Is he right

[Scareyclott]

I have had the hull peeled to rid some osmosis which was going fine, hot vac to dry then re epoxy, but the guy that's doing the work is now saying that after the peel there is massive signs of resin starvation all over the hull and that a biaxel is now needed to add a new membrane. The hull looks a mixture of White and pink the guy says it should all be pink

He seems genuine but is he telling the truth? Is he right or is he conning me?

Scott

 

[saltylegs]

The bare glass should be all the same colour I would think that the white he is referring to is Glass that has not been impregnated with resin. if you can also see the difference then I would have to say that you have answered your own question.

 

[lenseman]

. . . . . The hull looks a mixture of White and pink the guy says it should all be pink . . . . . He seems genuine but is he telling the truth? Is he right or is he conning me?

Hello Scott. When you buy fibreglass matting, it is 'very white' and flexible. Once it has been 'laid-up, it should be a pink or a yellowy/browny colour and solid.

As stated above, if you can 'see' a difference in colour than I suspect that the resin has not impregnated all the fibres correctly.

Take a small bladed pen knife or small screwdriver and do a very careful inspection of the 'white' fibres in the hull. They should not be flexible if you gently dig with the blade? They all should be glued to the next fibres and glued to the fibres below.

If they are 'loose' then they are not laid-up correctly.

 

[Deleted member 36384]

I would be worried just how deep this issue goes and would seek expert opinion before proceeding with any other work. Perhaps cores are required to be taken and analysed to determine the soundness of the hull. Perhaps other remedial techniques are available before completing the Osmosis works.

Would a resin be likely to penetrate between the free GRP fibres and stick them together I wonder, or just the ones in direct contact?

 

[noelex]

I am always surprised how resin starved and dry a fiberglass hull looks when you can see the laminate, This is very noticeable after major damage when there is a hole and you can see the various layers in cross section, but you get a similar impression after a gelcoat peel.

I would hope anyone competent enough to do osmosis repair would know the normal appearance and be able to distinguish a true case of resin starvation, but I would get a second opinion.

 

[charles_reed]

one of the main causes of osmosis is poor layup resulting in resin starvation of the glass fibre, so I suspect he's telling the truth.

There is tha old saw of keeping a dog to avoid barking yourself ;-)

 

[keesvugts]

White glass strands

The white glass fibers that you see are unlikely due to resin starvation during manufacture. What happens it that the resin surrounding the glass fibers is slowly removed as a result of hydrolysis. This is a progressive process as the resin that is removed provides a capillary space around the glass fiber That enables water to penetrate further into the hull.
With a bit of luck only the outer layers are affected, but it is possible that the problem extends deep into the hull. The layers where the resin has been degraded will have lost a lot of strength and of course continue to provide paths for future moisture to collect and travel.
Applying epoxy to this will not result in the epoxy entering these capillary spaces as epoxy is far to viscous for this and will have cured before any meaningful penetration will have been achieved. Applying a glass cloth to the surface with epoxy still leaves the capillary spaces and results in the cloth being attached to the surface of the white fibers only. Although this is an improvement over simply painting with epoxy, it adds limited additional strength and is not a good long-term solution.

I recommend that you explore deeper into the hull at a few places to see if the problem is localized to the skin out matting I.e. The underlying heavy roving is still in good order.

If this is the case I would remove all affected material until solid bright resin is reached and replace the removed material with An equivalent thickness of glass cloth and epoxy. I have done this before and must warn you that this is a lot of work.

If the underlying material is affected to a great depth than I would limit myself to a largely cosmetic repair, perhaps as suggested a layer of cloth to consolidate the surface material followed by epoxy coating.


This will restore some goodness to the hull that may well be adequate for what you what and may last long enough for you. However moisture will get back in and the process will continue to deteriorate the layers that have already been affected.

Regards,
Kees

 

[Rigger Mortice]

Resin removed by hydrolysis?

I've never had a problem with osmosis so I've never looked into it but I'm surprised to see that being said about it. Is hydrolysis really part of the problem?

 

[Scareyclott]

Thanks all for the advice. I have been to see the boat again today and had a surveyor friend look at some pics and yes he is right there are some areas that are resin starved, not sure if that is from the osmosis or initial lay up but it is there

I will now be having a new biaxel put on after another scrape. Looks like this job is going to cost me more than my budget but at least I had a contingency. However that does mean my new genoa is going to have to go on hold.

Boats who would have them

Mind you I have managed to talk the guy into fitting me some new skin fittings and doing a few small gel coat repairs as a freebe

Scott

 

[jwilson]

Resin removed by hydrolysis?

I've never had a problem with osmosis so I've never looked into it but I'm surprised to see that being said about it. Is hydrolysis really part of the problem?

I agree that it is most unlikely that hydrolysis is the cause of lack of resin in the fibres, if that is what is happening here.

One of the problems with the boatyard favorite job (gelcoat peel, then dry and recoat with epoxy) is that once the peeler touches the hull you've written a blank cheque.

Once the hull has been peeled and if you find large areas of unwetted fibres either localised or whole-hull peeling is probably going to be necessary to get a sound surafce to stick new stuff on to. If a lot of material has been peeled away in relation to the total hull thickness* then more glass cloth and polyester resin is the usual reinforcement needed before the final epoxy coat.

I really think you need a surveyor's advice, not a full survey, just to look at the hull now and see if the fibres are really not wetted out - ie resin-starved.

* A Gibsea 76 is a relatively lightly built boat, so the extra reinforcement might well be needed. On an old Nic 32 or similar era heavyweight the hulls are so thick to start with that this is unlikely to be needed

 

[Scareyclott]

* A Gibsea 76 is a relatively lightly built boat, so the extra reinforcement might well be needed. On an old Nic 32 or similar era heavyweight the hulls are so thick to start with that this is unlikely to be needed

Yep she is thin and she is now getting a full hulls worth of new biaxel cloth (not chop strand but the woven stuff) and resin added before the epoxy. I just keep telling myself I didn't need a new sail, I can clean the old one