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Old 05-21-2012, 12:38 AM   #1
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First long passage

We just completed our fist long trip, Dana Pont to Santa Barbara. Did it in two legs. Friday afternoon Dana Point to San Pedro and Saturday San Pedro to Santa Barbara, 121 miles total. A little rough on the first leg heading into about 15 to 20 and a 4 foot 9 second swell. We made a decision to burn diesel rather than daylight on both legs and pushed a little harder than usual. First leg averaged 7.62 knts and 1.18 miles/gal, second leg 8.08 knts and 1.2 miles/gal. Burned more fuel than expected. But i guess that is what you get when you are over hull speed. Everything went well, on the first leg got a little water on the forward bunk from all the water on deck and a hatch that could use some sealing. Santa Barbara is the new home for Fleur De Lys for the next 2 years. Looking forwrad to exploring the islands and doing some surfing and diving.
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Old 05-21-2012, 12:57 AM   #2
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Channel islands are really special

I'm thinking of cruising down from the Delta later this fall. It's been 10 years or so since the last trip out to the islands. Santa Cruz Island is a really special place to visit. It took me two trips to find Painted Cave. When I did it was hard to believe. You should really enjoy yourself.
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Old 05-21-2012, 06:11 AM   #3
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Burned more fuel than expected. But i guess that is what you get when you are over hull speed.

Indeed slow down a K or so and save half of the fuel burn.

SQ rt of LWL x 1.1 is about as fast as you can go cheaply. SL times .9 is even cheaper.

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Old 05-21-2012, 09:41 AM   #4
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The Admiral wanted to "make sure" we made it into our slip before dark. We normally cruse about a knt slower. 2 if we want to save fuel.
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Old 05-22-2012, 01:36 AM   #5
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make sure to eat at up stairs at Brophy Bros in the Harbor in SB, we had our boat there for eight years.. it is still my favorite place in California
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Old 05-22-2012, 09:26 AM   #6
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I would kill for that kind of fuel economy. My 210 Cummins (twin) burns 3.5 GPH at 8 knts. I have a 25X27 props on 2.66:1 transmissions. I plan on doing WOT sea trials with a good Lazar tach at various RPMs and then get a prop company to evaluate the data. I should be able to get better fuel economy at cruising speed. Not really interested in increasing top end speed, just want to save some $$$$$.
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Old 05-22-2012, 11:20 AM   #7
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Hi Dave,

I have the same motor cummins B5.9T at 210hp. However, since my boat is a single with a full displacement hull plus having a fairly narrow beam and fairly lightweight(20000 lbs). I cruise at 7.5 knots Rpm of 1500 and use 1.5 gal/hr.

Mathematically, I am using somewhere around 35 hp to move the boat at that speed, so the motor is considerably overpowered for normal duty in my case.

I turn a 3 blade 24 x 18 prop, the gear is a Hurth 2:1


Not to restart the argument about whether to run on one engine at a time while cruising issue, but some argue that is one way to help the fuel economy with twins.

I bet if you slow down to 7 knots you will improve your economy noticably
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Old 05-22-2012, 11:23 AM   #8
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Welcome to the neighborhood!!
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Old 05-22-2012, 03:26 PM   #9
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I am new to the forum. I am a sailor who is considering a transition to a trawler. My last boat was an Isander Freeport 41 motor sailor. I had a Ford Lehman 80 hp and burned .75 gph at hull speed (7 k) at 1800 rpm. I am looking into a CHB 39 with twin 150's. I don't know the make or model. I expect this will eat my fuel budget and not really gain me much speed at 39 feet, same as my IF 41. I would like to find a 36 footer with a single ford 120. Is the advantage of a second engine (in the event of breakdown) worth the coast of maintenance of a second engine? How many of you guys know of regular engine failure involving a tow or serious endangerment? Plus, at what size/displacement do I really need to consider a second engine to push the boat at hull speed against wind and tide? Is there a formula i.e 37 feet at 34,000 lbs = 160 hp???
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Old 05-22-2012, 06:18 PM   #10
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Welcome to the forum Bill. My first two boats in the late 80's were twins. After I got away from gas I have had single engine boats ever since. The single v twin debate goes on and on and if you had no problems handling your motorsailor with single then I'd say stick with it. To me its not worth the extra maintence and fuel for the twins. Larryw
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Old 05-22-2012, 06:31 PM   #11
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... Plus, at what size/displacement do I really need to consider a second engine to push the boat at hull speed against wind and tide? Is there a formula i.e 37 feet at 34,000 lbs = 160 hp???
There's virtually no limit to the size of a vessel that can be moved at full-displacement speed by a single engine, if so designed. Eighty horsepower should be sufficient (and 120 h.p. way, way more than needed) for the size of the boat described and move it at hull speed of about 7.5 knots, but it wouldn't fully counter a tidal current if that required going over hull speed.

The 80 h.p. diesel engine in my 28,000-pound boat is more than adequate to move it at hull-speed.
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Old 05-22-2012, 06:49 PM   #12
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I have twin volvo 150 HP turbo diesels. I figure that i can use about 1/2 the hp they can produce. Using the prop calculator on Boatdiesel.com i believe that i would use about 60-80 of my 300 available HP at hull speed. On my first leg going 9 knts i was probably usign 75 to 100 HP out of each. My normal cruse at 2500 rpm gets me just into the boost range of m turbos where they run cleanand i do about 8 knts. I did have some crazy guy in a sail boat turn right in to me saying "i am out of gas, i am going to the fuel dock (with his outboard at full throttle)!!!!" and my 300 HP got me out of his way. As far as single VS twin, the admiral does feel better having a second engine rather than a nice paddle. A single would need a bow thruster in these california harbors if you wanted to go in and out in the afternoon when the wind is blowing (or if you had bigger ones that me).
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Old 05-22-2012, 11:04 PM   #13
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I would kill for that kind of fuel economy. My 210 Cummins (twin) burns 3.5 GPH at 8 knts.
Dave
Dave, he's getting about 1.2 MPG and you're getting about 2.3 MPG.

I'd say you're doing just fine for efficiency.
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Old 05-23-2012, 05:45 AM   #14
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Is there a formula i.e 37 feet at 34,000 lbs = 160 hp???

There is a "Rule of Thumb" that works fairly well.

The displacement in tons (2240lbs) times 3 is about all the HP a displacement boat should need.

That might give a 7.5 K speed , smooth water no wind.
So your boat would be about 15-16 tons and require 45 HP .

On a well setup boat you will see 15-18HP for each gal of diesel.

3GPH

The sq rt of 37 is about 6 and somewhere between 6 x.9 and 6 x 1.15 will be your LRC , long range cruise speed , which should go to 2 GPH or less.

No displacement boat needs tons times 5 in HP.


Single or twin , That's RELIGION . reality need not apply.

See the anchor threads,,,more religion

My opinion a twin is 5% better at docking in hard conditions ,
If you usually dock someplace like the East River with 4K current great.

Otherwise its an industrial single for me.

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Old 05-23-2012, 08:12 AM   #15
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Thanks for pointing out my error Flywright. I read MPG and my brain saw GPH.
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Old 05-24-2012, 12:27 AM   #16
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I noticed a for sale for a mainship with a trubo perkins 160 that burned 5GPH with a note "good fuel effecience". Am I understanding this correctly that in one hour the boat will burn 5 gallons of fuel???
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Old 05-24-2012, 12:39 AM   #17
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I noticed a for sale for a mainship with a trubo perkins 160 that burned 5GPH with a note "good fuel effecience". Am I understanding this correctly that in one hour the boat will burn 5 gallons of fuel???
-------------------------------------------
If it were twins and running 2500+ rpm's in a 40 foot boat, that would be about right at 10k. Each engine should burn about 2.5 to 3.0 gph in my 6.354 experience. For a single 160 hp. If it is measured at WOT 2800 rpm maybe so?? But that's blowing diesel out the exhaust though.

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Old 05-24-2012, 01:04 AM   #18
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Am I understanding this correctly that in one hour the boat will burn 5 gallons of fuel???
Yep, about the same as I burn when I'm driving my pickup down the interstate. The difference is I travel about 75 miles in my truck and only about eight or nine miles in the boat. But I have WAY more fun in the boat during that one hour. Now, if you can convince your better half that my logic makes sense, then you'll be a happy boat owner...
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Old 05-24-2012, 05:46 AM   #19
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5GPH is only 70 - 80HP delivered to the water about what it takes to ctuise below hull speed on a 40 ft LWL boat.

Go slow , and you can cut the fuel burn rate in half.

But even below SL .9 it still takes fuel for skin friction , just not wave making.

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Old 06-01-2012, 10:23 AM   #20
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Nice Boat. I have a 40ft.
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