Marks on topside gelcoat

[Sailing newbie selsey]

I am trying to polish my gelcoat on my hull topsides, after using M3 cutting paste today and getting the hull marks off from scuffs from last season. I am stuck trying to get these marks off my gelcoat is a dull brown stain in a few places on my hull, that just don’t seem to want to go, despite using my electric buffer and cutting paste. Any tips please ?

 

[Fire99]

Before doing any further cutting, have you tried Y10 gelcoat stain remover, or suitable alternative (I forget the acid that is in it)? The Gel may be stained and this may help.

 

[Sailing newbie selsey]

Not tried that only the cutting paste so far, will give it a go

 

[adwuk]

Y10 or Starbrite Hull Cleaner are the products I use. Both very effective.

 

[[2574]]

Y10 or Starbrite Hull Cleaner are the products I use. Both very effective.

But make sure it is warm enough when you use oxalic acid, I think it has to be >10deg C. Below the recommended temp it is ineffective, check usage instructions.

 

[Whiterose]

Oxalic acid ..eBay cheap

 

[Sailing newbie selsey]

Oxalic acid ..eBay cheap

What ratio do you mix it too? Thanks

 

[jwilson]

I have seen enthusiastic use of machine cutting paste use cause patchy colour as the user is going almost right through thin gelcoat and the underlying darker (usually yellowish brown but sometimes black) laminate is starting to show through.

If you are mixing oxalic acid powder use hot water and put in as much powder as will dissolve.

 

[oldgit]

Oxalic acid from Ebay, 500g £8..00 or less. far far cheaper than chandlery grade (expensive) Y10 which has a tiny amount of oxalic in it, all you are paying for is plastic pot and whatever is used to bulk it out.
Watch the brown stains dissappear as you watch.
The downside, the bright white gelcoat which is revealed makes the rest of the boat look scruffy.
500g is more than enough to make a bucketful of solution for an entire hull for quick smarten up with some left to shift fro stubborn rust stains around stantions etc.

https://www.promain.co.uk › specsheets › Practica...

 

[Concerto]

I am trying to polish my gelcoat on my hull topsides, after using M3 cutting paste today and getting the hull marks off from scuffs from last season. I am stuck trying to get these marks off my gelcoat is a dull brown stain in a few places on my hull, that just don’t seem to want to go, despite using my electric buffer and cutting paste. Any tips please ?

Please when asking questions like this, provide details of the boat and its age. Since glassfibre has been used for boats, over 60 years now, different processes and materials have been used. This always affects the advice you need as some forum advice may be wrong for your type of boat. With direct reference to your question, is your gel coat brushed or sprayed? This does make a huge difference to any answer for the correct solution. Nothing none of the advice so far given is wrong, but may not solve your problem.

 

[Sailing newbie selsey]

Please when asking questions like this, provide details of the boat and its age. Since glassfibre has been used for boats, over 60 years now, different processes and materials have been used. This always affects the advice you need as some forum advice may be wrong for your type of boat. With direct reference to your question, is your gel coat brushed or sprayed? This does make a huge difference to any answer for the correct solution. Nothing none of the advice so far given is wrong, but may not solve your problem.

Sorry not sure if it’s brushed or sprayed, she is a Stag 28 built in 1979

 

[Concerto]

Sorry not sure if it’s brushed or sprayed, she is a Stag 28 built in 1979

A Stag 28 woukd have had a brushed gel coat at the time of moulding. From memory she was moulded by Halmatic and fitted out by Emsworth Boatyard for Salterns Yacht Agency.

The gel coat should be about 1.5mm to 2mm thick. This means if the treatments already advise do not work then look at my PowerPoint presentation on gel coat renovation. There is advice on more extreme things you can try.
https://wiki.westerly-owners.co.uk/images/8/86/Gel_coat_renovation_19May2020.pdf