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Discussion Starter #1
Just purchased a Watkins 29. Spent our first weekend aboard this past weekend and have absolutely fallen in love with her even with all of the work and maintenance I have ahead of me. Question is this. We have no fuel gauge. I'm trying to get an idea of how many gallons per hour she will burn. It has the Yanmar 2gm diesel with a 20 gallon tank. I will probably be investing in a jerry can in the near future for peace of mind.
 

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I would say .25 to .75 GPH depending on how you push it. Fill the tank and run it for an hour, then use a one gallon can to top it off. You will come close. Also a good way to find your sweet spot.
 

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Around .5 to .75 per hour sounds about right. You can use a dip stick as well. Top off the tank, go one hour then check with your dip stick, then go another hour and check again.
 

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Thanks for the valuable info. For our first cruise I keep her a little over half throttle. Boat speed about 4.7 knots.
 

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Discussion Starter #7
cant mark a stick, done thought about that. Fill hole has a curved pipe running to the tank. Is it odd not to have a fuel gauge? Never even thought to look for one when I was inspecting the boat. Didn't even cross my mind till I got ready to take her out.
 

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Yes odd, not to much to worry about. You would be surprised how far you'll go on a tank of fuel. How about a flexible dip stick? To much of a curve?

Installing a fuel gauge will give you a peace of mind on long trips,
 

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Discussion Starter #9
Pipe has a pretty good bend to it. Almost a s shape I can view it threw the engine compartment. I thought it was odd, but from what I've learned about these boats every one of the Watkins in this year range was custom built to the owners specs. Mine was obviously built for a live aboard. Microwave shelf, fold down tv stand and get this. A safe that is fiber glassed in under one of the quarter berths. I guess the original owner ordered his boat without one.
 

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You can do a dipstick with a bend in the filler. Almost every car has a bent dipstick tube.

You could also add a fuel gauge. I find having one important when filling the tank. My vent is lower than my fuel fill, and if I let the pump handle turn off automatically it will dump fuel into the water. It looks like the whole kit for doing so is only $50.
 

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hey nccouple , glad to hear of your new boat ! I have a 2QM 15 Yanmar I would say the consumption estimates that have been posted are accurate . If you don't want to do the gauge do the dip stick but don't go through the filler cap . Drill a hole in the tank and dip the stick in the hole , My stick is a piece of Oak . One other thing you will want to look into is getting the tank cleaned out .They call that a fuel polish . I don't get that name . They will cut some inspection ports in the tank and clean out all the muck . That would be a good time to do the dip hole .
 

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I towed a Erickson 29 in to the Marina (absolutely no wind) this past summer because he ran out of fuel. His dipstick said nothing. A fuel gauge probably would have been handy before he started the day.
In the long run it will save you some grief. I'm sure you can handle this yourself with minimal expense.
 

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I installed a fuel gauge the first year I had my boat. Never look at it.

Just keep track of how long the engine runs and at what RPM.

I have a Yanmar 2GM20. At 2000 RPM it sips 1 liter per hour. Makes keeping track pretty straight forward.

Here's a chart that might help: Yanmar Engine Fuel Consumption in U.S. Gallons per Hour
 
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Find out, all engines are not the same... I can tell you how if you like?

first, find a speed you like say 5 knots, and a comfortable rpm where the engine is not at max rpm" a good balance point speed vrs not over stressing the engine."

Now fill the boat all the way up with fuel to the top of the filler neck but not spilling any in the water.

While at dock and a filled to the top boat tie her stern to the dock " while in your slip, put her in forward and set her engine speed to your comfort rpm and pull for an hour.

At an hour shut it all down and measure the amount of fuel to fill it up to the top again..

TA-DA you now have a full load fuel consumption # now it will be a bit high of a reading because you were " under load " IE " the dock did not allow you to ever not be under a load.

This would be similar to a load in a storm under bad conditions but is a great tool to calculate fuel consumption on a trip or so.

I hope this helps you all.. And yes i work on Diesel's for a living.
 

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With a 20 gallon tank you will probably get through most of the season...:laugher

I have twenty minute minimum "commute" until I can raise the sails and only used about 3/4 of a tank all season. I have a US27 with a Volvo diesel.
 

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Nccouple;
Wecome to SN and the wonderful world of Watkins. :D
Your fuel gauge (probably) sits atop the tank, just out of sight when you open thestbd ccockpit locker. I use an inspection mirror. BI'd be more concerned with fuel going old than running out ;) At near to 200 mi/tank; you'll be long tired and ready to pull up to the fuel dock well before you run dry !;)
Lotsa info at the mail group and homepage. Can't paste link from here; but ya can find it in one of my posts down in the Watkins area.
 

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I installed a fuel gauge the first year I had my boat. Never look at it.

Just keep track of how long the engine runs and at what RPM.

I have a Yanmar 2GM20. At 2000 RPM it sips 1 liter per hour. Makes keeping track pretty straight forward.

Here's a chart that might help: Yanmar Engine Fuel Consumption in U.S. Gallons per Hour
That chart is right on for my 3GM30 so it's probably just as accurate for the 2GM. The best fuel efficiency (assuming your prop is the right size and pitch) will be where your hull speed meets RPM. If you look at the torque curves of the Yanmars, most of the popular ones start to peak out at 2500RPM or so. Getting the boat to reach hull speed at the beginning of peak torque, at 2600-3000 is optimum. Pushing it above the hull speed is a waste of fuel because you'll get increasingly less speed for a lot more fuel. I run my engine at around 2600 RPM for best efficiency and burn about .9 gal/hr.

My tank has a sending unit that I've never hooked up to a gauge in favor of a simple dipstick made from a spare piece of fg batten. Good advice above about cleaning the tank. If your tank has a screen over the end of the fuel uptake pipe, remove it or poke bigger holes in the screen. Diesel WILL get stuff in it that will clog those screens. Better off to catch it in the first fuel filter. I have siphoned out the tank occasionally to remove any growth and always use additives to minimize fungal growth, especially when the boat is stored. The use of a Bahama filter is also very effective when possible. It's amazing how much debris comes out of marine fuel pumps!
 

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over the 23 years I have owned my 28' S2, I have changed the fuel guage 3 times and it has rarely worked for more than a month. So, I carry 3 5 gal cans of diesel but only fill one for normal day sailing but fill all three for cruising. I have no idea of how much fuel I use but I estimate .75 gallon/hour. It is even hard to tell when I fill it because it will act full but take a few more gallons a few minutes later. I try to keep it more than half full and pour more in every 2-3 hours even while underway. I have never run out of fuel.
 
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