How Big Are My Fuel Tanks and How Far / Fast Can I Go ?

[lowride14]

So I'm only used to my 1963 sangstercraft 16.5' ski boat burning through its 25l tank in no time at all with its 100hp evenrude from 67. How big do you reckon my fuel tanks are? they arnt to much longer than what you can see i think.

Iv got 2 chevy v6, throttle body injection, 270hp motors from 2001 i think, so what is the gas consumption like on these old boats?

How fast do you think I can go?
And what would be a good speed for optimal fuel economy?

[perchance]

Not big enough!

[lowride14]

well there is 2

[cal40john]

Volume of a cylinder is H*PI*R^2. H is the length, R is the radius, PI is 3.14.

John

[lowride14]

while that is good to know john, i'm about 400 kms from the boat so i cant exactly go and measure it up. just looking for ballpark figures.

[skipmac]

As a wild guess you might get 12-15 kts with the 2 Chevys in a 38' old wood power boat. Not too familiar with gas engines in a boat like that but again a wild guess burn 6-8 gph at fast cruising speed.

Without something to show the scale of the tank photo could not even guess the capacity. I would expect a boat that size would have at least a couple hundred gallons or more.

[highamperage]

I have a 32'er with two Chevy 350's and it will burn about 20-30gph at a high speed. I usually idle and float haha!

It has a 200 US Gallon tank.

I'm guessing it's moving about 35mph (~55kph)

[lowride14]

Im thinking iv got 2 200 gallon tanks, may 150's

[capn_billl]

My 36' boat is fiberglass and I get .9 miles per gallon. I calculate 800 gals gross estimate assuming 8 feet long and 1.5 ft radius, and two tanks. From the picture lets say +- 30% 600-1000gals. Hull speed around 9 knots, every knot over that doubles fuel.

[highamperage]

Nice! I was originally looking at a boat like that. Didn't work out tho, but it looks nice.

[Sailbad]

How far can you go? We used to say 1/3 tank to get there, 1/3 to get home so leaving 1/3 to play with!

[boasun]

And in todays market: A sailboat will take you further, but a tad slower and it is the journey that is to be enjoyed not the designation.

[chris07732]

I had a similar boat, 1966 37' wood Egg harbor, twin v8's. It had 2 tanks, 145 gal ea. I fitted Floscan to it to check fuel consumption. I saw 22gph/hr/eng at 16kts, never got on plane. Never took boat for an extended drive out again!! It became a dock queen/hotel.

[BLUEwaterchaser]

Originally Posted by chris07732

I had a similar boat, 1966 37' wood Egg harbor, twin v8's. It had 2 tanks, 145 gal ea. I fitted Floscan to it to check fuel consumption. I saw 22gph/hr/eng at 16kts, never got on plane. Never took boat for an extended drive out again!! It became a dock queen/hotel.

Wow my friend that is quite a thirsty gal you have!
Luckily I don't have the same issue, tho I'm not running dual V8's either.

[Dockhead]

Originally Posted by chris07732

I had a similar boat, 1966 37' wood Egg harbor, twin v8's. It had 2 tanks, 145 gal ea. I fitted Floscan to it to check fuel consumption. I saw 22gph/hr/eng at 16kts, never got on plane. Never took boat for an extended drive out again!! It became a dock queen/hotel.

Per engine, eh? That's a ton of fuel!

So 16 knots will cost you 44 gallons per hour, which is almost three gallons per mile. So 290 gallons of fuel, costing $1000, will last you only 6.5 hours and get you only 100 miles. Whew! $10 a mile just for fuel! I can see why you turned it into a hotel.

That reminds of the old Soviet joke -- how do you double the value of a Lada? Fill the fuel tank.