gas milage

[Dive Girl]

SEA RAY 340​

2001


PERFORMANCE


“WILD RICE”


TWIN 454 MPI​

Speeds by GPS
Fuel Flows by computer connected to engines.

RANGE IS 215 GALLONS

RPM MPH GPH MPG RANGE

700 3.9 2.0 1.95 419

1000 6.0 3.6 1.66 358

1200 6.8 4.4 1.55 333

1500 7.9 7.0 1.13 242

I'm intersted in the rest of this chart. Please post, or PM me!
Thanks

 

[tobnpr]

I doubt you'd realize significant fuel savings.

What you're not considering is at least as important- which is that you'll be cutting your total engine hours in half. If it's a lengthy trip, that difference can be significant. Fewer hours= less maint $$ and higher resale $$. If this is only a weekend jaunt, I wouldn't even bother.

Not sure I would attempt it without a pilot, or if there's more to the trip than a "straight line" or two. If you've got to dodge crab pots, etc. forget it- you can't maneuver on a single engine.

You need a crossover line for your dripless seals as mentioned above, and you need to confirm with the manufacturer of your trannies that extended freewheeling in neutral will not damage or cause excessive wear to it. Otherwise you have to lock down the inoperable shaft.

 

[Sundancer]

Cruising mine at 8mph means running at about 3500rpm when I normally cruise at 3200rpm. Not fun.

Something isn't quite right with these numbers! I'm sure it's just a typo or something. :huh:

 

[VinceR]

Here it is Dive Girl

SEA RAY 340​

2001​

PERFORMANCE​

“WILD RICE”​

TWIN 454 MPI​

​

Speeds by GPS
Fuel Flows by computer connected to engines.

RANGE IS 215 GALLONS

RPM MPH GPH MPG RANGE

700 3.9 2.0 1.95 419

1000 6.0 3.6 1.66 358

1200 6.8 4.4 1.55 333

1500 7.9 7.0 1.13 242

2000 12.4

2500 18.6

3000 16.9 24.0 .70 150

3200 20.5 26.6 .77 164

3400 24.1 30.6 .79 168

3500 25.0 31.0 .80 172

3600 26.4 33.4 .79 170

3800 28.0 34.8 .80 172

4000 29.5 38.0 .77 164

4300 32.6 47.6 .68 147

 

[Four Suns]

Geez... some of the responses here rank right up there with "stupid crap posted by people without a clue."

Bill, Going straight is not a problem at 5mph on one engine. :smt001
You don't need power steering when going in a straight line. :grin:

Now... How many of you have been on the Chesapeake Bay (the OP's place of boating), or any other body of water with waves, where you could go "in a straight line" and not need the steering to keep it in a straight line? Anyone? I know when I am out on the water, keeping a straight line in any seas requires serious exercise of the steering system... this is not like a dodge neon in need of a front end alignment... sheez... but this advice comes from the same dude that runs WOT all day and pressure washes the boat every weekend.

To the OP's question.... The problem you are going to have (especially on the Chesapeake Bay) is you are not going to have enough rudder control in the seas running with one engine... or even two at displacement hull speeds. You have rudders the size of a couple pieces of toast... and they need a lot of water moving over them to keep the pointy end going where you want it to... Your trawler friend has a rudder(s) the size of picnic tables so his 8 knots work fine... I've been caught in squalls on the bay and with both engines engaged and 60 knot gusts it makes my steering useless at displacement speeds... something Chapman's doesn't tell you. The trawler will be fine though.

If you've been on the bay and cut one engine with a 3+ foot wave, you'll note that mother nature doesn't want your boat to go where you want it to go unless you are pushing enough water over the rudders to say "screw you!". One engine out and displacement speed in 3+ foot seas makes steering very difficult because of the lack of rudder size.... It's like trying to get an F-15 airplane flying at 80 knots... not happening...

Going down a canal or docking in the marina is one thing... going "cruising" on open water is another...

 

[earthmover17]

I like to engage Auto pilot while running one engine and watch it try to correct. It tends to have a pretty tough time doing it, and it pilots a lot better than I do.

Jack

 

[Four Suns]

put the autopilot on with the starboard engine turned off in 3+ seas and it doesn't work...

 

[tobnpr]

I like to engage Auto pilot while running one engine and watch it try to correct. It tends to have a pretty tough time doing it, and it pilots a lot better than I do.

Jack

Funny you mention that.
On the seatrial my surveyor shut down one engine, and engaged the AP. I didn't have a clue what he was doing and asked. He explained that's how he tests the performance of the pilot. She tracked straight as an arrow, but of course that was in a light bay chop.

 

[Nehalennia]

I'm asking to learn here on this one. He has a 360DA and I assume vdrives? Won't he have to also worry about the shafts leaking if one engine is shut down, or will it have dripless seals on his boat?

 

[my3sons]

We have drippless shaft seals and crossover water cooling lines. One motor running will pump water to both shaft seals to keep them lubed and cool

 

[Nehalennia]

We have drippless shaft seals and crossover water cooling lines. One motor running will pump water to both shaft seals to keep them lubed and cool

got it.

 

[Hampton]

Not contradicting anyone here, but adding some personal experience info. Remember about 3 years ago when I tried to calibrate my stbd fuel system? I ran out of gas on the stbd side while indicating 1/4 tank. We were cruising back to PCB from the SE out in the Gulf. We cruised on the port side only in 3 -5 foot seas with spray blowing over the bow. My wife later told me that it was the worst she's every felt on a boat.

I set about 1500 RPM or so and plowed through the waves with the rudders cranked over an appropriate amount. If I needed more port, I'd throttle back a little. If I needed more stbd, I'd add a little power. It was a little work, but the worst part was cleaning the cabin and washing the boat down.

80 Knots is fighting speed in the F-15. The perfect speed in a knife fight (slow close fight) is 90 knots, full afterburner, 35 degrees nose high climbing up to build turning room to go offensive against a less capable, heavier, or less efficiently flown fighter.

Against F-16's in a slow fight, we've been known to stand the jet on the tail and let it fall backward as the F-16's flight control computers limit the nose attitude and angle of attack, causing them to fly out in front of us - when pure vertical, we have zero forward velocity. Just sayin'.

We always brief the minimum airspeed in a visual fight. I limit students to, "The minimum speed required to keep from going ballistic and becoming a leaf." This is well below 70 knots.

 

[Four Suns]

John....

To keep the analogy right... you can't apply power... running a boat on a single engine at 7 knots is not "afterburner"... Does your F-15 wing's provide enough lift for the plane weight with with no power and 70 knots?... My point was the smaller the rudders, the more water needs to flow over them to provide the force necessary to move the boat in seas. The conditions you describe are normal cruising in a trawler and not something you would casually do in a Sea Ray with one engine turned off. Your boat must be better than mine with bigger rudders as 3-5' seas push my boat around enough that both engines engaged requires a lot of work trolling while fishing... and put the bow under water from time-to-time if I'm at displacement speed.

So now we are telling someone that "Sure! Your boat will do fine in open water on one engine with displacement speeds as long as you rev the engine through it's power band (i.e. apply afterburner) and adjust the rudders accordingly."

Sounds like "limp home" and not "cruising" to me....

 

[Alex F]

Last season I had a problem with starboard engine and I had to take it to my local MM dealer for diagnostics and repairs. I had to travel through Point Pleasant canal, which has very strong current and is usually rough due to boating traffic. To avoid turbulence from boating traffic I did the trip after the sunset.
My 320DA has the cross-over cooler/lubrication. But, I had advice from fwebster that some trannies can be damaged from freewheeling shafts. I wouldn't want to find if my trainy can handle it, the hard way. I had big wrench so it was easy to secure the shaft. I also checked to make sure it stays in place while I travelled for about a mile. The trip was fine and I made pretty good time. I had no issue steering the boat while underway (of course at idle speed it’s more difficult, but otherwise it was fine). I was doing about 6kts using 3gph @1800rpms. I’ve noticed that by adding more RPMs the speed wouldn’t get much better while the fuel burn was climbing up. So, I found 6kts@1800RPMS was the better spot.

To address the OP question, I would think that 360DA might be travelling at a little faster speed at similar RPMs, therefore I would think that it’s possible to find the compromised speed that would work for both boats.

In summary, I think there’re 3 primary items to consider based on all the suggestions you’re getting:

• Ability to have good steering control when using either engine (only one at the time).
• Seas condition. You have to consider advice from experienced captains who know your local waters. If seas are not calm forget the one engine idea, unless you have no choice (mechanical failure).
• Make sure to find out if your transmissions will not be damaged from freewheeling shafts.

I have similar situation all season long, my friend has a sailboat. My approach is simple, I get to the spot, drop the hook, get settled and I usually have good 45min to 1hr before he shows up. By that time we go for a swim and have good time on the beach. This is why we have power cruiser that can take us to the destination at decent time frame. The only way I can see ourselves travelling together if it’s after dark (I usually don’t go faster than 5-6mph).

Good luck and have fun with your trips.

 

[my3sons]

.Against F-16's in a slow fight, we've been known to stand the jet on the tail and let it fall backward as the F-16's flight control computers limit the nose attitude and angle of attack, causing them to fly out in front of us - when pure vertical, we have zero forward velocity. Just sayin'. .

Is that like "OK Goose, we're goin to hit the brakes and let 'em fly right by" ?

Gosh I liked that movie

 

[my3sons]

I think Alex has the best idea, Give it a shot, if it doesn't work out, radio your buddy that you're running ahead and you'll pick out a nice slip for him.

 

[Hampton]

John....

So now we are telling someone that "Sure! Your boat will do fine in open water on one engine with displacement speeds as long as you rev the engine through it's power band (i.e. apply afterburner) and adjust the rudders accordingly."

Sounds like "limp home" and not "cruising" to me....

It was definately limping home, but just not that painful (except for my wife).

As far as the flying analogy goes, you just tripped the switch in my brain which brings out the instructor in me.

 

[Hampton]

Is that like "OK Goose, we're goin to hit the brakes and let 'em fly right by" ?

Gosh I liked that movie

Sort of, but in reality, it's much more violent than depicted. While in a tight, slow speed turn - picture upside down, idle power, pulling nose down through horizon and then back up to about 45* nose low on the back side, then rolling another 180* and doing it again and again, drawing him closer and closer while denying a shot, and then going to full afterburner about 4000' above the floor and executing about a 135* slice directly back into the offender and suckering him into a gun attempt which you defeat with a timely out of plane maneuver and cause him to cross behind you, closely, with a solid vector to the outside of your turn circle, then you can go to idle, roll to put your lift vector (centerline out of the top of the jet), at his high six o'clock, aggressively bury the stick in your lap as you re-select full afterburner and pull your nose up to 70 degrees nose high and push forward on the stick to catch it at 90 knots, 35* nose high, and ride the elevator to the moon, then yes, he'll fly right by, except he's doing the same thing to try to maintain the offensive advantage, so you try to roll to his high six while he does the same to you and you enter a rolling scissors...

 

[my3sons]

I new that ...yeah right..
You lost me after the first sentence or so...

But I sure am glad you guys know how to do that stuff...

Thanks for all you do for us. :thumbsup:

 

[Four Suns]

I new that ...yeah right..
You lost me after the first sentence or so...

But I sure am glad you guys know how to do that stuff...

Thanks for all you do for us. :thumbsup:

He was talking about how to drive a boat in waves on one engine... not the airplane.