Propeller reconditioning

[Ron Hill]

Noah : Unless Bob has "reengined", he should have a M25XP engine with a Hurth 50 Transmission.

A thought

[Bobg]

Thanks Ron, yes I have the 25xp with the Hurth 50.  it is a 2;1 reduction, using a handheld laser  with reflecting tape on the crank pully and output shaft on the tranny, I read 50 RPM low at all speeds, i;e at 2000 rpm, I get 950 on the transmission shaft, never did check it before my prop re pitch, 50 rpm below half rpm probably not enough to reflect that much speed loss, can't turn the prop by hand while on the hard in gear, (one of the tests that was suggested to do on the tranny)
just wondering if its a possibility that a over pitch prop can cause the transmission to start slipping.  Is it something to consider when re pitching prop?

[Breakin Away]

My spec sheet says Hurth 50 is 2.05:1 ratio. If correct, that accounts for half your discrepancy.

I'm not an expert at this, but I can't imagine turning over the motor by turning the prop (especially at 2:1 nominal ratio) unless you have a compression release lever, and I don't think Universals have those, do they?

[Ron Hill]

Breaking : FYI, both the M25 & M25XP have compression release levers!!

A thought

[Noah]

Ron— curious did you or anyone  every successfully try to hand crank one?

[Ron Hill]

Noah : Don't know about the hand cranking, but I do know of someone that had a low battery start.

He hit the starter spinning the engine with compression release lever open and then closed it - causing the flywheel to continue to turn and it started the engine!!!
He's the same guy that showed me how to by pass the starter solenoid, by laying a long screwdriver shank on the threads of the starter  solenoid and then touching the engine block.  The starter immediately turns the engine over - don't leave the screwdriver on the block for more than a second!

He was an older gentleman ( had an early 1986 C34 M25) and was a line chief on B17s during WWII. 

A few thoughts

[Breakin Away]

BTW—C34 struts are "replaceable", albeit a big expensive job—it is thru-bolted, bedded, and glassed in. I just replaced mine in Oct. and coached another fellow C34 member on the east coast who had to replace his just a couple of weeks after mine, due wrapping a line around his prop and it torking strut causing cracking/leaking at hull joint. That photo is of my NEW strut. My situation for replacement is another story saved for a later write-up

Hope you never need a strut but Catalina Direct sells the replacement strut and has a factory install diagram on their site as well..

.

Just curious, since it is through-bolted, what is the bolt material? That might affect my selection of anode material for the strut.

As I mentioned previously, my boat is currently protected by zinc anodes, but I am considering switching to aluminum, since our ever heavier rains in the upper Chesapeake have reduced the salinity level significantly over the last couple of seasons. If we get a drought, the aluminum will still protect, it just won't last as long. But since I haul out every winter, it should last through the season and provide better protection. It's just a pain to find every one of the anodes in Al, especially the HX pencil. What do you other guys north of the Chesapeake Bay Bridge use for anode material. Zn or Al?

Finally, regarding my prop work, Atlantis has had it over a month but not done yet. He likes to do all the sailboat props in one batch because he has to change the machine to accommodate the smaller hole size in the props. I told him to check, clean, and true it up, but not to adjust the pitch at all. I want to re-verify my full throttle RPMs with a strobe this season before making any change in pitch.

[Noah]

The strut and bolts are silicon bronze.

[Bobg]

Ron..I'm.curious on what you meant on starter solenoid threads to engine block via a screw driver shank..do you mean the battery positive post on the solenoid then touch the engine block?

[KWKloeber]

Bob

To bypass the solenoid switch you bond the two large threaded terminals together. The upper being the input to the solenoid ("B post"; battery cable) and the lower being its output to the starter motor.



If you bond "B" to the engine it's a dead short and will probably weld the screwdriver tip to the engine.

To bypass the start switch you bond "B" (or any power source) to  "S" (the 1/4" quick disconnect terminal.)