Reply
 
Thread Tools Display Modes
 
Old 02-25-2016, 11:21 AM   #81
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
Trundlebug - What you say makes sense, but I asked the manufacturer about estimated time between overhauls (assuming normal maintenance routine) and at what continuous rpm duty cycle. Here is what they had to say:

Hello,
1. I would say that best rpm range considering fuel consumption and lifetime for this engine is 1400-2000rpm
2. We have seen hours up to 30000h without major overhaul for this engine family, with medium duty usage and good service. With good fuel and maintenance, 15000 hours should be no problem even with higher duty cycle.


I don't know how this engine compares against Deere or other similar brands, but it is basically a marine commercial engine, not really marketed to the recreational boaters. Perhaps that has something to do with the solid record of AGCO.
__________________
Advertisement

makobuilders is offline   Reply With Quote
Old 02-25-2016, 11:48 AM   #82
Veteran Member
 
Trundlebug's Avatar
 
City: River Trent
Country: UK
Vessel Model: Profile 33
Join Date: Jul 2015
Posts: 31
Mako,

That's good news. Having read through all the thread postings I was concerned that duty cycle hadn't been directly mentioned and thought it should be considered every bit as important as power & rpm.
Glad you've got it covered and the response is detailed and encouraging.
__________________

Trundlebug is offline   Reply With Quote
Old 02-25-2016, 11:53 AM   #83
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,709
I agree Trundlebug!
Fifty to 70% load should produce a long engine life.
And probably 80% load would shorten it a small amount like 5%?
But what would engine life be if run at 25 to 35%?
And to cut all corners what engine load would provide the longest life?
__________________
Eric

North Western Washington State USA
Nomad Willy is online now   Reply With Quote
Old 02-25-2016, 11:59 AM   #84
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,884
Mako- Good news on the balancer. I still would prefer a six for idle smoothness and to get cruise rpm and load lower, but that is your call.

Regarding CPP on your earlier post, I really LOVE CPP, but on your project I think it would be of minimal benefit. Aside from purchase cost, it has other costs down the road. If you pick an engine right and prop it right with a fixed wheel, you can optimize for hull speed and anything below that will be fine. Above hull speed sounds like a no go zone, and it would be with a CPP also, just that while hogging along you could load the engine properly. But what is the point in that.

Quote:
Originally Posted by manyboats View Post
So if I'm going to repower Willy I'm going to need to find a 37hp turbocharged, common rail, intercooled and electronicly controlled engine? Surley not. It would cost four times as much as I paid for my new Mitsu in 06. There must be a power cut-off so small engines can be cost effective. How would on replace an old Onan generator engine?
I'm not a student of the epa rules, but as I understand it, small engines are rated differently and still can be bought as mechanicals. I don't know the break point. Marine gennies are still mechanical. I think.
Ski in NC is offline   Reply With Quote
Old 02-25-2016, 12:09 PM   #85
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
Thanks for the feedback everyone. As I think about it, there is an advantage to running the engine at 80% load. Assuming the boat is floating somewhere near DWL then the prop will be almost loaded to its design and be relatively efficient.

I'm intrigued about this Brunton's Autoprop H62 since it will mount to a standard shaft. The Southeast Asian dealer is working up a quotation for me. An extra 10-15% fuel savings could work out well in the long run, especially on a 60 ton boat that barely gets 1 nmpg.

Regarding manyboats' comment, I had discussions with the EPA legal team and since your boat would be a repower then you would not have to abide by latest tier, only us guys dumb enough to be building new boats. Give it another year or so, and Tier 4 will be here - can't imagine how sucky that will be.
makobuilders is offline   Reply With Quote
Old 02-25-2016, 12:19 PM   #86
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,199
Your duty cycle comments are spot on except that some commercial engines are rated at full load 24/7. Typically they are down rated heavy versions of high hp family of engines for pleasure craft.
bayview is offline   Reply With Quote
Old 02-25-2016, 12:37 PM   #87
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,518
"I'm intrigued about this Brunton's Autoprop H62 since it will mount to a standard shaft.


Beware , many of this style prop is made for sail or motor sailors and might not have the required blade area for a pure power vessel..

Check in Skines , what area you need or with your NA. The blades look thin to me.

The 80% load at 90% of rated RPM was given to me by an engineer that kept HUGE! gen sets going for years at desert hospitals.
\
For best efficiency a fuel map or BMEP graph is still required!!!!

DEMAND one before you purchase the engine.

Maybe they will part with one.
FF is offline   Reply With Quote
Old 02-25-2016, 01:20 PM   #88
Guru
 
dhays's Avatar
 
City: Gig Harbor
Country: United States
Vessel Name: Kinship
Vessel Model: North Pacific 43
Join Date: May 2015
Posts: 5,080
Quote:
Originally Posted by makobuilders View Post
I'm intrigued about this Brunton's Autoprop H62 since it will mount to a standard shaft. The Southeast Asian dealer is working up a quotation for me. An extra 10-15% fuel savings could work out well in the long run, especially on a 60 ton boat that barely gets 1 nmpg.
I would be cautious. I have an Autoprop on my 40' sailboat and love it. It allows me to motorsail very efficiently. It changes the effective pitch to account for the variable power being provided by the sail, allowing the engine to change its effective power at a given rpm. (or at least that is how my simple brain envisions it). It has allowed me to get very good motorsailing performance while reducing prop drag when strictly under sail.

A power boat is going to be different. I suppose that wind and sea state would be providing variable resistance much like my sail is providing variable assistance. But you don't need to worry about drag while under sail and the prop won't be as efficient in reverse. Brunton does a good job of sizing their props for different applications, but you want to be sure that the prop isn't providing too much load.

The only discussion more heated than anchors on a sailing forum is the discussion of props. There are some sailors that hate Autoprops and some, like me, that love them.
__________________
Regards,

Dave
SPOT page
dhays is offline   Reply With Quote
Old 02-25-2016, 01:22 PM   #89
Guru
 
City: NC
Country: US
Join Date: Jan 2014
Posts: 636
Quote:
Originally Posted by makobuilders View Post

Regarding manyboats' comment, I had discussions with the EPA legal team and since your boat would be a repower then you would not have to abide by latest tier, only us guys dumb enough to be building new boats. Give it another year or so, and Tier 4 will be here - can't imagine how sucky that will be.
The last I had read, the EPA was NOT going to require Tier 4 in the engines used by most trawlers/small boats. I hope that has not changed. I most likely read this when the engine emissions discussion was ongoing last year.

Later,
Dan
dannc is offline   Reply With Quote
Old 02-25-2016, 02:52 PM   #90
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,709
My little 37hp is Tier2.

Something I've been hesitant to introduce is best working loads for turbo'd engines compared to NA's.
Say you have a Cummins 115hp NA engine and you put in a turbo'd 210hp engine. I think they are basically the same engine. If the best working load for the NA engine is 50 - 70% load what would it be for the 210hp? With a Lehman a minimum load of 50% means a min. of 3gph as the FL burns 6gph at full load.

What will the 210hp engine burn at full load? And not a number derived by using the hour meter and gallons put in the tank but actual fuel flow. Would the 210 burn double or more at full load and rpm? Then the load per the 50-70 rule would be WAY higher heat wise and mechanical forces factor than the 115 engine.

Seems to me the 50-70 rule (that of course isn't a rule) would'nt apply to the 210 engine. I would guess that after all the variables were factored in the turbo engine's rule (if there was one) would probably be much lower than as a percentage of power delivered compared to max than the NA engine.

Or is the turbo engines so capable that they can run at 50-70% of max power just like the NA engines? And perhaps an engine designed as a turbo and was/is not offered as an NA may need yet another catergory of minimums and maximums.

What do you turbo people think of my thinking. Bashing permitted.

Tom I only have 900hrs on my Mitsu.
__________________
Eric

North Western Washington State USA
Nomad Willy is online now   Reply With Quote
Old 02-25-2016, 03:09 PM   #91
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,199
Many:
Both engines would use about the same fuel at the same load even though one was running with lower percent load than the other. To reasonable estimate 4 stroke diesels produce 20 Hp per gallon of fuel per hour. Electronic engines may be a bit better.
bayview is offline   Reply With Quote
Old 02-27-2016, 11:17 PM   #92
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
manyboats - those are some good questions about the good ole "50-70 rule." The old 2 strokes (like 6-71s) have to be run hard because those blowers would cool them off at low loads. All the research I've done indicates that mechanical engines (2 and 4 strokes) are happiest at 70% load, continuous. Not sure about electronic engines though. Fuel metering is so precise that they can be run at 30-40% without fouling, but I would still suspect that they are happy at the high numbers.

Perhaps there are some mechanics on the forum who know more.
makobuilders is offline   Reply With Quote
Old 02-27-2016, 11:27 PM   #93
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,262
Quote:
Originally Posted by makobuilders View Post
[B] ... All the research I've done indicates that mechanical engines (2 and 4 strokes) are happiest at 70% load, continuous. Not sure about electronic engines though. Fuel metering is so precise that they can be run at 30-40% without fouling, but I would still suspect that they are happy at the high numbers.

Perhaps there are some mechanics on the forum who know more.
Are you speaking in relation of fuel consumption or engine revolutions? When speaking in terms of load/work, don't engine makers speak in terms of fuel consumption?
__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 02-28-2016, 01:16 AM   #94
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,690
[QUOTE=manyboats;417383]Mako,
When head seas cause me to change power/throttle I never increase it. Almost always I lower it 300rpm. Never needed "extra" power. However I frequently slow down a bit but not less than a knot.

Exactly! Hull speed is hull speed. anything more is waste of power/fuel. Eric nails common sense.

Al -Ketchikan
Al is offline   Reply With Quote
Old 02-28-2016, 08:49 PM   #95
Guru
 
Insequent's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Insequent
Vessel Model: Ocean Alexander 50 Mk I
Join Date: Mar 2012
Posts: 1,425
Quote:
Originally Posted by makobuilders View Post

..snip....

SPECS - My boat was designed with a displacement of 56.5 cubic meters of seawater at DWL. 56.5 long tons. It's LWL is 47 ft. Tranny is 3.46:1 ratio and prop is calculated at 37"x23" in a 3 blade fixed. We don't need the Kort nozzle in the original design.

...snip....
Mako
Given the design of the boat and expected speeds I don't know why you would not use a nozzle, and indeed I would opt for the Rice Nozzle
Rice Speed Nozzles more efficient than Kort 19a Nozzle

Rice have a website, although the English pages are not that great maybe the Spanish ones are better. The only reason not to go with a nozzle is if you expect to get into low teens speed range as they are less efficient there than an open prop.
__________________
Brian
Insequent is offline   Reply With Quote
Old 03-01-2016, 12:47 PM   #96
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
Insequent
Nozzles work in situations of propellor slip. That is why they have maximum effectiveness at zero speed, working against a tow or trawl net. At free running speed they are only a detriment. My shipyard installs them on every tug they build, clearly told me I would lose 1/2 knot. So even if the Rice provides higher fuel efficiency I don't think that would be a great advantage against the added drag and slower cruise speed. The prop protection would be wonderful of course, but it is easy enough to add ice horns for that purpose.

In any case, do you have any idea how much a typical 44-48 inch Rice nozzle would cost with the special propellor?
makobuilders is offline   Reply With Quote
Old 03-01-2016, 01:06 PM   #97
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,709
It's not "propeller slip" ....
It's water sliding over the ends of the propeller. Same thing that led to the development of winglets in aircraft. The nozzel on a boat propeller does the same thing. It reduces the tip loss from fluid spilling over the end of the propeller. That's why long wingspans on airplanes are more efficient and high aspect ratio propeller blades are too. But perhaps you could call it slip ....

The advantage of the shroud or nozzle that I'd like is the elimination of prop walk.
__________________
Eric

North Western Washington State USA
Nomad Willy is online now   Reply With Quote
Old 03-01-2016, 01:53 PM   #98
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,884
It is propeller slip. Nozzle reduces it, and that is a big advantage pulling hard at low vessel speed. When not towing, little is lost spilling over the tips and nozzle adds a good bit of drag just by skin friction. Not a part of Mako's list of decisions to make.
Ski in NC is offline   Reply With Quote
Old 03-01-2016, 02:02 PM   #99
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
So if you compared large prop/slower rpm versus a smaller prop/higher rpm (provided by different gear ratios on same engine) which would result in more pronounced prop walk?
makobuilders is offline   Reply With Quote
Old 03-01-2016, 02:12 PM   #100
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,709
Small dia large pitch = max prop walk. But pitch has the greater effect.

Think about a prop w so much pitch the blades are 90 degrees to the shaft. Zero thrust but the work being done is to throw the water radially and of course the bottom of the prop swing throws the water to one side depending on rotation. That's why prop rotation dictates which way the prop walk moves the stern.

In the first pic w a low aspect ratio prop there will be much higher tip losses. Much more water will be able to get around the end of the blades lowering the vacuum on the back side and lowering the high pressure on the face of the blade.
The second pic is of prop w high aspect ratio blades. Much more efficient than the first pic. The ends of the blades are small so the spillage over the blade tips is also small. Like a sailplane w long skinny wings. High aspect ratio bladed props have limited usage on faster boats. Not even usable on outboards. Airplanes probably couldn't even fly w the low aspect ratio bladed props we use on boats.
Attached Thumbnails
Click image for larger version

Name:	DSCF1587 copy 3.jpg
Views:	26
Size:	181.1 KB
ID:	49436   Click image for larger version

Name:	DSCF1527 copy 2.jpg
Views:	21
Size:	101.6 KB
ID:	49437  
__________________

__________________
Eric

North Western Washington State USA
Nomad Willy is online now   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 12:09 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