fuel consumption

[mahani]

My wife and I are new to bigger boats and are thinking of buying a 1988 30ft Carver Santego with twin 230hp Mercruisers. The vendor is unable to give us accurate fuel consumption figures. The specs suggest a top speed of 30Kn and a cruising speed of around 24Kn These boats are hard to find in Australia and we are having trouble finding this information locally. We plan to do some coastal running and would like to figure the range we can expect

Can anyone give us an information that may help us?

Any other info on this boat would be appreciated as well.

 

[NorthernWave]

Try these guys, they may be able to help

http://www.carveryachts.com/

or maybe mercruiser

 

[DavidJ]

I have a 37ft with 230hp diesel Volvos and get about 2mpg which in Oz language is about 14 km per litre (please check my calculation!). Assuming your engines are still giving 230hp you might get to 32-34 knots on a flat sea.
What part of Oz?, we have had some great boating with friends at Surfers Paradise near Brisbane.
David

 

[Deleted User YDKXO]

I think DavidJ's figure is a bit optimistic because I think your Carver is shaftdrive rather than sterndrive and is a fairly heavy boat. I would think you could expect something in the region of 1.5mpg at cruising speed. I would be surprised if the boat did 30knots though. We are talking diesels?

 

[Wiggo]

Agreed. We're just under 40' with 230's on shafts. With half fuel, no water an none of our usual cruising crap we can just make 30 knots, downhill with a following wind. Fully loaded, we're just over 10 tonnes, and we average around 1.3 mpg over the season. Or, if you want another way to look at it, a comfortable cruise (20-22 knots) burns about 12 gal/hr (6 gal/hr per engine).

Keeping the revs down (i.e. about 70-80% of max revs) will get you the best fuel economy (I know, I know - tickover and displacement speed etc etc, but I'm assuming he actually wants to get somewhere). Depending on what your boat displaces and the hull shape, those revs could give you anywhere from 17/18 knots to 22/23 at a guess.

Follow up: just did a google, and the Santego looks to be around 11 tonnes and 34', so I suspect you'll be at the lower of the speed figures i.e. cruise at 16-18, flat out at 24-26 (assuming engines are not too tired).

 

[DavidJ]

11 tonnes!
Yes, I think my post was optimistic. I think mine is only about 7 tonne
David