Twin diesels vs. single on a Mainship

[Fish53]

Yep...you just admitted. You cannot do it! I have owned all configurations. Some are more maneuverable than others. Why you cannot admit that is beyond me. I can back and fill. I can spring ff of a dock. I can nudge a piling. AND I can admit some boats are more maneuverable than others. And YOU are the one that has turned this into a pissing contest. That happens when you act like a know-it-all child.

Not really sure where you get that from but I respectfully suggest you reread my initial comment. Careful examination will show that it wasn't directed at any specific individual, yet you made it so. While I'm more than impressed with your breadth of knowledge I'm not as impressed with your inability to present it in an intelligible form, a limitation that I'm confident accompanies your others. Just to make things clear I am hardly a child but while I am not a "no-it-all" I am quite well versed in the subject at hand. You may not like what I write but making a half baked attempt to refute it doesn't reflect well on you or your contentions. If it will bring a merciful end to this I'm happy to concede to whatever will accomplish that end and make you happy again. You are correct in every way and I was completely mistaken, please accept my humble apologies.

 

[Nomad Willy]

I'm constantly amazed by some comments about twin vs single engine. The common refrain is maneuverability and redundancy. A good boat handler can do anything with a single engine that you can do with two and proper maintenance and a little knowledge are all that's needed to avoid the expense and complexity of twins.

That’s correct of course but ....
Very few rec trawler skippers accumulate enough experience to become “good boat handlers”. I know I haven’t. I’m going down today to try some new backing in variations to what I have been doing. But I’ve witnessed some amazing skills demonstrated by fish boat skippers in Craig Alaska.

But most of us here just play w our toys.
Fish boats are mostly single screw for prop to fish gear clearance and economy. The big reason is economy.
But if I had the money I’d choose a twin. However the twin/single issue is far down on my list of preferences. It’s unlikely I’d buy a twin if I found a single I really liked. Like when I bought the Willard.

 

[Baker]

Not really sure where you get that from but I respectfully suggest you reread my initial comment. Careful examination will show that it wasn't directed at any specific individual, yet you made it so. While I'm more than impressed with your breadth of knowledge I'm not as impressed with your inability to present it in an intelligible form, a limitation that I'm confident accompanies your others. Just to make things clear I am hardly a child but while I am not a "no-it-all" I am quite well versed in the subject at hand. You may not like what I write but making a half baked attempt to refute it doesn't reflect well on you or your contentions. If it will bring a merciful end to this I'm happy to concede to whatever will accomplish that end and make you happy again. You are correct in every way and I was completely mistaken, please accept my humble apologies.

Hey I can appreciate a passive aggressive childish apology like the next guy!! Thanks man!!

 

[Mako]

Oh goodie, a school yard fight!!!
My license is bigger than your license.
Oh yea?
Ya yea!!

FYI, years ago, I could 'light-off' a submarine nuclear powered steam plant.
These days, it would be unwise to let me heat a kettle of water w/o supervision

Ha! I can boil water with my twin kettle much faster than you can with your puny single kettle.

 

[rslifkin]

That’s correct of course but ....
Very few rec trawler skippers accumulate enough experience to become “good boat handlers”. I know I haven’t. I’m going down today to try some new backing in variations to what I have been doing. But I’ve witnessed some amazing skills demonstrated by fish boat skippers in Craig Alaska.

I'll absolutely agree with this. I'd say my boat handling skills are "pretty good", certainly far better than the average few weekends a year boater that stops trying to improve their skills as soon as they can manage to get the boat in the slip without banging it off the dock 20 times. But compared to the professionals that are out there on their boats every day in all kinds of conditions fishing, towing, etc. my skills are probably complete garbage.

 

[T210DRVR]

Superior skills didn’t help the Crabber in Oregon that capsized his 40’ boat with a full load of gear on the aft deck. I can’t find the video now but the vessel did a slow roll over after leaving the fuel dock. It looked like the C.G. of his gear exceeded his seamanship ability. https://www.kezi.com/content/news/4-RESCUED-ON-CAPSIZED-BOAT-566511771.html

No dispersions intended against anyone on the forum. Anyone can have a bad day.

 

[FoxtrotCharlie]

When looking for a boat a few yrs ago I was set on a single, hopefully with bow thruster. But we found this nice 42' sundeck with twin Lehman 135's, and my wife loved the boat. While on the TN River this past fall we lost a transmission on the starboard side, at an inopportune time - was nice to have the 2nd engine. Two weeks later lost the port engine (fuel filter) while circling waiting for a lock - also nice then to have the 2nd engine. Lesson learned.

 

[OldDan1943]

But most of us here just play w our toys.

A bit of information I learned here or somewhere else.
Right turning screw, put the rudder over to 30 degrees port, slow in reverse, you will back straight. Practice that for a while.

 

[markpierce]

My single propeller shaft came apart years ago. Thankfully, was drifting into my home berth at the time.

 

[markpierce]

A bit of information I learned here or somewhere else.
Right turning screw, put the rudder over to 30 degrees port, slow in reverse, you will back straight. Practice that for a while.

But I have a counter-clockwise turning screw! :lol:

 

[markpierce]

In the often-shallow waters of the SF bays/rivers/sloughs/estuary, I appreciate a keel-protected single rudder and propeller.

 

[Fish53]

Hey I can appreciate a passive aggressive childish apology like the next guy!! Thanks man!!

And I appreciate your passive aggressive acceptance. I also appreciate your editing out the A**hole comment, you don't have to like me or even see my comments, that's why there's a block button. I may be unpleasant at times but we have to draw a line somewhere and I respect that you did. As I'm being contrite and conciliatory I'll go a step further and modify my comment to say that I can do anything with a single screw vessel that can be done with a twin screw, it may take slightly more time and finesse but it can be done. The one exception is I can't spin around and around forever, although I admit I've never tried.

 

[sunchaser]

The one exception is I can't spin around and around forever, although I admit I've never tried.

On this thread spinning dizzily around seems the objective.

 

[Baker]

On this thread spinning dizzily around seems the objective.

Now that is funny!!!

Thanks fish. We are finally getting somewhere. I imagined a boat handling contest where time is a factor. Or a handling course where each boat has to do the same maneuvers. And the reason why it takes more time in a single is that it takes more maneuvering(and skill). Hence it is more “difficult”. That Is all. See we agree after all.

 

[catalinajack]

Just wondering about all the single screw experts opining here. How many dockings/years did it take to become proficient? Sure, it can be done. However, any new boater can be a proficient and safe docker much sooner having twins. Even with twins it took me about 250 days into doing the Great Loop before becoming very confident of my boating skills. That said, I would consider purchasing a single screw now that I have some experience on the water. Learning to dock, for many, is a daunting and sometimes frightening experience. It seems to me that some of the single-screwers here are, well, snowflakes.

 

[Fish53]

Now that is funny!!!

Thanks fish. We are finally getting somewhere. I imagined a boat handling contest where time is a factor. Or a handling course where each boat has to do the same maneuvers. And the reason why it takes more time in a single is that it takes more maneuvering(and skill). Hence it is more “difficult”. That Is all. See we agree after all.

I'm not sure how for a person with skill something becomes more difficult? Not that I referred to handling either as "difficult"? But in the spirit of love and togetherness and to show that for new year I'm making a resolution to not be such a dick anymore I wholeheartedly agree. Have a great New Year! (sincerely)

 

[Baker]

I'm not sure how for a person with skill something becomes more difficult? Not that I referred to handling either as "difficult"? But in the spirit of love and togetherness and to show that for new year I'm making a resolution to not be such a dick anymore I wholeheartedly agree. Have a great New Year! (sincerely)

You too my friend!!! And good luck on your mission!!!

 

[Fish53]

Just wondering about all the single screw experts opining here. How many dockings/years did it take to become proficient? Sure, it can be done. However, any new boater can be a proficient and safe docker much sooner having twins. Even with twins it took me about 250 days into doing the Great Loop before becoming very confident of my boating skills. That said, I would consider purchasing a single screw now that I have some experience on the water. Learning to dock, for many, is a daunting and sometimes frightening experience. It seems to me that some of the single-screwers here are, well, snowflakes.

As single screw snowflake I would have to say that it's impossible to say how long it takes to learn. Just look at drivers on the road, some are great but others never seem to get it no matter how long they drive. In way of suggestions it would good to do a little off vessel research to familiarize yourself with things like right and lefthanded wheels and their effects on handling, type and size of rudder and so on. Second would be that if you were accepting of instruction find an experienced single screw boat handler and buy them a case beer if they'll spend a day or two instructing. Third is just plain practice and not just on good days. Last would be learning some actual proper line handling and how to use springlines. I'd suggest myself as a teacher as I've taught many but it has to be below 32 degrees or in melt.

 

[OldDan1943]

But I have a counter-clockwise turning screw! :lol:

Are you looking fwd or aft?

 

[Nomad Willy]

A bit of information I learned here or somewhere else.
Right turning screw, put the rudder over to 30 degrees port, slow in reverse, you will back straight. Practice that for a while.

Hey Dan I like that.
I’ll experiment w it.
But w a left hand screw I usually kick the stern over a bit (about a foot) and w that momentum back and then steer w the rudder when I have a bit of way on. Rudder is big. Takes a knot or two of sternway ... more likely two but for sure three. But the rudder is then in danger of flopping over hard enough to possibly damage something. So must hold on to the helm tight.
My Albin25 did that too.

 

[JohnP]

Hmm! Drivesavers--another thing to worry about-- Happy New Year!

 

[DNT99611]

I gillnetted a 34 foot Westport single for a number of years. The first year was my first time running anything bigger than an outboard skiff. I did the slow and careful thing that most subscribe to. I got myself into all sorts of messes. An older/experienced friend took me aside that winter and explained that the throttle can be your best friend if used correctly. At some point it became easier to dock that boat than it was to dock a skiff for me. While I believe twins are easier for most folks, especially those just learning, to me they are not a must.

 

[T210DRVR]

I gillnetted a 34 foot Westport single for a number of years. The first year was my first time running anything bigger than an outboard skiff. I did the slow and careful thing that most subscribe to. I got myself into all sorts of messes. An older/experienced friend took me aside that winter and explained that the throttle can be your best friend if used correctly. At some point it became easier to dock that boat than it was to dock a skiff for me. While I believe twins are easier for most folks, especially those just learning, to me they are not a must.

Running a smallish fishing vessel I was very comfortable working the throttle on the single screw approaching the dock. When I graduated to a twin screw I found the transmissions were my friend. Keeping things slow seems to work best for me when guiding 35,000 lbs to the dock.

I admit that I got my masters license on YouTube.

So far I haven’t hit anything by accident.

 

[OldDan1943]

Hey Dan I like that.
I’ll experiment w it.
But w a left hand screw I usually kick the stern over a bit (about a foot) and w that momentum back and then steer w the rudder when I have a bit of way on. Rudder is big. Takes a knot or two of sternway ... more likely two but for sure three. But the rudder is then in danger of flopping over hard enough to possibly damage something. So must hold on to the helm tight.
My Albin25 did that too.

I read that somewhere, maybe in a different thread, tried it and daymn, I looked good. Add a bit of speed, your stern will back to port. Really impressed the man with me. SMILE

I always go bow-in because of the length of the finger pier and RIB overhang at the stern.

Neutral is a gear, use it. Slow speed, maintaining steerage is your friend after all, speed makes a big difference between a "touch" and a crash. OOPS

 

[BruceK]

Right turning screw, put the rudder over to 30 degrees port, slow in reverse, you will back straight. Practice that for a while.

Having abandoned a twins 42 after survey, now considering a single36+thrusters, that`s a good hint.

 

[Fish53]

A bit of information I learned here or somewhere else.
Right turning screw, put the rudder over to 30 degrees port, slow in reverse, you will back straight. Practice that for a while.

As a righthanded screw in reverse kicks the stern to port if port rudder (or more appropriately left) is applied it's pretty hard to back straight. The rudder needs to be in position to counteract the movement of the stern to port caused by propeller walk. Counter clockwise rotation of the propeller as view from astern would require right or starboard rudder to back straight. Much of this such as power and rudder size and design make practice with your individual vessel necessary. My boat with a relatively large propeller and considerable rudder area will actually steer quite well in any direction when backing while a vessel with a smaller wheel and limited rudder area may not respond well at all.

 

[markpierce]

Are you looking fwd or aft?

Prop-walk is to starboard.

 

[Fish53]

Prop-walk is to starboard.

Propeller rotation is defined as looking from aft just like engine rotation is defined by looking at the flywheel from behind. So when looking at a righthanded propeller turning ahead the rotation would be clockwise. Prop walk is always viewed as though the propeller was a wheel rolling in the direction of rotation thus a righthanded propeller in ahead causes the stern to shift to starboard. Conversely when a RH propeller is in reverse the stern goes to port. When backing with a RH propeller with the stern moving to port right rudder is necessary if backing straight is desired. It's also important to know that without prop wash acting on the rudder In reverse having some way on is necessary to provide pressure on the rudder to help overcome the movement to port. This phenomenon is also present in twin screw vessels making turns more pronounced in one direction depending on propeller rotation of the particular vessel, some have RH on port and LH on starboard others the opposite, some I've operated even have the same rotation on both. Learning what setup you have and how to use it to improve vessel handling is a great thing to know. Please before jumping on me to argue try researching, it's all on the web and easily found. Thanks

 

[Dougcole]

Propeller rotation is defined as looking from aft just like engine rotation is defined by looking at the flywheel from behind. So when looking at a righthanded propeller turning ahead the rotation would be clockwise. Prop walk is always viewed as though the propeller was a wheel rolling in the direction of rotation thus a righthanded propeller in ahead causes the stern to shift to starboard. Conversely when a RH propeller is in reverse the stern goes to port. When backing with a RH propeller with the stern moving to port right rudder is necessary if backing straight is desired. It's also important to know that without prop wash acting on the rudder In reverse having some way on is necessary to provide pressure on the rudder to help overcome the movement to port. This phenomenon is also present in twin screw vessels making turns more pronounced in one direction depending on propeller rotation of the particular vessel, some have RH on port and LH on starboard others the opposite, some I've operated even have the same rotation on both.

Learning what setup you have and how to use it to improve vessel handling is a great thing to know. Please before jumping on me to argue try researching, it's all on the web and easily found. Thanks

Well said.


Yes prop walk is the key to close quarters handling. It even makes a difference in twins, but not as much, and can be overcome by using more or less power on one engine or another.


I used to be partners in a 35' pontoon houseboat that we used for a duck camp in S. Louisiana at the mouth of the river. It had twin 40 hp outboards without counter rotating props. Because of the setup of the stern brackets (don't ask, it was a terrible boat) the motors didn't have full range of steering so you couldn't really use the directional thrust of the lower units. The props were so small they didn't really walk one way or another, or at least not enough to turn that slug. It also had a ton of windage. It was the hardest boat to dock I've ever run.



One of our partners was a Mississippi river pilot, the same guy who later miraculously kept a tanker that lost power from running into a casino in New Orleans and saved a ton of lives. He is the best boat handler I've ever known, by far. Even he cussed it. Coming in slow and tossing lines like a tourist in a rental boat was about all you could do.



That boat sank in Hurricane Katrina. I wasn't real sad to see it go.

 

[Nomad Willy]

Mark,
You said propwalk is to stbd. Most people talk about their propwalk in reverse.
Assuming you have a left hand prop ..........

The prop wash that moves the boat to L or R comes off the top of a prop. Water being “slung” off the prop w a left hand prop from the lower part of the prop mostly gets slung downwards and has little effect pushing the boat sideways. But at the top of the swing the proximity of the hull impedes the likelihood of the water getting slung upwards. So the prop blade and the hull bottom work together (w a LH prop) to sling the water to port and thus pushing the boat to stbd.

If you have a left hand prop try this ... while taking up your lines gently push or pull a bit to keep your boat in position then after the last line is untied get aboard and push the stern out about a foot. While it’s slowly moving to port go directly to the helm and put the gear in reverse. Give it 1200 - 1500rpm. As you back the boat will try to walk to stbd but since it’s a bit to port and w a bit of momentum it will back just about straight.

I did this over 100 times in Alaska in a slip like yours.
When you get some way on like 2-2.5 knots you may be able to steer in reverse depending on your rudder.
Also you can set the rudder before backing left or right (try right first) or you can back w/o any rudder. But if the rudder is not hard over (to either side) you should hold the rudder firmly so it won’t slam up against the stops or to the end of your hydraulic cylinders range. Possible damage.

Of course if you have a right hand prop you’ll need to find a port tie slip to practice on. And of course you’ll need to change numerous lefts to right ect. Should be obvious what to change and which way.

Once you have some tools in your box like the above you’ll be able to make numerous maneuvers gracefully. At least good enough so you can throw out a good save when needed.