Newbie questions....come on you know you love them!

[crossbowjim]

I just bought a boat, 16'3" Key West center console 25hp four stroke Yamaha. I intend to use it on rivers in Maryland, tributaries of the Chesapeake bay. So my question is about the size of the gas tank. It comes with a 12 gallon tank. How long can I expect to be out with that size tank? I know it all depends on how fast I go, wind speed, smooth water vs rougher etc. but on average how long will it last?

 

[keninaz]

Re: Newbie questions....come on you know you love them!

Many variables here, some that you mentioned. Running against a tide and load in the boat will affect you too of course. And of course keeping the boat up on a plane helps a lot too.
Prop pitch and RPM are some of the bigger factors also. I know I had a motor that I changed the prop on and it changed my fuel economy by almost 3 gallons per hour on a V8 I/O that I had.
I would suggest you find out where that motor produces it's HP and torque ratings. I know most motors I have had in the past have a "sweet spot" that they get the best fuel economy.
I suspect however with that boat that you will be running that 25 HP pretty fast to get what you want out of it.
Enjoy the new rig. If you are like most of us you will want a bigger boat by the end of the season.

 

[dwco5051]

Re: Newbie questions....come on you know you love them!

An old rule of thumb is to divide your HP by 10 and that is the gallons burned per hour. In your case that would come to just under 5 hours. To get a better idea fill your tank, run the boat as you would normally would for two hours and then fill the tank again and see how much you used. Another good rule is to burn 1/3 of your fuel getting there, the other 1/3 to get back and the remaining is you safety reserve.

 

[Bondo]

Re: Newbie questions....come on you know you love them!

How long can I expect to be out with that size tank? I know it all depends on how fast I go, wind speed, smooth water vs rougher etc. but on average how long will it last?

Ayuh,.... Until it's Empty...

 

[Home Cookin']

Re: Newbie questions....come on you know you love them!

a general reply to a general question: 12 gallons is plenty for a 25 2 stroke; should be better for a 4 stroke? If it makes you feel better, carry a 1 gallon "reserve" can--that's what we do with unreliable fuel guages.

Speaking of fuel gauges, never rely on them. I have a 17' Key West with a 17 gallon tank (70 hp). Because the tank is so flat, the gauge can't swing enough to be accurate. I am "full" until I have a quarter, "half" with an eighth. So I just use it like the warning light on a car dash board. Therefore, if you hav an in-hull tank, in the process of learning your boat, you need to run it down to empty. As you fill it, see what it registers with each 3 gallons (quarter).

You may find the 25 is underpowered and want to look for the opportunity to upgrade. Should be no trouble selling 25 while it's in good shape; it's a popular motor. What does your rating plate say?

Is yours the "bay boat" design or the deep V? If it's the former, it's a great shallow water and inshore boat; gets a little wet in the chop but still safe--just trim up the bow.

Welcome to I boats

 

[JoLin]

Re: Newbie questions....come on you know you love them!

An old rule of thumb is to divide your HP by 10 and that is the gallons burned per hour.

That's at WOT (wide open throttle). In the OP's case (25 hp on a 16' CC?), that may be his 'cruise' consumption, too. I suspect he'll be using a lot of throttle...

My .02

 

[Silvertip]

Re: Newbie questions....come on you know you love them!

At wide open throttle the fuel consumption of a four stroke is very little different than a two stroke. Just on plane is where the four strokes have a slight advantage. But be aware that almost without exception, at any given RPM a two stroke will be pushing the boat faster because of the differences in prop and gear ratios. Lets put it this way however, with 12 gallons of fuel on board, you have plenty of fuel for a day on the water provided you are not running wide open 100% of the time. Besides, there is no answer to your question.