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ENichols56

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Posts: 8
Reply with quote  #1 
I have been experimenting with different props on my rig since I mounted this new to me engine last summer.  It is a 1984 Grady White Seafarer with a 2007 250 ETEC (sorry i don't have the serial number handy) originally with a cut down transom, but now with a full transom and stainless marine full platform/bracket.  The bracket was mounted on the low side (by previous owner), so even with the engine mounted all of the way up, it was still too low, i.e. lots of water coming over the cavitation plate.  I tested four different props with it in this configuration (I know, I know, I should have raised the motor before prop testing).  I ended up liking the Rebel 15p the best. Recently I put TH Marine 5" vertical extension brackets on the boat and started it raised by 2.75" from where it was previously, but water still coming over the cav plate.  So, I bumped it up another 3/4" to a total of 3.5" above the previous mounting height.  There is still some water coming over the cav plate, but I hesitate to raise it any more as some blow out while trimmed and turning was starting to fringe on unacceptable in my book. All testing was with a light load of people, gear, fuel. Nonetheless, when the weather warms up and I have more hours testing with heavier loads I'll see how I like it. WOT is right at redline with a light load, so I think I'll be in the sweet spot with my normal, heavier load.  

With the motor in original (too low position) I tested the following props.  The first 3 were ones I could get my hands on easily before deciding to pull the trigger on the 15p Rebel.

- 19p viper
- 17p SST OMC
- 15p Stilleto
- 15p Rebel

Subsequently, after moving the engine up, i tested:

- 15p Rebel

Also in the midst of all this testing, I put a NMEA 2000 backbone on the boat and wired in my garmin gps so I can see fuel consumption.  I only have data with the 15p Rebel in the low position and the new high position.  Best cruise (~3700 rpm) went from 2.89 to 3.02 mpg purely from the motor height adjustment.  I don't have any fuel consumption data with the other props.  Previous engine was a carbureted 200 yamaha.  Great engine but routinely saw a best of 2.0 mpg overall.  All speeds and consumption are based on statute miles, not nautical. MPH vs RPM.jpg  Slip vs RPM.jpg 

stimpy

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Posts: 232
Reply with quote  #2 
Congratulations!

Seems you found the correct propeller and height for your boat and engine.

Sharing information like this is good, so other members can benefit from it.

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Silver Hawk 520. E-Tec 90 hp, E90DPLSRC, s/n 05071973, Powertech RED 17"
ENichols56

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Posts: 8
Reply with quote  #3 
Quote:
Originally Posted by stimpy
Congratulations!

Seems you found the correct propeller and height for your boat and engine.

Sharing information like this is good, so other members can benefit from it.


Thanks Stimpy, I'll admit I take more than I give to this forum, so happy to help out.
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