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Best cruising speed for 34' Luhrs.

N

nightstalker

Regular Contributor
Can anyone give me an idea of what might be an optimum cruising speed for my 1990, 34' Luhrs with twin 454's weighing in at 12,500 lbs. I'm looking for the best cruising speed considering RPM's, speed, fuel consumption, etc.
Nightstalker
 
Invest in a floscan (or equivalent), install it, and then take some data....each hul is different and loaded to suit the owner's needs. It will likely be up on plane with the secondaries closed but you won't know until you get the data.
 
makomark said:
Invest in a floscan (or equivalent), install it, and then take some data....each hul is different and loaded to suit the owner's needs. It will likely be up on plane with the secondaries closed but you won't know until you get the data.
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I've got the flow scans on order and am waiting for my brother-in-law to come up from NJ to install them. Probably have then installed by the beginning of August 2015.
Nightstalker
 
Between now & 2015 when you get your floscans running 3000-3500 RPM will get you in the ball park. You need enough power to keep her fully on plane. If you have trim tabs they can keep her up on plan closer to 3000 than 3500 at about 20 GPH. Running "up hill" below 3000 will burn more fuel than running 3500. If you run faster than 1500 you should go up to 3000 -3500. Believe it or not you will burn less fuel going faster. Of course going above 3500 to WOT 4400 fuel burn will be in the 55 GPH neighborhood.
 
rfdlou said:
Between now & 2015 when you get your floscans running 3000-3500 RPM will get you in the ball park. You need enough power to keep her fully on plane. If you have trim tabs they can keep her up on plan closer to 3000 than 3500 at about 20 GPH. Running "up hill" below 3000 will burn more fuel than running 3500. If you run faster than 1500 you should go up to 3000 -3500. Believe it or not you will burn less fuel going faster. Of course going above 3500 to WOT 4400 fuel burn will be in the 55 GPH neighborhood.[/QUOTE

Thanks for the info. Are these GPH #'s per engine? That means that I would be burning a total of 40 GPH at 3000-3500 RPM. How cum most of us on this forum can't spell. I guess it has something to do with crawling around the bilge inhaling all of those fumes.
Nightstalker
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That should be total for both engines. Remember like the say "Your millage may differ". I have found that my arms must have shrunk. Places that i used to reach are now out of my grasp.
 
Hey NIght,

I don't know if you have had previous use of this boat ie: in our case we ran the boat for a year or more before we added fuel monitors and gas was about $4.10/ gal. Once we did, the first run opened our eyes WIDE. Many of these numbers look interesting and you may be quite close with these estimates....its' when you start calculating the cost per gallon times the gallons per hour that the ride gets exciting :)
 
rfdlou said:
That should be total for both engines. Remember like the say "Your millage may differ". I have found that my arms must have shrunk. Places that i used to reach are now out of my grasp.
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10 GPH per engine for a total of 20 GPH sounds a whole lot better than 40 GPH at 3000-3500 RPM. I thought I couldn't do things like I used to because I was increasing my age, not my waist line.
Nightstalker
 
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