Shortening integral stern tube to fit PYI PSS

[SV STENTATO]

Has anyone cut their stern tube on the inside of the boat in order to fit a PYI PSS shaft seal? We are in the process of replacing our prop shaft, cutless, coupler, and shaft seal. I’ve already removed all of the old gear and a supplier in the yard we’re at ordered us the parts. We’ve received the parts and I went to install only to find that the distance from the tranny side coupler to the stern tube is so limited that once the seal is in place and rotor is on the prop shaft I do not have enough space to assemble the coupler to the shaft. Our boat is a 1970 Pearson 35’ sloop powered by a westerbeke 33 with a HBW 100-2R tranny. The stern tube sticks out from the hull into the boat about a one and a half feet or more. I’m wondering if it is reasonable to shorten our stern tube by a few inches in order to make the installation of the dripless shaft seal set up work? Any input is greatly appreciated! I will post some pictures shortly.

[Dsanduril]

Quite reasonable in the scenario you describe. Just remember that as you shorten you get closer to the hull/keel. You still need enough clearance under the tube for the rubber sleeve and hose clamps of the PSS to fit. If you can shorten 3-6" and still have room for the sleeve to be well clear then get out the hacksaw.

[SV STENTATO]

Thanks for the reply I just wanted to check with the folks that have more experience than I do before I make any modifications to our boat.

[gamayun]

On my Freedom, I have about 6.75 inches between the coupler and the shaft tube. (I think... I'm not at the boat and I don't have my notebook with me.) PYI sells the seal without the burp tube that will give me just enough room to clamp with one hose tube on the shaft. Use the type of hose clamp you can buy in the marine store that has the 2 bolts (a "T clamp"?). You have remember to burp it when you splash. Just an idea if you'd like to consider another approach and you even have that much space.

[Suijin]

18" shaft tube sounds pretty long to me. I think you are safe shortening it.

Be sure to smooth/fair where the boot clamps onto the tube for a good seal.

Consider also giving yourself enough room to put a safely collar up against the seal part in the shaft. A zinc will work but a stainless collar will take up less room.

[Maclir]

Yes I have shortened my Stern tube with great difficulty. The problem was poor access for hacksaw. I did it with a hacksaw blade, and motivated myself with thoughts of sawing my way out of prison

[SV STENTATO]

Thanks for the idea gamayun. I have already purchased the PYI with the burp tube attached and we are a bit tight on time so I may end up cutting our stern tube it’s quite long any how so I should have plenty of room to shorten it without getting to close to the hull. I’ll post some pictures once I’ve got it all buttoned up.

[SV STENTATO]

Thanks for the reminder on the safety collar in front of the seal. Have read about using a safety collar and was one of the reasons I wanted to shorten the stern tube. I could probably just barely fit the seal and rotor as is now but there would not be enough room for a safety collar and would make installing the shaft coupler properly a night mare. Hack saw it is! Maclir you bet I will imagine I am sawing my way out of dry dock to stay at it. Literally have to hang over the motor to access the damn thing. Does anyone have any idea on torque specs for the shaft coupler mounting hardware? I’m using a 4” flange Buck Algonquin split coupler. I haven’t been able to find anything on the web for torque values. I know it is pretty critical to torque the clamping bolts on the shaft evenly to ensure a square fit to the shaft.

[Michael Pope]

Hint for the day buy the hose clamps from PYI they are SS316 L and are worth the high price.
The L stands for "Low Carbon" makes a huge difference in life or can get ELC Extra Low Carbon but at an Extra High price . not much better than L MP