Fuel consumption of a 19' boat with '76 140 mercruiser I/O

[luva63]

Hello,I'm thinking of buying a'76 aristocraft nineteen with a 140 mercruiser and was wanting some input on how much fuel I could expect to burn in one hour at say 30 mph. Any ideas appreciated.jim

 

[Bt Doctur]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

the 140 is very fuel efficient but I`d guess 4-8 GPH

 

[thumpar]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

At 30mph you are going to be toward the upper range of the RPM. You will get much better economy if you back it off to around 3000RPM while cruising.

 

[UncleWillie]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

Just a typical wild guess.
Expect about 5gph at 3500rpm in the low to mid 20mph range.
9-10gph near 30mph.
and 15 gph at Wide open and in the upper 30's low 40's

140hp is considered a bit underpowered for a 19' boat by todays standards but still respectable and fuel efficient.

 

[Bullrider]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

My Merc 3.0 does very good on fuel. I get ethanol free and that helps. I havent done the precise math yet but it looks like Im getting 7-9 ghp at 32-35mph on a 19` cuddy with four people,extra gas,kicker, and a bunch of stuff. My boating buddy is a little disgusted when he is on my boat because his bigger one uses almost double GPH for the same fun. I like to believe my four blade prop is helping a tad too.

 

[luva63]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

Thanks to all for your help on this. I currently am running a 1962 Johnson 75 hp v-4 on a 16 ft '63 Aristocraft . It will go through 6 gal per hr at 30 mph or 6 gal in 45 min at 35 mph(WOT). I can back it down to say 20 and get approx 1hr 40 min out of the same 6 gal . I was hoping the 4 cycle I/O would cut fuel use close to 1/2. I guess the old v-4s aren't as thirsty as I thought.

 

[agallant80]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

Its kinda like asking what is the air-speed velocity of an unladen swallow. No one really knows. You can guess but you won't know until you log your trips and do the math. On the older motors you will want to use ethanol free though, the newer ones have rubber and plastic that won't be destroyed by it, the older ones will have the older materials which can be eaten by ethanol.

 

[MikDee]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

Thanks to all for your help on this. I currently am running a 1962 Johnson 75 hp v-4 on a 16 ft '63 Aristocraft . It will go through 6 gal per hr at 30 mph or 6 gal in 45 min at 35 mph(WOT). I can back it down to say 20 and get approx 1hr 40 min out of the same 6 gal . I was hoping the 4 cycle I/O would cut fuel use close to 1/2. I guess the old v-4s aren't as thirsty as I thought.

So, what did you expect, it's a 4 cylinder 2-cycle. You'll still do better with the 3.0 4-cycle, plus have twice the power.

 

[luva63]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

I expected the I/O to be quite a bit better on fuel than the outboard,but according to the numbers I've been given, that's not the case. And it will need twice the power to push the heavier boat basically the same speed.

 

[thumpar]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

If it was the same boat you may gain a little with the 140 but a 16' is a lot bigger than a 19' as far as motors are concerned. The 3.0l is small for a 19'. You are going to have to run it hard to get the boat going which hurts your GPH. Some would say you may get better GPH with a bigger motor since you will have to push it hard.

 

[luva63]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

If it was the same boat you may gain a little with the 140 but a 16' is a lot bigger than a 19' as far as motors are concerned. The 3.0l is small for a 19'. You are going to have to run it hard to get the boat going which hurts your GPH. Some would say you may get better GPH with a bigger motor since you will have to push it hard.

I may try to find a 165 in the same boat. I'm just wanting a little bigger easier riding boat. Just have to figure paying a little more gas money for the luxury lol.

 

[thumpar]

Re: Fuel consumption of a 19' boat with '76 140 mercruiser I/O

It is more about how you use the power than anything when it comes to GPH. I can use up the 40 gallon tank in a day on my boat if I wanted too. I have learned to keep the right hand in control to save the wallet.