anybody crusing with one engine off?

So how much are you adding to the depreciation on the boat by more the doubling the hours everywhere you go?

I don't have it in front of me, but I know my QSM-11 operators manual says not to run the engines at idle for an extended period of time...
 
Gary, I remember a while ago you made a comment that the depreciation is the biggest expense on a boat. I agree and think that it's one of those thing where you either pay now or later. However, when boarding several trawlers at Annapolis boat show I was surprised to see QSM11s on some of them. My assumptions was that these engines (as well as mine) are designed for planing hulls, but I guess if they're used on trawlers my assumption is incorrect. So, that brings to the next question what's the intend for an optimal use and speed/RPMs for these engines on trawlers? Although, those were semi-displacement hulls, IMO it's safe to assume that slow speed would be used most of the time, especially on a long legs.
 
Which version of the QSM-11 and what was the transmission ratio/prop size? Trawlers have their engines sized and transmission/props selected so they are running at optimal efficiency at displacement hull speeds. Not idling at 650 RPMs for hours on end. My boat runs at 6-8 knots at 650 rpms... which isn't too far from it's hull speed. At the published cruise RPM (2100), it moves along at 26-27 knots. Even the "fast trawlers" (ones that advertise cruising at hull speed OR planing) that have QSM-11's in them are such that their "fast cruise" speed is under 20 knots and hull speed is probably 8 knots or so... so when they are at hull speed, I'm betting they are turning 1200 RPMs or so... Also, some versions of the QSM-11 don't have turbos on them and are derated down to 400 something HP instead of over 600 HP like mine.

And depreciation is the biggest expense on a boat. If you can't afford the depreciation, then don't buy or run the boat. Oh wait... that's right... we blame the banks now when we get upside down on a boat loan and say f* you and walk away. I keep forgetting about this "new math."
 
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Next time I'll pay more attention to the engines HP and transmissions ration.

Interesting points regarding the idle cruising, but I think that it's a rare occasion when people actually practice that. I think I've read the same for my engines that idling for a long time is not "healthy" for them. The way I read the original question was for related to saving hours on the engines by running one at the time cruising as close as possible to the hull speed. So, if we keep one engine running at about 1000-1100RPMs consuming around 2.4GPH and traveling at around 6kts it's very possible to achieve that goal of saving on fuel and engine hours. The more I think about it the more it makes sense to try if the numbers in my example are close to be true. If they do, then it makes sense vs. having both engine running at 950-1000RPMs and travel at 7.5-8kts. The difference in speed doesn't justify the X2 accumulation of the hours.

Anyway, like you said, one has to make the choice saving on fuel now and accumulate the hours and then realize that the boat will have to be priced tens of thousands of dollars less, since the competitive models will have much less hours. When upgrading to diesels I knew that I can have them run for many-many hours, but I always keep the depreciation point in mind. My current rate is about 135hrs a season, if I go slow all the time on both engines, then my hours would easily reach over 300hrs per season, if I want to cover the same traveling distance. So far I go at hull speed at the rare occasion (when staying local or on a very short legs), but I'm interested in experimenting the one engine theory since I'm planning to do much longer cruising in the future.
 
There are thousands of large Sea Rays parked along ICWs dozens of miles from inlets. How do they survive? In the information gathering process, slams about decisions and budgets are inappropriate. In my case,I can cruise the coasts for 750 miles in seven days and consume 1200 gallons and about 35 hours and six Marina nights. Or, I can cut straight across, use 150 gallons, 30 engine hours and two nights on board in 2 1/2 days. It seems worth looking into.

Run four hours on one at the appropriate RPM, start the other, warm it up, Cruise fast for a while, idle back, cool down, shut one down, put wife at helm, sleep four hours, rinse and repeat. This cannot be any different than those who live on canals other than the single engine considerations.

So, back to the topic... cruising single engine.
 
John,

What's the distance from point A to point B when cutting across?
 
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About 400 miles. 50 hours divided by two for engine hours, or times 7 mph for range plus 5 hours at faster speeds with both engines. Rough numbers. Makes sense if it does no harm.
 
As you pointed out there are only two options, hug the cost and log a lot of miles and burn a lot of fuel or cut across at slow speed. IMO, your situation is not a brainer, I would cut across. Using boattest.com numbers for 480CE (just using it as an approx benchmark), when running on both engines I would try to keep her in the range of 850-900RPMs and expect close to 7kts cruise. This should provide around 700-750NM range. We have to keep in mind that your generator will be running (if not all the time, but at least during the night if you go to sleep down below with A/C on). I would plan on leaving good room for reserve b/c (as you know there's no turning back once you're committed).

420DB_Boattest_results.jpg

I can definitely see how much you can benefit from running on single engine and would do the same, even if it meant to lock the shaft (in case if you find out that your transmission cannot freewheel). IMO, you should see good fuel and 1/2 engine hours savings. It makes total sense to me for this particular scenario.

Have you tried contacting SR, ZF? How about asking Rusty?
 
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Hampton said:
There are thousands of large Sea Rays parked along ICWs dozens of miles from inlets. How do they survive? In the information gathering process, slams about decisions and budgets are inappropriate. In my case,I can cruise the coasts for 750 miles in seven days and consume 1200 gallons and about 35 hours and six Marina nights. Or, I can cut straight across, use 150 gallons, 30 engine hours and two nights on board in 2 1/2 days. It seems worth looking into.

Run four hours on one at the appropriate RPM, start the other, warm it up, Cruise fast for a while, idle back, cool down, shut one down, put wife at helm, sleep four hours, rinse and repeat. This cannot be any different than those who live on canals other than the single engine considerations.

So, back to the topic... cruising single engine.
Click to expand...

A little testy but I didn't say anything about cruising for a few hours down the ICW and not being able to survive. I just mentioned what is in my QSM-11 operators manual... Shall I call Cummins up and tell them I found an error in their publication?

I think you also have a simplistic view of the "cut straight across" thing. You must have the weather always on your side... Getting out in the middle of nowhere and then realizing when the seas kick up that the dinky little rudders won't hold a course at displacement speeds requiring you to throttle up seems a little... well... dangerous. It would kinda suck to realize you don't have enough fuel to finish the whole "sleep four hours, rinse and repeat" thing. These boats can cruise at displacement hull speeds just fine in calm seas... but they are not designed for that and getting over 4' seas or so is going to require some water moving under the hull to stabilize it and water moving over the small rudders to control it. If you look at even "fast trawlers", they have big rudders and keels... Sea Rays are considered "coastal cruisers" for a reason... they are not designed to cross the ocean.

Then again.. some people take bow riders and jet skis across the gulf stream.

Good thing you don't fly.
 
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Oh yeah... one other thing to add to the list is how the power steering works. On the 480 DB, there is a PTO hydraulic pump on the starboard transmission for the 2-stage power steering system. If you shut down the starboard engine, you can't steer the boat. I think on the smaller boats, there is a 12v motor driving the hydraulic pump... so what battery is that on? Starboard? Port?
 
Four Suns said:
A little testy but I didn't say anything about cruising for a few hours down the ICW and not being able to survive. I just mentioned what is in my QSM-11 operators manual... Shall I call Cummins up and tell them I found an error in their publication?

I think you also have a simplistic view of the "cut straight across" thing. You must have the weather always on your side... Getting out in the middle of nowhere and then realizing when the seas kick up that the dinky little rudders won't hold a course at displacement speeds requiring you to throttle up seems a little... well... dangerous. These boats can cruise at displacement hull speeds just fine in calm seas... but they are not designed for that and getting over 4' seas or so is going to require some water moving under the hull to stabilize it and water moving over the small rudders to control it. If you look at even "fast trawlers", they have big rudders and keels...

Good thing you don't fly.
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Touche.

Good points - especially about the weather. The good news is that at any point in my particular scenario, we could turn 90 degrees to the East and push her up - back to normal ops, just not making our planned route. I'm of the mind set that I like to look at all options, minimize my time, costs, and wear/tear, and maximize my cruising pleasure. I would absolutely love to be out in the middle of the Gulf at night - the sky has to be spectacular (Depending on the weather). I would love to troll during the day in the deeper waters.

The bottom line is that I'm acting like a sailboat, except I can pick up and run if I need to. We loved our previous cruise along the coast, but I would rather do a circular route than re-trace my tracks.
 
Gary,

I really look for your input and respect your opinions and knowledge. I don't like the phrasing sometimes and responded as such. I am not nearly well enough armed to enter into an argument with you, nor do I have any desire to do so with you or anyone else. I've been married for 26, no, 27, no 28...hell a long time. I didn't get there by enjoying arguments. My biggest regret on this topic is that sometimes I really want to understand your point, but can't pick it out of the criticism and sarcasm - this from a trained professional/retired ahole (found it's better to be nice, or at least easier).

Just got out of a endoscopy then rode 7 hours in a car with a female driver and a cat (new boat cat). I'm relaxing after having the doc ask me at least 4 times if I've been under a lot of stress lately (trying to avoid the cells becoming cancerous - you know the drill). So, yes, that's the best I can do. Now, where's my beer.

Love ya, man - deal with that!
 
We are all getting old. I just had a shoulder surgery 2 days ago....

Now where's my bottle of percocet...
 
Four Suns said:
We are all getting old. I just had a shoulder surgery 2 days ago....

Now where's my bottle of percocet...
Click to expand...

At least mine isn't due to getting stuck beneath a rolled over monster truck.
 
Four Suns said:
Oh yeah... one other thing to add to the list is how the power steering works. On the 480 DB, there is a PTO hydraulic pump on the starboard transmission for the 2-stage power steering system. If you shut down the starboard engine, you can't steer the boat. I think on the smaller boats, there is a 12v motor driving the hydraulic pump... so what battery is that on? Starboard? Port?
Click to expand...

Great point, Gary. I guess besides transmissions this is another critical component that has to be looked in to.

John, if they can do it, you can do it as well :thumbsup:

http://www.youtube.com/watch?v=CWOQ9PqMt64&feature=youtu.be

 
When I was out trolling in the ocean on one engine the AP had no trouble what so ever to maintain the course. The way John is planning to manage the single engine runs seems very doable to me. I can't imagine having an issue where batteries on one side will loose the juice from AP operation (providing this is is the side with the engine off). Alternating engines every 4 hours seems very much logical in regards to keeping all the batteries charged. Obviously, the minute the generator is fired up this argument is out of the window, b/c all batteries will be charged via battery charger.
 
Cute kid. Awesome video. 1800 RPM on their trawler. Great instructional aid as well.

Have already figured that I would indeed need to run the genny 1/2 of the time to power the bank that runs the autopilot. Mine also does well single engine in the rollers.
 
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