Reply
 
Thread Tools Display Modes
 
Old 04-23-2012, 06:32 AM   #1
Veteran Member
 
City: marco island
Country: usa
Join Date: Apr 2012
Posts: 79
single vs dual engines

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??
__________________
Advertisement

jann is offline   Reply With Quote
Old 04-23-2012, 07:25 AM   #2
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,896
Quote:
Originally Posted by jann View Post
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??
Not sure where in the Gulf you are out of communications... meaning that if your engine quits and can't contact anyone that setting off your EPIRB wouldnt bring help.

My preference would be a genset driven hydraulic system to drive the main shaft...there are a few very expensive systems that are available that are just bolt on or trannies designed to take the input. A wing engine/ hyd motor setup is also possible.
__________________

psneeld is offline   Reply With Quote
Old 04-23-2012, 07:29 AM   #3
Guru
 
Portuguese's Avatar
 
City: Salvador - BA
Country: Brazil
Vessel Name: Rainha Jannota
Vessel Model: Curruira 46
Join Date: Jun 2011
Posts: 662
Send a message via MSN to Portuguese
Jann

Use the site's search machine. There are more than 100 posts about this question. I am sure that you'll find your answer.
Good luck

Fernando
Portuguese is offline   Reply With Quote
Old 04-23-2012, 07:57 AM   #4
Guru
 
swampu's Avatar


 
City: Biloxi, MS
Country: USA
Vessel Name: Cajun Rose
Vessel Model: Biloxi Lugger
Join Date: Jul 2011
Posts: 1,144
There are also lots of topics on attaching an outboard bracket to the stern. That is usually the next question in logical thinking after the price of theother system.
swampu is offline   Reply With Quote
Old 04-23-2012, 08:03 AM   #5
Guru
 
Tony B's Avatar
 
City: Joe Wheeler State Park, Al
Country: Cruising/Live-Aboard USA
Vessel Name: Serenity
Vessel Model: Mainship 36 Dual Cabin -1986
Join Date: Jul 2011
Posts: 1,250
Almost every shrimp boat in the Gulf has just a single engine and they go pretty far ofshore. Once they leave the dock, they dont shut down their engine until they return to the dock which might be 2 weeks later.
Given the choice, I would go with a single.
__________________
Cruising the Eastern U.S. Inland Waterways and Gulf Coast. Presently on the ICW in Louisiana and heading Back to Texas.
Tony B is offline   Reply With Quote
Old 04-23-2012, 08:03 AM   #6
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,896
Quote:
Originally Posted by swampu View Post
There are also lots of topics on attaching an outboard bracket to the stern. That is usually the next question in logical thinking after the price of theother system.
And isn't the usual roadblock that if your boat isn't gas...carrying enough gas to push a 34 foot boat with a dingy engine isn't all that practical????
psneeld is offline   Reply With Quote
Old 04-23-2012, 09:26 AM   #7
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,153
Oh jeez... Here we go again!


__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-23-2012, 01:20 PM   #8
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,712
That's funny Gonzo........I have'nt seen that one yet and ditto the sentiments.

I think that twins are slightly MORE efficient than singles but in this example the efficiency of the two different total power of the examples could make a greater difference that twin v/s single. One example has 370 hp and the other has 480 hp. The 480 hp example will be forced to run more underloaded and be on a different part of the fuel burn curve than the 370 hp. How much power you really need is a big part of this equation. Also to be considered is the efficiency of the different engines but most skippers opt for more power than they need. And most trawler skippers put way too much value on fuel burn.
Nomad Willy is online now   Reply With Quote
Old 04-23-2012, 08:23 PM   #9
Guru
 
swampu's Avatar


 
City: Biloxi, MS
Country: USA
Vessel Name: Cajun Rose
Vessel Model: Biloxi Lugger
Join Date: Jul 2011
Posts: 1,144
ditto on the beating of the dead horse
swampu is offline   Reply With Quote
Old 04-23-2012, 08:24 PM   #10
Guru
 
swampu's Avatar


 
City: Biloxi, MS
Country: USA
Vessel Name: Cajun Rose
Vessel Model: Biloxi Lugger
Join Date: Jul 2011
Posts: 1,144
Quote:
Originally Posted by psneeld View Post
And isn't the usual roadblock that if your boat isn't gas...carrying enough gas to push a 34 foot boat with a dingy engine isn't all that practical????
And then the diesel outboard
swampu is offline   Reply With Quote
Old 04-23-2012, 09:00 PM   #11
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
This question keeps coming around and in the end, the right answer is always the same. Get however many engines it takes to make you, and more importantly your boating partner, feel confident and safe out on the water. Because in the end that's all that matters. If two engines fills your bill, you will justify the added expense of operating two engines. If one engine fills your bill, you will justify not having the redundancy of a second engine. And both people will be correct.
Marin is offline   Reply With Quote
Old 04-23-2012, 11:36 PM   #12
Guru
 
Join Date: Aug 2011
Posts: 511
If my boat were powered by electronically controlled engines I'd like twins. Just due to the notion that something can go KaFlooey in the computer with no warning or fault of your own. Mechanical diesels usually have issues with fuel cleanliness, and I can change a filter and prime my fuel system, I can't diagnose and repair a computer.
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 04-24-2012, 01:15 AM   #13
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,712
Jann,
In case you haven't figured it out we've had 55,000 posts on this in the past. All there for you to see if you ride the time machine back into the archives. Some newer members may/probably have new angles on this question and there's no reason they or others shouldn't do it over again or for the first time. It may be fun for us old timers to read the late commers opinions especially if they don't read the posts of the past.
Nomad Willy is online now   Reply With Quote
Old 04-24-2012, 07:58 AM   #14
Guru
 
Fotoman's Avatar
 
Join Date: Nov 2009
Posts: 621
Quote:
Originally Posted by twiisted71 View Post
If my boat were powered by electronically controlled engines I'd like twins. Just due to the notion that something can go KaFlooey in the computer with no warning or fault of your own. Mechanical diesels usually have issues with fuel cleanliness, and I can change a filter and prime my fuel system, I can't diagnose and repair a computer.
That's probably the best take on this question I have ever seen. Makes a lot of sense.
Fotoman is offline   Reply With Quote
Old 04-24-2012, 08:43 AM   #15
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,153
Quote:
Originally Posted by Fotoman View Post
That's probably the best take on this question I have ever seen. Makes a lot of sense.
No doubt!
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-24-2012, 11:28 AM   #16
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,712
I think there's plenty of doubt that that's a good philosophy. Are you guys tell'in me the electronics on your engines is the only thing you can't fix? I've done a lot of wrenching in my years know there's a lot of stuff I'd not mess w on my simple little Mitsu. Probably the electronics saves us from many other potential problems so the net result could very well be that the electronic engines are easier to deal w and more dependable than the old stuff most of us are running. Is the last airplane you flew on (not counting Marin's Beavers and the like) all mechanically controlled? I doubt it. The concept of an electronically controlled engines having the scary potential to leaving one engineless is more like the car mechanics of the 50s say'in radial tires would kill you. So I think there's plenty of doubt to that theory. Just say'in
Nomad Willy is online now   Reply With Quote
Old 04-24-2012, 11:45 AM   #17
Guru
 
Phil Fill's Avatar
 
City: Everett Wa
Country: US
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
Quote:
Originally Posted by jann View Post
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??

As stated before there is not right answer. However the present condition, how maintenance and more importantly how YOU are going to maintain is important. Also THE BOAT you really want to buy might have single or twins, so at that point it may not matter.

When my wife found/saw the Eagle it was TOTAL not the boat we were planning on buying. However, my wife wanted the boat. The only things it had going for it was being BIG, and the price. My biggest negative was being a single. However the engine had low hours, was well maintained, the DD 671 had a history of being reliable, and parts and service are available. So now I every year I have the engine maintained/replace and check every year so the change of the engine failing is at a minimum.

Also many single engines use the gen set as a get home to power the shaft/propeller, which I modified and made functional again. So it sort of has two engines. The simplest solution might be an outboard off the swim step. Many boats that size in the PNW have out boards for trolling/fishing as they can not go slow enough using the main engine.
Phil Fill is offline   Reply With Quote
Old 04-24-2012, 02:33 PM   #18
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Quote:
Originally Posted by manyboats View Post
I think there's plenty of doubt that that's a good philosophy. ....Probably the electronics saves us from many other potential problems so the net result could very well be that the electronic engines are easier to deal w and more dependable than the old stuff most of us are running. Is the last airplane you flew on (not counting Marin's Beavers and the like) all mechanically controlled? I doubt it. The concept of an electronically controlled engines having the scary potential to leaving one engineless is more like the car mechanics of the 50s say'in radial tires would kill you. So I think there's plenty of doubt to that theory. Just say'in
As usual, I think Eric is right on the money here. And his car mechanic analogy is spot on. Done correctly, modern electronic engine controls are brilliant things, indeed. Efficient, reliable, simple (in that if they do create a problem you change a box and you're done), lightweight, and no moving parts.

Virtually every jetliner in production today has no, zero, zip nada physical connection between the power levers on the flight deck and the fuel controls on the engine itself. Why? Because electricicals running back and forth along a wire are a hell of a lot more reliable and maintenance-free than cables moving back and forth and flexing over hordes of sheaves and having rotating connections at each end attached to even more moving parts.

Like every new technology, electronic engine controls went through a developmental period during which they could be problematic. But people-- particularly engineers--- don't just sit around and accept a problem as "that's just the way it is." They figure out how to fix it. And they've been "fixing" electronic engine controls for a few decades now. To the point where I daresay the electronic controls on most engines today--- automotive, aviation, and marine--- are far more reliable than the simple but very mechanical controls from the "good old days."

Plus, most well-designed electronic controls have work arounds built into them in case something does go wrong. They very rarely will leave you totally powerless. You might develop partial power, or you might have to engage a physical back-up system that provides a sufficient degree of engine performance to get you home.

One of the reasons we are toying with the idea of re-engining our boat is to get rid of the ancient, mechanical engine controls with all their inefficiencies and potential failure points and replace them with a pair of modern diesels with electronic controls that we can basically forget about.

I know you hate analogies, Eric, but you came up with a beauty with your old-time car mechanic comparison. That sums up the resistance to electronic engine controls perfectly, in my mind. Perhaps I have a different mindset to the typical boat owner, I don't know. I work in an industry which is focused full time on making things more reliable, more efficient, lighter, and more maintenance free than what came before. So I don't view technical advances as being scary, I view them as being solutions to the deficiencies in today's technology. In the words of a song, "today is tomorrow's yesterday."
Marin is offline   Reply With Quote
Old 04-24-2012, 03:42 PM   #19
Guru
 
Join Date: Aug 2011
Posts: 511
Quote:
Originally Posted by Marin View Post
As usual, I think Eric is right on the money here. And his car mechanic analogy is spot on. Done correctly, modern electronic engine controls are brilliant things, indeed. Efficient, reliable, simple (in that if they do create a problem you change a box and you're done), lightweight, and no moving parts.

Virtually every jetliner in production today has no, zero, zip nada physical connection between the power levers on the flight deck and the fuel controls on the engine itself. Why? Because electricicals running back and forth along a wire are a hell of a lot more reliable and maintenance-free than cables moving back and forth and flexing over hordes of sheaves and having rotating connections at each end attached to even more moving parts.

Here's where those thoughts fall flat, for me anyway. I've worked for both helicopter and jet based companies. Both of those had ridiculously rigorous maintenance schedules. they not only do maintenance, they also "test" components at scheduled intervals so that they can detect when something is starting to go awry, also some components are just R/R'ed for time in service whether it shows anything wrong or not! This is why these are so "reliable". Also these are used as much as possible as that is the way they make money. Pleasure boats are used at your leisure and can go for months (years in some cases) and people think nothing of going out and firing them up and going for a ride!
How many of us, while boat shopping, have seen engines and transmissions that were balls of rust yet the owner would twist the key and the engine would fire up and the owner would tell you how he'd taken the family out for fireworks on the 4th!!
Also lots of electronics REQUIRE a certain level of voltage to operate. Mechanical engines could have the alternator fall off, and the batteries could tear loose in a storm and become completely detached from the wiring and the engines don't care a whit.
How many 60yr old boats are out there still running and causing fun and have only had "routine" maintenance? I don't know how long the electronic management on the "new, improved" engines will last in a saltwater environment. I just find it hard to improve upon that kind of reliability.
This topic is like belly-buttons, which is better innies or outties? One would be easier to pierce and the other collects lint. Do you like lint or bling!
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 04-24-2012, 04:04 PM   #20
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Can't speak for helicopters--- I use them but I believe they are inherently evil and out to eventually kill you--- but in terms of commercial airplanes, a HUGE part of their operating cost these days is maintenance. So Boeing, Airbus, GE, Rolls Royce, etc. put a major, major focus on reliability and reducing maintenance. We can no longer depend on "rigorous maintenance schedules" to keep our products operating properly: our customers won't stand for it. They want to go for thousands and thousands of hours--- forever would be even better--- with nothing more than topping off the oil in the engines.

So we and the engine manufacturers have as our target exactly that. I've been to airlines all over the world, spent time with them, interviewed their maintenance and operations people, and filmed their entire operation. The image of mechanics and technicians swarming all over these things every time they come in could not be more wrong. In fact, a phrase we have heard at airlines all over the globe with regards to the 737 is "fly and forget."

We've filmed countless turnarounds of the 777, for example. Some of them are the first model, the 777-200. And here's what their "rigorous maintenance schedule" consists of. Plane comes in, fuel truck comes over and does its thing, a mechanic shows up and walks around the plane to make sure nothing's fallen off or leaking, checks the tire tread, and puts two or three guarts of oil in each engine. That's it. This is for the largest twin-engine jetliner in the world that operates for the airlines an average of 14 hours a day, 24/7/365.

If the plane's had a problem it told the airline's maintenance department about it as soon as it happened, which is long before the plane arrived at its destination. So if something did happen, that same mechanic that checks the tire tread already has the part and the tools he needs to change it, he takes his laptop (iPad more and more now), connects to the plane wirelessly, changes the part, the plane runs the diagnostic, shows the mechanic the results on his iPad, and the mechanic goes on his merry way. All this while they are still reloading the catering in the galleys and unloading the baggage and freight.

That's what electronics buys you.

I've met many mechanics and maintenance managers who were very skeptical of things like fly-by-wire flight and engine controls when they first came out. Talk to them today and they think they are God's gift to aviation. Why? Because they never have to mess with them. They just go and go and go.

A rusty old engine may start and run, but it's an inefficient, polluting, noisy, vibrating engine that takes fairly frequent servicing and maintenance to keep it operational. A modern electronic engine is none of those things.
__________________

Marin is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 02:16 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012