Stupid Question that nobody seems to ask

[jclk23]

I have a 2006 Nitro CDX 929 (20'9")bassboat with a 2006 Mercury Verado 250hp 4 stroke bought new everything is the way it was in the showroom. Havent used the boat as much as I had wanted. But going to get out more this year. Does anyone have a similar set up to mine? Before I start doing $800 Trial and Error tests on props. This is about how my boat performs cruises real nicely at around 45 mph at 4200 rpm at w.o.t. between 74-76 mph depending on water conditions at about 6k rpm. This is what I am looking to achieve better fuel economy and top end speed I am willing to give up hole shot. Should I just take a look at props or should I look at new outboards with maybe 4 mpg it gets expensive. Would just like to here someone elses specs on something similar.

thanks

Jeremy

 

[5150abf]

Re: Stupid Question that nobody seems to ask

So you want to go faster and get better mileage, if you can figure that one out you will be a very wealthy man.

Boats just don't get good mileage especially boats with supercharged 250 horse outboards, you can get more speed by going to a bigger engine or better mileage by going to a smaller engine but you can't go faster and get better mileage, there is no prop or engine that will let you do that.

You prop a boat for rpm and top speed is what it is and it sounds like your boat is propped really close to right so changing that won't do you any good, if you want to get better mileage stay around 3/4 throttle, that will give you the best speed/mileage combo.

 

[MH Hawker]

Re: Stupid Question that nobody seems to ask

Pull the throttle back to about 1/2 to 3/4 that's your only hope.

 

[jasoutside]

Re: Stupid Question that nobody seems to ask

250 horses? You want better mpg?

75 mph? You want to go faster?

Yikes!!!

 

[steelespike]

Re: Stupid Question that nobody seems to ask

Rule of thumb A motor will use "about" 10% of the rated hp in fuel per hour at wot.
In your case that would be about 25 gph. That's regardless if its a house boat or a speed boat.
if you insist on wot you might be able to get a tiny bit of speed with the right prop.But it would take a very long time to make up the cost.
If you can stand to back off a little a flowmeter will be worth its weight in gold for finding the best throttle setting for the best mpg and speed. Just running at an arbitrary reduced speed is not necessarily the best speed.
There are meters that can calculate mpg as you go.

 

[Frank Acampora]

Re: Stupid Question that nobody seems to ask

There are no stupid questions, just stupid people! LOL (I just love using that line!)

Seriously, if your engine were underpropped it would affect fuel mileage to some degree but at your current speed number we can't tell. We need to know the operating wide open throttle RPM and speed AND the manufacturer's rated wide open throttle RPM range.

Simply put, the faster you go, the more fuel you will use, so mileage will not improve with a prop change for more speed unless you ARE underpropped.

NOW: if you want to go faster and are correctly propped, then you need to explore cubic dollar additions: Nose cone, low water pick-up, hydraulic jackplate, and expensive custom props.

Just as an aside, so you know what fuel use to expect, my stock 125 propped to turn 5900 RPM at 60 MPH on a small hull used 15 gallons of fuel per hour. You want to go fast? You gotta pay!

 

[jestor68]

Re: Stupid Question that nobody seems to ask

Your Verado has a WOT rpm range of 5800-6400 rpm. It uses a 1.85 gear ratio.

So at 6000 rpm you're right in the middle of the rpm range; a good place to be.

I don't think there is any such thing as speed and good fuel economy. The only way to improve fuel economy is to slow down.

I can likely make you go faster; but not while burning less fuel. That Verado is going to use 24-26 GPH at WOT. Conversely, it burns about 9 GPH at a 4000 rpm cruise.

Go to the Mercury Marine site and see many engine tests of larger motors. Your's is doing about the same as the rest of similar HP. A 250 gets about 3.5 MPG at cruise and a little over 2 MPG at full throttle.

 

[dan02gt]

Re: Stupid Question that nobody seems to ask

You didn't mention a couple of things. Do you have a jackplate? What prop are you running? Are your speeds GPS? If you don't have a jackplate look into one. They can help you in all the ways you want. If your doing 76GPS WOT you're running really well for that boat and I wouldn't expect to get much more. Also I would recommend you checkout the bass boat guys at bbcboards.net specifically the setup forums and Nitro forums there's a ton of bass boat knowledge over there.

 

[glenn property of pam]

Re: Stupid Question that nobody seems to ask

if you think about it in mpg then it real doesnt matter all that much where the throttle is set at 74mph@6000 rpm uses about 25 gallons a hr equals about 2.9 mpg and at 45mph@4000 rpm uses maybe 15 gallons a hr which is around 3.0 so if you traveled 3 miles you still used a gallon of gas. im sure with a jack plate / flow meter / trim / prop etc you could get another .5 of a mile some where in the speed range but thats alot of money for very little gain.

 

[Faztbullet]

Re: Stupid Question that nobody seems to ask

You should have a Smartcraft gauge on that set -up, are you using the GPH setting? You can use it to see the best trim and speed to get your best GPH usage. Also the newer Verados get a little better MPG than the 06 did, also cleaning out the boat of unused items such as rods /lures/ropes/food will lighten boat and increase speed and MPG. For example I cleaned my boat last year and removed about 200 lbs of plastic lures and 6 rods,anchor ,excreta and noticed a big improvement in hole shot and a 1 mph increase on gps.

 

[lexer440]

Re: Stupid Question that nobody seems to ask

Fuel economy and boats do not mix as I think we all realise, but neither does fuel economy and wide open throttle. You cannot drive ANYTHING like that cheaply, car truck or boat. I think to modify an engine to give more power for less fuel is what the automotive industry calls the holy grail of engine design.

 

[Tail_Gunner]

Re: Stupid Question that nobody seems to ask

Well this is where Dhadley or Walleyhed's experience comes into play. Using a setback plate and a four blade could do both...Four blades by design increase lift..lower planing speed less drag. Setback's allow the engine to be lifted out of the water stream reducing drag....Four blades can also run higher than a 3 blade aka one blade out of the water at wot again less drag..notice its all about drag. And will your hull even run true with such mod's

But its expensive setback's...low water pickup's..cleaver type prop's...Its all about tinkering around and having fun not to much about economy..thats word is just a excuse to have some fun and blow some dough...

 

[1FASTLASER]

Re: Stupid Question that nobody seems to ask

You should have a Smartcraft gauge on
that set -up, are you using the GPH setting? You can use it to see the best trim and speed to get your best GPH usage. Also the newer Verados get a little better MPG than the 06 did, also cleaning out the boat of unused items such as rods /lures/ropes/food will lighten boat and increase speed and MPG. For example I cleaned my boat last year and removed about 200 lbs of plastic lures and 6 rods,anchor ,excreta and noticed a big improvement in hole shot and a 1 mph increase on gps.

Lol @faztbullet...its amazing how much better your bassboat runs and ha dles when you leave the tackle store at home aint it buddy.....LMAO I constantly take to much but always think....i just might need it....lol