Just use thickened epoxy to seal thru hulls?

[Andy Kirkpatrick]

Hi, I guess I know the answer, as well as the correct way, but why don’t people seal up old thru hulls with just thickened epoxy, with both faces well tapered? Wouldn’t this be stronger than the glass around it?

Sorry if this is a dumb question, but I have 5 thru hulls to close up, and just wondered why.

Best

Andy

 

[PCUK]

If you also added chopped ends to the mix that would give it more strength but the most reliable way is to lay up a couple of layers of bi-axial cloth and epoxy resin inside before filling the hole with the mix.

 

[[194497]]

GRP = glass reinforced plastic. It's stronger with the glass in there, that's what the glass is for...

 

[PabloPicasso]

... And great fun to be had when they have to be removed again.

Its not the sealant that seems to fail. Its our old friend corrosion (Unless you have composite type like tru-design).

Put them in with sicka, or other below the waterline sealants. TEK 7 even. And a hardwood backing pad.

You could use glass tape to reinforce it. Tape around the fitting with epoxy thickened enough, but ensure the mat can be wetted out fully.

Prep the surfaces as usual when laying up. Make sure the mat is the correct type for epoxying

 

[MikeBz]

... And great fun to be had when they have to be removed again.

The OP is talking about blanking off holes from skin fittings which have been removed.

As others have said it’s the fibre in fibreglass which gives the strength - otherwise hulls would be made from solid epoxy.

 

[Sea Change]

Epoxy is like cement, it's the glue that binds stronger materials together.
Used on its own, it's like mortar. Useful but not inherently strong enough to build a complete structure.
Glass fibre strands or matting is like the gravel in concrete, it's what gives it the real strength.

 

[PabloPicasso]

The OP is talking about blanking off holes from skin fittings which have been removed.

As others have said it’s the fibre in fibreglass which gives the strength - otherwise hulls would be made from solid epoxy.

Ok, I must have misread that.

Its ever decreasing circles of wetted out matt sandwiched from both sides after chamfering the edge of the hole then.

 

[john_morris_uk]

Hi, I guess I know the answer, as well as the correct way, but why don’t people seal up old thru hulls with just thickened epoxy, with both faces well tapered? Wouldn’t this be stronger than the glass around it?

Sorry if this is a dumb question, but I have 5 thru hulls to close up, and just wondered why.

Best

Andy

I wonder what you've got rid of to be in. a position to want to close off five hole?

 

[KevinV]

Ok, I must have misread that.

Its ever decreasing circles of wetted out matt sandwiched from both sides after chamfering the edge of the hole then.

I've read this before and don't get it - sure, this is necessary in the case of damage, but the hull was deemed strong enough with a hole in it, why is more than plugging the hole necessary?

On my own boat I filled a through hull hole by chamfering the hole inside and out, wetting the dry fibre with epoxy, then filling with epoxy /chopped fibre with a bit of spare smeared on the inside. Two years with no issues at all so far.

 

[Refueler]

I've read this before and don't get it - sure, this is necessary in the case of damage, but the hull was deemed strong enough with a hole in it, why is more than plugging the hole necessary?

On my own boat I filled a through hull hole by chamfering the hole inside and out, wetting the dry fibre with epoxy, then filling with epoxy /chopped fibre with a bit of spare smeared on the inside. Two years with no issues at all so far.

As long as the 'filler' used ahs the chopped strand in it - I agree.

Chamfering both sides and making sure its clean bare GRP you are bonding to .. is the deal.

My GoTo Resin with chopped strand included in the mix ... Devcon.

Trick to get nice smooth exterior finish ..... thin ploythene sheet stretched and fixed over flat sheet and then pressed onto the outside AFTER the resin mix has been applied slightly proud .. make sure the polythene sheet has no air bubbles between it and the resin mix ... Put a prop or other to keep the plate in place till resin cures.
The flat will create a nice smooth outer finish ... it will of course push excess into the hull - so inside will be proud of the hole ... you can smooth over with a painters spatula etc.

 

[gjgm]

I've read this before and don't get it - sure, this is necessary in the case of damage, but the hull was deemed strong enough with a hole in it, why is more than plugging the hole necessary?

On my own boat I filled a through hull hole by chamfering the hole inside and out, wetting the dry fibre with epoxy, then filling with epoxy /chopped fibre with a bit of spare smeared on the inside. Two years with no issues at all so far.

I believe bcz the addition of glass mat,chamfered, will make a stronger binding between the hull and the "hole". .it isnt to strengthen the hole itself. I think the risk is that the resin alone ( as in OP question)may fracture away from the hull. It is not unusual for even drill holes plugged with epoxy alone to crack around the joint. Pro repairers seem to mat even small holes, and in OP case, these are thru the hull.
West Systems have some online guides, somewhere; personally, I would follow them!

 

[AntarcticPilot]

I've read this before and don't get it - sure, this is necessary in the case of damage, but the hull was deemed strong enough with a hole in it, why is more than plugging the hole necessary?

On my own boat I filled a through hull hole by chamfering the hole inside and out, wetting the dry fibre with epoxy, then filling with epoxy /chopped fibre with a bit of spare smeared on the inside. Two years with no issues at all so far.

Because the fitting itself provides the mechanical strength. You need the glass to provide strength in tension; the resin alone is strong in compression but not so much in tension.

 

[KevinV]

Because the fitting itself provides the mechanical strength. You need the glass to provide strength in tension; the resin alone is strong in compression but not so much in tension.

Okay, that makes sense

 

[AntarcticPilot]

Okay, that makes sense

The glass also stops cracks from propagating.

 

[William_H]

Try a plastic bag filled with sand or even rags pressed on the inside of the hole. Champfered (tapered) and cleaned. Lay up pieces of glass cloth in the hole and progressively larger to fill the hole and the chamfer. When the resin is firm but tacky remove the inside bag and then lay up glass on the inside like the outside.
You can do it the other way propping a bag against the hole and starting inside. The glass will actually make the filling much easier than even very thick paste. And of course much stronger. Consider carbon fibre cloth being stiffer will be even easier to keep in place. ol'will

 

[Cerebus]

I friend removed the heads.

He asked me to seal the through hull fittings.

I closed the sea cocks and then used woven Matt and epoxy over the skin fitting ( did not remove it)

I then sealed the inside of the skin fitting and seacock valve in some fashion.

Right or wrong I considered it double protection; skin fitting seacock closed. Job half done. Glassed over inside and out; extra protection.

Sounds unconventional seeing other replies. No leaks ever noted.

 

[john_morris_uk]

I friend removed the heads.

He asked me to seal the through hull fittings.

I closed the sea cocks and then used woven Matt and epoxy over the skin fitting ( did not remove it)

I then sealed the inside of the skin fitting and seacock valve in some fashion.

Right or wrong I considered it double protection; skin fitting seacock closed. Job half done. Glassed over inside and out; extra protection.

Sounds unconventional seeing other replies. No leaks ever noted.

It ticks the box of not leaking but that sounds like a right mess of a job. A complete bodge IMHO.

Sorry to be blunt.

And why on earth did he remove the heads?

 

[Andy Kirkpatrick]

I wonder what you've got rid of to be in. a position to want to close off five hole?

It ticks the box of not leaking but that sounds like a right mess of a job. A complete bodge IMHO.

Sorry to be blunt.

And why on earth did he remove the heads?

It’s a 22 foot boat (Hurley 22), and it seems daft having a toilet and sink in such a small boat, as it just adds more weight (it’s porcelain), complexity (more to rust and break) and risk to the boat. Other holes are for log and old depth sounder. Trying to strip it down with a more mini transat state of mind (but for a 1969 boat). Less is more etc.

 

[john_morris_uk]

It’s a 22 foot boat (Hurley 22), and it seems daft having a toilet and sink in such a small boat, as it just adds more weight (it’s porcelain), complexity (more to rust and break) and risk to the boat. Other holes are for log and old depth sounder. Trying to strip it down with a more mini transat state of mind (but for a 1969 boat). Less is more etc.

Lightening a Hurley 22? A Jabsco compact weighs 10.8 kg

Opinions differ as to whether a toilet makes sense on such a boat. Our daughters Pandora 700 has a proper sea toilet (with Blake’s seacocks too!)

His choice though. I assume he sails alone.

 

[PabloPicasso]

We could start another thread on how heads only make boats more female friendly if kept clean and sweet smelling....