Mast Wedge Woes

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captairman
Posts: 11
Joined: Tue May 21, 2019 6:59 pm
Location: NY, NY

Mast Wedge Woes

Post by captairman »

In 2020 we noticed we had some very slight movement at the deck step (about .5-1mm) and loud thuds. We consulted a well-known freedom expert who advised us to replace the original wedges with pourable spartite. We did this and set off for our yearlong cruise. Unfortunately we heard the familiar thuds on the first downwind run. After stripping back my beautiful caulking job we found the spartite had been pressed through the deck where there was enough clamping force to do so.

The original pour was only about 1mm proud of the deck collar at the thickest point and we had shimmed the rest with starboard scraps, so I replaced that with thicker G10 shimming all the way around. Bolted down again. Situation improved but not resolved. I notice as I clamp down tighter that the spartite is being pressed through the deck partner and not "catching" sufficiently. I did a second spartite pour on top of the original wedges using a large clay dam and continue to tighten it periodically but a permanent solution is needed. I don't want to clamp to the point that it pushes through completely leaving the mast free to smash the boat apart if indeed it will never "catch" enough taper to compress rather than push through.

I hear the 1983 Freedom 39s were an "earlier" boat with a narrower mast wedge clearance. I wonder also if there is sufficient taper for a pourable wedge to be used at all, or if the wedge itself must have some taper to be jammed into the partner to provide sufficient holding force without pushing through the deck? Complicating this is that my boat is the one that has had its masts ground down and sleeved in add'l fiberglass rocketry "sock" as described by Eric Sponberg in his mast repair document (attached) so the masts are thicker than usual providing even less clearance.

I am now shopping for a tapered wedge thin enough to fit (~10-15mm) and hard enough to withstand the loading in such a narrow cross section. I pray I can find it and that my reasoning here is sound or the 10 years we spent saving for this journey may culminate in a pretty tragic end :cry: Perhaps I should just use wooden door stops...

Some candidates:
https://www.rigrite.com/Spars/SparParts/Mast_wedges.php "NGA-18" seems small enough to fill the gap, is it the right hardness though...
https://custom-rubber.myshopify.com/pro ... 1049252357 Same question here...
The narrow wedge area
The narrow wedge area
PXL_20210715_153347326.jpg (3.27 MiB) Viewed 972 times
Attachments
Freedom Mast Repairs (Spondberg).pdf
(1.32 MiB) Downloaded 100 times
"Shiloh"
F39PHS

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GeoffSchultz
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Re: Mast Wedge Woes

Post by GeoffSchultz »

[edited after re-reading the op]
I'm confused by what you mean by " notice as I clamp down tighter that the spartite is being pressed through the deck partner and not "catching" sufficiently.". Isn't your pour flush with the deck-partner ring? I wouldn't expect that tightening the ring down would move it at all.

I suspect that what you're describing is a common problem with the mast moving at the base. The first thing that I would check would be that the nuts which hold the "inverted pie-plate" base that the mast fits into are super tight.

If they are, and the mast (but not the base) is still moving, then you have an issue where the inside of the mast has worn and is larger than the base. To solve this, I pulled the mast, coated the base with release material, placed several wraps of fiberglass inside of the mast, and used the base as a mold. This made it fit perfectly and kept it from moving (and thumping when it did).

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

captairman
Posts: 11
Joined: Tue May 21, 2019 6:59 pm
Location: NY, NY

Re: Mast Wedge Woes

Post by captairman »

GeoffSchultz wrote:
Mon Nov 22, 2021 5:27 pm
[edited after re-reading the op]
I'm confused by what you mean by " notice as I clamp down tighter that the spartite is being pressed through the deck partner and not "catching" sufficiently.". Isn't your pour flush with the deck-partner ring? I wouldn't expect that tightening the ring down would move it at all.

I suspect that what you're describing is a common problem with the mast moving at the base. The first thing that I would check would be that the nuts which hold the "inverted pie-plate" base that the mast fits into are super tight.

If they are, and the mast (but not the base) is still moving, then you have an issue where the inside of the mast has worn and is larger than the base. To solve this, I pulled the mast, coated the base with release material, placed several wraps of fiberglass inside of the mast, and used the base as a mold. This made it fit perfectly and kept it from moving (and thumping when it did).

-- Geoff
Hi Geoff,
The spartite pour was perhaps a few mm proud of the deck partner ring and then was shimmed more and more so the collar has plenty of meat to clamp down on, so I expected that pressing down on it a bit would smoosh the spartite against the walls of the partner and mast to create a compression force that would retain the mast. As it happens, the force of the collar simply pushes the spartite through the deck and so far has not stopped. When I remove the cabin headliner, I see a few mm of spartite has extruded between the mast and deck partner long after the curing time, so I believe there is not enough taper in the deck partner to inhibit the wedge from being smashed down through the deck by the mast collar.

There are no nuts that hold the "pie plate / top hat" mast step at all, it's simply glassed to a box that mates to the hull as pictured. Please note that the fiberglass applique visible in the picture was my own emergency repair to prevent the mast from moving too much whilst underway. I plan to grind that off before removing the masts. We do plan to do something similar like coating the inside of the mast with agent and putting some thickened epoxy on the mast step while lowering the mast with the crane... Image
"Shiloh"
F39PHS

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