Ideal Prop Slip %
#42
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Joined: Feb 2007
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From: CDA, ID
I would just like to add a little clarity on this whole “New Bottom” discussion! We are in-fact “re-tooling” a new bottom for the 2009 Open Bow Thor only, not the current Thor. This effort is totally focused on the NEW 2009 Open Bow Thor and the modifications are directly related to the Open Bow version, not the current Thor! At Nordic Boats we will always strive to improve all of our products, and new versions with updates will add to our quest for continues improve; this applies to the entire company, not just one model or boat design! At Nordic we will strive to build the very best 100% wood-free Performance Boats on the planet!
The rumor was only partially true and I still say kudos to you.
Thanx for the clarification.
#43
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1.5 ratio, 6100, 89 GPS, 26 (25) Stock B1 was base # the boat came with.
1.5 ratio, 5800, 86 GPS 25 P5X in Havasu.
Standard height drive, prop is 4.5 inches below the keel of the boat. IMCO SC Xtreme (I thought I might have to much drive in the water but most everyone is about the same in terms of prop depth).
I was working down the path of the wrong gears , I.E. 1.34's because the slip actually pencils out at 12-13ish with a 1.34but I actually pulled the lower and confirmed 1.5's.
I need to spin 6100.... The boat usually runs in the 56 to 5700range with the 26.
1.5 ratio, 5800, 86 GPS 25 P5X in Havasu.
Standard height drive, prop is 4.5 inches below the keel of the boat. IMCO SC Xtreme (I thought I might have to much drive in the water but most everyone is about the same in terms of prop depth).
I was working down the path of the wrong gears , I.E. 1.34's because the slip actually pencils out at 12-13ish with a 1.34but I actually pulled the lower and confirmed 1.5's.
I need to spin 6100.... The boat usually runs in the 56 to 5700range with the 26.
#44
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From: CDA, ID
I'm late to this conversation, but your math is wrong. I've run the #'s you've listed and your slip is just over 10%. A fine slip # for any "V" bottom. Try a Merc. 26 Lab or John @ York propellers. 714-773-5444 He's responsible for 3 APBA Factory 2 Kilo records with our team.
The first # I posted, 6100 at 89 with a 1.5, was a stock 26 which some say is a 25. With a 25 that slip is 8.
But with that being said, the labbed 26 (bronson) I have right now is going to be the prop I use to test after I get a couple motor issues worked out.
More to come in the next week or two.
Thanxs,
#45
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The first # I posted, 6100 at 89 with a 1.5, was a stock 26 which some say is a 25. With a 25 that slip is 8.
But with that being said, the labbed 26 (bronson) I have right now is going to be the prop I use to test after I get a couple motor issues worked out.
More to come in the next week or two.
Thanxs,
But with that being said, the labbed 26 (bronson) I have right now is going to be the prop I use to test after I get a couple motor issues worked out.
More to come in the next week or two.
Thanxs,
#47
If you've managed to get your slip @ 4.5"s to 13.4% with a four blade, that's very efficient. You may not need to go any deeper. Great #s as always with the P-5X.
Have you run the blueprinted 28" P5-X? Based on these #s, it should be spot on.
Regards,
Steve
Last edited by Steve Zuckerman; 10-19-2008 at 09:02 AM.
#48
I spent all day Friday and Saturday doing back to back prop testing. Things were facilitated by Tim of OCM. We tested props at 4.5" depth (1 inch spacer) and then re-tested with prop depth of 5" (1.5" spacer). I have always felt that my boat (an open bow) didn't carry the nose high enough. Testing has now confirmed this, as going to a 1.5" spacer brought my speed up between 1.5 and 2 mph across the board. I was afraid that lowering the outdrive would drop my rpm's because of more prop bite and outdrive drag. Instead, the outdrive lifted the boat up more, thus reducing boat drag more than the lowered outdrive increased drag. The result is that I gained aproximately 100rpm on top end while reducing slip. At this point, the bravo 28 and the 30 bravo are both running 81.5 mph +/-. The 28 is just kissing the rev limiter at 5400, and the 30 is a little lazy getting to full speed. The 27 P5x is also just barely hitting the rev limiter, but is about 1 mph down across the board. Prop slip on the 28 Bravo is the most efficient of the bunch at 11.6%. My boat now has a more "nose up attitude" running across the water, and just plain feels better! At this prop depth (5" from keel to propshaft centerline), the 4 blade props are beating out the 5 blade props in both cruise speed and top end. The increased outdrive depth, decreased slip on the 4 blade props, but did not really affect slip on the 5 blades. The exception to this was when I tried Tim's 29 pitch, 5 blade, round earred, Herring. This prop was a little too big for my horsepower, but exhibited 9.8% slip. My cruise speed at 3000 and 4000 rpm went up 7 mph effortlessly. Top speed was 79.5 mph at 4800 rpm. This prop was extremely smooth in every way but the pricetag. My summation of this test is that open bow boats probably need more outdrive depth than the closed bow boats, in order to better carry the bow.
Special thanks to Nordic and Tim of OCM for making this testing possible by supplying props, outdrive spacers, and time.
NORDIC ROCKS!!
I will continue testing,
Thanks,
Chris
P.S. Steve, My son inadvertantly left the 28P5x Labbed prop at home and I was really bummed. I will be testing this prop, the next chance I get.
Special thanks to Nordic and Tim of OCM for making this testing possible by supplying props, outdrive spacers, and time.
NORDIC ROCKS!!

I will continue testing,
Thanks,
Chris
P.S. Steve, My son inadvertantly left the 28P5x Labbed prop at home and I was really bummed. I will be testing this prop, the next chance I get.
Last edited by CB-BLR; 10-23-2008 at 10:04 PM. Reason: Additional info




