My Cal 25 has a 20 gallon stainless steel fuel tank that stored diesel for an engine that was removed and replaced with a 2 cycle outward. I am considering using the tank as a fuel tank for the outboard. Any comments on why I should or should not?
Converting Fuel Tank
- Thread starter txcalsailor
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Make sure it is cleaned out and then you have to run the fuel hose with a typical gas tank primer bulb. I see no reason why you can't do this. The fuel deck fill should be replaced so it reads gas instead of diesel. Don't forget to mix oil with the gas.
only real thing to consider is how much fuel are you going to burn per season.... if the fuel will go stale before you use it, there is no point in filling it all the way up, although its probably nicely out of the way and you would have the fuel just in case you decided to motor about 30 hours, and thats a big plus.... I thought I motored quite a bit this past year, and I only used 4.5 gallons in my 10hp.(0.6 gal per hour actual consumption, running half throttle @ 5.8-6 kts)
in perfect conditions, a 10hp motor at around .75gal per hour if running just under theoretical hull speed in a 25 (around 6kts) would roughly equal a range of 150-170 miles from your 20 gallons of gas..... this is using very conservative math (rounding down)..... anyone can do the math and get the exact figure from this, but there are other factors in the real world that will easily change/disrupt any one of the factors in this equation..... but it gives you a general idea of how much fuel you might really need and whether it would go stale before it gets used.....
in perfect conditions, a 10hp motor at around .75gal per hour if running just under theoretical hull speed in a 25 (around 6kts) would roughly equal a range of 150-170 miles from your 20 gallons of gas..... this is using very conservative math (rounding down)..... anyone can do the math and get the exact figure from this, but there are other factors in the real world that will easily change/disrupt any one of the factors in this equation..... but it gives you a general idea of how much fuel you might really need and whether it would go stale before it gets used.....
Don't forget to vent the bilge. The old diesel tank probably did not have any sort of passive or active venting. Gasoline fumes are heavier than air and will settle in the bilge, Before converting the tank you should install a blower system with a switch near the helm so that you can activate the blower prior to starting the engine.
Take a look at most any large powerboat today and you will see a similar system. All modern gasoline powerboats are required to have an active blower system that can be activated prior to starting the engine to ensure the bilge air has been vented and to prevent the possibility of an explosion or fire due to gathered fumes.
Just be careful, gasoline greatly increases yoru chance for fire or explosion and in the enclosed space of our sailboats and bilges this is not a good thing.
Take a look at most any large powerboat today and you will see a similar system. All modern gasoline powerboats are required to have an active blower system that can be activated prior to starting the engine to ensure the bilge air has been vented and to prevent the possibility of an explosion or fire due to gathered fumes.
Just be careful, gasoline greatly increases yoru chance for fire or explosion and in the enclosed space of our sailboats and bilges this is not a good thing.
Good suggestions and also check to see if there is still a ground on the tank and if not put one on and make sure it is vented to the outside.
On the engine starting and activating the blower before, that might not be an issue so much, since the engine is not in the same compartment as the tank being an outboard. If the tank is in a compartment that is not isolated from the cabin then things get more complicated and also there should not be electrical devices in the compartment where the tank is that could cause an explosion.
We added an inboard tank to our Mac....
http://purplesagetradingpost.com/sumner/macgregor2/outside-35.html
...and put in a blower system but have never smelled gas there so don't run it with the outboard, but it is there and the tank is vented outside and grounded.
Sum
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Just something to add on metal gas tank ground based on something we do at a factory that makes electronics.
You don’t want a spark near a gas tank and there is a good chance you have DC power somewhere near the tank.
If you put a ground on the tank, it will keep static from building up - which is good. But if you accidently have 12 volts come in contact with the grounded metal tank, for sure you will get a spark.
However, if you ground the tank using a resistor (common to use 1 Meg in Electronics manufacture for "grounding"), the resistor still insures that there is no static buildup. But it limits current in case of the 12 volt touching the tank so no spark.
I don’t know what boating standards recommend (likely Mainesail knows) but I thought I would throw this out..
You don’t want a spark near a gas tank and there is a good chance you have DC power somewhere near the tank.
If you put a ground on the tank, it will keep static from building up - which is good. But if you accidently have 12 volts come in contact with the grounded metal tank, for sure you will get a spark.
However, if you ground the tank using a resistor (common to use 1 Meg in Electronics manufacture for "grounding"), the resistor still insures that there is no static buildup. But it limits current in case of the 12 volt touching the tank so no spark.
I don’t know what boating standards recommend (likely Mainesail knows) but I thought I would throw this out..
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