36 Contender 2 outboards! Best prop setup?

[Dilligas]

Hi everyone,

I have twin yam 250 ox66 outboards -I tested four sets of props on my 36 contander Monday. The best pair of props I tested where 3 blade 15 pitch and a I think was 15" diameter. Can not remember to brand props.

Results:
480 gallons on board- @ 4,000 rpm's boat cruized at 22 knots- burned 26 gallons per Hr. Top speed of 29 kn0ts.

Trying to get 25knots or better at 26 gallons per Hr or better.

Is there any one who has a twin setup or has done the testing and could give me the specs on what they run or somthing close in comparison.

Thanks
Robbie

[Enforcer2]

Dilligas, I had a couple of things for you to consider.

If you don't need 400 gallons of fuell don't filll her up. Fuel is approx 8 pounds a gallon you are carrying approx 3,200 lbs of fuel.

If you go offshore, a margin is nice but unless your running across the stream and back you'll never use it.

You will definetly find your speed just on this alone.

Is your O/B bracket mounted? If so where are the props shafts in relation to the bottom of the boat. They should not be buried. Depending on your set up, you can jack them up from splitting the water intake with bottom of boat or like my set up, prop shaft is approx 1" below bottom . MAKE SURE YOU HAVE WATER PSI GAUGES:eek:

And like you I have tried about 5 different sets of props, The four blade is without a doubt the way to go. I have experienced an 8mph increase in cruise speed going from a 21 Mirage 3 blade to a 22 Bravo one four blade.

I was able to run these due to jacking up engines and getting a rpm increase. I still have strong holeshot and a 1-2 mph increase in top end.

My boat is a 37' midnight express w/ 2 ft bracket and trip 225 optis. Boat weighs in at 12,500 with engines and 100 gallons of fuel.

Back to fuel, I can carry 1,000 gallons but I don't (unless I have to cross the gulfstream:D ). I have four tanks and all are empty except center tank. Inshore use under 100 gallons, offshore use 200-250, travelling 50-60 miles each way and then trolling for 4 hours.


At 4,000 RPM I am cruising at 40 mph. At 4500 I am cruisng at 48 mph!! Top end on boat is 5900 RPM.

[Enforcer2]

some picts

[Dilligas]

Thanks for the reply-How much fuel do you burn at 4,000 RPMs?

[Enforcer2]

The optis are burning 40% less then efi's. Basically My three are burning the same as your two.

[Enforcer2]

You should think about repowering with opti's or similar. Go with three, specs for your boat w/ trips (250 yamahas are ) 36 knot (42 mph)cruise and a 45 knot (51 +mph) top end

[Dilligas]

So at 40 MPH and 4,000 your boat is burning 26 gallons an hour. No way! Maybe 1 to 1 and that would be great.

[Enforcer2]

OPtis burn 40% less fuel then old style EFI, what you have.

I am burning approx 30 gph at 4000 rpm at 40 miles an hour. 1.1 mpg

4500 RPM I am burning 37 gph at 48 miles an hour at 1.1 mpg.

This is with triples

[Enforcer2]

For comparison, (Boating Mag TEst) a 33 Grady w/twin 250 Yamahas SW ox 66 Outbopards is burning

26.8 gph @ 4000 doing a speed of 27.7 knots (31.9 mph)

35 gallons an hour @ 4500 speed of 32 knots (36.9 mph)

they are usig 14 1/2 x 19 three blades

[Enforcer2]

And if I really wanted to save fuel I don't I would run my boat at 3,500 RPM burning 23 gall,ons an hour and travelling at 36 mph!!!!

Trust me, I have done the math over and over again. My speeds were takemn in radar each and every time and I made sure that all conditions were nearly the same.

Your best bet is to go to 4- blades

In the mean time, I am putting a fourth engine on:D

[Dilligas]

You have done your home work! I currently have tripple 250's and have been testing the two outside motors with different props to see if it would be better to run twins before I remove the center motor. Maybe I should consider leaving the tripples on and trying different props.

My triples at 25knts burn 38 gallons an hr. and at 35 or 37 knts about 43 gallons an per hr. with two merc marrage props and a yamaha prop 23 pitch, diamater I think is 15" I am the secong owner of boat this is the way I got it.

[Enforcer2]

I would definetly stick with trips, go to the four blades, I'm telling you you will gain. I speed at cruise. I gained 8mph with the four blades.Speed is the biggest factor with trips. You may be burning more but you are going faster which means you will get there sooner thus burning less fuel!

Check out the SKA sight Southern Kingfish Association. Theres quite a few of those guys running Contenders with trips. They would be able to help you.

Good luck

Tony Ocean City Maryland

[Dilligas]

Thanks for the tips.

Robbie

[Enforcer2]

No problem:cool: , if you need to feel free to recontact me.

Tony

[Lilstafo]

For sale ??