Good method to bed anode bolt into GRP hull?

Cardo

Cardo

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Hello all

During our refit, I need to replace one of the hull anodes as this is past its sell by date. Unfortunately, whilst I was removing the retaining nut from one of the bolts set into the hull, this came loose after the bolt seized due to the corrosion. As a result, I ended up removing the bolt with a view to clean it up and re-bed it into the hull.

Issue is, I'm now left with a nice hole in the hull and I'm wondering what the best way to re-bed the bolt would be!

The bolt is one of those special anode ones with a small metal plate welded on to assist in forming a seal with the hull on the outside. There are two nuts that go on the inboard side of the hull to keep it in place. What products should I use to ensure the bolt is water tight once this goes back on?

I wouldn't want a leaky anode bolt!
 
Cardo said:
Hello all

During our refit, I need to replace one of the hull anodes as this is past its sell by date. Unfortunately, whilst I was removing the retaining nut from one of the bolts set into the hull, this came loose after the bolt seized due to the corrosion. As a result, I ended up removing the bolt with a view to clean it up and re-bed it into the hull.

Issue is, I'm now left with a nice hole in the hull and I'm wondering what the best way to re-bed the bolt would be!

The bolt is one of those special anode ones with a small metal plate welded on to assist in forming a seal with the hull on the outside. There are two nuts that go on the inboard side of the hull to keep it in place. What products should I use to ensure the bolt is water tight once this goes back on?

I wouldn't want a leaky anode bolt!
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Sikaflex 291 would be a good choice.

Do MG Duff suggest anything in the fitting instructions on their website? http://www.mgduff.co.uk/leisure-craft/fitting-instructions/fitting-bonding.html
 
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Cardo said:
I had searched with Google with no luck, hadn't thought about checking the MG Duff website!

Looks like Sikaflex it is, then. I have a tube that's been applied generously all over the boat. Soon there'll be more Sikaflex than GRP!

Thanks for your help.
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I used Sikaflex 291 last april - no leaks so far and the boat's been in since then, Does 291 keep well once opened? I might spring for a new pack (they do small tubes)
 
Apart from the Sikaflex, or whatever sealant you choose, I like a hardwood block on the inside. If you do develop a weep, the wood will swell and seal it. If you can find an extra nut, you can marry two together on the inside which should stop the bolt turning when fitting the anode or securing the wire.

Rob.
 
Sea_Spray said:
I used Sikaflex 291 last april - no leaks so far and the boat's been in since then, Does 291 keep well once opened? I might spring for a new pack (they do small tubes)
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Sikaflex is the right thing to use for this job, but sadly it keeps very badly once the tube is open. There are various tricks to try to get it to last longer, but no magic solution.

Pete
 
Sikaflex will do a grand job I am sure.

Or (as I normally point out at this juncture) you could save yourself the bother and expense and use Silicone from the pound shop. Do glass in a backing pad though.

On another tack, the square plate on the tang of the bolt is designed to locate in the hull to prevent the fixing turning. The anode then sits flush with the hull. You see lots of boats where this has been ignored because, I guess, owners/builders are unwilling to rebate through the gelcoat. If you do this rebate, seal the raw grp with epoxy.
 
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doug748 said:
Or (as I normally point out at this juncture) you could save yourself the bother and expense and use Silicone from the pound shop.
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You didn't by any chance own a Cornish Yawl a few years ago, did you? :)

Some previous owner seems to have loved the stuff, squidged it all over. Nearly all of it has since failed.

Pete
 
prv said:
You didn't by any chance own a Cornish Yawl a few years ago, did you? :)

Some previous owner seems to have loved the stuff, squidged it all over. Nearly all of it has since failed.

Pete
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Yep, a common problem. Whatever sealant you choose to use, there is no short cut to taking things apart and doing the job proper.
 
I realise this is an old thread but I can't find much on this specific situation. In the hope that this bumps up and comes to notice by others in the know, I wonder if I could seek out some advice.

This may sounds simple, stupid or both, but what is the best way of applying the Sikaflex in this scenario? I'm genuinely wondering what the best method is for applying the Sikaflex at the same time as sliding the both through and tightening the nuts? Do I just squeeze it along the bolt or fill the hole-area first or what?

Any advice welcome.

Thank you

A.S.P
 
I'd;
1. insert the bolt
2. fit the nut and washer on the inside and do up until there's about 1"/25mm between the hull and the square plate
3. generously apply the goo to the gap between the bolt and the GRP
4. apply some goo to the inside face of the square plate
5. do the nut up finger tight(if using a nyloc then do up until the square plate grips a matchstick against the hull, then remove the matchstick)
6. wait until it sets, then do it up tight.

This is not the only way to do it, just my way.
 
penfold said:
I'd;
1. insert the bolt
2. fit the nut and washer on the inside and do up until there's about 1"/25mm between the hull and the square plate
3. generously apply the goo to the gap between the bolt and the GRP
4. apply some goo to the inside face of the square plate
5. do the nut up finger tight(if using a nyloc then do up until the square plate grips a matchstick against the hull, then remove the matchstick)
6. wait until it sets, then do it up tight.

This is not the only way to do it, just my way.
Click to expand...

Thanks mate. That makes a lot of sense. Nice and clear as well.

Thank you, much appreciated.

A.S.P
 
Unfortunately, Sikaflex (and now WD-40) are trade names which refer not to a specific product but rather a range of products with different characteristics and appropriate uses. Although users of this forum often mean Sikaflex 291 when they refer to "Sikaflex", and the classic water dispersant when they write "WD-40" this is not invariable, and it would probably be better if we all tried to use the full name of such products to avoid ambiguity.
 
alan_d said:
Unfortunately, Sikaflex (and now WD-40) are trade names which refer not to a specific product but rather a range of products with different characteristics and appropriate uses. Although users of this forum often mean Sikaflex 291 when they refer to "Sikaflex", and the classic water dispersant when they write "WD-40" this is not invariable, and it would probably be better if we all tried to use the full name of such products to avoid ambiguity.
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I understand and agree with the Sikaflex bit, but what would you have me call WD-40, instead of WD-40. :)
 
Again, I get that Viv.
But WD-40 is, and always will be the original formulation and it is known as WD-40 in their own blurb.
All the other stuff they do has another name as a suffix after" WD-40" on the can. The original does not.
WD-40 are using their famous brand name to sell other stuff (nothing wrong with that).
But the original is still called "wd-40" and does not need any additional "name" adding so that we all know what it is.
That was my point.
Any way, not going to argue over something as trivial as this. I'll continue to call it WD-40 until I get given the wrong stuff when I order it or someone doesn't understand what I'm saying. Not happened yet. :)
 
greeny said:
Again, I get that Viv.
But WD-40 is, and always will be the original formulation and it is known as WD-40 in their own blurb.
All the other stuff they do has another name as a suffix after" WD-40" on the can. The original does not.
WD-40 are using their famous brand name to sell other stuff (nothing wrong with that).
But the original is still called "wd-40" and does not need any additional "name" adding so that we all know what it is.
That was my point.
Any way, not going to argue over something as trivial as this. I'll continue to call it WD-40 until I get given the wrong stuff when I order it or someone doesn't understand what I'm saying. Not happened yet. :)
Click to expand...

They call it "Multi-Use Product" In the blurb and on the can

.
 
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