Prop Shaft

[WESTERNAERO]

V-drive pros, explain prop shaft material, diameter, couplers, nickel/shim adjustments and anything else that might educate the masses.

[78Southwind]

How about Whip Struts? From what I have read some seem to believe they're useless.

[gn7]

V-drive pros, explain prop shaft material, diameter, couplers, nickel/shim adjustments and anything else that might educate the masses.

Bigger is better, safer and will last longer. The diameter will effect the lift of the boat as well as drag.
material is like hair color on women.
shims/nickles are crutches for strut placement. If you have to shim your shaft, it simply means you put your strut to far forward using Teague's one size fits all formula. Don't shim the shaft, don't move the strut, change the HP until its right, up or down.
If you have more power than a lawn mower, you use a steel coupler with a minimum of 5 bolts, 6 preferably if you have the room. I don't see the other side of this subject. Its like buying your shaft material off the rack at some metal supply house. They did decades ago, but we've come a little ways since the learning years. Some things are no longer intelligently debatable.

[gn7]

I think if the shaft, coupler, prop are running true there's no need for one. Bob????

I have found them very useful for tearing out the bottom of the boat where they were attached.

[steveo143]

The 2 most recomended and used shaft materials are Aquamet 22 and K Monel. In high HP boats I will only use K Monel. In my DiMarco 21 with a projected 2500 HP it will be getting an 11/8" shaft of K Monel. With the source of these materials coming into play because of all the cheap shit coming out of China, you have to be extremely dilligent when sourcing a supplier. At this year's Enduro there were 4 propshaft failures all new shafts and all from the same supplier. 3 were material failures and 1 was caused by a thrown propshaft blade. All were 1" Aquamet 22 shafts. There are only 2 K Monel manufactures and/or distributors in the US and their base material is sourced from China. The GOOD K Monel shafts come from Italy and are made totally in Italy but are very pricy at about 1800.00 for a cruiser length shaft. Cheap really if you are running a Grose prop!!!! Whip struts, forget about it! Drag boats, 1" shaft, K Monel if you love you're prop. BAF, BAH,BFH 11/4" at least K Monel. I had a strut failure in my DiMarco 21' going 100-mph with an 11/8" K Monel shaft that was off of one of Sonny's race boats orignally and after about 15 years running it. It tried real hard to router it's way thru the bottom of the boat but got everything under control and idiled the boat about 2 miles back to the ramp on the Delta. That shaft was only bent from the strut end back and I still use it today to bore propshaft holes in the bottom of new boats and the prop suffered no damage whatsoever!!!!!!! My 2 fingers are tired again, time to move on1

[Sharp shooter]

I've seen whip struts in K boats. Specifically Revenge race boats. Just sayin...

[Sharp shooter]

[78Southwind]

Interesting. I've had several say good things and several say bad things about Whip Struts.

[HotWater]

Two different style's of machines and tooling used to cut the keyway's pictured. Is one of them less prone to develop a crack at the end of the cut?

[HotWater]

I don't like either one of those slots. Both have zero fillet radius. My opinion, they should have .040 minimum fillets. But between the two, I would take the shaft cut with the endmill(bottom) less work hardening with this process. I feel the slots on the prop shafts should be cut with a ball endmill and the key should have the same full radius shape.

Thank you for the response. I've never seen key stock radiused on one side to match a ball endmill slot. Is that common stock? Can you explain to me what fillet radius is and the benefit of it?