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Fuel guage for 1982 Hunter 33

Feb 21, 2021
6
Hunter 33 Northern Harbour
There is no fuel guage on my 1982 Hunter 33 Cherubini era sailboat. Anyone have suggestions to what type of fuel guage might be best to accommodate my boat?
 
Jan 7, 2011
2,839
Oday 322 East Chicago, IN
I don’t know your boat, but I found one of these on the fuel tank of my 1988 O’Day 322…

IMG_0239_Original 1.jpg

it has a visible gauge (very hard to read on my boat), but I learned it would also drive a standard fuel gauge…
Something like this..

So, you might want to inspect the top of the tank for something similar.

Greg
 
May 24, 2004
6,769
CC 30 South Florida
An "hour meter" Every engine independent of the boat, weather, loads has a "Burn Rate" as the fuel it burns in gallons in one hour at a set RPM. If you know the size of your fuel tank and how many hours you have ran since last fill up you will know how much fuel you have used and how much fuel is left in the tank. This method of measuring fuel in the tank has been used for many decades by professional and amateur mariners because it yields more accurate results and more useful information than the usual tank gauges sold in the market.

First you install an electrical hour meter powered form the On/Off key switch. This will insure that hour meter only runs when the switch is On while the engine runs. Unlikely the switch will be left On with the engine Off because of the racket made by the oil pressure buzzer alarm.

Second, calculate your engine's Burn Rate. The formula BR=gallons x hours. Just those two variables nothing else. The rule of "good enough results" is applied to use averages and approximations so that simple calculations can be made in the head without altering the information that we need as a result. (how much fuel we have left and do I have enough to get me where I want to go) The first approximation we use is Average Burn Rate, this allows for you to operate your boat under power as you customarily do. It is surprising how time after time you will have used a similar amount of fuel without having to account for RPM changes. To establish this Average Burn Rate you fill your tank to full and then run the boat for 6 to 8 hours , not necessarily consecutive. Then you proceed to top the fuel tank again and take notice of the fuel pump reading of the number of gallons taken in or used however you want to call them. Divide the number of gallons by the number of hours in the hour meter and that will give you the ABR. Over the years it has been observed that up to 10HP engines will burn under 1/4 GPH, a 20HP under 1/2 GPH, a 30 HP 3/4 GPH you get the picture and to be on the safe side round up your horsepower to the largest number. This is only a guide to be used in absence of a well calculated ABR.

Third, the size of your fuel tank. It is worth knowing that amount of usable fuel is less than the listed capacity in the boat specs. That is because the engine will start sucking air and quit before all the fuel is utilized. To account for this and to provide an adequate reserve for emergencies we reduce the usable fuel capacity by 20%. You will see how this is prudent when we start calculating range. Let's say the tank is listed at 30 gallons, the usable fuel will be 24 gallons. Just base your calculations on Usable Fuel Capacity of your tank.

Fourth, this component is the heart of the method. Start a log composed of;

DATE write the date every time you top of the tank.

Gallons Used: Write down the number of gallons

Hour Meter Reading: The Hour Meter does not reset so you must write down the reading to be able to calculate the hours at each fuel tank topping even.

Hours since the previous reading: this will the time in hours used for your calculations.

Average Burn Rate; Calculate your ABR and compare to other dates. Each time it will be different but it does not matter as by eliminating the Highs and the Lows you will narrow down your true ABR.

Now to simplify the calculations in our heads we use whole numbers, an ABR of 0.487 will be taken as 1/2 of a gallon/hour. Hours will be rounded to the next 1/2 hour. So lets say you are boarding the boat today and do not remember how much fuel you have left. Take a glance at your hour meter and substract the last reading on the log. lets say it came out to 8 hrs. you know your ABR is close to 1/2 GPH so you can tell you used 4 gallons and have so many left.

I like to test my figures and when I go to top off my fuel tank I will predict the number of gallons I'm going to take. I have never ran out of fuel since I started using the system and usually I'm not more than 1/4 of a gallon off. These are "good enough" results.

Now that you know how much usable fuel you got left, you can calculate how far you can go. Range is influenced by speed and speed is influenced by wind , currents condition of the hull and the usable capacity of your fuel tank. You need a speed measuring device. When on a trip I'm just interested in speed over the bottom so I will use a GPS reading. If I can only go 4 knots and I have 24 gallons left I know I can go 96nm before entering the reserve. As conditions can vary during a trip take a speed reading each hour and adjust your range accordingly from that point on recalculating fuel left and distance according to new speed.

Maintaining the log and practicing the calculations will make it almost 2nd nature to be able to accurately know your fuel status at any time. The hour meter has other uses, to help maintain maintenance schedule and parts replacements.
 
Last edited:
Jan 7, 2011
2,839
Oday 322 East Chicago, IN
An "hour meter" Every engine independent of the boat, weather, loads has a "Burn Rate" as the fuel it burns in gallons in one hour at a set RPM. If you know the size of your fuel tank and how many hours you have ran since last fill up you will know how much fuel you have used and how much fuel is left in the tank. This method of measuring fuel in the tank has been used for many decades by professional and amateur mariners because it yields more accurate results and more useful information than the usual tank gauges sold in the market.

First you install an electrical hour meter powered form the On/Off key switch. This will insure that hour meter only runs when the switch is On while the engine runs. Unlikely the switch will be left On with the engine Off because of the racket made by the oil pressure buzzer alarm.

Second, calculate your engine's Burn Rate. The formula BR=gallons x hour. Just those two variables nothing else. The rule of "good enough results" is applied to use averages and approximations so that simple calculations can be made in the head without altering the information that we need as a result. (how much fuel we have left and do I have enough to get me where I want to go) The first approximation we use is Average Burn Rate, this allows for you to operate your boat under power as you customarily do. It is surprisingly how time after time you will have used a similar amount of fuel without having to account for RPM changes. To establish this Average Burn Rate you fill your tank to full and then run the boat for 6 to 8 hours , not necessarily consecutive. Then you proceed to top the fuel tank again and take notice of the fuel pump reading of the number of gallons taken or used however you want to call them. Divide the number of gallons by the number of hours in the hour meter and that will give you the ABR. Over the years it has been observed that up to 10HP engines will burn under 1/4 GPH, a 20HP under 1/2 GPH, a 30 HP 3/4 GPH you get the picture and to be on the safe side round up your horsepower to the largest number. This is only a guide to be used in absence of a well calculated ABR.

Third, the size of your fuel tank. It is worth knowing that amount of usable fuel is less than the listed capacity in the boat specs. That is because the engine will start sucking air and quit before all the fuel is utilized. To account for this and to provide an adequate reserve for emergencies we reduce the usable fuel capacity by 20%. You will see how this is prudent when we start calculation range.

Fourth, this component is the heart of the method. Start a log composed of;

DATE write the date every time you top of the tank.

Gallons Used: Write down the number of gallons

Hour Meter Reading: The Hour Meter does not reset so you must write down the reading to be able to calculate the hours at each fuel tank topping even.

Hours since the previous reading: this will the time in hours used for your calculations.

Average Burn Rate; Calculate your ABR and compare to other dates. Each time it will be different but it does not matter as by eliminating the Highs and the Lows yopu will narrow down your true ABR.

Now to simplify the calculations in hour heads we use whole numbers, an ABR of 0.487 will be taken as 1/2. Hours will be rounded to the next 1/2 hour. So lets say you are boarding the boat today and do not remember how much fuel you have left. Take a glance at your hour meter and substract the last reading on the log. lets say it came out to 8 hrs. you know your ABR is close to 1/2 so you can tell you used 4 gallons and have so many left.

I like to test my figures and when I go to top off my fuel tank I will predict the number of gallons I'm going to take. I have never ran out of fuel since I started using the system and usually I'm not more than 1/4 of a gallon off. These are "good enough" results.

Now that you know how much usable fuel you got left, you can calculate how far you can go. Range is influenced by speed and speed is influenced by wind , currents and condition of the hull. You need a speed measuring device. When on a trip I'm just interested in speed over the bottom so I will use a GPS reading. If I can only go 4 knots and I have 20 gallons left I know I can go 80nm before entering the reserve. As conditions can vary during a trip take a speed reading each hour and adjust your range accordingly from that point on recalculating fuel left and distance according to new speed.

Maintaining the log and practicing the calculations will make it almost 2nd nature to be able to accurately know your fuel status at any time.
Yep…that works too…

…but a peek at the fuel gauge is way faster :poke:

Greg
 
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Likes: Ward H
Mar 6, 2008
682
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
1627158587828.png
t
This is what I use as sending unit. The display is a standard 240 ohms display. The wiring is simple. You will have to cut a 2" hole on the top of the tank and screw the sender on with gasket. Your fuel tank may not be linear so 1/2 tank display may not correspond to 1/2 tank fuel. But you can take notes how many gallons takes to fill up from its current display.
Available on Amazon $70.00
Haro
 
Feb 21, 2021
6
Hunter 33 Northern Harbour
I don’t know your boat, but I found one of these on the fuel tank of my 1988 O’Day 322…

View attachment 196483

it has a visible gauge (very hard to read on my boat), but I learned it would also drive a standard fuel gauge…
Something like this..

So, you might want to inspect the top of the tank for something similar.

Greg
Thanks Greg
 
May 24, 2004
6,769
CC 30 South Florida
Yep…that works too…

…but a peek at the fuel gauge is way faster :poke:

Greg
In my experience with fuel gauges I did not find that a peek was enough, I would peek and then tap it and if I got a different level I would repeat the tapping and peeking process again and at the end remain uncertain of how much fuel I had. Never knew when they were stuck or suffered a voltage drop. I guess they are OK for day sails close to fuel sources. An inspection port and a stick or a visual window would be best but not as quick, nor more reliable than a quick glance at the hour meter and some mental calculations. I like being able to calculate on the fly how many nautical miles I can travel before having to refuel.
 
  • Like
Likes: john1234
Jan 7, 2011
2,839
Oday 322 East Chicago, IN
In my experience with fuel gauges I did not find that a peek was enough, I would peek and then tap it and if I got a different level I would repeat the tapping and peeking process again and at the end remain uncertain of how much fuel I had. Never knew when they were stuck or suffered a voltage drop. I guess they are OK for day sails close to fuel sources. An inspection port and a stick or a visual window would be best but not as quick, nor more reliable than a quick glance at the hour meter and some mental calculations. I like being able to calculate on the fly how many nautical miles I can travel before having to refuel.
Excellent point…I am primarily a day sailor, running engine 15 minutes in and15 minutes out of my marina. Seldom do I motor any long distances (maybe 5 miles from time time to time).

I kept track of my hours last year. Never had to fuel up until end of season. Seemed like a lot of note taking for me…a gauge will tell me if I am over 1/4 full, when I will add some fuel. I just put 5 gallon Jerry can on board “just in case”, but gauge said 1/2 full yesterday as I was making my 15 minute motor back to the slip.

I can certainly see the value of knowing your burn rate and hours on the tank if you are planning jumps between fuel stops, etc.

Greg
 

RoyS

.
Jun 3, 2012
1,167
Hunter 33 Steamboat Wharf, Hull, MA
My H33 had a mechanical fuel gauge on top of the tank. There is an access panel you open to see it in the quarter birth. However, the Hunter boys installed the tank backwards which put the gauge on the wrong side where it cannot be viewed, except with a mirror. You can install an electric gauge sender in its place and put the gauge somewhere visible. Suggest you buy a flexible sender unit due to the tight clearance above the tank to make installation possible. Watch screw hole placement as it will only fit one way! Watch this tank for leaks! Just replaced mine a couple if years ago.
 
Apr 22, 2011
727
Hunter 27 Pecan Grove, Oriental, NC
My H27 plastic tank had the same type fuel gauge as as RoyS. It was so difficult to see, that I would often take a photo of it and expand the picture to read it. Moeller made the original gauge and they also make a replacement sender for connecting to a fuel gauge. The bolt pattern for the replacement is the same and the install was straight forward.
 

Ward H

.
Nov 7, 2011
3,097
Catalina 30 Mk II Barnegat, NJ
Excellent point…I am primarily a day sailor, running engine 15 minutes in and15 minutes out of my marina. Seldom do I motor any long distances (maybe 5 miles from time time to time)
Same here.
I did calculate my average burn rate over the first two years of ownership but much simpler to look at the fuel gauge for my type of use.
When I see I’m at or just under 1/2 on the gauge I make it a point to fuel up at the next pump out.

I installed the Moeller @heritage linked to. Works well.
 
May 31, 2007
747
Hunter 37 cutter Blind River
When I had a H33, the fuel fill was in the cockpit sole directly over the tank. A length of dowel with notches cut every inch or so sufficed as a gauge. Simple and fool proof although a bit smelly.
 
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