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Old 01-22-2013, 11:08 AM   #21
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Originally Posted by markpierce View Post
Exactly. Why have two tons of ballast unless one likes a snap-back roll? Or is your Willard looking for substantial sails to become a motorsailer? Hey Eric, isn't your Willard basically a motorsailer without sails?
Don't know for sure, but I believe that removing ballast would increase roll rate, not decrease it. Adding weight above the W/L certainly decreases it, as any sailor who has been dismasted will attest, or piano player who uses a metronome.
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Old 01-22-2013, 11:50 AM   #22
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hypersloth,
Let me guess. The sloth is because you have a trawler and the hyper is for the twin engines. Your'e a slow guy but no slug. Well I'm a slug w one engine and a speed of 6 knots.

Re your question I think there is no doubt running single on a twin saves fuel. But I wonder why there's so many asking about it. It seems to me there's lots of guys w twins that should have singles. Perhaps it's just that there are lots of guys interested in safety re the perils of loosing power.
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Old 01-22-2013, 11:54 AM   #23
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Best not to confuse gph with engine efficiency. On gas and diesel engines the term Brake Specific Fuel Consumption or bsfc is the more relevant tool for measurement of engine efficiency. In general that will require running an engine at somewhere in the 65 to 80% range of power draw. Most of us can't do this since our engines are way too big for the vessel. It would appear Eric, Daddyo and Mark are closer to the best bsfc targets than the rest of us.

I'm the grinch on all this BS anyway, bragging rights on ultra low gph sounds good but has little to do with my fun on the water. If you really want to save on fuel costs cruise less or sell your boat! Obviously many do this with lots of boats for sale averaging less than 100 hours per year.
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Old 01-22-2013, 12:09 PM   #24
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"Originally Posted by markpierce
Exactly. Why have two tons of ballast unless one likes a snap-back roll? Or is your Willard looking for substantial sails to become a motorsailer? Hey Eric, isn't your Willard basically a motorsailer without sails?"

This is an old post isn't it? I must have left this unaddressed. Sorry. Rod Swift designed the boat and I think he was in some way into sailboats. Whether or not that has anything to do w the ballast I don't know. But I think the main objective is to make the boat more seaworthy and to give it a slow pleasant feel in most situations. I've talked w Willard people that place great importance on a trawler having lots of mass below the WL and hull to go along w it. This mass and feel makes the essence of "trawler" they feel but very few trawlers share this feature. By previous boat was an Albin 25 Swedish boat that was very light (2 tons) and had a terrible "snap roll". One of the main reasons I left her. The solid feel of a heavy boat can't be matched by anything else. And a low CG is always good.

Fishermen have put rocks in their bilges for centuries to get a seaworthy boat they could live w on the rolling sea.


I see your post above Tom and like all you said very much. But I run my engine faster than ideal for best efficiency. I burn 1gph and aren't motivated to make any sacrifice to burn .975gph.
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Old 01-22-2013, 12:11 PM   #25
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I'm the grinch on all this BS anyway, bragging rights on ultra low gph sounds good but has little to do with my fun on the water.
Amen...
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Old 01-22-2013, 01:13 PM   #26
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...and some retire early and pinch pennies spent on fuel because the average number of hours underway dwarfs the vacation boaters hours ...
plus we have put thousands of miles and hundreds of ports under our keels before something medical or otherwise happens and the dream remains a dream...
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Old 01-22-2013, 01:41 PM   #27
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At my normal cruising speed of 6.3 knots at 1800 RPM, I'm getting 85% of the JD's 80 horsepower consuming about 1.7 gallons an hour.
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Old 01-22-2013, 01:45 PM   #28
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Its nice to see that the OPs WOT rpm are on the money, proving that the propeller sizing and gearing are in spec, He is way ahead of the game compared to most
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Old 01-22-2013, 01:49 PM   #29
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Quote:
Originally Posted by sunchaser View Post
I'm the grinch on all this BS anyway, bragging rights on ultra low gph sounds good but has little to do with my fun on the water. If you really want to save on fuel costs cruise less or sell your boat! Obviously many do this with lots of boats for sale averaging less than 100 hours per year.
What it boils down to is that I'm interested in three things:
1. Maximizing the use and enjoyment of my boat
2. Maintaining safety on my boat
3. Maximizing the efficiency of my boat

Sorry if discussions of efficiency don't mix with your definition of boating, but it's part of our lexicon and deserves a place at the table. The more safely and efficient I can operate the boat, the more time I can enjoy operating it. It's all part of the equation of boating.
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Old 01-22-2013, 02:14 PM   #30
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3. Maximizing the efficiency of my boat
Sorry, Al, but I have to disagree with you on this one. Simply taking your foot off the throttle doesn't = efficiency. I had a gasser that was more efficient at 18 knots than it was at 8 knots. (I measure efficiency in mpg.)
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Old 01-22-2013, 02:26 PM   #31
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The more safely and efficient I can operate the boat, the more time I can enjoy operating it. It's all part of the equation of boating.
Flyright

I agree completely with the above statement, however my point is once again, high or optimum engine efficiency and gph are not necessarily related, one must do the bsfc calculation.

I betcha my Et is better than yours. At 7.8 knots I consume 4.7 gph dragging about 55,000 to 60,000 lbs. Nothng close to Delfin though, he is the TF Et champ - size matters!
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Old 01-22-2013, 02:33 PM   #32
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I'd like to see some efficiency in moorage rates.

I'd have to run about 50 hrs a week to come close to my moorage rates and I'm at the cheapest joint around.

Fly I can see that knowing what your'e doing as in how much fuel you have, all the logistics about where your'e going and where there is fuel and can you afford it and what makes a boat efficient and all the other boat "lore" that makes the boating experience fun and engaging is "part of the equation" re the boating experience as aptly put by you but obsessively dwelling on fuel consumption takes away from the experience in enjoyment as I see it.


I see you again Tom and size does matter. Pile up all the enjoyable hours of boating and compare it to how much you spend on boating. I'll bet my small size would deliver a good score. Yup .. size matters. The smaller the boat the more ya boat. Heard that plenty.
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Old 01-22-2013, 02:50 PM   #33
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Large container ships must have Et numbers that are quite high then.

I may be missing something, but based on the CAT 3306 Performance Data chart for prop demand hp and fuel consumption at 1250 rpm(verified by the fuel consumption gauge), plus our speed , we move 130,000 pounds through the water at 7.2 knots using 50 hp, which I guess gives Delfin an Et of 57.4.

Have I made a mistake?
Moving a large weight slowly is very efficient......

No mistake that I can see. Your FNv at that speed and displacement is 0.6.....If you look at the graph in post #12, go across the bottom to .6 and run up to 57.4 you'll see Delfin lies directly on the dotted 1975 line.....
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Old 01-22-2013, 04:45 PM   #34
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Moving a large weight slowly is very efficient......

No mistake that I can see. Your FNv at that speed and displacement is 0.6.....If you look at the graph in post #12, go across the bottom to .6 and run up to 57.4 you'll see Delfin lies directly on the dotted 1975 line.....
Thanks Tad. I can use these calcs with the Admiral. I am not becoming fatter and slower, I am becoming more efficient....

Sweet.
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Old 01-22-2013, 05:13 PM   #35
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I'm not comparing my efficiency, speed, or Et to other boats, but am interested in operating the one boat I own at the proper balance of speed, efficiency and safety to maximize my enjoyment. Everything is a balance and in my case, the speed difference between efficient cruise 7.4 and my previously normal cruise of 8 kts is not significant.

I also measure efficiency in MPG and am satisfied knowing that 2.78 MPG is achievable at a practical speed in my boat. I'm not anxious over the fuel costs, but I am interested in saving where I can, within reason. Obviously sunchasers's remark about not boating at all would result in max efficiency and safety (no fuel consumed/slip fees and no chance of a boating accident or failure), but throws out the baby with the bathwater.

Eric makes a good point that cutting slip fees makes a bigger impact on the overall cost of boating. That's something I'm also looking at, too, but also for reasons like reducing the enroute time to fishing waters and allow better access to new areas.

Eric, I am not now and never have been "obsessively dwelling on fuel consumption." I merely posted the results of nearly 100 hours of testing various power settings to find what feels like the right balance to me.
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Old 07-11-2013, 04:01 PM   #36
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I have been tracking different power settings on my 34 Californian with twin Perkins 4.236 engines over the past year or so. I have run 30-40 hours between refuelings at the same power setting to provide a good sampling for each setting.

I seem to have found the sweet spot I am comfortable with for now, a good compromise between efficiency, speed and noise. If I slow to 7 or 6.5 kts, I'll likely save more fuel and even eclipse 3 mpg but the speed feels too slow for me to endure for a 30 hour test period.

Here's what I have found on my 2800 RPM (WOT) engines:

2350 RPM (84%), 8.0 kts, 3.70 gph, 2.16 mpg
2100 RPM (75%), 7.6 kts, 2.79 gph, 2.72 mpg
2000 RPM (71%), 7.4 kts, 2.66 gph, 2.78 mpg

I'm sure these numbers would pale in comparison to single engine boats, especially the new technology diesels, but I'm happy with this level of efficiency from a pair of old school 1977 85 hp Perkins naturals.

I have not takent he time to write my numbers down, but I have been keeping track in my head. It turns ou that I am getting very similar numbers to yours. I run at 1800 rpm forn long hauls (over a couple of hours) and for jaunts less then an hour or two I run at 2000 rpm. If i figured out the difference in cost/time savings I am sure it would be negligable. So mostly I just try to enjoy the journey. (i run the engines slower when on long runs so the noise isnt so loud... noise is the biggest factor for me)

My next project is to redo the insulation for better noise management...
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Old 07-11-2013, 04:04 PM   #37
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We can't really figure ours out bc we also have diesel heat and a generator. Over the past almost three years we average six gallons per hour but that does not account for the heater and generator. I can't remember if matt said we've spent four thousand or six thousand on diesel since we bought the boat. He has it all on a spreadsheet.
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Old 07-11-2013, 04:28 PM   #38
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At my normal cruising speed of 6.3 knots at 1800 RPM, I'm getting 85% of the JD's 80 horsepower consuming about 1.7 gallons an hour.
I thought that boat had a propeller at the end of the shaft ...

Unless you have changed it to wheels or some kind of cable drive it should be putting out about 30 hp.
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Old 07-11-2013, 08:12 PM   #39
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PG,

How'ed you arrive at 6gph? Sounds about right though.

Mark I think you stepped in it.
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Old 07-11-2013, 09:19 PM   #40
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Mark I think you stepped in it.
That's OK with me. (I looked at the wrong power curve.) I enjoy giving RickB a "lift."
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