Anyone else run on just one Iron Jib?

[Helia 44]

Just curious... Thought maybe some might like to compare notes as it had not occurred to me until now.. I have been finding some real advantages to only run on one engine.. Is this a wide spread school of thought? I mean I am an old school monohull Sailor, this is my first Cat and I have the larger engines option on the Helia 44... So a little advantaged by two 55 hp diesels.

It was used for over a year by "Multihull Solutions" as a Show Boat and Demonstrator. I have no complaints, as I got a very good deal on it with about $150k in gear and modifications, all positive and good. But I have a discrepancy in the hours on the Port to Starboard engines. Like the Port engine has been used (I think) to make hot water more, heat exchange HWS on the Port side, and it has over 100 hours more run time... When it was run across the south of Australia from the Perth Show, and they had to use the engine I think they ran the Port D2-55 more to make hot water..

The advantage of the larger engines IMO is fuel economy. I mean I can do 6 to 7 knots on one engine at 2000-2300 RPM, and only about 9 -9.5 knots with both engines so why bother running both. When I had a distance to motor, I have been just running on the one engine. With a little help from a slight breeze motor sailing, I will run the starboard engine at about 1800- 2000 RPM, or when in a rush for some reason push it up to 2300. The difference is like 2 litres per hour at 1800 RPM to 3 litres per hour at 2300, unless I am in a hurry it is a why bother issue..

Anyway, the larger engine option is one of the reasons I bought it, and the layout is rare (Maestro) and the gear list is extreme. I am very happy, but just out of curiousity does anyone else just run their Cat on one engine out cruising?? Only comparing notes and ideas as I am new to having twin diesels..

Kind regards, Helia 44 "AVALON"

[weavis]

Originally Posted by Helia 44

Just curious... Thought maybe some might like to compare notes as it had not occurred to me until now.. I have been finding some real advantages to only run on one engine.. Is this a wide spread school of thought? I mean I am an old school monohull Sailor, this is my first Cat and I have the larger engines option on the Helia 44... So a little advantaged by two 55 hp diesels.

It was used for over a year by "Multihull Solutions" as a Show Boat and Demonstrator. I have no complaints, as I got a very good deal on it with about $150k in gear and modifications, all positive and good. But I have a discrepancy in the hours on the Port to Starboard engines. Like the Port engine has been used (I think) to make hot water more, heat exchange HWS on the Port side, and it has over 100 hours more run time... When it was run across the south of Australia from the Perth Show, and they had to use the engine I think they ran the Port D2-55 more to make hot water..

The advantage of the larger engines IMO is fuel economy. I mean I can do 6 to 7 knots on one engine at 2000-2300 RPM, and only about 9 -9.5 knots with both engines so why bother running both. When I had a distance to motor, I have been just running on the one engine. With a little help from a slight breeze motor sailing, I will run the starboard engine at about 1800- 2000 RPM, or when in a rush for some reason push it up to 2300. The difference is like 2 litres per hour at 1800 RPM to 3 litres per hour at 2300, unless I am in a hurry it is a why bother issue..

Anyway, the larger engine option is one of the reasons I bought it, and the layout is rare (Maestro) and the gear list is extreme. I am very happy, but just out of curiousity does anyone else just run their Cat on one engine out cruising?? Only comparing notes and ideas as I am new to having twin diesels..

Kind regards, Helia 44 "AVALON"

Many Cat owners run on one engine and then swap over after a preset time. For example after two hours or so.

[maxingout]

When there is no wind on an ocean passage, I go twelve hours port engine and then twelve hours starboard engine, alternating until the wind picks back up. When the boat speed drops below four knots, I turn on one engine.

The only thing that makes me decide which engine to run is I avoid running an engine if someone is trying to sleep in a bunk on the side of the engine. If someone is asleep aft in the port bunk, I run the starboard engine.

I always check the oil after a twelve hour run. I check the oil on the engine that I am starting up.

[Palarran]

It's not many cat owners but almost all run on one motor at a time. You can do a google search on this forum and find about 4 or 5 threads on this topic. Also, we don't run one motor for an hour or two before switching but rather a day on one, then switch. 10 hours or a 100 is minor when your expecting to get 10,000 hours out of them. Don't forget to get a full throttle period in there every once in a while.

[colemj]

Likewise, we almost always motor on one. The switch interval is based on an estimate of how long we will need to motor - half the time on one and then the other. Since there is only two of us, we just sleep on the side not running.

If the wind picks up, or we are just motoring a couple of hours, the log book tells us which engine was used last.

Mark

[cwjohm]

Absolutely the first thing you learn when cruising.

I alternate the engines at around 4 hour intervals but always make sure that the port engine runs for the last hour otherwise there is hell to pay when showers are cold.

This is important as when you motor your apparent moves forward so if you decide to motor for any reason and you have wind behind the minimum wind conditions increase so that you can maintain the same speed sailing.

On the way north we typically had 5-15Kn directly behind so we did quite a bit of motoring. Motorsailing you can typically get 8kn on one engine at 2200 using about 3lt fuel per hour. Typically on the Helia if you want to sail at 8Kn with wind behind you need a good 15-20Kn unless you have a large spinnaker which frankly I have decided not to bother with as it runs quite well with screecher and genoa wing on wing.

In this case we often wanted to get to a destination before dark so motoring was necessary. If I was making passage over days things would be different as I would be happy to sail at 4kn in 10kn with wind behind, unless I was in a hurry to get to the final destination.

[clownfishsydney]

As mentioned above, virtually every cat owner only runs one engine when they need to use the engine.

We get about 6.0 to 6.5 kts at 2200rpm on one engine (Yanmar 30 hp) and only 7.0 to 7.5 on two engines. Fuel economy so far (we have not owned all that long) is about 2.3 litres per engine hour at these revs. We run for a couple of hours and then swap. We are lucky that both engines heat water for showers, so no need to think ahead to have one engine do the last bit.

We only use both motors entering or leaving port or a couple of times when we really needed the extra speed.

[David R Broise]

I deliver big cats and regularly run on one engine motor sailing as one mentioned this brings the apparent wind forward which helps when you are being asked to keep to a schedule. That said I have experienced all sorts of different sail combinations and here is food for thought have several times used Parasails on cats large and small for down wind work and they do work a treat, stable at the same time. OK there is a cost for such a sail but those owners who have gone to the trouble swear by them. Several atlantic crossings in some very lumpy seas- winds light, fresh, and very strong , and still they worked well.

[rbrentp]

I have 35 foot Prout that runs with twin outboards. Behavior is the same (except I don't get hot water). One 15 pushes about 6 knots at 3000 rpm and 7.5 at 4800. Both at the same time 7.5 and 10 respectively. Fuel burn about 2 liters and three liters per engine. I use two into a strong headwind or docking. In cruise I tend to use the leeward engine for straighter sailing to balance the wind.

[Cheechako]

I almost always just ran the lee engine when motorsailing or trying to make port before dark going to weather in a cat.
Oh... and it's very handy when "racing" a fast mono to weather who is above you...! They cant see the exhaust! :>)

[monte]

Yep we do the same and alternate as long a period as possible, usually around 5 or 10 hours and try to heat the water as well, so if it's a short motor we just use starboard water heating engine. Which side also depends on the wind, as one engine cocks the boat 5 degrees or so, so while we may not be able to motor sail to windward on one engine, the other might work better. Both engines are only really used for docking and anchoring and occasionally pulling up the main. We don't worry too much about keeping the engine hours the same but if they get 20 hrs or so difference we favour the lower hour engine till they're the same.

[Sail IC]

New to catamarans, but I also use one engine for most of the time.

Maybe unnecessary but when motorsailing with main only I try to use the windward engine to get the boat to naturally track a bit straighter (at least I think it does).

Using two engines when there is a decent headwind, but I have 2-blade folding props and that might have something to do with it. Feels better for the engines too.

[Helia 44]

Well Thanks to all of you for the replies..
I am glad I am not the lone Ranger here with this idea..

In forty years of sailing, it is a unique feeling to me to have TWO diesel auxiliaries, and quite frankly I am thrilled with it.. On the Helia, the port engine is used to make hot water through the normal heat exchanger in the stainless marine HWS.. Because of that, since my boat was a demonstrator the port engine has more hours on it than the starboard. I have been concentrating on using the starboard engine as much as possible to catch it up to more even balance of hours..

Why? Oh, things like a mandatory valve adjust at 500 hours, probably a re torque of head bolts and such and then the well broke in customary valve adjust.. I would like to even them out a bit before I do that..

Anyway, from my engineering perspective, there is more strain on the rudders as you are canted off center to compensate for the offset power, but I could see no problem. I am glad it is commonplace and I am not reinventing the wheel with my deductions on the benefits of running one one engine.

It will also greatly extend the lives of the diesels, as you alternate. And if on sail assist you cruise at the lower RPM you save fuel as well.. I am not sure, but on initial calculations I think at around 1800-2000 rpm it might be just over 2 ltr per hour..

Comment for new Multihull Buyers: It is all very efficient and one more reason to get the larger engine option if you can. Bigger diesel are more efficient doing the same job as they are not working as hard, and that equals fuel economy.. And a longer live on the diesel. With the bigger engines option, it seems to me that most of the time Cats will do fine and more efficiently on just one engine. IMO: Running the second does not gain you enough to bother with in most conditions... THAT is one more reason to take the bigger engine option if you can, as you lessen the need to run both in most cruising conditions IMO..

Thank you all for the feed back... Helia

[monte]

1800 rpm is just under 3l/hr, 2000 rpm is just over 3l/hr
http://www.yanmarmarine.eu/theme/yan...nmar-4JH5E.pdf

[colemj]

Originally Posted by Helia 44

It will also greatly extend the lives of the diesels, as you alternate.

Not really. You will have the same engine life as a monohull who uses up one engine and buys another.

It is easy to fall into the trap of thinking that you have double the service interval, double the life, etc - but you need to remember than you have double the engines too!

Mark