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On my 29er (bought secondhand) there is a piece of metal attached at the very base of the mast, which creates the hinge between the mast and the deck. I'm not sure of its name. There are two bolts which come in from either side of the mast to attach to this piece. The bold comes in from the outside and the nut is on the inside of the nut. I have noticed that they are both loose.

I have 2 questions:

- Are these bolts supposed to be loose? (It is possible that the system is designed this way, and they use lock nuts to hold them loose intentionally)

- How do you tighten them!? I cannot see how I would reach the nuts to tighten them, but I only really need to know this if they're not supposed to be loose.

Thank you


EDIT: I think the part in question may be called the Mast Heel Plug, although the one on the ovington website doesn't look exactly the same as mine. 

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The part that "plugs" into the bottom of the mast is indeed called the Mast Heel plug.

And the part that is screwed down onto the hull, in this case the Mast Partner and Mast Plinth, is called the Mast Step.

There is a pin, often a bolt that allows the mast to hinge, it's also refered to as a tabernakle, this adds the lowering and rasing of the mast.

There should be 2 x M6 MT [metal thread] that go through the the lower mast alloy and a internal sleeve into the Mast Heel Plung and they are tapped (Threaded) into the alloy of the Mast Heel Plug.    If they are loose and you can't tighten them, then move the holes 90° and re-tap into clean alloy.   (or use Heil-coils)

The Mast Step, which looks like a channel, is screwed down into the Mast Partner and also into the Mast Plinth.    There is upwards of 10mm of FRP mass there and 4 x M6 CSK MT down is often more than enough.   If that is stripped/loose, then you could try 1/4" BSW bolts, or, again, you can try Heil-coils (also know as re-coils)

The Metric thread system uses quite fine threads.  The BSW [British Std Witworth] system uses much coarser threads, and are far better suited to alloy and FRP materials.

Also 1/4" = 6.4mm, so its a bit bigger.

Heil-coil are often used to enhance the grip of a bolt into a part.  They came to fame bolting the head of engine block down, when people post turbo-ed a std motor.     Then look like little springs and are made of SS.  The inside of the spring matches the thread of the bolt, so you buy a kit for M6 (say) which will include a tap, a inserter, a break off tool, and upwards of 10 Heil-coils.  I would epoxy them in place, let it cure, then put a new bolt in place.    They work in anything inc alloy and FRP and increase the holding power of a std MT 10 fold.   You shoud be able to buy them from a good auto place or your local up-market nuts and bolts shop.

They solve a miriad of problems.


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Thank you very much for your replies and for all the detail you gave Julian.

In my case there are definitely two bolts which enter from the outside of the mast on opposite sides, and have a nut on the inside. I can see the nuts when I lower the mast as the plug has a small hole in the bottom. I can turn the bolt and see the nut turn inside. It is not screwed directly into the plug in this case. But my plug does look a bit different to the one on the ovington website. An older model perhaps...

The bolts are loose, but since they have lock nuts, they are staying in place on the bolt. However the plug is not held tight into the mast. What I need to know is really whether the plug is supposed to be held tight into the bottom of the mast, or whether some play is required/ok here. It could be possible that it is not supposed to be tight to avoid transferring all bending on the mast into that small joint on the fibreglass deck via the mast step... But I'm not sure. The boat is quite new to me.

I have attached an image of it. Perhaps you can see that the plug is not right into the base of the mast there. I think the rigging or forestay was not tight at this point so the mast was leaning back a little.

I really hope I don't have to tighten these bolts as I have no idea how they were accessed in the first place! I see how on the ovington website they sell a single bolt which goes all the way through, which makes a lot more sense!

Thanks again


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Very strange and very ingenious, and very non-standard.

My guess is they have suffered a lot of electrolysis and not used barium cromante or Tuff-Gel.

Anyway, at racing level, you don't want it to move, you get a walking stock effect from the spinaker and it will affect the spreader angles.

The bolts will limit the rotation to a few °'s and for learn to sail, or non serious racing that's just fine.    Even if you get to tighten the bolt, it wont stop the tube twisting on the plug completly.

It's a pretty old boat, (Fredericesen jib track and sider pre re badging by Ronstan, also the mast step channel is a give away) but the hull is fully cored and has a lot of laminate so they are near impossible to kill so go have a ball, and don't worry about it too much.


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I am the happy owner (since now 16 years, it does not make me younger...) of hull #487, same mast step & plug set-up as yours. I have the same play between the plug and the mast, and have never seen the benefit of eliminating it: when you put tension on the rig, the mast pushes down on the heel plug and "closes" the gap.  When you release the forestay tension (unrigging the boat) the mast leans backwards and the gap reopens. I even find it beneficial, when riggin / unriggin the mast, as it gives a little degree of freedom to the mast to pivot in either direction without forcing on the mast step (I have seen boats with sheared screw heads - the one that hold the mast step down to the partner - due to mishandling during stepping/removal of the mast - eg when you forget to remove the rear mast step pin, or when you lower the mast with the pin inserted and not on the center line of the boat...).

I understand that this gap may allow the mast to rotate a (very) few degrees around a vertical axis when sailing, unfortunately the loss of performance in my case will be completely negligible with respect to my sailing skills :-)

And mechanically speaking, it seems not to have induced any consequences in the past 16 years, mast is still pointing upwards ;-)

Enjoy your new (old) boat!


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