Gel Coat Yellowing on Bavaria Vision 46

[SofiaB]

Gel coat is yellowing on outside corner areas of my 2016 Vision 46.  It started yellowing after 5 months of use and continues to get worse.  I wash the boat weekly and wax twice per season with a short season of 5-6 months.  I've read online that this may be caused due to having gel coat which is too thick.  On the Vision, there is a 3" wide area parallel, alongside traveler track which is the worse.  Since this is an area which would be more difficult to apply gel coat into the mold, I'm starting to believe what I've read, that the thicker gel coat is the cause of the issues.

Is anyone else experiencing this issue and if so, what have you attempted to remove the yellowing? 

Has anyone reported this issue to Bavaria or your dealer?

[Kibo]

Hi Stuart,

No issues with my Vision 46 2014 model. 

I agree that those areas may have thicker gel coat. Not sure why that would cause yellowing in and of itself though...... I am a polymer chemist by training and if you have yellowing then it is likely caused by oxidation of the gel coat surface and not easy to rectify since it is a systemic issue rather than a surface issue solely. It is the actual vinyl ester resins that will yellow on oxidation/age. White pigments will mask/hide this....

The more likely explanation is that there is not enough white pigment in those areas and that the resin oxidation is "taking over" and making the area look yellow since it is not masked by the white pigments. Those pigments will typically be fine powder mixed into the gel coat. The best \ strongest white pigments are Titanium Oxide. These are expensive so it may be that reducing the amount of pigment may have been some cause of this issue... Obviously this is conjecture on my part but from a chemical perspective this makes sense.

I am not sure there is much you can do apart from covering this area with paint or extra gel coat.

[Club 56]

Hi Stuart,

Yes we had this problem on our 2013 Vision 42. Hope photos show it.

Australian agent after contacting Bavaria came back that it was excess release agent used in the mould. This section is apparently made off site.
Solution was either replace, respray or polish out. We chose polishing out carried out by a local fibre glass pro/repairer.
Worked OK however that area now needs some extra polishing to stop it chalking up sooner than areas around it.

Hope this helps.

Cheers
Keith
Club 56

[Conralph]

SofiaB,
we also created the same pictures. Our Vision42 also has these discolorations in the top parts of the deck. With a polishing machine and the 3M polish, you get the discoloration completely removed. Even after two years, the discoloration does not return. In order to get the old high-gloss Gelcoat surface again, surely more polishing steps are necessary.

Ralph

[Kibo]

I consulted with a couple of other gel coat experts... No one suggested too much release agent so not sure about that.

In addition to a possible lack of pigment another cause maybe an excess of styrene in the mix. Styrene is used in Gel Coat as an aid to curing (a crosslinker) and also has the effect of acting as a solvent or thinner to the gelcoat. Sometimes if gelcoat mixes are too viscous then a little extra styrene is added. If you buy a new boat or have mixed gelcoat then you will be familiar with the smell of styrene.

If there is an excess then it does not completely react into the vinyl ester/polyester mix during curing and then can bloom to the surface over time and be oxidized causing yellowing.   In this case buffing out the surface until all excess styrene has evaporated should stop further yellowing so surface buffing should work if this is the cause.

Hope it helps further....

[SofiaB]

Ralph,

What 3M product did you use?  You said polish, but did have compound?  I have a buffer also. What pad did you use? 

Thanks everyone for the information. I’m hoping to remove this yellowing over the winter. Just pulled off the sails but waiting to unstep the mast. Have had high winds on Lake Erie. Blowing 42 knots as I write this.

[Conralph]

Hello Stuart, our ship is a bit away from us, so delaying the answer. We used the fine grinding paste from 3M. The polishing machine is a Superpolish P7 with a "medium hard" polishing pad (gray).

[IslandAlchemy]

Just been reading this thread.  I would recommend rubbing the surface down with 1,000 grit wet & dry to get the top discoloured layer off, then use 3M Fastcut followed by 3M finess-it, and then wax.