400db to gas 400da, or diesel to diesel for that matter, same year...appples to apples...and the dancer weighs more....hmmmm. My vote is the 400db weight is understated. I've seen loa's and other details off before so I'm not sure it's that unusual of an occurrence.

Everyday we learn something new. I agree with your point comparing apples to apples.
 
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Don't "put too much weight" on specs found in the SeaRay brochure archives. If you examine the archives closely, you'll come across mistakes and inaccuracies very quickly.

I've long-suspected that the 400DA's dry weight listed in the brochure archives was measured with diesels.

As far as other factors, aside from the air filling the cabin, balsa is probably the lightest material on a boat. It's used to increase rigidity while reducing noise and weight.

Also, I doubt a V-drive adds any weight? In fact, it may even reduce the overall weight because there's less shaft. It certainly moves the weight aft though.
 
I have a 2001 400Db in the slings it's weight is 32000 lbs. that is with a full load of fuel no water and not much of our gear on the boat. Mine has the Cummins diesels and they do add about 3000 lbs to the boat.
The Sea Ray spec is dry without fuel or water with the gas engines with no options on the boat. with fuel, water and gear with the gas engines you would mid to high 20k lbs for real weight.
 

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