Pro Max on heavy boat?

[Marshfly]

The two props I run on my boat have been a 23" Turbo TXP OT4 and a 24" Pro Max. Well, last weekend I broke about a third of one of the blades off of the ProMax. On closer inspection the adjacent blade had a nick in the same spot that would catch your fingernail and looking at the separation, you can see where there was a crack that then tore the piece off by the abrupt change in direction and color of the metal. We had done a high speed run and then about 5 minutes after slowing down to about 45mp[h felt the engine get loose which is when I assume it separated.

My boat is fairly heavy but because of the stepped hull has significantly less drag than other boats it's size once on plane. My question is this. Is it possible that my boat is too heavy for the Pro Max and surfacing it is putting too much stress on it due to the weight of the boat?

I'd like to know before plunking down the cash for another one. I really like the prop when I am bass fishing and especially in the winter because it has significantly better economy then the OT4 and is faster.

If it's just not in the cards, I'll just get a 24" OT4 for my winter light load prop.

[Cajun Pop]

It would be interesting to see how a Rev 4 works on that boat since they are recommended for stepped hulls. On a bass boat it gives great hole shot and midrange and lifts the entire boat.

[21XDC]

I would try a Rev4 if they made taller pitchs than 25... The holeshot on a heavy boat and promax prop may over vent and surge too much for a good choice... I with they made a promax on a larger diameter and full size barrel.

[Marshfly]

I would try a Rev4 if they made taller pitchs than 25... The holeshot on a heavy boat and promax prop may over vent and surge too much for a good choice... I with they made a promax on a larger diameter and full size barrel.

I'm worried the Rev4 won't be enough prop. If I get another Promax, it will be a 25 beacause I'm able to 6100 with two guys on the boat with the 24.
I'm pretty sure a 25 Rev4 runs considerably smaller than a 25 Promax but maybe not.

I'm really asking if my heavy boat contributed to the cracked blade or if it was a freak accident due to a microcrack from the nick. I don't want to by another expensive prop and have it break in 6 months.

[Savage]

I don't think that Promax prop cares how much a boat weighs..........Weight didn't cause the prop to fail!

[Marshfly]

I don't think that Promax prop cares how much a boat weighs..........Weight didn't cause the prop to fail!

That's what I think too, but in the back of my head I know that the stress from a surfaced prop blade going in and out of the water can only be greater with a heavier boat.

[linesider 159]

Don't mercury props have a 1 year warranty for manufacturer defects? Seems this would apply.

[Marshfly]

Don't mercury props have a 1 year warranty for manufacturer defects? Seems this would apply.

It was bought secondhand.

[Savage]

It was bought secondhand.

A second hand prop already has some wear and tear, which increases the odds of some type of fatigue failure. Buy new this time, with warranty.

[Marshfly]

A second hand prop already has some wear and tear, which increases the odds of some type of fatigue failure. Buy new this time, with warranty.

The prop had one hour of run time on it when I bought it. It was as new.

You must have missed the part in the first post where I stated that it had a nick that looked like it propagated into a crack which then tore off. No one should warranty a crack due to damage and I wouldn't expect them to. I also never stated how long I'd had the prop so I'm not sure where the warranty comments came from.

Looks like there are zero comments supporting my fear that hull weight has any bearing on propensity of a prop to crack so I'll be ordering another one, just in 25" this time. Thanks guys.

[linesider 159]

The prop had one hour of run time on it when I bought it. It was as new.

You must have missed the part in the first post where I stated that it had a nick that looked like it propagated into a crack which then tore off. No one should warranty a crack due to damage and I wouldn't expect them to. I also never stated how long I'd had the prop so I'm not sure where the warranty comments came from.

Looks like there are zero comments supporting my fear that hull weight has any bearing on propensity of a prop to crack so I'll be ordering another one, just in 25" this time. Thanks guys.

I got the idea it was less than a year old from this: "

I don't want to by another expensive prop and have it break in 6 months.

"

Regardless, I don't think boat weight had anything to do with it, and odds are you aren't truly surfacing that prop since you have a sho and they can only run so high even with the low water pickup.

[Marshfly]

I got the idea it was less than a year old from this: "

I don't want to by another expensive prop and have it break in 6 months.

"

Regardless, I don't think boat weight had anything to do with it, and odds are you aren't truly surfacing that prop since you have a sho and they can only run so high even with the low water pickup.

Ok. Haha sorry about the confusion.

The prop is running higher than you'd think. All the way down on the jack plate, just on plane, the cavitation plate is about an inch out of the water. I can hear the blades surfacing at all speeds no matter the height of the jack plate. I filled in the top half of the intake grates with epoxy and can run the jack plate at 4" plus at full speed now with full water pressure. They should come that way from the factory. I get better water pressure at all heights and speeds now. I run between 3 and 3.5 on the plate for a max speed run.

Linesider, if you haven't had a chance to really play with a YF21 propped right, you'd like it. These boats are fast. I can almost hit the limiter at 72mph with another guy on board with the TM and a gps on the bow with that 24" Promax and this boat is almost 22ft long. It would be mid 70s with the right prop. People have done 76+ with the SHO on this boat. Bigger than a BCB Jaguar. Faster with the same power too.

[linesider 159]

Ok. Haha sorry about the confusion.

The prop is running higher than you'd think. All the way down on the jack plate, just on plane, the cavitation plate is about an inch out of the water. I can hear the blades surfacing at all speeds no matter the height of the jack plate. I filled in the top half of the intake grates with epoxy and can run the jack plate at 4" plus at full speed now with full water pressure. They should come that way from the factory. I get better water pressure at all heights and speeds now. I run between 3 and 3.5 on the plate for a max speed run.

Linesider, if you haven't had a chance to really play with a YF21 propped right, you'd like it. These boats are fast. I can almost hit the limiter at 72mph with another guy on board with the TM and a gps on the bow with that 24" Promax and this boat is almost 22ft long. It would be mid 70s with the right prop. People have done 76+ with the SHO on this boat. Bigger than a BCB Jaguar. Faster with the same power too.

Never gotten to play with one honestly, although I wanted to. Plugging the intakes is interesting, that's an old merc trick!

Id like to try a promax on my boat but haven't had the chance

[Marshfly]

Last time I ordered from SIM Yamaha I threw a spare set of grates in the cart and then followed this thread and loved the results.

http://www.bbcboards.net/showthread.php?t=821456