Broken shaft

[Markv]

I felt vibration in my 2000 28' TE with 370 Cummins while cruising at 2400RPM (20 knots). I slowed and reversed to potentially clear the prop. When I put the transmission back to forward, I had no propulsion. When the boat was pulled, the shaft had broken. Anyone have an exact spec on the prop for this boat?

Many thanx,

Mark

[Jkraft]

Ouch! How does that happen? Was there any vibration before?

[Norseman]

Wow...

Previous owner of my boat reported that the shaft and prop disappeared in deep water somewhere around 2014.
He had no idea how or why it could happen, but it did.

[Markv]

There was no previous vibration. I slowed and reversed as soon as I felt it.

[Pitou]

I felt vibration in my 2000 28' TE with 370 Cummins while cruising at 2400RPM (20 knots). I slowed and reversed to potentially clear the prop. When I put the transmission back to forward, I had no propulsion. When the boat was pulled, the shaft had broken. Anyone have an exact spec on the prop for this boat?

Many thanx,

Mark

Shafts for the 6BTA spec are 1.5" Aquamet 22 stainless.
This was the shafting in my 28TE with the 370 - 6BTA.
H&H Propeller Shop of Salem, MA machined and provided the shafting and propellerss for Albin and have all of the specs at hand. Contact them to fabricate and ship:
800-325-0117

https://www.hhprop.com/shafting/custom-shafting.php

[MerryKate]

Sorry to hear that. Spec on my 1997 motor box 28TE shaft was 1.5” Aquamet 22 (Cummins 250B running 18x21 3-blade cupped through 1.4:1 gear)

Yours failed at the keyway, which is most common. Could have been an installation issue. Though the 370B is transmitting a lot more torque to the drivetrain, assuming Albin was still using 1.5” shafts in that application.

[lwarden]

A 1.5" shaft is on the light side for a 370. Not super surprised it broke. Look for crevice corrosion from the keyway, that's probably all it took.

[jleonard]

A 1.5" shaft is on the light side for a 370. Not super surprised it broke. Look for crevice corrosion from the keyway, that's probably all it took.

Yes 1 1/2 inch is marginal for that horsepower. I know when I repowered my old Mainship I used a 270 hp version with a 1.5:1 gearbox and I had a safety factor of about 2:1 which should have been 4:1 according to some experts.

Corrosion as mentioned above or bad machining of the keyway could have introduced a stress riser.
The keyway should have a nice smooth radius from the milling cutter (with no chatter marks) and the key will have to be chamfered to clear that radius.
Spooning the transition is also supposed to relieve any stress riser (assuming is is done properly).
You should also lap the prop bore the the shaft during installation to insure a good fit on the taper.
And reduce the distance from the cutlass bearing to the prop as much as you can with still being able to assemble a collar zinc.
Don't mean to be too geeky but since the shaft sizing is marginal you need everything you can get in your favor.