Centaur - Faded hull polishing

[tarik]

Greetings,


Next weekend I'm lifting the Centaur out for a couple of weeks for some tlc. The hull which is/was dark green is in need of some serious polishing to try and bring it back to its former glory.

I would very much appreciate some advice as to the best products and method to achieve some positive results.

As always many thanks for any replies.


David

 

[Tranona]

Hard work and use a cleaning system from your favourite polish supplier. 4 or 5 (at least) different brands available in any chandlery. You will probably struggle with getting dark green back to any level of gloss as it is one of the worst for fading.

 

[ghostlymoron]

Try CIF its a mild abrasive which is What You want. If that doesn't work try T cut a bit more aggressive. I avoid any specific boat products as they seem to be the same stuff at three times the price but others disagree. Likewise I use Turtle Wax for polishing (which I don't do often anyway) whereas the purists use Mequirs or similar.

 

[FWB]

I used to use Farecla G3 followed by G10 on my black hull. It definitely restored the shine but it is abrasive. In the end I had the hull Awlgripped.

 

[ghostlymoron]

Once you resort to. Paint, you're on a slippery slope and will have to repeat every few years (even if you use Awlgrip paint). My advice to the op is to try restoring the existing gelcoat. If it hasnt been done before, there should be sufficient thickness to make a good job of it. Only if that proves impossible, resort to paint.(retires and waits for contradiction).

I used to use Farecla G3 followed by G10 on my black hull. It definitely restored the shine but it is abrasive. In the end I had the hull Awlgripped.

 

[richardbrennan]

It's basically a three stage process; 1) Compound, 2) Polish, 3) Wax. You will be wise to buy a decent polisher; you'll get lots of advice as to which this might be, but get the lightest one you can afford, I have a Rupes which weighs less than two kilos. I have also had very good results in the past with 3M products on my Westerly with a dark blue hull. I now use Gtechniq Nano Polish and C2, which is different technology and appears less aggressive than traditional compounds, check out their website, also with good results. However, if the fading is really bad, you'll probably be better off with the 3M Imperial Compound or its equivalent. Marine Reflections, who does this professionally, will probably also be along with some advice which will be well worth noting. There's also lots of demos on YouTube.

 

[pcatterall]

It's basically a three stage process; 1) Compound, 2) Polish, 3) Wax. You will be wise to buy a decent polisher; you'll get lots of advice as to which this might be, but get the lightest one you can afford, I have a Rupes which weighs less than two kilos. I have also had very good results in the past with 3M products on my Westerly with a dark blue hull. I now use Gtechniq Nano Polish and C2, which is different technology and appears less aggressive than traditional compounds, check out their website, also with good results. However, if the fading is really bad, you'll probably be better off with the 3M Imperial Compound or its equivalent. Marine Reflections, who does this professionally, will probably also be along with some advice which will be well worth noting. There's also lots of demos on YouTube.

Yes 3 stages. Test an area and determine just how aggressive you need to be with compound..you are removing the top layer of dirty and oxidised gel coat. I recently used Tcut but it took 2 sessions of hard work by hand, I then filled some scratches and found that my sanding down still left the gel coat whiter and brighter where I sanded. next rub down I might try a very fine wet and dry around 1500 grit!

 

[Tam Lin]

All good advice which I took when doing my boat. Ended up painting her!

 

[Crowblack]

My yard uses this stuff http://www.aoc-resinsuk.co.uk/product.php?xProd=81

Watched them do a few hulls before I got them to do mine - with very good results.

You do need a machine to do it - the yard used a paint brush to apply the compound in slabs down the hull then just polished it off with the machine.

The supplier is very approachable and happy to give advice - been there myself to pick a tub to use on the deck sides similar results - no association other than happy punter.

Coincidentally - last boat I saw the yard do with this stuff was the hull on a dark blue painted Centaur which was badly bloomed - came up a treat.

 

[AndrewL]

My boat has dark blue gelcoat which is also prone to fading. The previous two years I have spent a full day of hard work on hull polishing. I used Farcela products, both a coarse and fine compound, then polish then wax. I bought a Draper angle polisher, which is good for not too much money.

It did look much better once done, but after a few months it was looking faded again. I won't be doing it again. I will just accept that my boat is old and her hull is faded. Instead I will spent the limited time I have for maintenance on things which improve sailing and then go sailing.

 

[pcatterall]

My boat has dark blue gelcoat which is also prone to fading. The previous two years I have spent a full day of hard work on hull polishing. I used Farcela products, both a coarse and fine compound, then polish then wax. I bought a Draper angle polisher, which is good for not too much money.

It did look much better once done, but after a few months it was looking faded again. I won't be doing it again. I will just accept that my boat is old and her hull is faded. Instead I will spent the limited time I have for maintenance on things which improve sailing and then go sailing.

I had a navy blue hull years ago. I T cut it one season and it looked great but soon faded. 2 years later I did the same but applied several 'coats' of wax, it lasted several seasons looking good.

 

[richardbrennan]

When I bought my boat, the surveyor said that there are two things people only do once. The first was buy a boat with a teak deck, and the second was buy a boat with a dark blue hull; i am grateful I don't have a teak deck!

Seriously, you realistically cannot expect to simply bring back the hull to a gloss and then forget it. It's a bit like varnishing in that you need to keep on top of it with frequent cleaning and applying wax or some other protection from UV. My boat is now 18 years old, 16 years in my ownership, and the hull still comes up well. The only problem I have is what I am told are mould marks on the stern which experts tell me are not something that can be removed.

 

[pvb]

The trick is to use the least aggressive compounds which achieve the result, so start with very gentle stuff. You don't want to scour through the gelcoat! Afterwards, it's essential to apply both polish and wax. The polish helps to seal the surface; the wax helps to protect it. On my old Hallberg-Rassy, I used to use light compounding on the dark blue hull stripes, followed by 2 coats of Meguiars polish, then 2 coats of Meguiars pure wax. It improved the appearance, but perhaps only for 6-9 months until it needed doing again.

One thing you could try is a coloured car polish, this might help to bring the green colour back.

 

[NOHOH]

Try the `New Glass 2` system...........completely reversible if you don`t like it. http://www.newglass2.com/

Just a satisfied customer

 

[LittleSister]

Bear in mind that Marine Reflections, the forum professional expert on these matters (mentioned in an earlier post, and hopefully will be along soon) always says it is vital to thoroughly clean and degrease the hull before you start using compound and polish, otherwise you are just grinding the dirt (some near invisible) into the gelcoat, and spreading grease and grime about which will undermine your polishing and waxing.

The other thing to bear in mind is that there is only a limited thickness of gelcoat. Even if you are prepared to redo the hull each time it looks faded, that approach will eventually run out of gelcoat to compound away.

I do not have any particular expertise in these matters but, being owner of a boat with a faded dark blue hull, have read avidly the numerous threads about these matters over a number of years in the hope of finding the magic solution.

 

[Marine Reflections]

Indeed, the reason a good clean is so important, is it reveals the raw gelcoat surface and allows you to choose the right tasks to move forward.

On many occasions one wrongly assumes that the surface is badly oxidised, when in fact the surface may only have very light oxidation, or be perfectly fine, but be under a layer of dried water spots.

When you wash down and fail to dry the surfaces, you'll be left with water spots. (unless you are a super geeky sad case like me, in which case you'll have a multiple vessel water de-ioniser and purifier running in-line on the hose, that turns 300ppm tap water into pure 000ppm) in which case you won't have to worry about it, nor will your neighbour.

The impurities and minerals in normal tap water will remain on the surface if water droplets are allowed to evapourate in the sun.

Imagine many months of cleaning or rinsing the hull sides, but not being able to effectively dry the water that beads. You'll be left with some water spots. On a hot day you stand no chance of being able to wash then dry without the sun baking the impurities onto the surface. Which is why it's a good idea to wash down without the sun on your back.

These waterspots can build up and up into layers over the months and dull the surface, which behind it may be not as oxidised as you thought.

This is the reason a good clean is offered.

Now I don't just mean a clean with suds, I mean whatever it takes to be certain that what you have in front of you is raw gelcoat and not scale, old dried wax, sealants or an entire shelf of Halfords polish section on the hull.

If you suspect there is scale then use a suitable de-scaler such as Viakal or similar / stronger.

If you suspect there is old wax, then use a de-greaser and so on, until the surface can be classed as "clean".

So now let's assume it's clean / cleaner.

The restoration process; be it a wipe over with a spray polish and cloth, or multiple tasks from wetsanding to polishing, is determined by reading the surface.
This can be with the naked eye, or with tools such as the sun, bright lights (Sun Gun), revealing powder (guide coat) and so on.

Do you have light oxidation, or heavy.
Is the surface marred by very tiny scratches and swirls from previous restoration attempts.

What will it take to return the surface to better than its former glory with minimal removal of the remaining good gelcoat?
Perhaps just as important, what will it take to make it last?

I'm sorry to disappoint, but the more I understand about this process the further away from being able to explain it properly I seem to get.
There are so many variables that make it near impossible for any advice to be relevant and future proof accross the board, to everyone.

Gelcoats are at different degrees of hardness and resistance, so what works well on one surface might not work so well on another.
How I might work an area might be no use what-so-ever to someone that doesn't have the same equiptment, products, patience or indeed the desire to achieve a high clarity reflection and therefore long lasting results.

On many occasions I will demo / test an area and perhaps try many different techniques before I understand which one will work the most efficiently for that surface. Of course starting out with the least aggressive.
Technology and techniques are changing, even today I was testing products I'd been given for a certain stage of the correction process that I'd never used before and found them to have the edge on what I had been using prior.
So even what works well today, will be old hat tomorrow. Use what you have, it will all work.

I know that we would all like to have a surface that can withstand whatever we and the elements throw at it.
Ironically, getting the surface to near perfection and keeping it that way through protection is the most effective way possible I've found and the true "easy option" long term.
But, it is an orchestra of tasks and that requires a sincere interest in the subject.



On the subject of darker coloured hulls, the pigment means that they will react / reflect differently to white ones, therfore accelerating the degredation process.

One tip (and I see this often) is that many folk correcting dull surfaces are merely tickling the surface and not really getting to a point where the surface is being corrected.
Many products contain oils that are within products to provide slip and workability when working with a machine.

These oils will wet the surface and will give the user the impression that the surface has been corrected / polished, when in fact it is just a temporary glaze of the highs and lows of the gelcoat.
When the oils evaporate (and they will do so quickly) the original (un-corrected) surface will re-reveal itself, giving you the impression it has oxidised once again.

The chances are, it was never corrected in the first place.

Here's a video I took last week utilising a standard correctional process for light to medium oxidation.

Using the following after a good clean (Step 1):

Working a Flex Pe-14-2-150 Rotary with a white lambswool compounding 2 sided pad and 3M's Imperial compound. (Step 1)
A 3M yellow 2 sided polishing pad with 3M's Finesse it finishing material. (Step 2)
3M's blue Ultrafina foam pad on a soft 125 mm backing pad using their Ultrafina to jewel the surface. (Step 3)
In between stages I'm wiping down with Isopropanol alchohol to remove oils from each of the products so as not to affect the next stage.
The protection stages are:
Gtechniqs C1 to inhibit UV, seal off to oxygen and create a strong durable scratch resistance to the surface. (Step 4)
Finished off with Gtechniqs EXO for some seriously high water beading. (Step 5)

 

[jwilson]

When I bought my boat, the surveyor said that there are two things people only do once. The first was buy a boat with a teak deck, and the second was buy a boat with a dark blue hull; i am grateful I don't have a teak deck!

I once had both, on the same boat with lots (really lots) of varnished teak trim and polished bronze fittings. Looked fantastic, but the work .......

The first to be let go was the polish on the bronze (winches, fairleads, cleats, ventilators etc). A nice patina still looked OK. The varnish on the brightwork I kept up, strip to bare wood every other year and revarnish, touch-ups between. The dark blue hull eventually got Awlgripped - far better finish than the gelcoat ever was. The teak deck just stayed bare: it was still (just) OK when I sold the boat.

When we went out to look for a newer boat the spec was "white hull, GRP decks, as little external wood as possible and no varnish above deck."