It's stuck! How to shift a recalcitrant centre plate bolt?

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FinesseChris

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The Finesse 24 has a centre plate pivoting on a 170mm M20 bolt, which passes through the iron keel. Both ends of the bolt are recessed.

It's reckoned good practice to occasionally check and if necessary replace the bolt, and some owners do this every season.

Good plan, we thought. We managed to get the bolt ends exposed - they are covered with a layer of silicone filler - and to get the nut off. We have sourced a replacement bolt.

But can we drive the old bolt through? No, it will not budge. "Just tap it throu with a drift" say the experts. In our case, nothing will move.

We have tried inserting a crow and then a wedge to lift the plat a fraction, in case the weight of the plate was binding on the bolt. No luck. We have treated the bolt to copious sprays of easing oil. No luck.

Any ideas?

Thanks

Chris
 
Is there a bush in the plate or is there just a hole the bolt passes through. If there is no bush can you turn the bolt with a socket on the head to break the corrosion? Good fitting socket essential. Lots of Plus Gas.
If there is a bush it doesn't really help as the bush may turn in the plate but not the bolt within the bush.

Perhaps your hitting skills need upgrading

Just had a look at the Dog's Dinner of a website for Finesse owners. It seems there wouldn't be a bush in the plate. It also seems that the bolts wear at an alarming rate.
It also seems that the bolts wear at an alarming rate. There is talk of bolts wearing 50% in a year.
Could it be that your bolt has a groove worn in the "top" that the plate is sitting in and preventing the bolt coming through?
If so turning the bolt 180° with a socket should present an unworn face to the bearing surface of the hole in the plate and you should be able to drift the bolt out easily.
 
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Thanks, Lakesailor, for your thoughts. I am reluctantly coming to the same conclusion: there is a dip in the bolt caused by wear.
Sadly it is a coachbolt, with domed end, so no way of applying a socket to the other end.....
Hitting skills have been upgraded by application of sheer rage, and knowledge that the crane is due in three weeks for the club lift, but to no avail.
Gone to think....
Chris
 
OK. lift the plate by jacking in 5mm increments and whacking the bolt. At some point you will come to the original orientation and the bolt should move through. The plate may need a bit of rocking fore and aft as well to get the perfect position.
 
If it's designed to use a coachbolt, presumably the square section below the domed head locates in a square hole. If so, the bolt shouldn't rotate.

Can you raise the centreboard up fully? If so and the bolt doesn't rotate, the pivot hole should no longer be resting on the groove in the bolt shaft and the bolt should be removeable with a drift and hammer.
 
I think if a bolt of that type is stuck there are only two ways to shift it. The only way to move it intact is to whack it hard enough which may need to be very hard indeed with a decent size (4lb) club hammer. If that doesn't work - or if you bend it instead of removing it then you will have to cut it off flush and drill it out.

If it is corroded in place as badly as that you're probably going to have to replace it anyway but fitting a nut on the end to take the blows from the hammer will protect it to some extent. A hardwood drift may help too but it might soften the blows enough to prevent the "hold" from breaking.
 
MASH said:
I think if a bolt of that type is stuck there are only two ways to shift it. The only way to move it intact is to whack it hard enough which may need to be very hard indeed with a decent size (4lb) club hammer. If that doesn't work - or if you bend it instead of removing it then you will have to cut it off flush and drill it out.

If it is corroded in place as badly as that you're probably going to have to replace it anyway but fitting a nut on the end to take the blows from the hammer will protect it to some extent. A hardwood drift may help too but it might soften the blows enough to prevent the "hold" from breaking.
Click to expand...
if corroded to the plate it would turn as the plate is raised/lowered
 
It would also turn as the plate is moved if a groove has worn though, as previously mentioned.

I know FinesseChris won't want to hear this, but would it be possible to get at the bolt at the sides of the plate with a hacksaw blade, presumably - but not necessarily - from underneath ?

I haven't read the website blurb, but by Lakesailors' description of the bolt wearing 50% in a season, it really sounds like this bolt has got to go !
 
Seajet said:
It would also turn as the plate is moved if a groove has worn though, as previously mentioned.

I know FinesseChris won't want to hear this, but would it be possible to get at the bolt at the sides of the plate with a hacksaw blade, presumably - but not necessarily - from underneath ?

I haven't read the website blurb, but by Lakesailors' description of the bolt wearing 50% in a season, it really sounds like this bolt has got to go !
Click to expand...

A coach bolt should not turn if the sq end is firm;ly held in the timber
 
Not if it incorporates wear on the bolt, which by desription is highly likely.

Whatever our theories, FinesseChris needs help by the sound of it.

Just had a thought; I know it's a long shot, but would there be any safe ( non boat damaging ) way of putting lots of long well vertically supported / backed bits of wood on the facing structure - maybe one end in the engine bay ? - and having a go pressing the bolt end with a jack ?
 
sailorman said:
the groove would have been worn rounded
Click to expand...
But it will still be as much as 50% in just the top of the shaft of the bolt. Thus creating lips either side of the groove which prevent the bolt from being knocked through.
The plate will be sat down in the groove and needs lifting so that the hole and bolt are concentric again.

Unfortunately the archive on the owners site with pictures is down during "updating".

Two comments from their forum
I also had the centreplate pivot bolt replaced which was down to 20%
of original size - I will replace it every five years in future.
Click to expand...
Mine fell off because the bolt wore through - it was about a 20mm bolt but it
had worn/rusted to nothing in the middle.
Click to expand...

No-one on their forum has mentioned a coachbolt. I reckon that has been a bodge. They all mention 20mm x 170mm galvanised (or stainless) bolts. Stainless is less popular due to wearing the hole in the plate. Consensus seems to be to check and change the bolt regularly.
 
Just a thought... Is it possible to use something loke Dremel and to cut a straight line across the head of the bolt quite deep. Then get a very large screw driver with a wrench attached to the screwdriver to help turn it.

good luck

Peter
 
Actually FinesseChris describes it as ' a coachbolt with a domed head ' so can movement of the head be easily seen ?

How about watching the bolt closely while someone jacks / jiggles the plate up, to see if plate and bolt move as one ?

I agree with lakesailor that waggling the plate in some way while hitting the bolt end may be the only way, thinking about grooves in plate and bolt engaging to prevent the bolt shifting along.

It might be worth thinking about what position the plate spends most of it's time in - probably but not necessarily up - and raising the plate vertically in that position to try to get out of the hypothetical slots in plate and bolt, while applying increasingly frantic amounts of hammer & drift...

It would also be worth having A Plan in mind for when this bolt is out, to avoid going through this again next year !
 
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OK. The possibility it is a coach bolt with square corners is hardly relevant. If it is locked in place the bolt shaft will have mainly worn on the top. If the bolt has been able to turn it will have worn all around.

How do I know?


This is a Finesse 24 swing keel bolt


Centreplate+bolt+from+Sea-Pie.jpg


The keel is an L-shaped piece of 1/2" steel plate so will not be terrifically heavy. About 100lbs


Centreplate+Template+.jpg

You can see from the picture that the bolt needs to be concentric with the hole in the keel to be able to be drifted out. The plate is held by a cable at the opposite end to the pivot bolt, so the answer is jo gently jack the plate up from beneath the pivot bolt until the bolt and hole are concentric.
Frankly, as the aft -and heavier- end is held up by a cable it should be possible to jiggle the pivot end of the keel about whilst someone inside is hitting the end of the bolt. It should pop out at some moment when everything is aligned.
 
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Lakesailor said:
OK. The possibility it is a coach bolt with square corners is hardly relevant. If it is locked in place the bolt shaft will have mainly worn on the top. If the bolt has been able to turn it will have worn all around.

How do I know?


This is a Finesse 24 swing keel bolt


Centreplate+bolt+from+Sea-Pie.jpg


The keel is an L-shaped piece of 1/2" steel plate so will not be terrifically heavy.


Centreplate+Template+.jpg

You can see from the picture that the bolt needs to be concentric with the hole in the keel to be able to be drifted out. The plate is held by a cable at the opposite end to the pivot bolt, so the answer is jo gently jack the plate up from beneath the pivot bolt until the bolt and hole are concentric.
Click to expand...

but that is a hex bolt init, so free to turn
 
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