Prop shaft question

[rspecops]

This may be some really dumb questions. But I have learned a hard and expensive lesson. I have been trying to get my prop shaft coupling off for several weeks so I can replace cutless bearing, new flax in stuffing nut and shaft log hose. Finally gave up and cut the prop shaft. I discovered that on the prop shaft, on the coupling end it was threaded and a nut held it on the shaft. It was never coming off. I could not see the inside or transmission facing side of the coupling when it was down in the boat. I never read or saw anything that said the shaft coupling end was threaded. So anyway I am ordering a new shaft. Question is, since my engine has reverse rotation (counter clockwise) in forward does the new prop shaft I order need to also be threaded up on the coupling end or are all prop shafts threaded on coupling end and I never knew this? I have a Crusader 350 in an F 26. prop shaft is 1", does that require 1/4" or 3/16" stuffing or flax in the stuffing nut? Thanks for any help. I got to get the prop shaft and all back in the boat, been a bit of a set back on my reonovation.

[ready123]

Finally gave up and cut the prop shaft.

OK... is this serious?
Can't believe this is what anyone would do without asking others first

[jimbo36]

I would expect that your engine is Standard Rotation.

[larryeddington]

According to bob at beacon they used reverse rotation engines in signle screw apps, for whatever reason, he is not sure, they performed better. I am only passing this on as the messenger.

On the thread issue I did not know any couplers were held on with a shaft nut, I thought just press/set screw or pinch type couplers. I wrote an article n what I used to get mine off.


http://www.trojanboats.net/wforum/viewt ... ht=coupler

[Paul]

rspecops,

Not all prop shafts are threaded this way. Many couplers are a straight bore pressed onto the shaft with a key and set screws included. The set screws are typically wired together to prevent them from backing out. My F-26 came with this type of coupler. I have since replaced the shaft and coupler with the same type that you have cut out. Its my opinion that this is a better coupling system. The shaft is tapered, keyed and threaded. the taper lock created between the two by tightening the Nyloc nut, located in the counter bore of the coupler, is enough to harness the torque on the connection by itself. The key is insurance to eliminate the chance of the coupler rotating on the shaft. And yes, this can be used on a right or left hand application. The thread applies only linear tension to the shaft, its not there to take up any right or left hand torque.

As for the rotation, if your looking at the prop from the back of the boat your and it rotates clockwise for forward motion its a right hand rotation. A standard rotation engine is left hand rotation. I'm assuming here that you have an in line 1:1 transmission. Right hand prop rotation can also be achieved in these old boats with a left hand rotating engine if the boat has a V drive.

Hope this helps

[The Dog House]

According to bob at beacon they used reverse rotation engines in signle screw apps, for whatever reason, he is not sure, they performed better. I am only passing this on as the messenger.


http://www.trojanboats.net/wforum/viewt ... ht=coupler

A "normal" single screw inboard has a right hand rotation at the prop. This results in the boat prop walking to port when put in reverse. If the transmission is not reversing the rotation direction, a reverse rotation engine (right hand rotation) would be required to have the boat handle like the majority of single screw inboards produced. This is probably why Trojan used reverse rotation engines in the single screw inboards that were straight drives.

[rspecops]

Thanks for all the replies. Yes I will be dummy of the day for not asking about possibility of a prop shaft having a nut on coupling end. Not too big of a deal, new shaft for my boat going to be about $250. I will ask this now. I want to go with a new split type prop shaft coupling. Anyone got any opinions on the split couplings?

[prowlersfish]

I don't have any issues with the split coupling .

[Big D]

I don't have any issues with the split coupling .

+1

Reverse rotation engines were used in straight single screw applications (not just Trojan) to comply with standard prop rotation (right hand rotation). This was a standard set years ago for the marine industry. Part of the standard also dictated that in a twin application, the standard rotating prop would be on the starboard side. In a twin application, this setup also provides some riding benefits due to it's effect on how the transom rides in the water. In some racing applications, the rotation of twins is reversed, again to take advantage of the effect the rotation has on the transom (lift and lower) when in forward gear at crusing or WOT speeds.