hwsii - TP prop discussion

[180shabah]

H - Your comments about TP prop on the other thread are interesting and I would like to continue the discussion, but I didn't want to completely hijack, so.

You said you have tested them on 9 different occasions, but with eratic results. I have only personally dealt with 3, and all three were originally equiped with merc's black max 3 blade. All three boats were similar, 18-19' bowriders with 17-20* deadrise. All three times the swap was beneficial.

With that said I am very curious to find the common denominator that lead to poor performance on your swaps. There are so many variables and I would hate to recomend it to a friend/neighbor only to find him be dissappointed. On your negative results, do you have data for x-dimension, exhaust routing, hp, boat installed on and what was the original prop it was being compared to?

 

[steelespike]

Re: hwsii - TP prop discussion

I read somewhere that a 3.0 I/O sometimes will struggle with a Hustler prop.
Don't know if its from too aggressive a selection or perhaps a mismatched power curve?Perhaps a boat that needs more than a 3.0?blah,blah.

 

[hwsiii]

Re: hwsii - TP prop discussion

Shabah, those tests were a long time ago, when I was trying to find a better aluminum prop for most modified vee hulls. At that point I was not keeping a database like I do now, and I don't even keep that information now, although I do keep up with manufaturer and model.

I am not saying they are bad props, but what I continue to see, even on here, is that one time the RPM will change as expected and then the next time the prop will act like it is 2" more in pitch, and drop the RPM accordingly, than what it says it is.

That is the reason I picked the Solas 4 blades for most of my recommendations, it is great for water sports and it always reduces prop slip considerably. It likes working at height and will work well on boats that don't even need stern lift.

On your negative results, do you have data for x-dimension, exhaust routing, hp, boat installed on and what was the original prop it was being compared to?

You know I always try and recommend raising the motor as a first step, so I am sure they work well at heights, I can say they were all thru hub exhaust and that all of the original props were aluminum. But other than that I don't have any data left.

Shabah, I have no ideas why this happens, it doesn't make sense to me now and it didn't then either. That is why I never recommend them, I know exactly what I can expect out of the Amitas, and that is why I recommend them. I believe you ought to keep on recommending the TP just like you have in the past, you have had good luck with them, I just didn't.

I can tell you that to the best of my knowledge there have been different configurations of the Black Max, but the only information I have on them right now is that they are regressive pitch instead of progressive pitch, and that means that the leading edge has a higher pitch than the trailing edge, which is just the opposite of a progressive pitch, that could be a major difference.


Here are the specs I have for aluminum Black Max's at this time, but the SS version of the Black Max has a 3" progressive pitch.

Black Max

H

 

[180shabah]

Re: hwsii - TP prop discussion

I understand the difference between progressive and regressive pitch, but what are the pro's cons of each design.

 

[hwsiii]

Re: hwsii - TP prop discussion

Shabah, the Black Max regressive pitched props are designed to create some drag by having the higher pitch on the leading edge all the way from the hub to the tip and the lower pitch on the trailing edge, this enhances the hole shot of the prop, but also lowers the maximum speed attainable because of this.

Progressive pitch has the lower pitch on the leading edge and the higher pitch on the trailing edge which creates a camber between the two, and thus enhances top speed. It may be a 17" on the leading edge and a 21" pitch on the trailing edge, thus the manufacturer normally states the pitch as being a 19" pitch.

I have looked on the site here and also found the same situations I have found with my tests in the past. The only semi logical explanation I ever came up with is that they mismarked the actual pitch of the props at the production facility.

H