Wing Engine Discussion

Hi,

Please show me a 53' Trawler that fishes deep sea with a single donk and has an auxiliary drive.

Vetus does a hydraulic drive that can be piggy-backed from a genset.

Most Trawlers I've seen have a small 2 bladed folded prop which has a low drag factor for an aux drive. Would not a 3 blade feathering prop be more efficient, with little more drag that a 2 blade?

I remember asking the same question some years ago when speaking to a rep and at that time he said the blocks were made by Kamatsu. I am not sure if that is still true today.

Hi,

I believe you are correct, I heard they were based on Komatsu a good few years ago too.

Here is a link for one that is Komatsu based http://news.nauticexpo.com/press/northern-lights/lugger-by-northern-lights-l6125h-21501-8091.html

Here is an interesting bit about them as well. http://www.boatdesign.net/forums/diesel-engines/lugger-diesels-outlawed-25583.html#post247444

From the website of the Lugger/Northern Lights UK representative:

http://www.energy-solutions.co.uk/lugger-engines.html

I'm a complete novice, but have thought about this quite a bit. Let me talk about the system I have, but then suggest an alternative for consideration.

I have the Keypower system, which has a few advantages, and a few disadvantages, when compared with a wing engine.

The greatest disadvantage is that it does not provide a completely independent driveline since it drives the main prop via the main shaft. Thus, if the main prop is fouled, the system is of no use. For an example of where the wing engine approach is better than the approach on my boat, see this excellent account of Phil Eslinger's Pacific crossing last year.

The greatest advantage of the Keypower system (or the BAT drive) is that in the case of a failed main engine, you are still able to drive the main prop, putting more flow over the rudder, and so on. This gives you centerline thrust, over a good prop, right past the rudder. But none of that helps if the main prop is fouled.

There is another option -- having a wing-engine setup, but instead of driving it with a diesel engine, drive it hydraulically from a PTO from the genset or main engine. That way, you have a completely independent driveline, but don't need to buy/maintain another space-consuming diesel engine.

I'm happy with my system, but I do acknowledge that I do not have redundancy in the event of a fouled prop. I mitigate this in a number of ways, not the least of which is carrying a set of pneumatic tools (from Sears) that I can dive with, and quickly saw/grind through any ropes/cables that are fouling the boat. I don't pretend that this would be easy or safe, but I felt it prudent to be prepared. The tools are non-marine cheapies, but I consider them to be one-time-use disposable when used in seawater. I also carry a kayak helmet and Brownie Snuba system. With the exception of the cheapie tools, all these things serve other purposes on the boat.

A sea anchor or drogue of some kind might also be prudent, since in rough weather, I believe maintaining steerage is the most important offshore task, and maintaining position gains in importance as the shore looms closer.

Despite Phil Eslinger's report, I strongly suspect that the vast majority of losses of main propulsion have to do with fuel starvation (clogged filters) or blocked injectors. In these situations, the main engine will stop, but the prop is not fouled. In this case, having the ability to continue driving the main prop via the Keypower provides a very good backup. It relies on the assumption that the source of hydraulic power for the system (usually a generator) will keep running. However, to me, that seems quite likely, since filters/injectors will not clog all at the same rate.

But there's no question -- fouled props do occur. But when they do, there's at least a reasonable chance that the other prop (the wing, for example) will foul too.

No perfect solution. As usual

Dan

... then the generator or whatever you plan to use for a secondary source of power. Spare filters and injectors are cheaper than spare engines, hydraulic pumps, motors, props, shafts, and all the other hardware that will be just as useless as the main when it fails due to the fuel problem you recognize as the most likely reason for problems in the first place.

This whole "wing engine" thing seems like a solution looking for a problem.

One caveat here, at least the way I see it:

It is possible to run the genset (or wing) from a separate day tank, significantly increasing the independence of the two in the event of a fuel problem with one of them. I have seen this in some expedition trawlers. My boat does not have this, drawing genset and main engine fuel from the same day tank. If true independence is not possible, I think it would still at least make sense to draw genset fuel from a somewhat higher point in the tank, or at least from a different part of the tank.

Of course, having two day tanks also increases stale fuel possibilities due to inadequate procedures. There is definitely an argument for keeping things simple to protect the operator from himself (and to make boating more fun and less of a chore).

Bottom line as I see it: To protect against engine and fuel failures, a Keypower/BAT type of clamp-around hydraulic drive is very good. To protect against fouled props, there are two ways to go: wing engine of some kind, versus spurs/line-cutters/scuba-gear to prevent or undo a foul. Of all of these methods, none is foolproof, all have as many costs as they have benefits. Since fuel issues are the greatest cause of loss of propulsion, the greatest benefit can be had by simply ensuring that the fuel is clean and doesn't have the wrong molecules in it (esp. H2O). Having done that and therefore solved 90% of the problem, the remainder becomes a matter of preference.

Dan

A day tank is a small tank that is filled from the storage tanks via a centrifuge or filter and transfer pump. The source of fuel is the same no matter how many day tanks you have.

How do you figure pumping the same fuel into two day tanks "significantly increases the independence" of anything?

I'm sure he's thinking that, if you had multiple tanks that are filled seperately (I ran one boat with 4 seperate tanks), you could, in theory, have fuel from a different source in each. That however would fix the bad fuel problem for all motors and gens.

I have to really struggle not to write a humorous but very cynical description of that process and how it would work on a cruising yacht ... or even one that only runs around the local area.

Like I said earlier, it's a solution looking for a problem. It is beginning to sound like a solution that has found a whole new universe of other problems to cause.

agree.

The nature of bad fuel is you probably don't know you have it until it has done its dirty work.

It seems to me that the tank feeding the main engine(s) could easily have bad fuel in it for a variety of reasons, while the backup engine's tanks might have good fuel in -- even if all fuel was loaded on the boat at the same time.

For example, the main engine's tank has a vent which could allow water to enter due to a leak or problem, while the backup engine's tank's vent isn't allowing moisture in.

Alternatively, the main engine's tank could be half-empty, allowing condensation to occur, while the backup engine's tank is full, disallowing condensation.

Another example: some tanks might have sludge in them, and in a rough seaway, that sludge could get mixed in with the fuel, clogging the filters. But the backup engine's tank might not have sludge in it, or might have its pickup in a different point.

It seems to me that in any of these situations, having an independent day tank could give vital time to change filters on the main, without losing steerage or headway.

Indeed, it seems to me that there are only a couple of situations where the backup engine's day tank (and its filters) would prove useless.

One is where bad fuel was taken onboard and was then pumped into both the main engine's and the backup engine's day tanks at the same time.

Another is where good fuel was taken on, but through neglect, was left to go stale.

None of these things have ever happened to me - most of my opinions on this subject come from reading about people's experiences in forums such as this one. So I may very well be missing something fundamental. But I would summarize the entire issue as follows: When the main engine stops, is there a backup engine source of propulsion at all, and will it still run? While having a backup source of propulsion is common, a backup source of fuel is uncommon. Since issues such as water/sludge in fuel need not apply equally across all tanks, it seems that having an independent day tank has at least some merit. The biggest downside is that it adds complexity to the fuel system.

Dan

Having a separate day tank ensures that "made on the boat" fuel problems that stop the main engine won't stop the backup engine. Still, it would be much better to never make fuel go bad aboard. This means avoiding or removing sludge buildup, and keeping water out of the fuel tanks.

If I were specing a boat with my current level of knowledge, I'd ask for this: take the backup engine's fuel feed from a couple inches higher up in the tank than the main engine's fuel feed. That means the main can stop due to water/sludge being kicked up, but the backup will likely run. Even then, my goal would be to keep the darned tanks clean and water-free! But the approach I've mentioned avoids the complexity of a second day tank, yet maintains the benefits of a slightly "independent" source of fuel.

Dan