1 vs 2 diesels, insights please..

[sunchaser]

A decade ago we priced out new a new build KK 52. We did it two ways. One was with a single JD 6068 and a get home system. The other was with twin JD 4045s. Guess what, little if any difference in capital cost.

BTW, an owner of an N60 found a similar little cost difference so he ordered it with identical twins. In both these cases the cost of a larger single when combined with a small get home puts the cost into a near equal situation.

Nordhavn has a full order book for their twin powered 41. The twin setup is pretty simple and to potential buyers, believable. The rationale for twins in this case imbued in Nordhavn's "get home" philosophy, a great sales pitch.

So again, to me this debate seems boat specific with many competing factors, rather than a mere single Vs twin simplified discussion.

 

[High Wire]

I’ve owned singles and twins. For a coastal 7 knot boat 40 ft and under, a single is a very good choice. If you want to go fast or bigger go twin. If you end up not liking your choice, sell it.

 

[PierreR]

I feel a little bit unique in the fact that I have no opinion one way or the other at present. I thought I knew but I no longer do. I have owned may singles over the last 50 years. I bought my first twin a month ago.
The new boat is substantially different than my last boat. My last boat was a single with controllable pitch propeller and bow thruster. I could walk it straight sideways into a tight slip against a wind.
The twin is very predictable but will not at present walk straight sideways. Going from a controllable pitch propeller to a twin is a bit confusing at first and I am still getting used to it so, the verdict is still out.
I was not reluctant to go to twins and they seem easy to control the boat, but the boat seems overpowered. From past mindset I wish it got better mileage, but I can afford it none the less.
The vulnerability of the stabilizers seems greater than the props. I could be wrong, but it just looks that way. My last boat had paravanes and I snagged a few things with those too. They just spin you around.

 

[rslifkin]

Getting any boat to move sideways without a bow thruster is tough. Some will do it with twins but many won't. My boat doesn't do it. It's very maneuverable, but you can't go directly sideways. And it pivots fairly far forward so it's hard to move the bow sideways without moving the stern around a lot. But that's all easily planned around.

 

[Mako]

SD and planing boats generally do not walk sideways well. My old cruiser (FD, twins, no thruster) behaved absolutely perfectly in this regards. Then I tried to teach my friend on his 34 Mainship (twins) and it was horrible. A big part of the problem is those tiny rudders.

 

[PierreR]

SD and planing boats generally do not walk sideways well. My old cruiser (FD, twins, no thruster) behaved absolutely perfectly in this regards. Then I tried to teach my friend on his 34 Mainship (twins) and it was horrible. A big part of the problem is those tiny rudders.

The rudder on my old boat was large and covered the entire face of the prop and was close to the prop. In the plan view of the new boat, the rudders only cover about 2/3 of the prop and the props are further away from the rudder. There is also a substantial keel. Seems like the props provide too much forward thrust under the rudders and the slight forward motion on the keel prevents walking sideways.
I will play with more reverse throttle on the dock side propeller, but I am not hopeful. I have been taking the boat out with the previous owner who was a tub boat captain coordinating 5 tugs to tow and anchor drilling rigs. He says the boat will not walk sideways very well. He says you need a large fender near the stern and put the stern to the dock at zero forward speed and balance the dockside prop thrust with the outboard motor in forward and just rotate the boat in, or a springer.
I would put my boat in the not FD but just inside the SD category. The Buttock lines are fairly steep and the chines not totally hard, but the boat can be driven to S/L ratio of 1.6 with 224 hp and 18LT on 38ft WLL. That alone tells me the designer did not intend for a full displacement hull even though it is listed as such.

 

[sunchaser]

Pierre

We have a different boat, DF 48, with a likely very different hull. So naturally it will behave in its own way. It has a bow thruster and twins. We have little trouble getting it to walk sideways even in strong winds but side currents can get befuddling at times.

As example when docking to starboard it is dead slow the boat, rudder over, forward touches on starboard and touches of reverse on port. It generally works every time. Big rudders and a keel too, with the keel helping to hold it steady in winds.

 

[Kapodisn]

So in hindsight, everyone is wrong and everyone is right at the same time.......

It is a personal choice and everyone is very personal about it. But I did learn a lot of good things from the thread.

(Sarcastic Jokes)
1) Pick a controversial topic and then walk away.
2) Pick apart everyone's answer.
3) Your answer is the word of the bible.
4) If someone uses a boat in a way you have no intention of using, then that is the correct way of doing things.

(Honest learned from)
1) Tow Membership is a very affordable and smart choice, no matter how you intend on using your boat.
2) Cost is a hazard, it will blind you, it will steer you, and it will make your decisions for you. Get comfortable with the cost and you will find your answer.
3) Twins give you peace of mind, and singles enjoy boating more.
4) Ask questions to those that have what you are looking for. Twins know how twins act, and singles know how singles act.
5) MArina fees will cost you more than engine room upkeep (Not upgrades or maintenance fixes).

Very interesting post. I enjoyed reading every post. very good information

 

[rslifkin]

SD and planing boats generally do not walk sideways well. My old cruiser (FD, twins, no thruster) behaved absolutely perfectly in this regards. Then I tried to teach my friend on his 34 Mainship (twins) and it was horrible. A big part of the problem is those tiny rudders.

I've never quite figured out what combination of stuff prevents it on my boat. The keel and deep forefoot make it hard to move the bow sideways, which certainly doesn't help. It's also got a ton of prop walk and the rudders aren't as tall as the props, so not all of the thrust gets redirected. It has plenty of rudder authority in any other situation, but will still pivot slightly against the rudders when trying to move sideways.

The right balance of thrust on the engines with full rudder will get it to more or less move diagonally though. I've rarely had a reason to try to move directly sideways, so I haven't played with it enough to nail down the exact inadequacies.

 

[mvweebles]

I've never quite figured out what combination of stuff prevents it on my boat. The keel and deep forefoot make it hard to move the bow sideways, which certainly doesn't help. It's also got a ton of prop walk and the rudders aren't as tall as the props, so not all of the thrust gets redirected. It has plenty of rudder authority in any other situation, but will still pivot slightly against the rudders when trying to move sideways.

The right balance of thrust on the engines with full rudder will get it to more or less move diagonally though. I've rarely had a reason to try to move directly sideways, so I haven't played with it enough to nail down the exact inadequacies.

Confrssion. I'veve tried the sideways-walk maneuver for years on a variety of boats and never had much success. And I've never really seen it done either. With a bit of forward momentum, pretty easy to get a boat to slide sideways with use of some rotation augmented with appropriate prop walk, but sideways walk from a dead stop? Beyond my skills. I wonder if it's maritime myth. And I wonder if it's very useful (sort of a Lipizaner Horse show maneuver) - given the long lever arm from bow go props, even a small amount of adver wind or current will undercut any effort. Plus, if you're that good at driving, chances are you use other techniques.

Peter.

 

[koliver]

Confrssion. I'veve tried the sideways-walk maneuver for years on a variety of boats and never had much success. And I've never really seen it done either. With a bit of forward momentum, pretty easy to get a boat to slide sideways with use of some rotation augmented with appropriate prop walk, but sideways walk from a dead stop? Beyond my skills. I wonder if it's maritime myth. And I wonder if it's very useful (sort of a Lipizaner Horse show maneuver) - given the long lever arm from bow go props, even a small amount of adver wind or current will undercut any effort. Plus, if you're that good at driving, chances are you use other techniques.

Peter.

Peter

I use the sideways maneuver frequently, though it is limited in where it is useful. I frequently dock at a YC outstation that has a number of 150' finger docks protruding out into the fairway of a narrow inlet. There, when it is busy, I frequently need to coast in between other boats before sliding sideways to the dock ahead of one boat and behind another. This without allowing the off side of my stern to get close to the boat on the next finger over so no option to swing it out.

In other places, where there are no such constraints, other maneuvers work well, and are preferred, such as coming at the selected spot at a 45° angle and then bringing the stern in.

It is good to have this maneuver available, as it can be very useful and is not just for showing off.

 

[Portage_Bay]

Confrssion. I'veve tried the sideways-walk maneuver for years on a variety of boats and never had much success. And I've never really seen it done either. With a bit of forward momentum, pretty easy to get a boat to slide sideways with use of some rotation augmented with appropriate prop walk, but sideways walk from a dead stop? Beyond my skills. I wonder if it's maritime myth. And I wonder if it's very useful (sort of a Lipizaner Horse show maneuver) - given the long lever arm from bow go props, even a small amount of adver wind or current will undercut any effort. Plus, if you're that good at driving, chances are you use other techniques.

Peter.

I saw it done once on a heavy deep draft work boat. The operator walked it sidways off the dock. It took a lot of power and a farily long time in no wind or current. I've tried it on many boats including my current boat a Californian 42 LRC and have never gotten it to work.

 

[Mako]

Strange.

I loved moving the boat sideways. It was fun and I used the technique often. Yes it took liberal use of power.

In tight fairways when the wind would start drifting me too close to the side, the technique would be used to push the boat back into the center for more maneuvering room.

However, a bow thruster would allow the same result on most any vessel with either single or twins.

 

[PierreR]

Confrssion. I'veve tried the sideways-walk maneuver for years on a variety of boats and never had much success. And I've never really seen it done either. With a bit of forward momentum, pretty easy to get a boat to slide sideways with use of some rotation augmented with appropriate prop walk, but sideways walk from a dead stop? Beyond my skills. I wonder if it's maritime myth. And I wonder if it's very useful (sort of a Lipizaner Horse show maneuver) - given the long lever arm from bow go props, even a small amount of adver wind or current will undercut any effort. Plus, if you're that good at driving, chances are you use other techniques.

Peter.

In the case of my previous boat, the boat had a tidal keel. Deepest at the stern and nothing under the bow. It had a big balanced rudder and a controllable pitch propeller that you could maneuver well above idle from forward to reverse almost instantly. A constant forward to reverse with opposite rudder along with a very powerful bow thruster would allow me to walk the boat against a wind or a current.
So, in hindsight, it made me look like a real pro but probably had more to do with the boat than with the operator. The new twin engine boat does not appear to have that maneuverability.

 

[rslifkin]

Peter

I use the sideways maneuver frequently, though it is limited in where it is useful. I frequently dock at a YC outstation that has a number of 150' finger docks protruding out into the fairway of a narrow inlet. There, when it is busy, I frequently need to coast in between other boats before sliding sideways to the dock ahead of one boat and behind another. This without allowing the off side of my stern to get close to the boat on the next finger over so no option to swing it out.

In other places, where there are no such constraints, other maneuvers work well, and are preferred, such as coming at the selected spot at a 45° angle and then bringing the stern in.

It is good to have this maneuver available, as it can be very useful and is not just for showing off.

In a tight spot like that, I often do a 180 into the empty space on the face dock. You build more sideways momentum than you do coming in facing the correct direction. However, it has to be done carefully and definitely has wind and current limits. If you get it wrong, you can easily end up with a very firm arrival against the dock (as you don't really have sideways brakes). And the last few feet of the procedure has very little bail-out ability if there are boats close in front and behind.


If it's so tight that a true sideways move is the only way in and out, I'm simply not docking there. With no thrusters getting in would be a challenge, and if there were any meaningful wind or current holding me to the dock when I wanted to leave, I'd be stuck.

 

[fgarriso]

Twins have more moving parts to break or fail. (two complete engines and drives)

Twins will burn more fuel

Twins have some redundancy or safely

Twins are more expensive to maintain (oil and filters)

Twins are easier to dock. You can pivot the boat in its own length. You can walk the boat sideways when docking.





Singles have less parts to fail.

Singles burn less fuel (but not a 50% fuel saving, more like 20-25%)

Singles do not have the redundancy of twins. You can get home on one engine.

Singles have less under water drag.

Singles are less expensive to maintain. (1/2 the oil and filters)

Singles are more difficult to dock, but can be done efficiently with practice.


My boat has twins even though it is more expensive. I like the advantages of twins. I have had several boats with twins and singles, but for the advantages stated above and this point in my life I choose the twins. I am no longer planning to make long range trips over 2500 miles so I don't need the extended range singles offer.

 

[backinblue]

Twins are easier to dock. You can pivot the boat in its own length. You can walk the boat sideways when docking.

My boat is a single with B&S thrusters and can do both of those things very easily, in fact probably easier than someone with twins.

 

[psneeld]

Confrssion. I'veve tried the sideways-walk maneuver for years on a variety of boats and never had much success. And I've never really seen it done either. With a bit of forward momentum, pretty easy to get a boat to slide sideways with use of some rotation augmented with appropriate prop walk, but sideways walk from a dead stop? Beyond my skills. I wonder if it's maritime myth. And I wonder if it's very useful (sort of a Lipizaner Horse show maneuver) - given the long lever arm from bow go props, even a small amount of adver wind or current will undercut any effort. Plus, if you're that good at driving, chances are you use other techniques.

Peter.

Don't feel bad, I never made or really saw a boat move perfectly sideways in one maneuver with twins either.

Willow leafing in.... sure, sideways when there was a decent current or wind on the nose.... sure, less than perfect conditions and done in more than a few boat types and I would love to see "sideways" compared to what I am seeing in my mind's eye.

Maybe someone can YouTube a drone video of them walking their boat "sideways" so I can get a better understanding.

I know the technique, and handled quite a few boats, but sideways is not how I would describe my results.

 

[slowgoesit]

As noted previously, the OP joined on September 17th, 2022, started one thread, posted one time, and has never been on since . . . . hope ya'll are having fun! Just sayin' . . .


Just out of curiosity, what anchor would you all suggest he buy after he gets a boat? And please thoroughly document your recommendation!

 

[ranger58sb]

I've never been able to do it, nor have I seen it done.

Hadn't ever heard about the "liberal use of power" thing that a few have mentioned here... so maybe I've never goosed it enough.

On the other hand, if I were in a situation that demanded walking the boat sideways, I think I'd more likely decide that's not a situation where I'd want to be at all adventurous with the throttles...

So if I couldn't get into that slot with spring lines, I'd more likely be looking to dock elsewhere...

-Chris

 

[mvweebles]

On the other hand, if I were in a situation that demanded walking the boat sideways, I think I'd more likely decide that's not a situation where I'd want to be at all adventurous with the throttles...

True dat.....

I cut my teeth in tight quarters shoe-horning boats for a semi-annual local boat show (Jack London Square, Oakland). The marina was mostly 36-ish foot slips with appropriately narrow fairways, but for the boat show, mostly 40+ foot boats (many well into the 50's) would assemble. The result was the fairway between the bows of the stuffed boats was often less than the length of the last few boats. To back-into a slip, you had to delicately wedge the bow between two boats on the opposite side of the fairway and swing the stern being careful not to tap the bow of the boat next to your target slip. Not a place to goose the throttle. Not a place for green crew either. Guy who taught me the finer points of docking was a gruff old guy married to his crew, a tiny Asian woman who I swear could easily fit in carryon luggage. I developed adequate skill, but they had true talent. Astaire and Rogers.

I guess I'm surprised at the number of people who state they can get a boat to move sideways from a standstill. It requires rudders to be handover. When topics of turning a twin come up, I don't recall anyone stating the rudders should be moved from their center position, meaning I don't recall anyone suggesting rudders be used in close quarters - full stop. So a contradiction. I personally have no bones about using rudders on twins in close quarters, though I did not teach it as it can be confusing (full disclosure - I am so rusty at this point, I wouldn't use rudders these days).

Since the OP is long gone, we now have liberal license to drift.

Peter

 

[psneeld]

I have experienced a lot of boats and situations where using rudder with splitting engines is necessary to overcome conditions or with a really long boat, small props and rudders where the shafts are close together.

But I learned to not have any wheel in with outboards or outdrives with a classic engine split as the boat might start to pivot the opposite way you want it too.

 

[heysteve]

We cruise a single engine trawler in the Sea of Cortez. The boat was in the right place at the right time at the right price so we went for it.

The perceived vs actual risk calculation really plays out here. Do I worry about my engine failing in a remote area? Sure, but unless I'm really unlucky it will probably not lead to catastrophe.

As older folks, the bigger actual risk is probably a significant medical issue in a remote location. There are many anchorages where your VHF call will go unheard and even if there are other cruisers nearby, it may take many hours to evacuate a person (just read of a heart attack case where the guy had to be taken to shore on a kayak!).

So yeah, one picks the things to worry about. It's a wonderful life cruising down here but you only get to experience it if you actually leave the dock and get to it.

 

[Portage_Bay]

I routinely use the rudders when maneuvering a twin in tight quaters. It increase the rate of pivot and changes the pivot point. Both very useful once understood and practiced.

When topics of turning a twin come up, I don't recall anyone stating the rudders should be moved from their center position, meaning I don't recall anyone suggesting rudders be used in close quarters - full stop. So a contradiction. I personally have no bones about using rudders on twins in close quarters, though I did not teach it as it can be confusing (full disclosure - I am so rusty at this point, I wouldn't use rudders these days).

 

[Portage_Bay]

I've often thought the same. So much emphasis on engine failure, fuel problems ancor dragging and the like. All real concerns to be sure. But for me cruisng in remote areas the two biggest concerns are serious medical and fire.

As older folks, the bigger actual risk is probably a significant medical issue in a remote location. There are many anchorages where your VHF call will go unheard and even if there are other cruisers nearby, it may take many hours to evacuate a person (just read of a heart attack case where the guy had to be taken to shore on a kayak!).

 

[rslifkin]

With twin inboards I tend to default to rudders centered, but there are definitely times where some rudder is useful to get the boat to do something it won't do with just the engines.

 

[Dirtdiggaler]

I prefer twin engines when you’re going through the Pacific Northwest’s bars. Even with twin engines I’ve had a close call in Newport Or. I accidentally installed the wrong fuel filters on our Bayliner and had to get towed in by the Coast Guard. Right when we were at the tips of the jetty and returning both engines died. I was able to get one engine started just for a small push away from the jetty tips. I had to call the Coast Guard and they came and towed us in right before we drifted on the reef. My aunt’s boyfriend taught me to always go in and out of the very center of the jetty and be ready to anchor if needed. If I would’ve been right next to the jetty we would’ve ended up on the rocks.

 

[SteveK]

With twin inboards I tend to default to rudders centered, but there are definitely times where some rudder is useful to get the boat to do something it won't do with just the engines.

Have you spun around on a dime?
For clockwise, rudders hard over in the direction of spin (starboard), reverse starboard engine for prop walk, forward on port. Increase throttle to about 1500.
counter clockwise port rotation reverse above. Try that with a single.

 

[rslifkin]

Have you spun around on a dime?
For clockwise, rudders hard over in the direction of spin (starboard), reverse starboard engine for prop walk, forward on port. Increase throttle to about 1500.
counter clockwise port rotation reverse above. Try that with a single.

Yup, a faster spin (or to help swing the bow into a strong wind) is exactly where rudder comes into play.

Plenty of singles can be spun (in one direction) however, as long as there's not too much wind. If it walks to port in reverse, you spin to starboard (clockwise). Full stbd rudder, give it forward thrust. As soon as the boat starts to move forward at all, put it in reverse. When the boat stops (but before it starts to back), switch back to forward.

Repeat and the boat will spin (as you're using directed forward thrust to push the stern around followed by reverse to check the forward movement and let prop walk help continue pulling the stern around the correct direction). Trying to spin the "wrong" direction with a single isn't very effective though.

 

[koliver]

Have you spun around on a dime?
For clockwise, rudders hard over in the direction of spin (starboard), reverse starboard engine for prop walk, forward on port. Increase throttle to about 1500.
counter clockwise port rotation reverse above. Try that with a single.

I am surprised when knowledgeable posters come out with statements suggesting they have never explored the capabilities of their own boat, or others they have been aboard. One of the first things I ever did when I bought my boat with twins, after having sailboats with only one engine and only one rudder, was to see what happens when .... I don't think there is any maneuver that I didn't try. Some worked better than others, some not at all, but to say things like "always" is just silly.