Gasoline Storage, Usage, and Consumption

General Thoughts on using Engine Power.

Sailing in Chile requires the use of the engine. Although the Pacific can be windy, quite often the wind is quite weak, and there are often days with no usable wind at all (maybe 30 % of the time), and nothing is more frustrating than making 2 to 3 knots in light wind! On engine (in my case, a 5 HP outboard Tohatsu), one can make about 5.5 knots on flat water.

If you navigate southern channels and fjords, the tidal currents and the frequent lack of wind make the use of an engine obligatory.

So, if you are not a real masochist, be prepared to motor a lot, and to have enough gas for it!

My personal attitude is that I am not in a regatta and I do not have to prove anything to anyone, so what is valid is for me is to get from point A to point B, usually as fast as possible. This dictates my strategy for the use of the motor:

  • When the wind is weak, under 6 - 8 knots, the use of motor is required and obvious, and setting sails does not usually contribute much to the speed (at best 0.3 knots). When running on engine and sails, if you go with the wind, the apparent wind will be a couple of knots only, and hardly will contribute anything, and if you sail sharper than half-wind, the apparent wind will be too sharp to fill well the sails...
  • When the wind is about 8 - 12 knots, I use both the sails and the motor. However, if I have to go against the wind, using just the motor is a perfect option, and speeds close to 5 knots are usually possible. With beam reach or fuller, the combination of motor and sails are perfect, and I can make 6 knots. Without engine, maybe 4 knots.
  • When the wind is in the midrange of 12 to 20 knots, the sails provide nice speed. With 20 knots from behind and the standard jib, I can make 6 knots... But putting the engine at half power in addition to the jib will improve that to 7 - 7.5 knots (Yes, this is way above hull speed of Catalina, but I have quite often clocked speeds above 9 knots, and the record was 12 knots with the help of some waves from behind!) So if you have to make 80 nautical miles in a day, you will think twice about whether to stick just to sails! If I have to sail against the wind, I would prefer sailing rather than motoring, because going against wind and waves will result in heavy slamming, stresses to the rig and hull, and the occasional overspeeding due to propeller exiting from water. Because Catalina is not very good at sailing up-wind (50-55 degrees is sharpest it can make), even if you run on sails at 5 - 5.5 knots, your real speed over ground after taking tacking into consideration would be around 3 knots. If I motor against 20 knot wind, I can make about 4 knots. The limiting factors are the impact stresses from the waves. For half-wind the sails are definitively the best! You can make 6 knots easily, and if you try to run on motor, the lateral impact of waves will make the propeller exit the water on every second wave!
  • When the wind is above 22-25 knots and waves are above 3-4 meters, it is usually not possible to run the engine because the propeller either exits from water and the engine overspeeds or the engine gets flooded (and often it is an "and," not "or"). In these conditions, only sailpower can be used, and good speeds of around 5 knots are easy to attain against the wind, and 6+ knots if running with the wind.

Gasoline Storage

So, how does one store the fuel on such a small boat?

I do not store fuel inside the hull because of the danger and the smell, and also because I eliminated the standard venting (I believe it makes the boat not safe in terms of the possible flooding through the vents). So the only good place for storage I found was the cockpit.

The Catalina 22 has a huge cockpit which is not very adequate for high seas due to its volume (more than 300 liters). So one way to deal with the problem was to fill the cockpit space with gas tanks. The standard configuration is a 45 Liter main tank and 2 x 25 liter gas canisters. All these three tanks are stored below a board firmly attached to the cockpit and which allows to organize neatly the gas tanks and prevents them to float away in case of a capsize or sea entering the cockpit (there is also the option to tie a line so that these tanks would not float from under the board should the worst happen. They also reduce the cockpit volume by more than 100 liters!

The only downside to storing gasoline there is the fact that the center of gravity will br raised somewhat, because the cockpit floor is not very low.

The 45 liter tank has a connector for the gasoline hose, and the other gas canisters must be siphoned to the small 15 liter tank

On this photo, one can see the two blue canisters, each for 25 liters. The red 15 liter gas tank is usually on the floor of the cockpit, and there is another 45 liter tank hidden behind the two blue canisters. Also, there is some space left for a couple of 2 liter bottles which can be tucked in the spaces between the 45 liter tank and the cockpit walls. So all together, I can have about 120 liters stored here!

The maximum I have taken on board were 180 liters. That extra gas (60 liters) was stored in 2 liter bottles and 10 liter canisters which were placed inside the cabin to keep an eye on possible leakage.

Gasoline Consumption

I have run some tests on gas consumption. At full power the Catalina 22 runs at about 5.7 knots and consumes 2.5 liters of gas per hour (for a two-cycle 5 HP engine), i.e. making some 2.3 nautical miles per liter. 5.7 knots is very close to the maximum hull speed, so that reducing the speed only slightly can dramatically increase the mileage. For instance, running at 5.0 knots (15 % less than the maximum) reduces the gas consumption by almost 40 %, i.e. the mileage increases to 3.2 miles per liter. And going 4 knots will almost double the mileage.

This is important to bear in mind in case that one would run low on gasoline. If there is no wind or current going against the boat, reducing speed will significantly increase the distance which can be travelled. And with 180 liter the range is anywhere between 300 and 600 nautical miles, depending on speed, wind, and currents.