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1890 SE Prop Size/Pitch

DanOmiteDanOmite Posts: 119 Deckhand
Hey guys,

Got 1999 1890 SE with 2007 F150 Yamaha.

Current prop is 3 blade Yamaha Reliance 13 3/4" x 19.

WOT is only seeing about 5200-5300 RPM at ~45-47 MPH. This is with motor trimmed up to the #2.5 position on the Yami gauge, trim position indicator.

Should I be seeing anything better? I thought RPM should be a few hundred higher.....Maybe different Prop?

BTW - I am ok with hole shot right now, it gets up pretty skinny.....

Replies

  • dholleydholley Posts: 91 Greenhorn
    The gear ratio on the F150 is 2.00 which means at 45-47 mph you have 4-8% slip which is really good. The max RPMs for the F150 is 6000 and you need to be there to get the most power from the engine.

    Are you sure that's as high as you can trim it up? Reason I say this is the boat will pick up 3-5 mph and several hundred RPMs if you can get it up on the pad. I would trim it up at WOT until it blows out and you start losing speed/grip.

    If that's the most RPM you can get out of it with that prop, I would look into a Mercury Tempest in 17P or possibly have that prop re-pitched.
  • DanOmiteDanOmite Posts: 119 Deckhand
    Thanks for the response.

    When I am on plane and the motor is tilt at #2.5 position on the yami gauge, I can only raise the jack plate an inch or two before the speed drops. I though for sure I could go a little higher before losing speed/grip.

    What is the best way to get the boat on the pad? Tilt motor up and raise jack plate or just tilt motor?
  • dholleydholley Posts: 91 Greenhorn
    Since I'm without a jackplate my answer is trim up. A different prop that can maintain "bite" at higher elevations is what you're looking for.

    In my case, I had a Yamaha painted stainless 21P x 13 7/8" that would top out around 55-56 mph @ 5800 RPMs. If I tried to trim beyond a certain point lets call "X", the prop would blow out and I would lose speed.

    So I traded it out for a Merc Tempest Plus 21P x 14 5/8". Typically the larger diameter will produce lower RPMs. However, in my case the Tempest allowed me to trim past "X" and continue to pick up RPMs and speed all the way to 60 mph @ 6100 RPMs (call this position "Y").

    Both props performed the about the same in terms of speed and RPMs at trim position X. Only the Tempest could get the to position Y.

    You're looking for a prop that provides lift. The Tempest, as well as others, do this really well.
  • DanOmiteDanOmite Posts: 119 Deckhand
    Settled on a Power Tech PTC3. 14.25 x 17P. It has pretty aggressive cup that will allow me to trim up higher and still maintain bite. That should get me to the higher RPM range.
  • DanOmiteDanOmite Posts: 119 Deckhand
    tried the PTC from power tech in 17p. Allowed me to run up to 5700RPM. It also allowed me to run a bit higher than before on my jack plate, but not a whole lot. Overall hole shot was a bit better and lift was better. less cavitation turning too. But still would like RPM closer to 6000.

    Talked to power tech and they recommend a PTZ in 17p. Basically same exact prop with less cup. Should get me 200 more RPM, right where the motor needs to be running.

    On order.
  • DanOmiteDanOmite Posts: 119 Deckhand
    Update:

    PTZ was just right. I can now rev up to 5900RPM trimmed out. I can also stay on plane with plate up and tabs down around 2900RPM. My hole shot is better and less cavitation during low speed turning. Better grip overall. Lost a few MPH on the top end but totally worth it for the extra power and handling. Trimmed out at WOT I am at 48MPH on GPS, good enough! NOw my engine is running at the proper RPM at WOT. Overall happy with the PTZ in 17P.

    Hope this helps to anyone with AC1890 with 4 stroke.
  • LeeWirelessLeeWireless Posts: 2 Greenhorn
    DanOmite wrote: »
    Update:

    PTZ was just right. I can now rev up to 5900RPM trimmed out. I can also stay on plane with plate up and tabs down around 2900RPM. My hole shot is better and less cavitation during low speed turning. Better grip overall. Lost a few MPH on the top end but totally worth it for the extra power and handling. Trimmed out at WOT I am at 48MPH on GPS, good enough! NOw my engine is running at the proper RPM at WOT. Overall happy with the PTZ in 17P.

    Hope this helps to anyone with AC1890 with 4 stroke.
    Do you have use your trim tabs to keep the 1890 from Porpoising with the PTZ4 at cruise? Can you tell me what your cruise speed/RPM? How does the prop hold in tight turns? Thanks...
  • DanOmiteDanOmite Posts: 119 Deckhand
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