DQX propellers? Worth it?

Discussion in 'Downeast Engine Room' started by CaptV, Jan 13, 2020.

  1. CaptV

    CaptV Member

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    I need some advice please....I am thinking about buying a new propeller this off season and a friend told me to look at the DQX. The boat is a 35 five islands with a Cummins CTA 430 and currently has a 23 dia x 28 pit 4 blade LH. The propeller has been bastardized since I bought the boat 5 years ago as we have been constantly manipulating it to "make it work." I'm trying to get more out of the boat and engine and hoping that the new propeller will allow me to achieve that.

    Thanks
     
  2. Keelboater

    Keelboater Captain

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    DQX style props are great for boats that have limited tip clearance like your 35 Five Islands which originated in the 35' Bruno mold.
     
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  3. powderpro

    powderpro Captain

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    Yes, 23” diameter is small for that hp and size of boat, so I would recommend the larger blade surface of a DQX style prop. If you can jump up in diameter that will help too.
     
  4. CaptV

    CaptV Member

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    Snapped some quick picks this am... any insight is always appreciated
     

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  5. MikesMarine22

    MikesMarine22 Senior Member

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    I have this if you have any interest. 1-1/4 shaft size
     

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  6. powderpro

    powderpro Captain

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    A more accurate measurement for what prop will fit is to measure a little farther forward on the shaft, where the middle of the prop would be. But based off what I see, and assuming you have a little more clearance on top versus the bottom, a 24” diameter should work good. Increasing diameter 1” and going with a DQX should net you some positive speed results
     
  7. Gurryman

    Gurryman Captain

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    What are the current performance numbers with the prop you have? Also what ratio is the gear?
     
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  8. mike@mpi

    [email protected] Senior Member

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    Here's my take on the DQX. I repowered my 26 JC from the original 7.4 liter Ford to a 370 Cummins. Somewhere on here going back a few years I wrote about propeller issues. The old engine spun a Hy-Torq 17X14 with a 2:1 gear. Hy-Torq is now Michigan's DQX adding to the line of the old 3 blade Dyna Jet and 4 blade Dyna Quad. Since the boat came with what is now called the DQX but now would be larger and with less tip clearance with the increased torque with the Cummins I stayed with the Hy-Torq style and wound up with a DQX 18x21 behind a 1.5:1 Twin Disc which works out to about the same shaft RPM but raised the boat's top speed from 18 to 25 MPH. After 2 seasons and about 300 hours I saw severe pitting around the root where the blades attach to the hub. I thought cavitation from running behind a keel was the problem and had the pits welded up. This went on for 4 more years, 400 more hours, 2 more repairs and then the DQX threw a blade. I got Dave Gerr's propeller handbook and learned it was blade overloading that was causing the damage to the prop. The only fix is to get more blade area. Talked to Michigan and there are no 5 blade wheels that small but they recommended their DQ 486 which in 4 blades brings blade area up .74 to .86. It also in my small size prop weighs like 7 lbs more.. That's a lot of metal. 7 seasons and a 1000 hrs and the only thing I had to do to that 486 was have an inch of pitch taken out of it because it was grabbing so much more water that it was overloading the B. Now at 18x20 the boat gained 1 MPH and can turn up past rated RPM. If you can, look at both of them and see which is way beefier. I should also point out that in either wheel I didn't spring for Nibral.
    So no, I don't like the DQX.
    I don't know this is fact but I heard that the DQ486 is what Dave's original Tuna.com was running behind that big Mack E-9 American Marine.
     
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  9. CaptV

    CaptV Member

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    The boat is upwards of 20000 pounds fully loaded with 6 customers, myself, ice, and fuel. Gear is a twin disc 507a 2:1. at 2100 where I cruise I'm around 14.5 kts. At 2625 its at 22kts. I feel like i Should be getting more out of it. I am also adding some zipwakes this offseason as well

    I'll head down in the am and get better pictures. I went quick at there was a massive puddle
     
  10. OLD BAY

    OLD BAY Captain

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    I have a 20x22 bronze DQ and a 20x21” nibral DQX in my Wasque with 1.5:1 gear. I have limited tip clearance with the 20” diameter and had rumbling at speed with the DQ.

    The DQX is smoother/quieter and a few tenths of a knot faster throughout the RPM range, including top end (I think 0.4 knots, but I reported it somewhere on this forum). I didn’t track this closely, but I have a floscan and I believe I get slightly better fuel burn for the same speed with the DQX. I used to get about 1.9nmpg at 20knts with the DQ and now I think I get about 2.0 nmpg. YMMV
     
  11. Keelboater

    Keelboater Captain

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    [email protected] - I think you have a unique case with such a motor in that 26' JC. Your boat sounds like a good candidate for a keel modification. Bill D has a 370 Cummins with 1.5:1 gear on his 25' TJ and swings a 20" DQX prop, and if memory serves, he doesn't use the max HP. Sounds like you have it ironed out though. Nibral might have helped as well.
     
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  12. ripta13

    ripta13 Senior Member

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    I had good results going to a DQX in my 31 BHM.
     
  13. plowin

    plowin Captain

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    Tell us what the results of the DQX on the BHM were. I never would have expected that with most BHMs, there is a ton of room for a large diameter wheel. What motor and reduction do you have?
     
  14. Blitzen

    Blitzen Captain

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    Had a DQX Nibral prop on my last two boats, smooth as silk and very efficient. The DQX design has a higher blade area than most 0.82 I believe and is great for boats that have limited prop aperture for the given power. With the increased blade area you can reduce diameter and pitch allowing the prop a little more room to work. Keep in mind most DE boats will do best with a prop that is a little over square. And shaft speed is also a consideration when choosing a good prop.
     
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  15. ripta13

    ripta13 Senior Member

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    430cummins 2:1 twindisk. Pretty sure the old wheel was 4 blade Michigan nibral 26x28 it was tired so I was due for a new wheel. So Bossler & Sweezy on Long Island recommended 26x27 DQX I got my RPMs back and gained a little bit of speed at 2200 from where I was at. I was happy. This will be my 6th season with it.
     
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  16. winterking

    winterking Captain

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    hey Ripta, would love to hear what kind of numbers you’re getting with the 430 in a bhm?
     
  17. blinsquirrel

    blinsquirrel Senior Member

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    I tried a DQX on my 36 BHM. Had zero gains in speed and efficiency. The wheel was singing at trolling speed. Prop shop said the harmonics were a result of the blades being 99.9% true since they are cut on CNC machine. They recommended taking a file to the trailing edge of the blades.

    I sold the DQX and put my original DQ back on the boat. I think the DQX really shines on hulls that have limited tip clearance....not my BHM.
     
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  18. ripta13

    ripta13 Senior Member

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    Clean Bottom inshore fishing 2220rpm 16-18kts depending on the tide. Iv scene 19 and 15kts at 15gph. Canyon load with ton and half of ice loaded for 3-4 days is another story. I stick 1450-1500rpm 8.5-9kt 5gph. She’s a pig 4,000 plus lbs heavier. 14kts @15-16gph

    Not to derail the thread but the 2 people I know that tried the DQX and everything I read here were all were pretty positive except $$
     
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  19. eyecatcher

    eyecatcher Senior Member

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    You want to accomodate the largest prop while maintining adequate clearance. Need a pic from center shaft to the top and to the bottom from midway on the taper to confirm max diameter but at the moment looks like you might be able to fit a 24X26 4 dqx. Should be an noticiable improvement due to added blade area. They do have a flat edge out of the box that can sing when there is no cup depending on machining. Personally, I would recommend a radius on the leading edge and chiseled edge on the trailing with no cup.
     
  20. mike@mpi

    [email protected] Senior Member

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    Just by looking at it the DQX seems to have more engineering put into it then the Dyna Quad. But if you put the DQX and the DQ 486 side by side the 486 is a lot heavier and grabs more water. There's no doubt that a 370B is pushing the boundaries of a 26' boat and it doesn't help that the prop is so close to the keel that there is just enough room for a collar zinc. But when the boat is soft grounded to a dead stop from over 20MPH (not me I swear, it's the ladies messing around with that damn box wine) and they can just back up off the sandbar with no harm done I'm glad it doesn't have a strut.
     
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