alj

Hey... Perfectmix! get back to me Josh. I finally got the monster out on the water and the bugs mostly worked out. Started to get the rpms up on the new motors after break-in and just in time for the labor day holiday....BAM a whole new problem on the F402. On friday afternoon cranked the beast up and off goes the blade on one of the props. Boy ain't that an interesting vibration on a KAAMA drive. I have the kiekaffer three blade cleavers on this boat. They are 17 x 24 with 4" hubs. Out comes the boat 20 minutes after putting it in! Here's the best part. I borrow a right hand prop from my buddy Ron's F302 KAAMA. You all know what comes next, don't you? On the way up the chain to the sand bar on saturday morning, I open this thing up again. Bam....Ron's prop is now a two blade in need of some serious balancing. Heres the wierd thing. Both props broke at the same place near the hub. Both breaks appear as though the metal is fatigued at the thick point at the rear of the cleaver (trailing edge) and at the inside of the blade almost at the hub. Obviously these three blades won't hold up to the new torque and horsepower but this is ridiculous! Anybody have any history with these props breaking like that? These were the early speedmaster #3 short hub cleavers from what I can gather. Perfectmix, I would like to know how your conversion to 25 spline props went and what pitch and diameter you are running on your F357 KAAMA. The search for props is now on and any help from out there would be greatly appreciated. I have a local guy with small shaft Speedmaster #4 props that might be willing to part with them. They are 6" hubs and they are labbed to 16" diameter and 27 pitch. I'm not sure if the smaller diameter is going to make up for the increase in pitch though. I'm having trouble getting rpm out of the three blade 24 pitch props. I guess that's a mute subject now though! My biggest concern at this point is that I broke blades off two props on my port drive in less than one hour of running time. Based on what these two broken props look like and the fact that everyone that has seen them agrees that the metal looks poorly cast at the break, I'm praying I don't have a drive problem.....aka-a vibration that sets up a harmonic in the prop a certain rpm. Even with the three blade props on there the drives seem to be very smooth. Until the prop lets loose of course. Any ideas out there?????

Audiofn

How did you come out of the hole? Hammer down or power on slow?

Jon

Perfectmix

alj
Man does that suck!! You just brought back some bad memories. The word "interesting" is an understatment to describe that nasty vibration.
If I remember correctly you were installing new 540's in your 402. I was wondering what ratio your trannies and drives are. I am suprised that you are having trouble spinning 17"x24p three three blades. My 357 has spiced up 420's I spin a labbed 16.5"x26p 4 blade 5300. My trannies are 1.54-1 and the kammas are 1-1. I have set of 17"x28p small shaft 6" hub 4 blades that you are welcome to try if you would like. I can't spin them with my wimpy 420's. As far as the adapter from small to large shaft. I have been using one for a year and it is working great. It adapts from the older 19 spline small shaft to the 26 spline large shaft I think they are #6 ssm props on my boat.
I bought them from Earl Lanier @ Lanier Marine in Florida. He also has a large selection of ssm and Kiekaffer props in stock. He was easy to work with.

Sounds like plain bad luck to break two props in one weekend on the same drive. I would think you would notice a serious vibration before the prop snapped if there was something wrong with your drive. Probably would notice some oil leaking past prop shaft seal if you had a shaft bent.
Before you purchase new wheels have them flux checked for hair cracks.
Give me a call if I can help 989-350-8444

Josh

alj

Good morning guys! Well, I bring it on plane by applying power up to about 2800 to 3000 RPM initially. This spins up the props (almost blows them out) but they grab in only about 10 to 14 seconds and the boat planes off. Time to plane seems much faster than my buddy's F302 KAAMA. When I bought the boat the previous owner had changed the drives to spin outwards. I had a hell of a time getting the boat up on plane with these same props but the top RPM was much higher. I changed it back to the stock (turning in rotation) and it comes up on plane very nicely. When underway it really seems that the boat is straining to reach 4000 to 4400 RPM. But then....10400 lbs of boat, 600 lbs of human beings, 1200 lbs of fuel......this thing is a beast. Add 40 % more horsepower and Houston; we have a problem. These broken props have a spot at the break that looks almost like a void in the casting. In the thin areas of the blade and in the leading edge of the thicker rear portion of the blade, the blade broke off and left a very jagged edge. It looks like what you would expect a piece of broken stainless to look like if ripped apart. The very leading edge of the blade (the thinnest part) is even twisted a little like the blade hung on there the longest. But there is this spot that looks like a half moon that doesn't even look like it was connected. It almost looks like when you break a crystal or glass or cast aluminum or something like that. Now that this metal is exposed to the air, the area that is like a void is actually oxidizing or rusting as well. The other, more jagged areas, are staying the same color as normal stainless. Its like the crappier metals in the alloy separated out and migrated or concentrated in the thickest areas of the blade where you need it to be stronger. I'll try to get a few pics to post.
Josh, what props were you running when your prop let loose? If I remember you had the Compu-tech KAAMA props on. Those are 6"hub props aren't they? My concerns now are about what is going to work here. Is going to a 27 pitch prop or even larger going to cause even more rpm problems and can I fix it with a smaller diameter? I.E. do I jump up to the 27 pitch but reduce the diameter to like 16" get my rpm's up? What a pain in the keister! Hey josh, did you like the adapters? Do they seem beefy enough? How much were they? Large shaft props do seem more plentiful but not much cheaper in price necessarily. At least you see them for sale consistently. I'll check the drive and trans ratios and get back to you guys. Has anyone ever heard of the kiekaffer/ mercury props having casting issues or for that matter, breaking blades off? I was surprised to see that a number of guys had problems but they all seemed to be on KAAMA boats. Anyone hear of prop problems on speedmsters? I really don't feel this is a drive problem. Everything is very smooth until it breaks. Interesting coincidence though. All the guys that have broken blades off have almost the same set of circumstances. 4000 rpm or higher, running about 50 mph or so, drives and props under higher torque loads (accelerating). Obviously these are circumstances that would lead to a failure but nobody seems to have problems while running wide open speed wise or having the hull or drive leave the water and then re-enter. Do the big horsepower boats and the race boats have these issues? The constant entering, leaving, and rentering the water that a surfacing prop must endure has to be tough on them. Anyway, good to hear from you guys. Thanks........Al

Iggy

I'm no expert, but aren't surface piercing props under a lot of stress?
I thought I remembered reading that the props should be inspected regularly for stress cracks. Possibly even X-rayed for internal stress fractures.

Just my .02

Perfectmix

alj:
I broke my prop on a re-entry. Just barely came out of the water for a split second and bang. I had the original kaama 4 blades 16.5"x26p 6" hubs. I broke the port side. I purchased the ssm 17"x28p thinking I may be able to get by with these but to my dismay and $2500.00 later, they didn't work. I stumbled upon a set of 17" x 26p ssm #6 props bought the adapters ($300.00 per side) and I had an alright set up. I could only spin these 4900 so I sent them to Houston Prop and told Darrin what the deal was. He labbed them to 16.5" and did what ever else it is that he does and now I spin 5200 consistent. 67mph on calm water. Can't wait to get into some chop and gps this thing. It is a big hog to move with little 420's. It seems that every .5" diameter = 200-300 rpms. I would think that the 28's would be too much if the 24's spin hard. Must be some grippin 3 blades. You are welcome to try them if you want. The adapter sets are very nice looking. Beefy? yes! Easy?yes. The large shaft props are more available and you can actually find them used in good shape. I have talked to a number of guys with ssm drives that have had this problem. They all say; when its time its time. no real explanation for it. Just fatigued metal. Good Luck:

Josh

bford1

alj -

Sure sorry to hear about your troubles with the props. I know it doesn't help much but I can feel your pain.


Brent

alj

Hi guys,
Josh - thanks for the info. I'll try to call you tomorrow. I've got a few questions. I am going to attach a couple pics here. One is of the rig on it's way on friday to stress test inferior propellers. Next is our beloved logo's on the 402. And then the scientific results of the testing done on friday and saturday. Note the half moon shaped area in the thick part of the blades. And Brent, My pain I think is just beginning. Seems as though I'll be bending over real soon when I figure out what will be the new wheels to stress test on this pig. Got any K-Y? I hear the warming K-Y feels real nice! Here are the pics guys.........

alj

Here are the prop pics.....

cuda

When I read your post, that exactly what I thought. I couldn't believe that both props had a casting problem in about the same place, but after looking at the pictures, that's what it looks like. Did you have the original Kamma props when you bought it?