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Old 02-16-2020, 12:42 AM   #1
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Steering with engines? (more than just docking?)

I'm used to just using the (twin) engines to steer the boat when docking or otherwise in close quarters, and idle speed.

Hypothetically speaking - would this work at higher speeds, or would it tear anything up (like the transmission).

For example, if the steering went out with the rudders set straight - would it be ok to operate the boat at "trawler speed" (6-10 mph), and just vary the speed of the engines to accomplish turns?

Would this hurt the transmissions? If not, would it even be possible to run at higher than 10mph, simply steering by throttles instead of the wheel?
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Old 02-16-2020, 01:42 AM   #2
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Won't hurt the trannies or the engines. Depending on the boat and the sea conditions it might work ok or not ok. In rough stuff the rudders have more authority than a thrust differential. For example, with rudders working you can (usually) maintain steerage with one engine out completely.

But if I lost steering on a twin, I would certainly try steering with thrust differential.

To know for sure on your boat, go try it. It will work to some extent.
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Old 02-16-2020, 02:00 AM   #3
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Originally Posted by Ski in NC View Post
Won't hurt the trannies or the engines. Depending on the boat and the sea conditions it might work ok or not ok. In rough stuff the rudders have more authority than a thrust differential. For example, with rudders working you can (usually) maintain steerage with one engine out completely.

But if I lost steering on a twin, I would certainly try steering with thrust differential.

To know for sure on your boat, go try it. It will work to some extent.
What he said.
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Old 02-16-2020, 03:03 AM   #4
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We practiced this with destroyers. The rudders are locked on center and by an rpm difference between engines, a snake like course can be maintained. For wide turns, it's not necessary to reverse one engine, just stop the inside prop and let it drag. And that was with steam. Diesel or gas turbine controlled from the bridge would give a straighter course. I found longer twin yachts handle much like destroyers. It's why I like long boats.
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Old 02-16-2020, 03:16 AM   #5
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Of course!

I seldom use any rudder when docking. But, just occasionally I do, and, that's for another topic completely!

As I approach close to dock area [at idle speed] I leave rudders set straight ahead and seldom touch steering wheel again [same when I leave dock]. From that point I use forward or reverse of the engines to fully maneuver the boat. When needed I slightly increase throttle in forward or reverse of either or both engines. Never shifting when an engine is above idle. Sometimes one engine may be left in neutral for a short period. Currents and wind play a large part in my maneuvering by engines.

And yes...

If need be; you can pretty much [somewhat accurately] steer a twin screw boat by engines alone at most speeds [raising or lowering per engine rpm]. However... steering by rudder is much more responsive as well as safer and less effort. Also, don't take engine into neutral or alter from forward to reverse or reverse to forward until engine rpm is down to idle. Therefore, so that dangerous handling circumstance per engine prop speed conflict does not happen, basically, both engines should be at idle at the same time when shifting transmissions.

Get into some open, unencumbered water locations and practice. After doing it many times during the year, handling a twin screw boat at slow speeds, in low rpm by engines alone becomes second nature.

Good Luck!!
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Old 02-16-2020, 07:56 AM   #6
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Yes.... the degree of control depends on the boat, the differential in thrust possibilities, sea conditions, and positioning of the rudders.
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Old 02-16-2020, 08:54 AM   #7
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It will not hurt anything. In fact it is an interesting manuever to practice some day.

It is highly doubtful that you will loose steering when your rudders are dead ahead. More likely something will break when the stress of a turn is being added. I assume they will set themselves to dead ahead in the event of a failure though, just through prop wash. You can test this theory also. Add some turn degrees then see if you can straighten out the rudders with prop wash without using the wheel.

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Old 02-16-2020, 08:57 AM   #8
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If maneuvering with the rudders cocked is impossible, many just unllock the rudders if they plan on travelling with just the engines.

If possible, lock, tie or jamb the rudders when straight.
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Old 02-16-2020, 09:20 AM   #9
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As long as the rudders aren't too far off center, yes, it's quite possible. I'd keep the speed down, as turning tightly at higher speeds just won't happen with engine thrust alone. But at low speeds, it's entirely manageable.

I've always had the personal rule of thumb that on a twin engine boat you can handle loss of one engine OR loss of steering without a big problem, but if you lose both, you've got a problem.
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Old 02-16-2020, 10:02 AM   #10
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As long as the rudders aren't too far off center, yes, it's quite possible. I'd keep the speed down, as turning tightly at higher speeds just won't happen with engine thrust alone. But at low speeds, it's entirely manageable.

I've always had the personal rule of thumb that on a twin engine boat you can handle loss of one engine OR loss of steering without a big problem, but if you lose both, you've got a problem.
True!
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Old 02-16-2020, 10:29 AM   #11
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Just as an aside, my Albin, and I can only assume some, if not most trawlers, has a bracket on the rudder post, there is a stout oak pole stored in the lazarette which fits the bracket. In the event of a steering failure the post is fitted to the bracket and the boat is steered "tiller" style. Mine is a single engine, don't know if twin rudders would be set up like this but it's a comfort to me to know that it is there.

Short of a catastrophic rudder failure which would probably sink the boat anyway I can still get home if the helm fails.

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Old 02-16-2020, 10:40 AM   #12
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An emergency tiller setup could be rigged for twins as well. On my boat it would be tough to do just due to rudder placement, however. They're under the aft bunk just behind the fuel tanks. So there's not great access in there, and you'd need 3 people to do it anyway without some form of electronic communication device, as the person in the aft cabin wouldn't be able to hear instructions from the person at the helm reliably without a relay.
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Old 02-16-2020, 11:25 AM   #13
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When I made my rudder (single) I machined a 1 1/4" hex on the top of the post. A breaker bar and a socket now makes a tiller. I do need two people as tiller man would need to be below deck.

I would like to bore a hole in the deck above the rudder post so tiller could be used from the cockpit deck. I've got fair (not great) vis from there, but to be safe it would still be a two person job.

I'd love to find a bronze through-deck flush fitting with a screw-out plate that I could mount above the rudder post in the deck, but a little searching was not real productive.

Anyone have one laying around, I'm interested.
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Old 02-16-2020, 11:28 AM   #14
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On a twin, the use of the manual tiller should be just to get the rudders centered, thence use throttle as mentioned above. Some transmissions, at least Allisons in my case are not prone to be upset if you shift gears beyond idle speed, though I only had the nerve to test this a few hundred RPM above. I agree this is something that should be well practiced ahead of time, like other emergency procedures on a boat (such as losing an engine on a twin, MOB, etc). A poorly maintained steering system, be it mechanical or hydraulic can fail suddenly, regardless of how many engines you have.
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Old 02-16-2020, 11:53 AM   #15
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Just a tidbit about Allisons: I was on a Hatteras with 8v92 with a broker on the helm. He needed to slow down from 20kt 2000rpm. Pulled back on the levers and engines were not slowing down. So he pulled them all the back to idle. Ooops, wrong levers. Went into reverse at 2000rpm, 20kts. All hell broke loose. Big ball of water came into cockpit and down the engine room hatch, drenching me and my tools. Both engines were stalled out, buzzers going off.

After getting things under control, I checked everything, all looked ok. Got levers in correct place and tried a start. Engines ok. Tried a shift, gears worked ok. Got back to the sea trial thing and no problems. I was in touch with that boat for a couple years on and no problems with gears, shafts or engines.

That was a tough gear!!

Broker had to buy me some tools.
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Old 02-16-2020, 12:04 PM   #16
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You definitely can steer you boat and with twins other than docking. I hate telling stories but this summer we got hit by some ridiculous waves and 25-30 knot wind hitting port beam bow for 3 hrs.
If it wasn’t for being able to grab throttles to point the bow up and out of the trough it would have been ugly. Rudders did absolutely nothing.
I do not support the forward/reverse shifting and care not to test this. If I ever have to do it in an emergency I would do it with out hesitation and hope for the best...

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Old 02-16-2020, 12:08 PM   #17
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Taking this to extremes can lead to overloading the faster engine, A slight imbalance for a minor course change wont hurt anything. For something like following a serpentine course IMO you should go slow without rudders.

At slower speeds driving the strong engine too hard will overload it. The way i tell if the single speed is OK is to see what speed direction can not be easily controlled by the rudders and drop back from there.
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Old 02-16-2020, 12:54 PM   #18
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I think if the twins are not in sync they are already steering.
The wheel counters this and with hydraulics you don't even notice.
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Old 02-16-2020, 01:25 PM   #19
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We have a pretty simple engine sync unit on the lower helm. A red port and star light with a green in the middle. Keep it green you go straight!
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Old 02-16-2020, 02:03 PM   #20
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We have a pretty simple engine sync unit on the lower helm. A red port and star light with a green in the middle. Keep it green you go straight!
Have similar easy use, light emitting sync readers on fly bridge and in salon.

Love the melody of engines running in sync!
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