Need Help - boat is throwing blades like a ninja!
 

Looking for some help. I purchased a used 2007 42 Lightning - twin 525s and -2 XR Sportmasters - earlier this year. On our first dip in May, we sheared the starboard prop shaft completely off and lost a 5 blade labbed maximus prop. Today, we threw a blade off the brand new replacement prop on the starboard side which took a chunk out of the drive. We put a new one on the starboard side and then not even an an hour later, we threw a blade off the port side prop. We were not running in rough water, actually the water was probably the smoothest it has been in a long time, and we were running below 70mph both times.

Is there anything I can do to correct this problem? Has anyone else had this problem and if so, have you been able to correct it without losing speed?

Thanks in advance for any help!

send a message to TRL505 on here... I think he had the same problem a while back.

Trim height made a huge difference on my buddy's 42 PR. He was having the same problem and quit trimming the drives way up, no more thrown blades.

wow... expensive problem! good luck finding the way to fix this !

Sounds like you may be semi surface piercing the prop with the -2 shortie. Im almost sure that round ear Maximus props are NOT built to be semi-pierced...and the fact that they are labbed will make them even more susceptible. Check with Bblades or call Hydromotive. They make props that are meant to be semi-piercing. Do you know the dimension from the bottom of they hull to the center or you propshaft? This will give Bblades or Hydro a good idea as to what you need. You can also call Hering...big money..but bad azz props.

Good luck. Ive been in same situation with exact same setup as you have...very frustrating.

Thank you very much for the response. If you don't mind, I have a question. . . would the 6 blade Hering put too much stress on the stock prop shafts being that we already sheared one off this year and had to replace it? It also looks like there are already 1/2" spacers on the drives as well, would that make a difference? Should I be considering a different prop shaft as well? Up until the boat is trimmed at 4 it continues to pick up speed and any more than that it slows down. The first time the prop broke, it was not trimmed at all. We were just coming on plane. And that was the replacement prop from earlier this year that was not labbed. The second prop was labbed and we had the boat trimmed at 3 running in smooth water.

Not sure what to do but very discouraged and frustrated. What an expensive weekend and not going any faster than the old boat!!!! We even got passed by a pontoon boat idling back on the one motor. :o


Thanks for all of your help!

I have been there MANY times..I feel your pain. Honestly..it sounds like you may have some minor setup problems as well (drive height issues, prop selection, etc..). We tried to do the same thing you are doing for several years (self rigging) and had nothing but mixed results. I would honestly suggest you send your boat to RF Powerboats and have them "dial it in for you". We have our 42 there right now and they fixed all our problems we have been fighting for years in less than a few weeks. PM me and I can give you Lil Reggies number.

Surfacing prop blades and prop shafts experience bending as each prop blade enters the water and loads up, and then exits the water and unloads, on every rotation. This flexing leads to fatigue. Consider how you can tear a beer can in half after folding it back and forth a very few times. The prop shaft experiences the same flex, but instead of one cycle per revolution, one cycle per blade each revolution.

So its not necessarily what was going on at the instant the blade failed. The fatigue builds up over time.

If you look at the fracture, you will probably notice some black surface: that's where there was a crack, probably impossible to see with the naked eye, prior to the failure.

A small increase in blade or shaft thickness greatly reduces the amount of flex, and therefore the amount of fatigue. That's why Hering and other full surfacing prop blades are so thick.

Did you have the correct washers under the props ?

Thank you. We will keep that in mind.

Did you ever go to a 4 blade prop? Or lower the drives with spacers?

We have decided that we are going to call it quits for boating on the Fountain this summer and going to take some time to figure out what we are going to do.

The first time it threw a blade, the drives were all the way in. We were starting out and getting up on plane. The second time it threw a blade, we were running a nice, clean run, and the drives were trimmed at 3. Is 3 too far up?

Jimmy... stop beating yourself up for "running the boat wrong". It seems that in the 05, 06, 07 period Fountain got VERY aggressive with rigging these boats high. It nets a great number on the top end, but it's my personal opinion that it's pushing the limits of what a Bravo style setup and prop was EVER intended to do. Running these props and drives in a semi-surfacing application is simply pushing the envelope I feel. I know a bunch of people that have had the exact same problem as you. You have to remember that semi-surfacing applications CONTINUALLY load and unload components, including prop shafts and props. It's almost the equivalent of someone airing a Bravo boat out w/o pulling out of the sticks... that never lasts long. Inevitably the continual loading and unloading of the prop begins to fatigue the stainless, and eventually, sooner or later, there she goes.

I think your only options are to find a prop manufacturer (perhaps Herring) that's willing to understand that you are semi-surfacing this prop, and work with you on tailoring a set of props to meet your needs, or bury your drives another 1" or so and see what that helps.

Either way you split it... unload or slip a 5 blade prop on a Bravo/XR and eventually it's going to hook back up, and when it does the days are numbered for those prop shafts and blades.

Jimmy... all this is my opinion, and I'm sure someone in the "know" will step in, but it's a setup problem I've heard of on many of the later Fountains, straight from the factory it seems.

Thank you. We are perplexed at why these boats would come out of the factory with this setup knowing that is an issue. It's a little disappointing. So far since May we have replaced one sheared prop shaft and there is prop at the bottom of the Bay. Now we have two trashed Maximus 5 Blade props and still scratching our heads at the expenses this first year of owning the boat.

We are trying to figure out if we should change out the -2Shorties for -2 Sportmasters and move to a 4 Blade Bravo 1 and go through the uppers and make sure they are ok. It just seems that we would now be paying more money to downgrade the performance package on the boat. Or should we stick with the Shorties, add a 1" spacer and change out the prop shafts on both, fix the upper on the starboard side and go to Herrings. Just not sure what to do yet. I'm ok with losing top end mph. . . but I really don't want to loose cruising speed.

The performance, reputation, ride and speed of this boat is exactly why we purchased it. And now it seems that the only way to fix the problem, is to settle for less.

Jimmy, I may not be the man to ask, but I wonder how the boat would run if you buried the drive a bit and went to a 4 blade Bravo. You may give up some MPH on top, but deeper X and the fact that the 4 blade is far more forgiving may just equate to something sensible.

Should be pretty easy to try. I've always wondered how stock Bravos/XRs lived with 5 blades period.

I would talk to Reggie jr and then talk to Jeff at Hering , Hering does cast thicker blade based props for more durability and have a warranty .

+1....

Fountains DO NOT like to have drives run deep..they are not set up and engineered that way. The only reason why I know this is that Lil R and Reggie Sr. beat into my head when I was there. I agree with all that was said about you having the wrong props for the semi surfacing application you are running. However, I honestly think RF can fix your dilemma. There are dozens of FTNs running around with -2 shorties and Bravo XR's that are NOT smoking blades and shearing prop shafts...I would wager to say that the fix to your problem would be a pretty easy one..assuming you have someone look at it that knows how to rig boats. Good Luck!!

Had and outboard cat the was throwing blades like crazy, went through Mazco, Mercury and a very thick cleaver from Ron Hill.....bought a Hydromotive Quad 4 prop, it had a 1 year guarentee thought why not give it a try......prop ran for 4 years....no problems!