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-   -   Prop & boat pairing - tomorrow's the day to see how we did (https://www.offshoreonly.com/forums/active-thunder/340858-prop-boat-pairing-tomorrows-day-see-how-we-did.html)

scottgjerdingen 09-01-2016 10:00 AM

Please excuse my ignorance, I only started maintaing my AT 2 months ago and I still have a great deal to learn - what is a running gear? I google it and it appears to be the shaft the prop sits on? Most pictures I saw were of inboards. If this is correct, what does pulling it mean? Also, when I searched on it there was a lot of conversation surrounding painting it with anti-fouling paint...whatever it is, why the heck would I want to do that?

Gary - I'll check it out, thanks! Do you think I can spin these properly or are they a bit too much?

I just love and appreciate all the help you can get here on OSO!...especially in the AT forum :-)

Griff 09-01-2016 12:00 PM


Originally Posted by scottgjerdingen (Post 4477395)
the drives are 1.5, I am certain of this.

I sent the vendor who made this recommendation and sold me the props an email making them aware of this feedback and a few other things. I also will be calling them today.

When I purchase these I did inform them that this was a 1.5 with HP 450's. I get the vendor is probably not as knowledgeable of the boat than you and what others are running, but is it reasonable to expect that they should have at least come a bit closer to what you guys are suggesting?

One other follow-up question. Does this statement - "Chances are they have rubber hubs and thus the 350hp rating" in response to my question about what this rating means, does this imply that I am going to spin the hub? If not, what are the implications of this?

Thanks again!

Its possible the hub could spin, but not likely. I run Merc delrin plastic hubs in my props and they are also only rated to 350-400hp or so. I have only had one go bad in 7 years.

I would try and return or exchange the props you ordered

Griff 09-01-2016 12:04 PM


Originally Posted by phragle (Post 4477434)
BBlades will get you close and send you props to try before purchasing them....... for MUCH less than cost of collecting shiny stainless shelf sculptures..

He really shouldn't need to test. The 28 Bravo's should be very close. Get them labbed by BBlades after they have been run and tested for a while.

scottgjerdingen 09-01-2016 11:16 PM

1 Attachment(s)
I talked to the prop vendor today and they were extremely cooperative. What I was asked was to test out the props which was more than fine with me, this at least would keep me from being propless for the holiday weekend. I also learned of a 2 week trail period with any prop so working with them we would collaborate in a method to arrive at a very reasonable option. I really do believe in supporting local business and especially now that I know that they will really work to make me happy and test a few options. I've also purchased a few props from then and never had an issue not landing where I wanted to be. The have as cupped an lathed a couple props for me to and I was quite pleased. I have no doubt BBlades would nail it but I am half way down one path and I would feel uncomfortable abandoning the process at this point in time. If I am unhappy with the results,nextstop absolutely will be BBlades!

So I put the props on this afternoon and went for a spin. I had a few things working against absolute top speed, but now I have numbers. Things working against max speed; the hull, drives, tabs are all filthy with a nice thick layer of algae, boat was heavily loaded i'm extimating a good ~2K+ - way overloaded with tools gas, water, cooler, cleaning supplies, etc. I also think my trim needs adjusting. When I put the props on I noticed one raised up more, I don't think either went up as high as they possibly could or where I wanted them, one last thing, Lastly, I didn't have much time to get to a larger part of the lake and the bay I was in was probably no more than roughly a 1 mile runway for me to play in.

So, here are the speed/rpm numbers I captured (speed is GPS) and Gary was nice enough to compute slip for me. Slip look a bit odd and my wild theory on this is that for each speed recorded I took a pass down this runway are. Starting slow and on each subsequent fun increasing speed. My theory is that the decreasing slip at higher speeds could be from @ higher speeds may be a function of the algae and zebra mussels wearing down on each pass? :-)

[ATTACH=CONFIG]558983[/ATTACH]

I checked the top of the airfilter and it said max rpm 4800 - 5200

the fastest & wot run I believe could have seen the rpm continue to rise given a longer run. I say this based on a relatively slow to climb to 47-4800 rpm and it was starting to move to 4900 rpm when I ran out of safe water to run in. At that time I fumbled my gps reading while turning, trimming down). I don't think that reading would be significant anyways. I need to re-do this in a bigger part of the lake where I can stretch this out @ WOT until it levels off.

Myself, I was pretty pleased because I believe it can get a bit more with the removal some of the "baggage" I ran with (mentioned above) and a larger pitch prop. My slip numbers looked pretty good when I got closer to & @ WOT.

SO what does this mean to my tasks ahead and what actionable items come from the findings from this test?

Thanks so much!

Griff 09-02-2016 01:51 AM

With the trim cables adjusted properly, you can trim out to 8-8.5 on the indicator for max speed.
That puts the drives at max safe recommended angle for the u-joints per Merc.
Tabs all the way up at WOT, but really I see no speed increase at anything higher than 3 on the indicators.

Exactly what brand/make are those props???? The slip numbers are very low.
My slip numbers(around 12%) are lower than most 32's because I have ext boxes. Your slip numbers are crazy low.
Most 32's run slip%'s in the mid-high teens. Your boat could also have a deeper X dim since its a 1996 though.

ActiveThunder 09-02-2016 09:06 AM


Originally Posted by scottgjerdingen (Post 4477372)
Side note - What does HIGH ASPECT RATIO X-CUT GEOMETRY mean? - scott -

Something your boat does not have. Look at 3 blade Mirages.

DBleil89 09-02-2016 09:29 AM

^^^^^^^^^ that's the man I would listen to. He knows that boat as good as anyone I would imagine

LOTOWONTOPGUN 09-02-2016 10:09 AM

Things working against max speed; the hull, drives, tabs are all filthy with a nice thick layer of algae,

Your cracking me up.
Your funny.
Maybe your top speed should be to clean the hull first.

GLENAMY 242SS 09-02-2016 11:18 AM


Originally Posted by ActiveThunder (Post 4477820)
Something your boat does not have. Look at 3 blade Mirages.

As I understand he is having GlassDave re do the transom over the winter maybe something he should consider, after removing sea monster hair from wetted surfaces of course.

camptappakeg69 09-02-2016 08:34 PM

Zebra mussels and algae on a go fast...........that poor boat:eekdrop:


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