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Old 04-25-2012, 05:16 PM   #41
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PS, You make a great point with the experience you have had with your Ford truck. Unfortunately, I had a different experience with my 7 year old diesel Ford truck. At 92,000 miles the "quick connect" the holds the tube leaving the high pressure oil pump (6.0) had a portion of the snap ring come loose that dropped into the oil pan (that 3-5000 psi puts a lot of pressure on things). From the pan, this small piece of a clip was sucked through the low pressure oil pump screen and wiped out the low pressure gerotor pump. While "in there" I also replaced the plugged engine oil cooler (necessary due to the added temperature caused by the high oil pressures) and the EGR cooler as a preventative measure. Lucky for me it died in the driveway. Maybe Marin will be lucky enough to be sitting at the slip if he repowers his GB and happens to have a problem. That way the mechanic won't take a long time to show up!
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Old 04-25-2012, 07:54 PM   #42
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Maybe Marin will be lucky enough to be sitting at the slip if he repowers his GB and happens to have a problem. That way the mechanic won't take a long time to show up!
I know a lot of people with electronically controled diesels in their boats, and almost everyone I know has electronically controlled engines in their cars. Based on their record of almost 100% engine reliability, it's not something I'm going to even give a thought to if we re-engine the GB.

Y'all can live in terror of electricicals running your engines if you want to. I'm around electronically controlled systems every day and they are a hell of a lot more reliable and maintenance free than the mechanical systems I'm around.
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Old 04-25-2012, 09:46 PM   #43
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I'm going to do my best to tie in all the threads in the side bar together for those who don't want to read them all.
1. My VHF radio crapped out because it has electric parts that fried on my biloxi lugger style hull while talking to a friend on a center console who's bennett trim tabs blew a fuse when he hit the beach. I was bitching and complaining about the downside of my wooden boat while I was painting my VHF the same color as the Lehman engine parts that were thrown over the gate by Fed Ex. OH and here we are on the single vs. twins. Did that make since. This thread makes about as much since. Twisted I'm in you court on this one. I don't have anything even related to a computer on my boat. Keepen' it real....
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Old 04-26-2012, 07:06 AM   #44
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You are probaly right Marin, but still, a power surge or a short circuit will stop the modern engine dead in he water, not my Leahman. :-)
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Old 04-26-2012, 08:13 AM   #45
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I'm going to do my best to tie in all the threads in the side bar together for those who don't want to read them all.
1. My VHF radio crapped out because it has electric parts that fried on my biloxi lugger style hull while talking to a friend on a center console who's bennett trim tabs blew a fuse when he hit the beach. I was bitching and complaining about the downside of my wooden boat while I was painting my VHF the same color as the Lehman engine parts that were thrown over the gate by Fed Ex. OH and here we are on the single vs. twins. Did that make since. This thread makes about as much since. Twisted I'm in you court on this one. I don't have anything even related to a computer on my boat. Keepen' it real....
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Old 04-26-2012, 08:14 AM   #46
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I currently own a 30ft Mainship pilot but want to upgrade to a 34 for more room.
My problem is single 370hp or dual 240hp's yanmar engine.

I really want the single engine because of the fuel saving; protected keel ( here on Marco Island we have low water); and lower maintenance.

However, I take many trips to Key West and Marathon and are often out of communication in the gulf. So if my single engine fails I'm screwed.

Has anyone given any thought of using the Genset to power an electric motor mounted to the transit platform that can get you out of trouble.

Or another solution??
Back on topic. Jann I live/boat just up the coast from you. Here's another take on your original post.
Personally I'd pick the single for the reasons you listed wanting one. HOWEVER......you need to weigh your piece of mind in having twins for your trip. A single wouldn't bother me, but once again its a preference. If I were looking at the boats you are considering I'd probably price shop and take which ever propulsion set-up came cheaper. You can't go wrong with either, until something goes wrong and then you'll say "Why didn't I get the...."!

As for your get home engine, I'm a get-it-done kinda person so I've thought about this a little and a solution I came up with was to get a go-devil, put a continuous duty electric motor on it and rig up a quick connect to the swim platform. You could possibly even make it so that you could break down the frame (separate in to halves) and be able to store it in the lazarette until needed. Fire up the genny, plug'er in and atleast putter into a channel somewhere.
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Old 04-26-2012, 12:05 PM   #47
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Back on topic. Jann I live/boat just up the coast from you. Here's another take on your original post.
Personally I'd pick the single for the reasons you listed wanting one. HOWEVER......you need to weigh your piece of mind in having twins for your trip. A single wouldn't bother me, but once again its a preference. If I were looking at the boats you are considering I'd probably price shop and take which ever propulsion set-up came cheaper. You can't go wrong with either, until something goes wrong and then you'll say "Why didn't I get the...."!

As for your get home engine, I'm a get-it-done kinda person so I've thought about this a little and a solution I came up with was to get a go-devil, put a continuous duty electric motor on it and rig up a quick connect to the swim platform. You could possibly even make it so that you could break down the frame (separate in to halves) and be able to store it in the lazarette until needed. Fire up the genny, plug'er in and atleast putter into a channel somewhere.




I often wonders why a person colod not hook up a stern thrust that cold be turned to become a get home. There was a company in Canada that made one. the concerrn once again is being able to charge back equal to what the thruster uses?

The Eagle get home is hydraulic driven so it can run for hours.
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Old 04-26-2012, 12:51 PM   #48
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On topic again.......
I think the most important element of the twin/single question regarding the boats we usually think of is of weight and engine loading. A twin CHB is over a ton heavier than a single and it's engines are (now days) run at extremely low loads. But a twin w engines the same total power as the single is better than either. The obvious best route is to find a boat that has the amount of power you want and the number of engines you want. It's a sad thing that the majority of trawlers in existence were not offered that way. And if you agree in this ...... good luck looking or repowering.
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Old 04-26-2012, 12:56 PM   #49
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On topic again.......
I think the most important element of the twin/single question regarding the boats we usually think of is of weight and engine loading. A twin CHB is over a ton heavier than a single and it's engines are (now days) run at extremely low loads. But a twin w engines the same total power as the single is better than either. The obvious best route is to find a boat that has the amount of power you want and the number of engines you want. It's a sad thing that the majority of trawlers in existence were not offered that way. And if you agree in this ...... good luck looking or repowering.
Who says? Not from ANY professional I've ever read. If that were true...why wouldn't every vessel be built that way? Especially every commercial ship that depends on BOTH reliability AND economy... There's always a tradeoff...but I'd love to see the references you are getting your info from.
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Old 04-26-2012, 01:33 PM   #50
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You are probaly right Marin, but still, a power surge or a short circuit will stop the modern engine dead in he water, not my Leahman. :-)
Based on many years of being around electronic systems that if they fail people die, I think the chances of a "power surge" or a short circuit that disables the engine control system on a modern marine diesel (or my car) are so small as to be virtually negligible. At least on a properly designed system. Many of the GBs in the big charter fleet in our marina are new enough to have electronic engine controls and from what I'm told they seem to run just fine year after year and go back and forth to SE Alaksa with no engine problems year after year.

Perhaps it's because of the field I work in but I find all these Chicken Little scenarios you guys are painting of electronically controlled engines (or anything) failing left and right and at the dock and in the middle of the ocean and from power surges and short circuits that occur on an almost hourly basis and, "oh God, if you get one of these things you're doomed" scenarios quite amusing.

Twenty years go, sure. Electronic controls could be and often were pretty dicey. When I moved to Seattle in 1979 they were building six new ferryboats for the Washington State ferry system. For the first time they were incorporating computer control of the engines and drivetrains with their Beta propellers. The Issaquah class boats proved to have almost daily problems with their engine and propeller controls, hitting docks, losing propulsion (not because the engines died but because the props failed to respond properly) and so on. Presumably they ironed out the problems one by one or replaced the whole system over time as the boats seem to be operating okay today.

But that was over twenty years ago. Things haven't exactly stood still since then.
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Old 04-26-2012, 01:58 PM   #51
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I often wonders why a person colod not hook up a stern thrust that cold be turned to become a get home. There was a company in Canada that made one. the concerrn once again is being able to charge back equal to what the thruster uses?

The Eagle get home is hydraulic driven so it can run for hours.
I have a hydraulic stern thruster but it runs of the main. So if my Lehman craps, it's useless. I suppose I could rig my genset with a pump, but then I don't know if my thruster is big enough to do much. I think I'd be better off with my dinghy outboard on a makeshift bracket on the platform.
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Old 04-26-2012, 02:20 PM   #52
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psneeld,
My references are common sense that dictate that a slow boat's power requirement is dictated by design and to exceed what is needed by much is poor design. Been over that before. If a given boat of a trawler type requires 100 hp installing 200 hp or 50 hp is just stupid. My opinion. Of the two the 50 hp boat may be the better.
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Old 04-26-2012, 03:07 PM   #53
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psneeld,
If a given boat of a trawler type requires 100 hp installing 200 hp or 50 hp is just stupid.
Unless---- as we have discussed before--- the market for your boat wants to go faster than slow at times, and slower than fast at other times using the same boat. Assuming you have the hull that can do it, which most semi-planing hulls like GBs and the like can, it can be very advantageous to a boater with a schedule to be able to go 15 knots to his destination, say Desolation Sound, then bumble around for a week or so burning hardly anything and enjoying the scenery at 8 knots, and then run back home at 15 knots.

The semi-planing hull lets you make a boat that will do this. A late-model GB42 with the two standard 400+ hp Cat diesels will semi-plane somewhat efficiently (if you consider 23 gph efficient) at 15 knots or so, but then that deep keel and hard-chine flat afterbody hull gives you a pretty stable ride at slower speeds at 7 gph at 9 knots or so.

If the goal is to move a boat through the water as efficiently as physics and hydrodynamics will let you do it, that's the absolute wrong way to go, I agree. An easily driven hull with an appropriately sized engine is the right way to go.

But the market trumps theory almost every time. So if your market wants to go reasonably fast as well as comfortably slow in a fairly good-sized boat, which pretty much defines GB's market over the last twenty years or so, you do what they have done.

It might be bad theory, but it makes for good sales. Theory doesn't make the house payments, put food on the tables, or gas in the cars for the people who own and work at the boat manufacturer.

We (Boeing) could make our planes a hell of a lot more efficient and quiet and less polluting and cheaper to buy and operate if we didn't have to make them big and strong enough to carry all those heavy seats and the heavy people who sit in them and their heavy luggage and Acme Freight Forwarder's heavy cargo. If our only goal was to make a plane that would fly as efficiently as possible we could do it very, very easily.

But nobody would buy one because it wouldn't do what people want to do with an airplane. So we compromise all sorts of aerodynamics and physics laws and we make them big enough for the airlines to jam a bunch of seats in them and carry tons of revenue freight in the belly and put in an incredibly heavy entertainment system (did you know the inflight entertainment system in a modern jetliner is BY FAR the most complex system on the entire plane?).

Which means we have to put a pair of gigantor 115,000 pound thrust engines on the damn thing to get all this crap up in the air and go somewhere at a speed that makes it worth what the people going and shipping stuff there are paying to do it. And airlines line up in droves to buy them because the plane will do exactly what they need to do to make money.

That's an extreme example of what GB and others are doing. The market drives the design and configuration and pure theory has to take a back seat.
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Old 04-26-2012, 04:21 PM   #54
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psneeld,
My references are common sense that dictate that a slow boat's power requirement is dictated by design and to exceed what is needed by much is poor design. Been over that before. If a given boat of a trawler type requires 100 hp installing 200 hp or 50 hp is just stupid. My opinion. Of the two the 50 hp boat may be the better.
That is rediculous...I can't even imagine why you posted that....and even THAT is subjective...

First...if you think other people out there don't understand design and power like you...well I can't help that.

What I did highlight is your statement "But a twin w engines the same total power as the single is better than either" I take this that you mean if the hull is optimally powered by 100 hp...that you think twin 50's is better than a single 100 hp. Am I reading you correct on that?

If I am...there are dozens of tests that with identical boats with similar propulsion drives that prove the single is more efficient due to drag. Assuming someone took the time to get the right gear reduction, prop, etc...etc...
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Old 04-26-2012, 09:24 PM   #55
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psneeld,
I'm looking at my post to see if I stated it clearly.
"If a given boat of a trawler type requires 100 hp installing 200 hp or 50 hp is just stupid. My opinion. Of the two the 50 hp boat may be the better.
I did qualify the forgoing as an "opinion".
You wrote "that you think twin 50's is better than a single 100 hp. Am I reading you correct on that?" Yes. It is my opinion that twin engined yachts are better than single engined yachts generally speaking and with considering all the variables that I know of. It's just an opinion and that's what I think. There are many other people w much better positions to launch an opinion on this matter but I have never heard of a comparison that was really close to apples and apples. Too many variables to actually achieve a direct comparison.

Example:
regarding efficiency,
Arguing this issue people will say "w a twin you've got two prop shafts and hence twice the drag". No consideration is given to the fact that the 2 shafts and their struts are much smaller and create much less drag for each. And the keel of a single is very wide and heavy to accommodate the shaft of the single. So a much less draggy and slender keel could be made that could even be made of metal. The trailing edge of most all singles creates lots of drag and interfers w the efficiency of the propeller too....more than struts.

You can go back in the archives and see that this issue has never been addressed objectively. We argued extensively before you joined the forum and even if a perfect comparison was achieved the difference would probably be too small to consider.
But the question of redundancy can be argued quite well if the conversation is limited to yachts. Our kind of yachts.
To argue this issue again would take too much time and energy that I do'nt have right now so I'll sit back (mostly) and let the rest of you get your feet wet......or get good and soaked.....as in the past.

Hope this mends the wall a bit and helps our communication.

PS Marin,
Re your post....marketing and the bottom line do trump engineering.
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Old 04-26-2012, 09:31 PM   #56
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PS Marin,
Re your post....marketing and the bottom line do trump engineering.
Sad (usually), but true.
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Old 04-26-2012, 09:56 PM   #57
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Here's some tidbits that I remember reading awhile back and don't entirely agree with but mostly so....it's a bit of cut and aste...but I did so to emphasize the ideas that I was trying to communicate earlier....

Single Or Twin Engines- Which Is Best?
Written by Bill Parlatore
There are certain subjects that bring out spirited opinions in everyone. In trawler circles, a dead ringer for dockside debate concerns the argument of one engine versus two engines. There are claims that can be made to support either point of view.
Having said that, I now contend that much of the emotional and gut-feel intuition you have about this subject may be suspect-or at least open for analysis. You see, I intended this article to come together in a "Point...Counterpoint" format, showing the arguments on both sides of this popular Holy Place topic.
I discussed the subject with professionals in the marine engine industry, asking some pointed and open questions. By identifying the valid pros and cons, I thought we could all get a little more informed about the real issues, and the benefits of single engine and twin engines. The different opinions could be listed and shared with you, and then we could all choose up sides. Boy, was I in for a surprise...
The opinions of these marine diesel experts were decidedly one-sided-in favor of a single engine installation. This is simply amazing, considering the many thousands of boats built with twin diesels. However, these people know their business, and their experience/opinions are a direct result of many years in the marine industry- serving commercial, military, fishing, and pleasure boat applications.
There is apparently a lot of vaporous thinking out there concerning reliability, maneuverability, safety, economy, and applicability when discussing a single engine versus twin engines.
Obviously the final decision is up to you, the boat owner. But just listen to what these guys have to say...

Bill Naugle adds, "Maintenance and cost are pretty much doubled. If you have a specific horsepower requirement for a given hull, it doesn't really matter whether you power with two small diesels or one bigger diesel-the fuel consumed is pretty much the same (the smaller engines probably use a bit more). But all the other costs are doubled."
Bill Naugle of Caterpillar, "Having two small, hightech diesels to produce the horsepower of a big single diesel may be an option, but there is a question of overall life of the engine. The larger engine is going to live much longer than the smaller engines. If you are in a situation where life is at risk (as is the case offshore)-this is a consideration."
Bob Tokarczyk said it best. "With two engines, you have twice the worries, twice the maintenance, twice the instrumentation, twice the number of filter changes you have to think about-as well as everything else that needs to be done with two engines. Overall, the costs are far greater."
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Old 04-26-2012, 10:16 PM   #58
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While what the guys you quoted say is certainly correct, they seem to be focusing pretty exclusively on costs and maintenance. What they don't address--- at least not in your excerpts--- are the other, less tangible factors that cause a boater to prefer one configuration over another.

A lot of boaters feel that redundancy in the powerplant and drivetrain is a major factor in their confidence level. A lot of boaters feel that a twin engine boat makes maneuvering easier. And some boaters--- like me--- simply like runing multiple engines. It's part of what I enjoy about boating. I don't NEED two engines for the kind of boating we do, but I LIKE two engines. Some people like flying twin engine planes, some like flying singles. It's that simple.

From the purely logical point of view a single-engine boat would probably suit the needs of almost everyone on this forum regardless of what they have now. But there is a lot more to boating than logic. And a lot of personal preferences--- particularly those of one's boating partner--- are far more important to having a good boating experience than the cost and maintenance saving that can be had by having one engine instead of two.

A single-engine boat becomes totally worthless if one's boating partner---- for whatever reasons, logical or not---- feels insecure or nervous on a boat with "only" one engine. That boat will spend most of its time sitting at the dock. How does that cost--- an unused boat--- compare to the cost of running and maintaining an extra engine in a boat which everyone in a family is secure being on and enjoys using?

My wife is a classic example. She'll fly in a single-engine floaplane with an engine built during WWII into the middle of the Coast Range totally out of contact with the rest of the world and not bat an eye. But she feels far more comfortable and secure on a boat with two engines. And if one tried to reason her out of her position she'll point to the four times we've needed the spare engine to come home on and that will be the end of that discussion.

So there's a whole lot more to the single vs. twin discussion than just operating costs and extra maintenance and the number of oil filters you have to buy.
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Old 04-26-2012, 10:29 PM   #59
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Marin...that argument flies with me! It's the best one of all.

I flew ancient HH52A single engine helos from pole to pole...then I thought I died and went to heaven with the HH65A twin engine helos!!!! No worries...then we found out after maxing out the weight on every flight...the second engine was just more power to the scene of the crash!!!!

Just kidding. A properly set up cruising boat that strays more than a days run from assistance certainly has a strong argument for twins or a substantial get home engine. When all is said and done when rigging a get home set up...you might as well be a twin arrangement in most of our rec boats. Also if you run dangerous areas often...the security of twins and the peace of mind it brings is certainly worth it. If I were on your coast...I bet I would have looked for a little bigger boat and twins for the stuff I like to do.

No argument from me that twins vs single is subjective...use the right points for the right application and I am good either way.
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Old 04-26-2012, 10:54 PM   #60
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Good example of incorrect stuff.

"Bill Naugle adds, "Maintenance and cost are pretty much doubled. If you have a specific horsepower requirement for a given hull, it doesn't really matter whether you power with two small diesels or one bigger diesel-the fuel consumed is pretty much the same (the smaller engines probably use a bit more). But all the other costs are doubled."
Two small oil filters will cost about the same as one large.
Two small head gaskets will cost about the same as one large.
Oil changes? Big engine takes 14 quarts of oil small takes 7.
This argument just dos'nt hold water.
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