Prop Blade Breakages
 

Need some advice please. I have a 28 Daytona with twin 710 Vipers imco SC drives with 3 inch shorties with a 1.34 ratio. I can not keep blades on the starboard prop and once in awhile a port prop . I have tried props from most of the mfgs on this forum and they all have been great guys to deal with.
I need to run a 36 to get mph which is 136 to 140 depending on the prop mfg but I get up to speed once or twice and it throws a blade since it has become a surface drive with the short X. Once it took the lower with it and another time it took the 11/4 out shaft with it which i have the 17/16 shafts now and that time it pulled to the port side hard and did 3 360s at 130 mph on the starboard nose which was awesome for the other boaters to watch and we didn't lose any passengers. I cant keep a lab prop to last at all which makes sense due to it being thinner a stock 34 B1 will last a weekend and i haven't broken the stock 32 B1 that i have on now but slows me down to 122. I have tried 35 five blade hydro motive but took along time to get up on plane and forever to get to speed of 136 and the slip was great at 11% but made the back end loose at speed. I might send my five blades back for some 33s. Any advice other than lowering the drives.

Probably not what you would want to hear, but might want to consider upgrading drives so you can run speedmaster style props.

I dont think that any of the custom prop manufacturers can cast a thicker bravo style prop. Doesnt hurt to ask though.

Another thought would be to lower your drives a little, maybe keep some more prop in the water.

I talked to Hering and they said they can make me a prop with a thicker base on the blades. They need to be custom made due to my 1 7/16 output shafts all there B1 style props are for the 1 1/4 B1 shafts. Kind of spendy but might be worth it if they last.

Have you tried Cutting Edge Propellers yet? They cast their own from scratch so they are quite a bit stronger than a modified bravo or maximus. They also have the capability to make a bravo style prop with an effective pitch of 39 with a clever style blade shape....

I talked with Greg about my problem and we decided that with my high X that i would have the same problems with his.

Lowering the drive is a best bet option.

Thickening the root if done by Hering is a good option if the blades are letting go at the root. If they are throughing less than the entire blade, the Hering mod will not help.
If the blades are leaving at the root, you certainly do not want a propeller made by some one who welds on blades (be sure they actually are one piece casting. Some guys claim to have 1 piece castings but we know they are not.)

Labbing does not have to mean thinning the blades. Trueing or blueprinting the blades is the best option. If the P5X's are staying together, have them blueprinted and adjusted to get on plane better. We can do this if you desire.

With your application, forgings would be best, not castings.

Brett

They all break a inch or so from the base.
I will call you next week about the p5s. You might remember me I am the guy from Arizona who kept calling last summer and I can't rember if I bought 5 or 6 blades from you they all were high quality I just wish they were unbreakable.

This prop number 13 that I broke on Sat. This is the same spot every time this is a stock 34 B1 RH on the port drive. This has less than 10 min of use and broke at about 125 mph or so.

I think 33 hydromotives would be a good option as they are made to surface.

Anyone make adapters to adapt a speedmaster prop to that imco shaft? Not sure how it would run with a small hub prop but the outboard guys run small hub props all the time. Cut down speedmasters would most likely hold up.

That pic pretty much says it all. :cartman:
If they break that quickly, stress is a HUGE problem.
I think forged is the way to go or you'll have to drop the drives. Even after dropping the drives, I think you'll continue to have problems with breakage.... just be able to run them longer before they let go.

Tim Bostic,
Hoss Marine Props

Thanks
Who makes a forged prop that fits the 17/16 IMCO shaft with out spending 25K?

I got my new props from Hering last Thursday and tried them out over the weekend. Jeff did a great job with his recommendation on what to use, which was to use their B1 style 32.5 pitch with a thicker base on the blades and since I have the 17/16 output shafts they had to machine out the 1 1/4 splines and weld in the 1 7/16 spline inserts. They hook up great 132mph @ 6200 rpm that's like 7% and I never got better than 12% from any other props before. The best part is they lasted for three days and yesterday i went 11 miles at 130 mph with the trim set at the sweet spot where before the props would last maybe two minutes at that trim angle. They were twice the price of any other props, but the appearance alone made them worth the extra cost.

Sounds like you got the right set of props for your application.
11 miles @ 130 mph..... 5 minutes of running...... WOW !!!!! That's Cool !!!!

Tim Bostic
Hoss Marine Props

I know 5 minutes big deal:lolhit:

No.... Really..... I think it's cool !!!!!

5 minutes of running but you end up 11 miles away !!!!!!

........ COOL !!!!!!!

Tim Bostic
Hoss Marine Props

and you could actually make it back at 130 lol, congrats on solving the problem

Hydro-Motive is supposed to have a super strong alloy, have you tried them?