Single or Twin Screw!!

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Age would worry me more with accessories and cooling than with engine internals. Compression check, oil pressure check and oil analysis will tell you about internals.

An eroded elbow letting water backflow would worry me more. A bad injector can cause a piston failure.

One good old well-maintained engine better than two old neglected dogs.
 
All my failures were external , visible parts to the engine, not the base engine itself...except for the damper plate that failed right about on schedule and gave fair warning.

You can have a 20 year od base engine with low hrs and tip top maintenance give less problems than anthing.

You can also find dirt cheap boats with recent rebuilds...I did...not sure that is good...might have been easier and cheaper to rebuild the engine than the project boat.

A rebuilt Lehman is only a bit overv$10,000 last reports.
 
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O C Diver said:
Depending on the engine, rebuild it. I'd rather have one rebuilt verses 2 that you consider unreliable.

Ted
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Not sure I understand. Are you saying if I buy an 20+ year old boat I should automatically rebuild it. Wouldn’t I be better off buying a twin and waiting for one engine to break (ie throw a rod) and return to a marina for repair. I think if you have a suspect single the urgency to repair is much greater than if you had a twin and just waited for one engine to suffer a major breakdown. There seems to be no room for error on a single especially those unfortunate scenarios you may find yourself in. Also if you were about to return from the Bahamas and you heard a knock in your single what would yo do. I know what I would do with my twin.
 
Re post #60,
Can’t say Brooksie’s wrong but..
Comparing twins with singles is usually comparing 380 cubic inches of engine in boat A to boat B with 760 cubic inches of engine and a ton of extra weight.

This means that whether or not a boat has certian chacteristics has little or nothing to do w how many engines it has. Space consumed in the engine compartment, total weight of boat and cyl area as a heat sink is producing the differences in the boats ..... not the number of engines.

When you compare singles to twins the only meaningful way is to compare boats w the same total amount of power. Or comparing specific boats.
 
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NewbieFromNJ said:
Not sure I understand. Are you saying if I buy an 20+ year old boat I should automatically rebuild it. Wouldn’t I be better off buying a twin and waiting for one engine to break (ie throw a rod) and return to a marina for repair. I think if you have a suspect single the urgency to repair is much greater than if you had a twin and just waited for one engine to suffer a major breakdown. There seems to be no room for error on a single especially those unfortunate scenarios you may find yourself in. Also if you were about to return from the Bahamas and you heard a knock in your single what would yo do. I know what I would do with my twin.
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Well, you indicated that any boat you will likely buy will have what you consider unreliable engine(s) because of its age. So, I would consider buying a single high time engined boat and then take the savings plus some investment to have reliability.

Regarding your engine knock scenario, it's may be more likely that you will have a double engine failure with two 20 year old motors than my extremely well maintained 3 year old single engine. If you consider all the worn out parts in your two engines and your wait till it breaks approach, why would you assume the other engine isn't about to fail. Frankly, I wouldn't leave the land of Seatow and TowBoatUS, with the expectation of an engine failure in my future.

Ted
 
Sweet runner, drinks a little fuel, 14 gal hour @ 10 Knots, Twin Screws, but oh that sweet sound of the screaming jimmies, the longer you listen to them the quieter they get.
 
koliver said:
And don't forget the possibility of postponing expensive or time consuming repairs by simply running on one for a few weeks or for the whole season. No lost vacation time.
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Sounds good on paper. The reality of a TF member with a twin screw boat leaving on vacation on one engine...?Really
 
Ejdakins said:
Sweet runner, drinks a little fuel, 14 gal hour @ 10 Knots, Twin Screws, but oh that sweet sound of the screaming jimmies, the longer you listen to them the quieter they get.
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"... longer you listen to them the quieter they get." :thumb:

Well said - and true... to your "mind's eye", that is! :ermm: :popcorn: :D
 
Halifax Jack said:
Hello all. We have been looking at a trawler in the 36 to 40' range for some time now. I have had a bias toward a twin screw vs a boat with a single. A single must have a bow thruster to be considered. May I ask from personal experience your preference and why?

Thanks in advance
John
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Twins or singles -- have had both over the last 50 years and I am sold on singles -- less maintenance, more room to work, more storage room and in the PNW the prop is not on the outboard chines sucking in garbage. In terms of maneuvering my Mainship 34 has bow and stern thrusters and can turn in its own length
 
DryGuy said:
Twins or singles -- have had both over the last 50 years and I am sold on singles -- less maintenance, more room to work, more storage room and in the PNW the prop is not on the outboard chines sucking in garbage. In terms of maneuvering my Mainship 34 has bow and stern thrusters and can turn in its own length
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Thrusters take all the fun out of boat handling for me and add just one more thing to break and maintain, sorta like using crutches when you have no disability, in my opinion.
 
My ideal would be a single engine with a wing. The single engine is more likely to be less troublesome based on my 55years of boating. With a bow thruster, getting into difficult places with cross winds and cross tides will help both singles snd twin instalations.
 
Single or screw

First be honest with yourself on how you intend to use the boat. If you are doing inshore or coastal cruises of short distances the answer might be different than if you are going to cruise long distances to remote locations. A common thought is that two engines provide more reliability and there is some truth to this with one major caveat; probably the largest cause of diesel engine failure is fuel contamination so if one engine fails it's highly likely that the other one will fail shortly thereafter. Basically, a well maintained diesel engine is probably not going to fail. If you are doing inshore or coastal cruising and you have engine trouble Towboats US or Sea Tow will come get you. I have a single engine, no bow thruster. It's a challenge to back but it's a skill you can master and then you are fine. I can walk (crawl) completely around my engine which makes maintenance and servicing it as well as everything else in the engine room much easier. If you have someone else do your annual maintenance then you are looking at half the cost of two engines not to mention 2 stuffing boxes and cutlass bearings vs 1. Then there is the cost of rebuild/replacement if that becomes necessary. I'm a strong proponent of 1 engine.
 
Folks have been operating single screw vessels for over a hundred years without a bow thruster and amazingly enough, some still do today. It would be a serious mistake to buy a boat with a bow thruster or install one on a boat without ever learning to dock the boat without one, under ANY conditions.
Just like GPS, a chartplotter or a radar set, a bow thruster is an AID to safe boating, but should never be relied upon for your survival!
It may be tough learning how to handle your single-screw boat, but it is NOTHING compared to trying to drive or dock most twin screw vessels on one engine! Of course, the rationale that if one fails, you will have the other holds very true, unless it is fuel tank contamination problem.
But there is no bow thruster needed with a twin-screw vessel. You wanna look really sharp docking? After a little practice docking a twin screw boat, you'll look like a true professional every time, no matter the conditions, especially backing in. That's how well a twin screw boat handles.
You can do it nearly as well with a single screw vessel with enough practice, but there may come a day when you'll have to pick another dock or wait out the tide.

If fuel economy is of any concern, a single screw vessel is most probably designed for that. I don't think you will save an appreciable amount of fuel by running on one of two engines, but you will be stressing that one engine a lot more than you would with both running. That could necessitate more frequent overhauls, a not so inexpensive endeavor.
And let us not even mention TWICE the engine maintenance, another considerable expense. Oops sorry, it just slipped out.
Anyway, have fun on whichever boat you choose. That's what it's supposed to be about.
 
When we were looking to buy a Fleming 55, I met Tony Fleming at Southampton. I told him I wanted a single engine, not a twin. 'It comes with two,' he said. I replied, 'But I'm the customer and I only want one.' 'Piers, he replied, 'I'm the builder and it comes with two.'

I then asked why the lazarette and engine room were so large. 'If you pushed the engines aft you could have so much additional living space - enough for a centre cabin.' Again camec the laconic reply, 'Piers. Engines are far more imprtant that peopls. And it comes with two.'

The conversation ended .... and we bought a Fleming!
 
Piers, you raise a cogent point.

Tony is a guy who uses his twin engine Fleming to go to far away places we can only dream about. If he were a designer/builder of vessels for arm chair coastal cruisers it would be a single, and he'd of been long forgotten as would his vessels.

He also practices and believes in good maintenance and backs it up by having noted experts on boat care travel offshore with him from time to time. Just do nothing more than pull up a YouTube of his travels. Watch it from the comfort of your favorite chair while musing the nuances of single vs twin for imaginary boats - but really lusting for a Fleming twin, a real boat.
 
Fish53 said:
Thrusters take all the fun out of boat handling for me and add just one more thing to break and maintain, sorta like using crutches when you have no disability, in my opinion.
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But then as size increases, "thrusters" become "tugs" and if one of those "breaks" it's probably really expensive.

I guess I don't see much philosophical difference between thrusters for relatively smaller vessels or tugs for large usually commercial vessels...

-Chris
 
Fish53 said:
Thrusters take all the fun out of boat handling for me and add just one more thing to break and maintain, sorta like using crutches when you have no disability, in my opinion.
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Fish
Some of us don't have vessels designed for banging around with no worries about hull damage to our or other's vessels. BTW, thruster maintenance is about as simple as a lawn mower. Keep the blades clean and check the oil.
 
sunchaser said:
Fish
Some of us don't have vessels designed for banging around with no worries about hull damage to our or other's vessels. BTW, thruster maintenance is about as simple as a lawn mower. Keep the blades clean and check the oil.
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After years of instructing boaters over multiple years....

Like most peole, they lose necessary skills over the interruption of boating seasons or just available time onboard.

Many are really never operators to begin with, so lack of continuity of practice means difficulty advancing up the ability ladder.

Many need twins and or thrusters every time they dock to enjoy their boat without fear of damaging their boat yet again or worse, other boats. This fear often turns them into dock queens.
 
sunchaser said:
Piers, you raise a cogent point.



Tony is a guy who uses his twin engine Fleming to go to far away places we can only dream about. If he were a designer/builder of vessels for arm chair coastal cruisers it would be a single, and he'd of been long forgotten as would his vessels.



He also practices and believes in good maintenance and backs it up by having noted experts on boat care travel offshore with him from time to time. Just do nothing more than pull up a YouTube of his travels. Watch it from the comfort of your favorite chair while musing the nuances of single vs twin for imaginary boats - but really lusting for a Fleming twin, a real boat.
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Couldn’t have said it better. [emoji4]
 
Fish53 said:
Thrusters take all the fun out of boat handling for me and add just one more thing to break and maintain, sorta like using crutches when you have no disability, in my opinion.
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Fish,

For you experts that live on the water and boat 7 days a week, you can develop skills where you may not need a thruster.

For the recreational boater like me that live on the water and only boat 6 days a week, I love my thrusters and they love me. No, they are not absolutely necessary... most of the time. However, there's times when tweaking with the thruster makes the difference of getting in or not.

And the overall maintenance picture on them is bupkis ....
 
Seevee said:
Fish,

For you experts that live on the water and boat 7 days a week, you can develop skills where you may not need a thruster.

For the recreational boater like me that live on the water and only boat 6 days a week, I love my thrusters and they love me. No, they are not absolutely necessary... most of the time. However, there's times when tweaking with the thruster makes the difference of getting in or not.

And the overall maintenance picture on them is bupkis ....
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I understand that's why I said "for me" and "my opinion". I would never say and did not mean to imply that there was anything wrong with anyone else having a thruster.
 
sunchaser said:
Fish
Some of us don't have vessels designed for banging around with no worries about hull damage to our or other's vessels. BTW, thruster maintenance is about as simple as a lawn mower. Keep the blades clean and check the oil.
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I don't go "banging around", implying that you need a bumper car to handle a single screw vessel competently is incorrect, I suspect I've scratched less gelcoat and steel than many twin screw and thruster equipped boat handlers. I do admit that perhaps I've had more years of practice than many however. My comment was simply to say that I enjoy maneuvering a single screw boat as I also enjoy watching any other competent boat handler at work regardless of the vessels configuration.
 
Thuster Truster

My first "trawler" was a Lien Hwa 47 with twin Ford Lehmans. After running a sailboat for 20 years, I loved the maneuverability of twins. In the three years I owned her I had only one time that I really needed a thruster. I chose to back out of my slip and spin the bow into the wind to leave the fairway. Normal wind was at 1 O'clock. Now it was at 7 O'clock and I found that my twist action was not enough to get me turned into the wind without scrapping my neighbors anchor and pushing off manually.

Ok now fast forward to my newer 55 and bringing it in to my new down wind slip with an 16 - 20 knot wind blasting. Yes a smart guy would have taken the open end tie. Instead I dropped a helper off and proceeded to try to get safely into my slip. To complicate matters, my port engine did not want to reliably go into or out of gear. Three times I approached and retreated with each occurrence bringing me with inches of damage to us and others. Finally I got her in with just a scratch and swore I'd buy a thruster. That was a couple months ago. The port transmission linkage has been properly adjusted so we are now good there.

On a trip from San Diego to Los Angeles I lost the port engine due to a fuel issue. I was close enough to cruise in on the starboard engine and deal with the issue at anchor so I could use both engines to enter my windy slip.

In November I drove her from Los Angeles to Ensenada MX to have the thruster installed, painting, washing, waxing, etc. On the way home, running 1650 rpms with synchronizer engaged, I began feeling vibration at my feet. Going below, I could see the stb engine shaking a bit more than the port. I had good oil pressure, cool exhaust water. I dropped throttles down, ran the port engine up in gear and it was smooth. Ran the stb engine up alone and it was smooth. Activated the synchronizers and brought them both up smoothly for about 5-10 minutes then the vibration started again. Since I developed a small fuel leak in one tank I was running the fuel down knowing tank replacement was to happen soon. I think he fuel filter began to clog in the stb engine. I started to replace the fuel filter but it didn't really look bad. Since we were close, I just powered in the last few miles on the port engine. It did take me two tries to get the boat in with port engine and thruster. Second try was perfect. So for a 55 footer. Give me a twin with a thruster. I plan to replace the filters today.


Sorry for the verbose post.
 
Fish53 said:
I don't go "banging around", implying that you need a bumper car to handle a single screw vessel competently is incorrect, I suspect I've scratched less gelcoat and steel than many twin screw and thruster equipped boat handlers. I do admit that perhaps I've had more years of practice than many however. My comment was simply to say that I enjoy maneuvering a single screw boat as I also enjoy watching any other competent boat handler at work regardless of the vessels configuration.
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Well Fish, you opened the door by saying a boat with thrusters is like a person with crutches who has no disability. Take a step back though, you know nothing of my boating skills nor I of yours. This will not change nor does it really matter.

One thing we do know, there are boats crashed, sunk, grounded and lives lost aplenty with presumably professional skippers in charge. Years of practice and experience fall by the wayside as these disasters and accidents get reviewed.

My point being, if a skipper likes twins and thrusters and he feels safer doing it this way, so be it. Call it a belt and suspenders approach. It bears no relationship to skill or experience. Most newer yachts (likely 100% above 65 feet) are delivered this way, some to very proficient skippers.

This is a recreational boater's thread where thrusters and twins are very common and skills highly variable. A workingman's forum where relevant commercial issues abound can be easily found.
 
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I've seen little reference to the proper use of springlines when handling any boat in close quarters. This may be a technique and skill many have not developed or are familiar with but it's utility can prove invaluable in many situations particularly in the event of an engine failure or when the wind or current is overpowering the engines or thruster. A stout length of line properly placed can enable an otherwise difficult maneuver.
 
sunchaser said:
Well Fish, you opened the door by saying a boat with thrusters is like a person with crutches who has no disability. Take a step back though, you know nothing of my boating skills nor I of yours. This will not change nor does it really matter.

One thing we do know, there are boats crashed, sunk, grounded and lives lost aplenty with presumably professional skippers in charge. Years of practice and experience fall by the wayside as these disasters and accidents get reviewed.

My point being, if a skipper likes twins and thrusters and he feels safer doing it this way, so be it. Call it a belt and suspenders approach. It bears no relationship to skill or experience. Most newer yachts (likely 100% above 65 feet) are delivered this way, some to very proficient skippers.

This is a recreational boater's thread where thrusters and twins are very common and skills highly variable. A workingman's forum where relevant commercial issues abound can be easily found.
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So as you've decided to find a slur in my comment you'll forgive me if I feel a bit slighted by your invitation to take my conversations elsewhere. I admit I had no idea that recreational boaters were so adverse to others opinions, so perhaps I should go elsewhere in search of a less tender audience, I wasn't aware I was unwelcome here until now, my deepest apologies.
 
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Fish53 said:
So as you've decided to find a slur in my comment you'll forgive me if I feel a bit slighted by your invitation to take my conversations elsewhere. I admit I had no idea that recreational boaters were so adverse to others opinions, so perhaps I should go elsewhere in search of a less tender audience, I wasn't aware I was unwelcome here until now, my deepest apologies.
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Of course you're welcome here Fish. Neither of us should be tender. No insult intended if taken that way.
 
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