Prop size for 40 owners

[psneeld]

What are you guys running?

I plan on a prop reconditioning in during my Oct haul and want to see if I want to change. diameter/pitch...etc...

[jleonard]

Mine is 20 x 16 4 blade behind a 2:1 gear. I can just get to 2500 on the 120 Lehman so I think it,s correct although it looks small in dia compared to other trawlers
Engine temp runs right at 170 ish on the manual gage just like adc says it should, and 180 on the electric gages. At wot it creeps to 190 on the electics.

[psneeld]

Thanks!

Anyone else????

[GGUTHRID]

My 1980 trunk cabin single screw Albin 40 Bright Pleiades has a three-blade 22-inch-diameter propeller that until 2011 had been pitched at 15.6. Then, the 120-hp Ford diesel couldn't turn it faster than 2,250 rpm.

Digital Prop Shop, Tracys Landing, Maryland, repitched it to 14. Now, with a clean bottom and clean prop, it turns 2,496 rpm, just shy of the recommended 2,500 at wide open throttle.

The engine runs cooler now, and I've raised the cruise rpm from 1,800 to 1,850 to (a) get the same speed through the water as before, (b) burn slightly less fuel, and (c) run cleaner (no diesel dust on the transom anymore).

[rebuckley]

As dumb as this sounds, I am glad you posted this. When I haul this year I need to get the specs on this - right now my answer is "Uh - 3 blades"....in stating that I realize this is something I need to look into.

[jleonard]

What are you guys running?

I plan on a prop reconditioning in during my Oct haul and want to see if I want to change. diameter/pitch...etc...

Scott, did you make a change? What are you running now?

[psneeld]

kept the same...22x17

still running around 1600rpm for 1.9 gal/hr .....6.3 kts ....3.3NMPG

feel like others are doing so much better...but your post last year made me feel comfortable with those numbers.

I thought getting rid of the steel tanks and 300 gallons of fuel would help...it did lower my waterline so my transom is barely immersed...but the numbers are pretty close to the same as last year.

next year I'm going to rig an accurate/calibrated 2 gallon tank directly to my fuel manifold and run some measured miles with a digital tach the whole time...in the long run will I care? probably not till someone tells me my economy is way off for this model boat.

[psneeld]

My 1980 trunk cabin single screw Albin 40 Bright Pleiades has a three-blade 22-inch-diameter propeller that until 2011 had been pitched at 15.6. Then, the 120-hp Ford diesel couldn't turn it faster than 2,250 rpm.

Digital Prop Shop, Tracys Landing, Maryland, repitched it to 14. Now, with a clean bottom and clean prop, it turns 2,496 rpm, just shy of the recommended 2,500 at wide open throttle.

The engine runs cooler now, and I've raised the cruise rpm from 1,800 to 1,850 to (a) get the same speed through the water as before, (b) burn slightly less fuel, and (c) run cleaner (no diesel dust on the transom anymore).

wow...I run a 4 blade 22x17 guess I'll have to check my upper rpm again but I thought it was OK last time...

you sound way under pitched compared to me or I'm suprised I even hit 2000 rpm!!!!

[jleonard]

[quote="psneeldwow...I run a 4 blade 22x17 guess I'll have to check my upper rpm again but I thought it was OK last time...

you sound way under pitched compared to me or I'm suprised I even hit 2000 rpm!!!![/quote]

And you sound overpitched to me. LOL. Seriously, I am 20 x 16 and just make 2500 at WOT with a very light trace of smoke (with a 2:1 tranny). Assuming you are also 2:1 you are like 7 inches of pitch greater than me (assuming one inch dia = 3 inches of pitch).
I'm surprised our fuel numbers are close.