21ft speed-fuel burn question

[Stewart hanley]

21ft larson with a 5.8 volvo v8
8'6" beam
any ideas on a possible top speed, more importantly what i can expect for fuel burn? Anyone have a similar bowrider v8 set up?

 

[drrpm]

Re: 21ft speed-fuel burn question

Top speed will probably be if the low 50 mph range if the prop is optimized and load is light. Fuel burn will be largely dependent on how you drive it. Cruising at its most efficient speed will burn in the ballpark of 10 GPH. Water sports or running wide open will burn a lot more gas.

 

[spdracr39]

Re: 21ft speed-fuel burn question

My 21ft tahoe with the 5.0 efi mercruiser burns 5gph at cruise. I dont believe you'll burn 10gph unless your running at WOT.

 

[drrpm]

Re: 21ft speed-fuel burn question

A typical boat of that size will get around 3 mpg and have a best cruise speed in the 25-30 mph range. That yields a fuel burn of 8-10 GPH. Running WOT will probably burn in the 25-30 GPH range.

 

[spdracr39]

Re: 21ft speed-fuel burn question

I agree with your math however my experience does not equate to those results. A cruise from one end of my home lake to the other and back takes about 2 hours at cruise of 30 mph. that and a little swim time uses less than a quarter of a tank and my tank is 50 gallons. the two hours does not include loading unloading and in and out of no wake zones. I have never owned a boat that would run the tank dry in only 5 hours of cruise time.

 

[spdracr39]

Re: 21ft speed-fuel burn question

LOL so true. Fuel usage of the boat is really just a portion of the expense. Maintenance, Storage, Tow vehicle ...... It goes on and on.