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Old 04-13-2017, 06:16 PM   #1
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Single or Twins?

Hi everyone,

I know this has been discussed here at length before. BUT I'm just about to make an offer on one of two almost identical trawlers and I just need a little assistance clarifying my thoughts before parting with my hard-earned cash.

2007 Mainship 34 Trawlers. One with a single Yanmar 315 hp with 1,450 hrs. The other has twin Yanmar 240 hp engines with 800 hours on them.

We'll use them in BC and Alaska. We are old farts and tend to poke along at 6 - 8 knots.

Any thoughts on relative quality of either engine, dependability, fuel efficiency, maneuverability, security, maintenance costs and any other etceteras are very welcome.

Thank you all for your very valued advice,
Ron
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Old 04-13-2017, 06:41 PM   #2
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As you mentioned, much has been written on this topic. I'd suggest searching out some past threads. All the issues and arguments remain the same. Only the intensity of the comments changes.
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Old 04-13-2017, 06:58 PM   #3
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There is much to be learned from prior discussions of this topic, although the gist seems to be that the single engine guys wouldn't have it any other way, and the same is true for the twin owners.

You bring up a slightly different question, however, by introducing the 315 hp Yanmar vs 240hp Yanmar question. I don't know much about Yanmars, but I believe they are "high rpm" engines, which generally translates to reduced reliability (though I am sure many will argue, maybe correctly, otherwise) as compared to a lower rpm engine. To the extent that is true, I would think that the argument in favor of twins, based on redundancy, becomes stronger.
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Old 04-13-2017, 07:00 PM   #4
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Even being a die hard single guy...most of the time....yesterday, wished I had twins for the first time in 50 years of boating.

Just for convenience though, not safety.
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Old 04-13-2017, 07:16 PM   #5
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Even being a die hard single guy...most of the time....yesterday, wished I had twins for the first time in 50 years of boating..
Why? What happened yesterday?
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Old 04-13-2017, 07:27 PM   #6
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I've had a single engine trawler for 23 years.

Buy the twins.
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Old 04-13-2017, 07:32 PM   #7
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Make a List

Make a list, in writing, of the pluses and minuses of the 2(?3) engines, using your own thoughts and the thoughts of others posted here which you find helpful. You might visualize it without writing it down, but I find a list, on screen or paper,very useful.
Leaving aside the characteristics of the 315 vs 240 which others will know and post about,(is the 315 simply a higher output version of the 240?)you might be balancing things like redundancy, maintenance service costs,accessibility, reliability, fuel use, longevity, noise levels, simplicity, speed when required, maneuverability, the need or not for thrusters one or both ends and all that entails, etc.
I`m thinking either will be a fine boat, it`s a question of choosing best.There may be aspects of each boat to factor in, I`m sure you have that under control.
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Old 04-13-2017, 07:32 PM   #8
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I've been on Mainships with singles and with twins. Problem with the twins is on that boat the engines are cramped as hell. Access difficult.

If you want the twins, make sure you can put two hands on every part of the engines. Both sides and front and back. If you can't, I'd call it a no go.
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Old 04-13-2017, 07:34 PM   #9
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I'm a pretty diehard singles guy. That said, if you're going to remote areas that don't have Seatow or Tow BoatUS, there is a case to be made for twins or a get home alternative.

If you're going to be poking along at 6 to 8 knots, don't think it matters much which of the engines you have. Before you make your choice, see if you can work on the hull side of each of the twin engines.

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Old 04-13-2017, 08:13 PM   #10
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I think that Ski's comments are the most important. I am 59 years old, 6'2", 190 lbs. My ER isn't bad but I always could use more room in the ER. If the twins restrict that too much, it would make routine inspection and maintenance much more of the pain in the backside, plus you have to do it twice.

Disclaimer: I have never owned a twin engine boat.

Good luck with the decision.
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Old 04-13-2017, 08:33 PM   #11
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I have twin SP225 Lehmans in my boat. I like the the handling with twins, but working on the water pump impeller on the starboard engine last week made me wish I only had a single. Finally found a way to change it, but on a single it would have been a piece of cake. I would look very closely as to the workability around the twin engines. We looked at a 390 Mainship with twins and did not want to work on them. Not sure how much difference there is between a 390 and a 34. I think that I would opt for a single with bow and stern thrusters and would then have excellent handling.
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Old 04-13-2017, 08:54 PM   #12
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MYTraveler wrote that high rpm engines have reduced reliability. Not noticeably so IMO. Reduced longevity probably so in many (perhaps most) cases but I think reliability basically has nothing to do w engine speed. And you're a rare skipper if you can put enough hours on these engines to wear them out .. high rpm or low.
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Old 04-13-2017, 09:27 PM   #13
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Single or Twins?

For that boat, with a single I'd add a thruster. Those are relatively light boats with small rudders - put an oxygen tent on there for the PNW and its going to be hard to maneuver on occasion. I'd put the money into an awesome tender that could - if it had to - tow the vessel. And tow the tender.
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Old 04-13-2017, 09:31 PM   #14
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Quote:
Originally Posted by maineman View Post
Hi everyone,

I know this has been discussed here at length before. BUT I'm just about to make an offer on one of two almost identical trawlers and I just need a little assistance clarifying my thoughts before parting with my hard-earned cash.

2007 Mainship 34 Trawlers. One with a single Yanmar 315 hp with 1,450 hrs. The other has twin Yanmar 240 hp engines with 800 hours on them.

We'll use them in BC and Alaska. We are old farts and tend to poke along at 6 - 8 knots.

Any thoughts on relative quality of either engine, dependability, fuel efficiency, maneuverability, security, maintenance costs and any other etceteras are very welcome.

Thank you all for your very valued advice,
Ron
Taking into account what everyone else posting on here has said, realistically are you intending to do all the engine maintenance..? If not then the access is perhaps less of an issue, (mechanics tend to be younger and more supple), and the get-home on one redundancy, (thinking of where you will be cruising), plus extra speed potential and much easier manoeuvrability, might well win the day for the twins, especially as they have half the engine hours on them. Depending, of course on whether the condition, layout, and price difference are significant factors, and that is coming from one who has only ever owned a single. It might save the cost of installing thrusters, eg. Maybe they both have these, but you don't mention that. I manage without, even with a single, but I have been doing it for a long time. If I had the money I would have one if buying a single much newer, but with twin engines, probably not..? If it had one though - all the better.
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Old 04-13-2017, 10:36 PM   #15
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Single screws have a fine chime, keel and rudder that protects the prop. Twins are tricky. Study your needs and the design...
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Old 04-13-2017, 10:50 PM   #16
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Single screws have a fine chime, keel and rudder that protects the prop. Twins are tricky. Study your needs and the design...
I've never really thought of a rudder protecting a prop, but I guess if I had to lose one or the other I'd save the propulsion and Macgyver something up to steer with like a drogue.
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Old 04-13-2017, 11:16 PM   #17
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I've never really thought of a rudder protecting a prop, but I guess if I had to lose one or the other I'd save the propulsion and Macgyver something up to steer with like a drogue.
I suppose in reverse, the rudder would protect the prop, but I think what he meant is, the combined set-up of aft part of the skeg, the foot, and the rudder shaft, protect the prop because it is in between them.
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Old 04-13-2017, 11:25 PM   #18
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I think that the idea of a single prop being protected by the keel and rudder may be a bit overblown. We have twins and a deep keel. Coming up the Hudson and Erie Canal last spring there was a huge amount of debris in the water. We were very diligent in looking out for the debris, but much of it was submerged. We had 20+ hard strikes. By saying hard, I mean ones that we could definitely feel on the flybridge. I was sure that we had damaged one or both props. We even had a haul scheduled after the Trent Severn but when we went through Big Chute the lockmaster went under the boat and checked the props. He said they looked OK. So we cancelled the haul out. When we hauled for the winter, I inspected the props and found zero damage. I guess that our keel was enough protection. After this experience I am ambivalent about single vs twin in regards to prop protection. I would definately agree with the idea that if you are doing your own maintenance that a single wins vs twins due to access.
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Old 04-13-2017, 11:32 PM   #19
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If you want the speed, then I would go with the twins. If you feel you need the redundancy, go for the twins. Otherwise, I would go single. Another thing is the condition of the boat. If one is in significantly better condition or better equipped, I would throw the engine debate out and just get the best boat. I have owned those 4LHAs before and they are excellent engines. Many even say one of the best engines Yanmar has ever made. Go for the best boat....and I would lean toward single if speed is not desired. That 315hp would barely get that boat up on plane and it would take everything it has to keep it there.
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Old 04-13-2017, 11:38 PM   #20
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Are there other significant differences in the boats ? Are they the same price ? I'm assuming the twin engine boat is in better shape due to the lower hours....but that may not be the case. Are the other major options the same ? Heat, A/C, Generator, Electronics, Autopilot, maintenance history, etc ? Have they both been surveyed ? Does either need to be shipped ? The decision probably should involve more factors then just the engines
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