Stuck...

Prop shaft , size length and where?

Marine Trader 1977 double cabin, 40 foot, stuck in Socastee North Carolina needing a prop shaft replacement. All I know is the shaft is 1 3/4 inches. Does any one know the length for my particular boat and a supplier? Thank you in advance

Find a boat yard with a good mechanic. He will direct you to a machine shop that can cut and finish your shaft- taper, keyway, etc. You will need a mechanic unless you are going to do the replacement yourself, so why not work with one to get your new shaft made?

In other words, you don't order a prop shaft, you get one machined to match.

David

I would pull the shaft and take it so it could be matched exactly.

apagano said:

Marine Trader 1977 double cabin, 40 foot, stuck in Socastee North Carolina needing a prop shaft replacement. All I know is the shaft is 1 3/4 inches. Does any one know the length for my particular boat and a supplier? Thank you in advance

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Wish I had a better answer, but I believe prop shafts are custom fitted for engine configuration. As a reminder, these boats were built in locations with very low labor costs. Close tolerance manufacturing techniques were doubtful to be a priority. If it were my Willard 36 built in California in 1970, I wouldn't trust the measurement of a sistership even if it were the previous hull number and had the same engine/gear. Just not how boats were built back in the day

Your best bet is to put a measuring tape on it.

Peter

Yes, you will almost surely have to measure the old one. I doubt that you could take someone elses boat and use theirs. You could easily end up 1/2” short, costly mistake.

Pictures show clearance on both ends of my prop shaft - not a lot of play especially since coupling on engine side and line cutters on prop side are not show Might have 1-inch give or take.....maybe.

Bottom line, if I were building a boat, prop shaft would be the last piece of the drive train I'd install. First, I'd mount engine and gear, then install/align the struts, and last step would be to put a measuring tape on it to see what length shaft I needed and machine accordingly.

Measuring tape is your friend here. There is no safe alternative.

Peter

Remember that you don’t want the shaft to be too long either. If, for example, you have a 2” diameter shaft there should be no more than 2” between the front of the prop and the back of the strut. No more than 1 shaft diameter is the most you want unsupported.

What is wrong with your present shaft? Many can be straightened. Pull it and take it to a shop, if they can't fix it at least you can get an accurate measurement.

pete

Pete Meisinger said:

What is wrong with your present shaft? Many can be straightened. Pull it and take it to a shop, if they can't fix it at least you can get an accurate measurement.

pete

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Right question Pete. Picture of my shaft being trued a couple months ago.

Peter

Rent a car. Drive up to Marine Machining in Myrtle Beach. They sell props and shafts and have onsite machining.

https://www.marinemachining.com/

Have SeaTow tow your boat to Myrtle Beach, haul out facilities are available.

Apagano, did you try the split coupling?

Pete Meisinger said:

What is wrong with your present shaft? Many can be straightened. Pull it and take it to a shop, if they can't fix it at least you can get an accurate measurement.

pete

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From his other thread.....


"Help please , advise needed quickly, i am presently cruising down ICW and am in South Carolina 30 miles north of Georgetown and my starboard prop shaft disengaged from transmission. Local mechanic informs me I need a new shaft and all hardware that goes with it. meanwhile He is trying to make a temp connection so I can steer and put my trawler in a better berth. The shaft end is worn down a couple of thousands of an inch and is slightly pitted. I am in need of advise regarding a full replacement, would I have any other options? Feedback would be appreciated. BTW my boat is a 40 Marine Trader with 2 lehman 120 engines. Thank You
Alfonse"

Apagano- I got your private message stating that the mechanic did not want to use a split coupling. But did not go into detail as to why. Go into more detail. It should be a decent fix to get you down the road.

I am moving to split couplings, put one on last winter and going to put the second one on this winter. They are much easier to get on and off. I don’t see any downside.