[Roweje]

Today I did test runs on the current propellers that are on the boat. The current props are Michigan Wheel EPX 23x27 Nibral with a #6 Cup. When I purchased the boat, the original props that came on the boat when new were Michigan Wheel EPX 23x30 #7 cup, were under stored on the boat, however they were bent. I have those being repaired by the Prop Shop since no used in having bent props as spares, and I don’t know why one of the previous owners would have changed both the pitch and cup. Boat is 2007 3600 Open, QSB 5.9 380 hp, only 783 hours. 

So I thought I would do some test runs on the boat and get good data because I am thinking it best to put the original props that came on the boat back on it, figuring Tiara and Cummins new best when they chose them. Boat seems to run fine with these props, however would like others opinions.

I have attached all of the data on the current ones, hoping to get some insight from Tony and other experts on the forum.
I have my data with my props in the colored sections, and in the grey sections, I have the Tiara Performance Data they sent me for the original props.

I ran at all RPMs and measured, Furl burn, Boat Speed, Engine Load, and Engine Temps.
At all RPMs for the most part is burning less fuel, but of course the miles per hour is less at all RPMs and I assume it is because the pitch is 27 vs 30 and the cup is #6 vs #7.

It does go wide open to 3060 RPMs but the load is only 85%? 
Probably lower than what it should be, but maybe that is what the previous owner wanted.

I would be really interested in others opinions, on putting the original props back on, and should I expect my boat perfor,anc  to match the Tiara test data?

Thanks in advance, as I have read a lot of the knowledge on the forum.

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Today I did test runs on the current propellers that are on the boat. The current props are Michigan Wheel EPX 23x27 Nibral with a #6 Cup. When I purchased the boat, the original props that came on the boat when new were Michigan Wheel EPX 23x30 #7 cup, were under stored on the boat, however they were bent. I have those being repaired by the Prop Shop since no used in having bent props as spares, and I don’t know why one of the previous owners would have changed both the pitch and cup. Boat is 2007 3600 Open, QSB 5.9 380 hp, only 783 hours. 

So I thought I would do some test runs on the boat and get good data because I am thinking it best to put the original props that came on the boat back on it, figuring Tiara and Cummins new best when they chose them. Boat seems to run fine with these props, however would like others opinions.

I have attached all of the data on the current ones, hoping to get some insight from Tony and other experts on the forum.
I have my data with my props in the colored sections, and in the grey sections, I have the Tiara Performance Data they sent me for the original props.

I ran at all RPMs and measured, Furl burn, Boat Speed, Engine Load, and Engine Temps.
At all RPMs for the most part is burning less fuel, but of course the miles per hour is less at all RPMs and I assume it is because the pitch is 27 vs 30 and the cup is #6 vs #7.

It does go wide open to 3060 RPMs but the load is only 85%? 
Probably lower than what it should be, but maybe that is what the previous owner wanted.

I would be really interested in others opinions, on putting the original props back on, and should I expect my boat performance to match the Tiara test data?

Thanks in advance, as I have read a lot of the knowledge on the forum.

[Sapphire]

Not an expert but I agree with you.  The RPMs could be limited by a governor and thus you get to the max RPMs without 100% load and not overrevving.  I think this would explain the fuel burn differences as well. Try those 27 pitch once repaired and keep the 26s for spares.  Good luck.