Reply
 
Thread Tools Display Modes
 
Old 02-07-2014, 03:16 PM   #181
Guru
 
Tad Roberts's Avatar
 
City: Flattop Islands
Country: Canada
Vessel Name: Blackfish
Vessel Model: custom
Join Date: Dec 2012
Posts: 707
Quote:
Originally Posted by dannc View Post
Looks like the boat got 8.6 NM per US gallon of fuel.
This seems highly unlikely.

The numbers quoted, 1044 hours under way consuming 3000 L of fuel is only .76 usg per hour. That's about 15HP, which should push a 60,000 pound boat at about 5.5 knots in flat calm (Not open ocean) conditions with no wind, 6.5 knots will take twice the fuel, for about 30 HP.

I know a DD 47 (design displacement 70,000 pounds) uses 2.9 gph at 6.6 knots, that's about 52 HP. Why is the 44 burning so much less?
__________________
Advertisement

Tad Roberts is offline   Reply With Quote
Old 02-07-2014, 03:30 PM   #182
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,372
Quote:
Originally Posted by Tad Roberts View Post
This seems highly unlikely.
Why is the 44 burning so much less?
Yes, I noted this thought on a different thread, missed fuel bill I'd guess
__________________

sunchaser is offline   Reply With Quote
Old 02-07-2014, 06:11 PM   #183
Guru
 
Insequent's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Insequent
Vessel Model: Ocean Alexander 50 Mk I
Join Date: Mar 2012
Posts: 1,426
Quote:
Originally Posted by sunchaser View Post
Yes, I noted this thought on a different thread, missed fuel bill I'd guess
On that theme, started with full tanks, but on arrival at destination did not refill, leaving it for owners pleasure. Delivery crew just added up fuel they purchased en route?
__________________
Brian
Insequent is online now   Reply With Quote
Old 02-07-2014, 07:51 PM   #184
THD
Guru
 
City: Seattle
Country: US
Join Date: Apr 2012
Posts: 1,142
I may have posted this earlier in this thread, if so, apologies. If anyone wants a seriously ready ocean crossing Diesel Duck, do a Google search on "Doramac". A 46' immaculate, incredibly equipped owned by Randall Johnson. For sale in London. I happened to see this boat about 5 years ago and since then I think they completed most of a circumnav. From their listing, you may not even need to fuel up for the trip back across the Atlantic!
THD is offline   Reply With Quote
Old 02-12-2014, 05:58 PM   #185
Veteran Member
 
Ghostrider42's Avatar
 
City: Vesty
Country: Iceland
Vessel Name: GhostriderIII
Vessel Model: 28m ocean tug
Join Date: Feb 2014
Posts: 81
Quote:
Originally Posted by Insequent View Post
On that theme, started with full tanks, but on arrival at destination did not refill, leaving it for owners pleasure. Delivery crew just added up fuel they purchased en route?
We used exactly what we stated - we refueled twice (Madeira & Cape Verde) before heading across to UY.
__________________
Capt Freddie
M/V Ghostrider III
28m ocean tug, DD671NA, keel cooled, dry stack
Ghostrider42 is offline   Reply With Quote
Old 02-12-2014, 11:00 PM   #186
Guru
 
Insequent's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Insequent
Vessel Model: Ocean Alexander 50 Mk I
Join Date: Mar 2012
Posts: 1,426
Quote:
Originally Posted by Ghostrider42 View Post
We used exactly what we stated - we refueled twice (Madeira & Cape Verde) before heading across to UY.
Ok, pretty amazing! Thanks for confirmation.
__________________
Brian
Insequent is online now   Reply With Quote
Old 02-13-2014, 11:08 AM   #187
Guru
 
City: NC
Country: US
Join Date: Jan 2014
Posts: 636
Quote:
Originally Posted by Ghostrider42 View Post
We used exactly what we stated - we refueled twice (Madeira & Cape Verde) before heading across to UY.
Ghostrider42,

What engine is in the boat?

What RPM was used during the trip?

One of the reasons I like the Diesel Duck design is low fuel usage. I do not want to be running across the water at high speed, so moving along slowly is just fine. I am looking at the Diesel Duck design details and looking at various engine specifications trying to figure out which RPM would give about 1 GPH. This is simple to do.

My concern is that low RPM to get 1 GPH might not be good for the engine. I have a JD tractor and most of the work I do with the tractor does not require PTO speed which is about 2600 RPM. The engine tops out at 3000 RPM. For a few years I would run the engine at about 1600 RPM but used oil analysis showed fuel in the oil. I bumped up the RPMs to 1800ish and no more fuel in the oil. The amount of fuel in the oil was within specifications but I don't want fuel in the oil at all. And I sure would not want fuel in the oil in a boat engine.

I also would prefer to have a normally aspirated engine but looking at JD engines it seems I would have to have a turbo to get the HP specified by the boat design. There are normally aspirated engines around 80-85 HP which seems adequate.

The other issue I have is does the boat rally need all of this HP? The Diesel Duck 48 will use about 14 HP to go 7.4 knots and 40 HP to go 8.8. Well, 7 knots is fast enough for me, so does the boat really need 100+ HP?
To go 15% faster, takes almost 3 times the HP and corresponding fuel usage.

The engine needs to supply some power and maybe hydraulics but I do not see why the boat needs a 110 HP engine. The higher the HP the worse the fuel burn and I wonder about running the lower RPMs to use less HP to minimize GPH.

Later,
Dan
dannc is offline   Reply With Quote
Old 02-13-2014, 12:10 PM   #188
Guru
 
healhustler's Avatar
 
City: Longboat Key, FL
Country: USA
Vessel Name: Bucky
Vessel Model: Krogen Manatee 36 North Sea
Join Date: Oct 2009
Posts: 4,181
Quote:
Originally Posted by dannc View Post
The higher the HP the worse the fuel burn and I wonder about running the lower RPMs to use less HP to minimize GPH.

Later,
Dan

Dan: There may be a few moments where the extra HP and torque could be useful...currents, winds, inlets, rivers, tides, etc.. I think you're right about the 85 or so rating, but don't do yourself completely out of spare HP.

My boat originally came with a 90 Volvo but was refit with a 140 Yanmar. I too, feel this is unnecessary HP, but both engines are 3600 RPM, and I'm still turning the same 22 X 13 prop as the Volvo. Thus far, I haven't been able to determine more fuel usage by the Yanmar over the Volvo, maintaining the same speeds over the same waterways. I'd expect that if I kept it nailed that that increased fuel usage would appear, but the figures for 7.5 knots or under are too close to call and nearly identical to the original chart published for Manatee buyers. At least two other Manatee owners whom have tested my boat have noted that a useful increase in "kick" can be felt that helps with handling. When testing their boats, I can't feel it the way they do but for sure the Yanmar revs quicker.

Could it be that Diesel Duck also experienced this with the current power offering and that the additional power could be an asset at times? Maybe at the typical operating range, any increased fuel consumption of their chosen power-plant really hasn't been a significant issue, and the somewhat lower load on the engine hasn't been an issue either.
__________________
Larry

"I'd rather be happy than dignified".
healhustler is offline   Reply With Quote
Old 02-13-2014, 01:42 PM   #189
Guru
 
City: NC
Country: US
Join Date: Jan 2014
Posts: 636
Quote:
Originally Posted by healhustler View Post
Dan: There may be a few moments where the extra HP and torque could be useful...currents, winds, inlets, rivers, tides, etc.. I think you're right about the 85 or so rating, but don't do yourself completely out of spare HP.

...
My dad had a 33 foot sail boat that was 15,000 pounds and had a 50 HP engine. That seems like a lot of HP for the boat. We had quite a few interesting moments dealing with current in tight spaces in South FLA and the Keys but I can't remember if I ever had to use all of the throttle. If I did have to use full throttle it was not for but a few seconds.

One certainly needs the power but the danged difficult question is how much is enough? It seems like if the HP needed for max speed is 40 HP in perfect conditions having an 80-100 HP would be enough and better for the engine if running at 1 GPH.

I have read that one should use the engine at 50-75% which fits perfectly with my experience with truck and tractor engines. Looking at the performance curves on the JD engines, the 80-85 HP non turbo engines would be running at around 60% where as the 107-135 HP engines would be in the low 50% at one GPH.

Now, one could hang a big alternator on the engine for power generation but since the boats I am drooling over, errr, researching, have a generator it seems that it would be to minimize power generation on the engine and use the genset AND solar and/or wind power.

Fun to think about this stuff with 6-8 inches of snow on the ground while dreaming of a trip to the South Pacific.

Later,
Dan
dannc is offline   Reply With Quote
Old 02-13-2014, 01:58 PM   #190
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,154
Quote:
Originally Posted by dannc View Post
Fun to think about this stuff with 6-8 inches of snow on the ground while dreaming of a trip to the South Pacific.
I disagree... It's kinda depressing.
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 02-13-2014, 02:07 PM   #191
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: 10,265
Quote:
Originally Posted by dannc View Post
One certainly needs the power but the danged difficult question is how much is enough? It seems like if the HP needed for max speed is 40 HP in perfect conditions having an 80-100 HP would be enough and better for the engine if running at 1 GPH.
Dan, I believe expecting less than 1.5 GPH is unrealistic.

See post #1 at
Throttle settings
__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 02-13-2014, 03:45 PM   #192
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,722
With a FD hull the proper or correct amount of power is clear cut. Enough to comfortably cruise at 1/2 a knot to 1 knot below hull speed. And another 5 to 10% for unusual circumstances. There really is no need to reach hull speed.

We have the "gotta have lots of extra power" from our automotive culture. Most of us grew up in the 300hp V8 era and we love lots of power.

My FD trawler has 5hp per ton of displacement and I've never run it over 500rpm down from it's rated speed of 3000rpm for more than a minute or two. So I've never used more than 30hp.

BUT w a SD hull much more power and a little bit more speed is a desirable scenario. That's why we have so many over powered SD boats. If more speed (over HS) is what the owner wants to do then he should not have a FD boat. A GB 36 (SD) could run regularly at 15 knots ... Or 8 knots. One could ligitamately have 100hp or 500hp. All depending on what the owner wants to do. So unlike the FD hull the SD has no clear proper amount of power.

After saying that when a SD hull is on the drawing board the NA design's it for a speed range that's suitable for her hull form. A DeFever 49, w sufficient power could be designed to run at hull speed or slightly above. To go much faster one would want a faster hull. To go 2 to 2.5 times HS a hull that is closer to a planing hull would make more sense.

You can run a SD hull like a FD hull but to best pull this off you'd need to re-power and select much smaller engines.

So you could apply the "enough to cruise + 10%" philosophy to basically any boat and never go wanting for more power. One really doesn't NEED more than that. The above applies to FD and SD hulls only.
__________________
Eric

North Western Washington State USA
Nomad Willy is online now   Reply With Quote
Old 02-13-2014, 07:25 PM   #193
Guru
 
City: NC
Country: US
Join Date: Jan 2014
Posts: 636
Quote:
Originally Posted by markpierce View Post
Dan, I believe expecting less than 1.5 GPH is unrealistic.

See post #1 at
Throttle settings
I think you may be right, or maybe I am afraid you are right, but I have seen 1 ish GPH mentioned here and there so I figure it is a best case number but most likely Unitanium.

The fourth edition of Voyaging Under power has some real world fuel usages in Appendix C and a FEW boats/trips got close to 1 GPH. Most of the entries were getting 1-2 NMPG but the Diesel Ducks were were getting around 4 to almost 5 NMPG. Dora Mac which is for sale got 4.93 which is 1.2 GPH. She has one of the JD engines, 135 HP, which I have been researching. The Idelwild has a passage getting 4.6 NMPG and on their website they mention burning 1.3 GPH. The Idelwild is 30k pounds and has a 55 HP engine so she is in the 4 HP per ton recommendation.

I did see your thread and found it very interesting.

While 1 GPH might be ideal or Unitanium I am still concerned with running the engine to get the best GPH AND maximizing the engine's lifetime/reliability. Course, the engine is just turning that thar prop dohickey, which is another topic.

BTW, am I spending too much time reading about Diesel Ducks when I start recognizing boats? I LOVE the yellow roof on a certain DD. Our sea kayaks are yellow on the top.

Later,
Dan
dannc is offline   Reply With Quote
Old 02-13-2014, 07:29 PM   #194
Guru
 
City: NC
Country: US
Join Date: Jan 2014
Posts: 636
Quote:
Originally Posted by Tom.B View Post
I disagree... It's kinda depressing.
Hey, it could have been worse, we could have had that ice that was first forecast and we thus lost power! Then no boat talking! I think we got lucky with this storm. <whew> It was bad enough as is.

Later,
Dan
dannc is offline   Reply With Quote
Old 02-13-2014, 08:31 PM   #195
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: 10,265
Quote:
Originally Posted by dannc View Post
... I LOVE the yellow roof on a certain DD. Our sea kayaks are yellow on the top.

Later,
Dan
Sorry, a yellow pilothouse roof is a protected trademark. License fee is $500. Send me a PM to arrange payment.
__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 02-13-2014, 08:43 PM   #196
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 13,176
Quote:
Originally Posted by manyboats View Post

So you could apply the "enough to cruise + 10%" philosophy to basically any boat and never go wanting for more power. One really doesn't NEED more than that. The above applies to FD and SD hulls only.
Need? Much of boating isn't about need. It's about what one likes and enjoys. For us, that's significantly more than "need" but we "need" it for our full pleasure.
BandB is offline   Reply With Quote
Old 02-13-2014, 08:46 PM   #197
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: 10,265
Quote:
Originally Posted by BandB View Post
Need? Much of boating isn't about need. It's about what one likes and enjoys. For us, that's significantly more than "need" but we "need" it for our full pleasure.
There are needs, and then there are wants.
__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 02-13-2014, 11:56 PM   #198
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Country: USA & Thailand
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 890
Quote:
Originally Posted by dannc View Post

One of the reasons I like the Diesel Duck design is low fuel usage. I do not want to be running across the water at high speed, so moving along slowly is just fine. I am looking at the Diesel Duck design details and looking at various engine specifications trying to figure out which RPM would give about 1 GPH. This is simple to do.

My concern is that low RPM to get 1 GPH might not be good for the engine. I have a JD tractor and most of the work I do with the tractor does not require PTO speed which is about 2600 RPM. The engine tops out at 3000 RPM. For a few years I would run the engine at about 1600 RPM but used oil analysis showed fuel in the oil. I bumped up the RPMs to 1800ish and no more fuel in the oil. The amount of fuel in the oil was within specifications but I don't want fuel in the oil at all. And I sure would not want fuel in the oil in a boat engine.
Dan
Wouldn't the newer electronic controlled, hi-pressure, common-rail diesels eliminate this 'excessive fuel' problem at the lower RPM's ??

brian eiland is offline   Reply With Quote
Old 02-14-2014, 05:35 AM   #199
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,531
>My concern is that low RPM to get 1 GPH might not be good for the engine.

The amount of fuel in the oil was within specifications but I don't want fuel in the oil at all. And I sure would not want fuel in the oil in a boat engine. <

Fuel in the oil is usually from the rings not sealing due to too light loading.

The simplest (not cheapest) way to solve the problem is with a CPP and EGT gauge.

The engine can be run a bit harder at low speeds , so the higher combustion pressure can enable proper pressure behind the rings , sealing them .

This stops the slobbering and blowby of light loading, and will extend engine life.

Inshore a cruising prop works fine , but for offshore where the boats displacement will vary as a ton of fuel is consumed , or climbing 8-20 ft waves will require different power levels.

The CPP solves the problem. Controllable Pitch Propeller, not as expensive as you might imagine.
FF is offline   Reply With Quote
Old 02-14-2014, 10:47 AM   #200
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 13,176
Quote:
Originally Posted by markpierce View Post
Sorry, a yellow pilothouse roof is a protected trademark. License fee is $500. Send me a PM to arrange payment.
Actually a yellow roof is not just a very colorful accent. It is very much a potential benefit in both theft and problems at sea, making the boat far easier to see and identify. We always had our trailer roofs (as in tractor trailers) painted brightly with our logo. We (company I worked for) had two full trailers stolen in about the three year period. Our pilots took one of our company planes and found them each time in less than two hours. In one case they'd driven it about two miles on a dirt drive through the woods to an huge barn deep and out of sight. They were unloading it as police cars descended on them and our pilots watched from overhead. Solved about a dozen other thefts at the same time. Even while unloading, they were already painting the sides of the trailer too. Just weren't aware of the top.
__________________

BandB 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 03:20 AM.


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