Fuel consumption

[johnotte]

Hi all,
My wife and I just bought a Carver 1999 406 aft motor yacht. It has twin 7.4 L Crusader gas engines.
We are trying to get some kind of a range of fuel consumption at different rpm levels.
Any ideas please.
Thanks, John

[Lyndon670]

John,

The 406 is a huge boat, tons of room - a great Carver design. However the 7.4 is the smallest of the big blocks and was the base engine. Boats in the 39-40ft range are on the verge of needing Diesel engines or at least the 8.1 blocks. IMHO the 406 is grossly underpowered to run at planning speed with the 7.4s BUT will still be efficient at hull speeds. You should see about .75MPG at 8kts. My buddy has the identical boat and this is what he runs. You need to be quick on the controls when docking because of the windage of your boat as it is virtually a sailboat. You will use quick jabs of throttle with forward and reverse to dock it without thrusters due to where the torque is in the RPM band of the 7.4.

Great boat though, and the smaller engines make servicing a dream, lots of room in the bay.

[waybomb]

Had a 4207 with 330hp mercs. Had to sell the boat; it was so woefully underpowered. With that sale I bought my 2700 hp beast. Got slowness outa my system.

Even our 3697 with 350 Crusaders could use a bit more juice, but it runs nice and at least gets out of its own way. I have no problem being in weather with it.

You did not say where you boat, but listen to weather radio and if you can, install a honkin radar so you can see weather approaching from afar. Heading into the weather is not so bad, if directly into it. Any other angle will leave you concerned, and a following sea will just push you all over the place and even get the boat sideways once in a while.

Point being, great boat, but avoid weather at all costs. If you ever grenade an engine, go diesel. Biggest ones you can shoehorn in.

[Lyndon670]

Fred, I never even thought to comment on weather - very good point. On calm seas, I would be surprised to see a 405 with 454s break 18kts, probably 15 max turning mid 4000RPMS. Wouldn't even be close to that in any seas bigger than a chop.

[g36]

i have a 1997 405 and it can easily come up on plane to 4000 rpms at 22knts or 25 mph. and wot open a little bit better. i have the twin crusader 454 h.o. xli engines. yes i boat inland waters but how much time am i going to be planing off, not much. i've got a jet ski or my runabout for that,i didnt buy my 405 for speed and gas is fine for me. i did bring my boat back to my home almost 500 river miles and upstream tennessee river all the way to chattanooga. got very close to avg .8/gal. for me the additonal costs involved i cant see the benefit of diesels i looked at both before buying what i have. have not been happier.

[Lyndon670]

As I said, at hull speeds the boat will be very economical. But I wouldn't be comfortable spinning those motors at 4K all day - that is serious centrifigul stress.

[merc50]

Enjoy your new boat.

[Majetak]

So the same question but for a different boat I have a 2003 Carver 366 with 340hp Mercruiser engines does anyone know what the normal fuel consumption is for this boat?

[bud37]

This will put you in the ballpark....not dead on for your HP but close enough...hope this helps a bit.

http://www.boat-fuel-economy.com/mercur ... ngine.html

[Majetak]

Thanks