Ski boom repair

Hi guys, the ski boom in my 73 Mustang is loose, the wood that supports it rotted out and right now has angle brackets supporting it to the stringers. I can replace the wood, but I was wondering if anyone has used the aluminum setup on the later boats, I like how it runs the lengths of the stringers and would be a lot sturdier.

Similar to this.
http://www.mindspring.com/~bwmitchell/Boat%20Pics/Nautique/Aug%2015%202.jpg

Oh I'm sure it could probably use new stringers. But the couple places I drilled into the stringers seems pretty solid still. The alignment I haven't checked, but I need to replace the shaft anyways since it isn't press fit in when I bought the boat. It was modified and has two bolts locking it in place. I'm looking into the dual taper, I just wish they weren't so much.

TRBenj wrote: Modifying the floor and stringer design to accommodate an engine cradle is certainly possible, but not a minor undertaking. Most people do not bother to make these changes unless undergoing full stringer and floor replacement.

Underline the part that says"not a minor undertaking"
I made my pylon mount and engine cradle separately. Certainly a major task.

pylon mount


engine cradle

chau8238 wrote: The alignment I haven't checked, but I need to replace the shaft anyways since it isn't press fit in when I bought the boat. It was modified and has two bolts locking it in place.

Phillip,
The two bolts you mention holding the coupling to the shaft, are they set screws like this:



If so, more than likely the set screws are original. Before the common practice of installing safety collars on the prop shaft, the set screws were used as a safety means. If due to misalignment the shaft and coupling became loose from fretting, the set screws where there to keep the shaft from exiting out the back of the boat.

I suspect your boat has or has had some bad alignment fretting the fit at the coupling and shaft.

chau8238 wrote: As for my shaft coupling, it has been modified some since there are nuts welded to it.

Modified? Not necessarily true. It was common to drill dimples into the shaft for the set screws to seat into. One method of dimpling was to press the shaft onto the coupling half, drill through the coupling wall slightly into the shaft and then the nuts were welded on. This way, drilling didn't disturb any pre existing threads tapped into the wall of the coupling.

Duane in Indy wrote: The same guy probably used nails for cotter pins too.   Surely you don't endorse that method Pete.

Certainly not to retain the coupling but as a safety, the set screws were used for years and years. My 1915 launch prop shaft had set screws running into dimples on the shaft. Duane, lots has been done through the years without the advantage of having a tool maker on board!!

What welded on nuts?

chau8238 wrote: It definitely has some hack job fixes on it. He used a cotter pin..... https://i.imgur.com/iUwk8q5.jpg

You are lucky that that cotter pin did not fly out.
Helpful constructive criticism:   Replace that cotter pin and install a new one it correctly.

Phillip,
I know you're not flying or repairing aircraft so here's a picture of the proper cotter pin install in a castle nut.



Long leg over the end of the shaft. Short leg clipped to fit laying flat on nut flat.

I know how to install a cotter pin, that's an old pic and it has since been changed. I'm just saying, he didn't use a nail.