HELP! Vosper Stabilizer Fin Removal

My 1970 Willard 36 has original equipment Vosper stabilizers (Naiad purchased them some time back). Any tips/tricks to removing the fins?

1. Picture of fin - mechanic has a hand-pump hydraulic press attached but will not budge the fin (see oil is just seeping past the shaft and weeping down top). Should there be some sort of tool or fitting in place (see next too)? FYI - these mechanics have worked on Naiads, and I believe Wesmar stabilizers, so have experience, though are not 'factory' mechanics.

2. Picture of Naiad removal from Internet (attached PDF). I found a decent write-up on removal from someone a year or so ago (may have been this forum, or perhaps Hatteras). They mention a Naiad tool, and mention using a hydraulic press, but I cannot figure out from the description if the tool is solid billet, or if there is a threaded shaft through the cylindrical column, etc. I would think the puller would be a simple long bolt that bottoms-out on the shaft, then pops the fin after a few turns, but the shape of the tool with the smooth cylinder makes no sense to me. FYI - Naiad states there is no tool, so the the mechanic in this original post must have made it himself.

I wonder if Vosper's attachment is different than Naiads? Naiad folks are of little help - just said to use wooden wedges to lever the fins off.

Best thinking is appreciated!


View attachment Naiad Vosper Removal.pdf

can't comment on 1970 vintage but modern Naiads come off like the pdf you attached.
1) Remove the bolt (threaded into the end of the shaft) from the fin
2) Carefully thread the Naiad jack screw into the outer threads of the fin. (I say carefully because any marine growth makes it easy to cross thread and you can't see the threads engage since they are at the upper end of the fin). That is why the Naiad jack screw has a long smooth barrel - to help keep it centered in the fin while you engage the threads.\
3) Crank the jack screw until max tension, then a good whack with a hammer on the socket extension should break loose the taper

There is also a hydraulic version but I haven't seen it used. Most larger yards have one or both

Good luck

Flatswing said:

1) Remove the bolt (threaded into the end of the shaft) from the fin
2) Carefully thread the Naiad jack screw into the outer threads of the fin. That is why the Naiad jack screw has a long smooth barrel - to help keep it centered in the fin while you engage the threads.
3) Crank the jack screw until max tension, then a good whack with a hammer on the socket extension should break loose the taper

Click to expand...

Thanks for the response - very helpful to have a conversation. Engaging this via public post versus PM for posterity

Question: is the Naiad tool a 2-part tool? Sounds like there is an outer threaded body that is screwed in-place and landed atop the fin-shaft. Then, an internal 'jack screw' (preferably fine-thread) is tightened to pop the fins?

Sounds like something is seized or rusted in place. Have you used any anti-seize penetrating oils and let it sit for awhile? Are both behaving the same? If so, possibly there is a keeper ring in place that needs to be removed. Do you have installation drawings that appear accurate?

A decent yard machinist should be able to get the units apart. Also, do you have a good source for parts such as new seals, rings, bushings/bearings and possibly even a shaft?

sunchaser said:

Sounds like something is seized or rusted in place. Have you used any anti-seize penetrating oils and let it sit for awhile? Are both behaving the same? If so, possibly there is a keeper ring in place that needs to be removed. Do you have installation drawings that appear accurate?

Click to expand...

The fins have not been serviced in over 20-years (frankly, I didn't know it was a regular service item - my bad). As you can see in the original picture, hydraulic oil has been forced through the tapered shaft fitting, so probably as good as you can get for penetrating oil. Yard is in Mexico, and while they have experience in stabilizers, it's not a specialty like it would be in places like Fort Lauderdale. But still, this should not be rocket science.

Yes, I have amazingly have the original drawings and manuals. Turns out that back in the day, an engineer/designer at Vosper Thorneycroft drew detailed drawings - I have full sized sepia blue prints of the installation and assembly on my vessel.

Yard informs they have tried wedges between the hull and the fin, which was also Naiad's suggestion (recall, they said no tool available). What I don't know is the size of the wedges - should be long and slim-taper I suppose.

Finally, if my understanding of Flatswing's response is correct, the attached tool is an example of the Naiad tool, though I am not at the boat so have no idea of the actual configuration. The threaded adapter (outside male threads into fin, inside female threads accept off-the-shelf jack screw from McMaster Carr or something).

Thoughts? I'm a little worried.....folks in Mexico are pretty tenacious. Uncommon for them to be confounded by something like this.

sunchaser said:

....do you have a good source for parts such as new seals, rings, bushings/bearings and possibly even a shaft?

Click to expand...

Yes.....and no. The seals and bushings are still available via Naiad, presumably NOS from Vosper inventory. Other mechanical parts and electrical parts are not available, though I did find some odd parts from a Hatt owner who replaced with new, though unfortunately they had lost many of the more interesting parts. Replacement system from either Naiad or Wesmar or Seakeeper is beyond reach so I have my fingers crossed.

Have you tried a brass rod and heavy hammer in the spot where the jack screw is shown?

I would fill taper area with ATF and try a whack or two

Could there be a set screw added , not on the blueprint?

Plan B would be to have a local machine shop simply make the removal tool.

Finally, if my understanding of Flatswing's response is correct, the attached tool is an example of the Naiad tool, though I am not at the boat so have no idea of the actual configuration. The threaded adapter (outside male threads into fin, inside female threads accept off-the-shelf jack screw from McMaster Carr or something).

View attachment 95301[/QUOTE]

I have not seen a 2 part tool as you have depicted. The Naiad tool is a single piece (same as the Hat pdf u originally referenced) There are threads in the Naid fins already.
Sorry I can'tell be more helpful. Make sure u have blocking under the fins. When they release they drop in a hurry & decent weight.

Well, it's not looking good. I am told they have already tried everything I can think to suggest, including using long, lightly-sloped wedges (diagram below). As mentioned, boat is in Mexico, and I have to tell you Mexican's are amazing at mechanical salvage of lost causes. Current plan is to keep it wet with hydraulic fluid for a few days with a kid banging on the fin for a few hours a day with a mallet.

At some point, if not immediately, I will need to make a good-money-after-bad decision. The electronics - especially the gyro - has not been available for 20+ years. As mentioned, seals and bearings are available now, but all else would need to be scavenged from a catalogue or fabricated. Might be time to replace.....

We had Vosper stabilizers on our previous Defever. When it came time to remove the fins to service the seal, the boat yard gave up after a short while fearing they would cause some permanent damage, so I called a boat yard in Seattle who worked on Niad stabilizers. They sent out a young man and he had it out in a short while. All I remember is some wedges and and very large hammer. You may be dealing with a yard that does not have the necessary experience to get the job done.

Be very careful on giving the green light to non trained yard guys to take something apart. In their unbridled zeal they may cause some hull damage.

Having worked around huge shafts, bushings and bearings there are techniques that are available to trained and experienced personnel. Penetrating oil and banging on it may well break it loose, in time. If not, suggest you formulate a plan B for location and mechanical expertise.

This thread will hopefully inspire those with active stabilizers to get them serviced per the book.

sunchaser said:

This thread will hopefully inspire those with active stabilizers to get them serviced per the book.

Click to expand...

Amen to that! I'll post an update in a week or so with the final outcome. I'm sort of eager to know myself......

Hopefully a good ending to this dilemma.

Thanks for asking. Am waiting on a separate mechanic to give a try, but not looking good. Given the age of the system - 50 years old and many key parts no longer available, -might be time to replace. Ouch, but given the duration of my planned cruise, not something I want to compromise on. Next owner will get a great deal.

to release fin inside the bottom of the fin are two holes you have to make a tool to release the bolt inside once done you can then take two wedges at top of fin near shaft one on each side big hammer swing at both steel wedges buy at home depot. crib the fin so fin does not hit the ground causing damage at this point you can begin the disassembly process starting from the top of the stabilizer. get a qualified Naiad tech or dont do it.

Did you ever get them off?

I’m looking at a 46 footer with Vosper mini fins. Curious about your experience with them, besides fin removal difficulties that is.

No I didn't. Came to find later that I'm not sure I had the right guys on doing the work so possible operator error. I installed new Wesmar.

If you move forward with the vospers, let me know. I have the gyro and brains from my old vospers which are no longer available so good spares to have.

Vospers worked fine. The bushings and such are still available from naiad.

Hope your luck is better than mine. Honestly, I didn't realize how frequently they should be serviced so could be partially my fault. I wouldn't buy the boat unless the vospers were serviced by PO. If there's a problem, it means replacement.

Peter

This is the Naiad manual jackscrew tool

mvweebles said:

No I didn't. Came to find later that I'm not sure I had the right guys on doing the work so possible operator error. I installed new Wesmar.

If you move forward with the vospers, let me know. I have the gyro and brains from my old vospers which are no longer available so good spares to have.

Vospers worked fine. The bushings and such are still available from naiad.

Hope your luck is better than mine. Honestly, I didn't realize how frequently they should be serviced so could be partially my fault. I wouldn't buy the boat unless the vospers were serviced by PO. If there's a problem, it means replacement.

Peter

Click to expand...

Thanks for the offer, will keep [all of the above] in mind if we move forward.