PEERPSI

Before you get excited the picture of the GPS is kilometres per hour so converted its 50.125 using the rough figure of 1.6 kilometres per mile. This is a Proboat BJ55 with CC pro mod and aluminum powermaster 2" band. 7015/3 SS from Dasboata.

Still have a problem with the prop shaft strut setup though. Pretty much toasted another bushing again today. I did get the right material for the spacer though. No wear on that yet.

My crew helped out the best they could. Before anyone says anything I know I should have cut the grass before playing with the boat but oh well!

Dan S

Good for you Bud.

can you put a pic of your strut with the shaft and prop installed (side view).

Dan.

Justaddwata

My Feedback: (3)

Nice work. How much faster you going to get her going?

Good to see the pit crew on the job - cute

PEERPSI

Thanks guys, new goal is to get it to live up to it's name! After that the crew are barking about water skiing?

See attached. I think I figured out my problem with the strut. I was having trouble getting the new prop shaft into my bushings when the shaft was new. I tried to remove a burr at the end of the threaded part with sand paper. I suspect what I in fact did was cause a surface roughness problem that lies outside of the materials specs.

Also during my research I found that most of the readily available bushing material is designed for shaft speeds of 400 feet per minute. At 20000 RPM we are doing 1308 feet per minute with a 1/4" shaft.

thevirginian

PEERPSI,
It looks like you have some sort of washers between the strut and the drivedog. You should have about 4-6mm space right there. At hight speed the cable will twist and consequently get shorter. With washers you will bind the cable from shrinking.

PEERPSI

Square drive at both ends so the flex cable floats. The picture shows teflon washers from WHH but I now use a machine one piece plastic spacer.

Hesco Racing

I would chuck the proboat strut as it does not allow for a thick wall bush to be used. Buy a strut from Top-Secret or WHH or one of the reputable suppliers wich is going to alleviate so much of you head ache. I use a 9mmOD x 1/4ID x 10mm oillite bush on both sides of the 40mm strut I make and have shafts with well over 20 hours of race speed running on them. They have so little wear that you have to put a dial indicator on it to see movement.

That's some nice speed out of a Blackjack. Show some video of how she runs.

Regards

Cobus

PEERPSI

Actually the OD of the Proboat bushings is the same as the WHH ones. I used oillite as well to turn up some bushings but ultimately I think the surface roughness on the prop shaft is the culprit. I have a new strut on the way from WHH along with new prop shaft and two sets of spare bushings.

Now if I can just figure out why our lathe is causing 6.76 nanometres of roughness on these lenses........

You think boats are difficult, you don't know!!

dicko

I'd personaly ditch the plastic washer & get a thrust bearing between your dog & strut. It will free up the drive a lot & last a lot longer than any bushing.

Also do you pump grease into the grease nipple hole shown in the pic of your strut before each days running? You should pump grease into that hole until you see grease squeeze out each end of the strut. That will also help reduce wear.

Justaddwata

My Feedback: (3)

Going to depend 100% on what kind of collet your running. If your running a round collet then indeed you will need to compensate for cable shrinkage with torque. If your using a square collet however - you will see no additional load due to shrinkage of the cable.

PEERPSI

I've been applying spindle saver grease, it's supposed to stay in place despite the water and it's not supposed to fling off. I even tried a dry graphite lube.