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Posts: 2
| I just re powered my 1999 Tuffy 1700 GT Tiller with a 60 Hp Merc 4 stroke Command Trust Big Tiller. I have Terrova and Traxxis along with 3 group 27 batteries as my normal load.
I have had three different props on it so far and cant seem to find one that works good.
The first one was a 15p 4 blade Splitfire which was way too big and I could only turn about 4600 rpms at about 25mph.
Then he had me try a 13 Splitfire. With that the I was able to get to about 5300 rpms at around 28 mph by myself with light load/
Today I tried out a 11p Splitfire and I can easily blow past 6k rpms with out even trimming it out. 2 people full load. I could only hit around 25 mph at around 3/4 throttle.
The dealer told me it would make no difference in RPM going from the 3 blade Black Max form the 4 blade Splitfire. Merc doesnt seem to make a 12p Aluminum prop for this gear case.
Anyone else have something similar to this set up that can give me some advice?
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Posts: 265
Location: Manitowish Waters WI | I run a 11.5 aluminum on my esox mag with my 2009 60 merc. Played with pitch props from 10-13 and the 11.5 is the perfect happy medium. On my own I hit rev limit wide open at 6k and 31 mph. With a full boat of people and gear I can get out of the hole and still get 28 mph. 12 pitch I struggled getting out of the hole. 10.5 would rocket out of the hole but rev limit and only do 25 mph. Its fine tuning. Mercs website prop selector put my esox mag at an 11 pitch. |
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Posts: 1091
Location: Hayward, WI | 14X12 is available in a Vengance stainless steel prop. The Command Thrust units on boats can be pretty goofy to prop. Trying a 14x13 3 blade might be a good idea, some boats just don't like the Splitfire props. |
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Posts: 3480
Location: Elk River, Minnesota | Hiya,
I've been thinking a bit about this set up and assuming your boat alone is fairly heavy (I'm guessing around 1100 pounds or so alone?) The gear case on the motor I would say was a great idea...
with that in mind...looking at the splitfire propeller the design looks a lot like the OMC aluminum propellers, which in my humble opinion were never a great design, but served a large amount of people for overall running.
Going 4 blade I think is a great idea on this boat as well as the extra surface area of the 4th blade will definitely help keep the bow up a bit and still lift the stern and keep it on plane.
That being said, I am wondering if trying a 3 blade black max in a 15 pitch might not be a possibility. I would think they might have a few different diameter props you can try in the same pitch (not totally sure on that as it is dependent on hub size), but they do have a larger array of pitches to try as well. The black max is a bigger eared propeller, so you will still get decent bite, but more rpm without the 4th blade in the water. I'd say try a 15 pitch and a 13 pitch and see where things are from there.
When you test, keep the goal in mind to be at your max rpm with just you and your gear in the boat with about 1/2 tank of gas or so... By maxing your rpms at this load level, you have room to add people/gear without having to make a prop change.
Steve
Edited by VMS 9/13/2017 10:03 AM
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Posts: 2
| Thanks for the replies. I talked to the dealer and now I am trying out a 3 blade black max 13p x 14.
I am hoping this one works out and it seems like it should. I hope to get it out this weekend to test. |
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