Outrigger Flex-Shaft Drive Set-up

[David Bryant]

I'm setting-up a new 67/80 outrigger, I'm contemplating whether to use .250dia flex-cable w/.250dia stub-shaft all the way through? Or .250dia flex-cable w/.250dia step-down-to .187dia stub-shaft?

I already have custom-made .250dia Hughey flex-shafts with under-water Octura Flex Ferrule welded to one end (.250dia flex-cable to .187dia stub-shaft). I'm not sure if there are problems using under-water ferrule (servicing flex-shaft, etc.,...)?

Or is it just better and cleaner using "conventional" flex-shaft (welded directly to stub-shaft)?

I hear under-water ferrule provides security if flex-shaft snaps? But I'm thinking .250dia flex-shaft (welded directly to stub-shaft) should be robust enough?

 

[gil sonsino]

In my opinion "conventional" is better...... so keep it simple. Gill

 

[Rick Reisinger]

The positive of square drive is the prop is not pushing on the engine bearing's ......

Ball bearings do not like thrust load ~ Timken taper bearings is what we put in the front end of our

hot rod's because they were desinged to take lateral load.....

by putting a thrust bearing on the strut and loading it all your engine has to do is make horse power to spin the prop , not use up the power to compensate for the drag created from thrust load on engine bearings ....





Learned this one from Martin Davis & Jim Irwin ~~ 25 Years ago................

 

[David Bryant]

thanks for your input..........

Also looking for proper stuffing-tube brass tubing stock (for .250dia flex-cable). Is there thicker-wall stock available? (seems to bend nicer and provide additional strength), Or are most folks using just commonly found K&S brass tubing?

 

[Tom Foley]

IMHO use conventional flex setup for reliability and simplicity . Do not use a stepped down shaft in a rigger of that size swinging larger props or you will be buying shafts and props . My twin VAC 91 rigger originally had Mac 84's in it , been running it for 10 years and just put a set of shafts in it . You will not just break a shaft unless you have a major mis-alignment issue . Use a shaft oiler system and remove the shaft for cleaning and inspection after the weekend . Std .K/S tubing is very good stuff and very easy to work with .

KISS is a great system to employ !!

 

[MarkDanielsSr]

Was about to type almost exactly what Tom just said.

 

[David Bryant]

IMHO use conventional flex setup for reliability and simplicity . Do not use a stepped down shaft in a rigger of that size swinging larger props or you will be buying shafts and props . My twin VAC 91 rigger originally had Mac 84's in it , been running it for 10 years and just put a set of shafts in it . You will not just break a shaft unless you have a major mis-alignment issue . Use a shaft oiler system and remove the shaft for cleaning and inspection after the weekend . Std .K/S tubing is very good stuff and very easy to work with .

KISS is a great system to employ !!

thanks Tom and Mark. Looks like I'll most-likely be going .250dia all the way (flex-shaft/stub-shaft). Was looking to get some concensus.

Looking at a number of random available props (11.0cc to 13.0cc displacement):

Octura 1662 (.187 dia shaft)

Octura 1667 (.250 dia shaft)

Octura 1760 (.187 dia shaft)

Octura 1957 (.187 dia shaft)

Octura 2160 (.187 dia shaft)

Octura 2260 (.187 dia shaft)

Octura X462 (.187 dia shaft)

Octura X465 (.187 dia shaft)

Prather 255 (.187 dia shaft)

Prather 260 (.187 dia shaft)

Prather 265 (.187 dia shaft)

Most of these come stock .187 drive shaft bore. Are you guys boring the hub's to .250dia?

 

[DaveThynne]

Abc h-32! Is what most run

 

[Tom Foley]

Forget the X series props for outrigger app. The H- 32 , cut down 1667 's are great props . Stick with the full .250 shaft ,no reason to venture into props that have a .187" shaft in a hydro of this power range .

 

[David Bryant]

thanks

 

[shoboat]

David,

H-31, H-32, H-38, H-48, & 1667 would all be good choices.

Enjoy,

Mark Sholund

 

[David Bryant]

Will probably run, or start with, Picco P67 Marine w/Rossi drum-valve rear-end. Can use either Carl Brey exhaust throttle with Jet Ring venturi, or stock Rossi carb with conventional exhaust header.

Later may switch, or experiment, with Rossi R80 Marine.

This will be my first "big-horsepower" outrigger project. I've had this, and other, kit's stored in my garage for years, just getting around to completing. I've run an assortment of mono's over the years.