Boat polishing tips: How we got the PBO Project Boat’s topsides gleaming

After a failed attempt to make Maximus gleam, James Wood calls in the boat polishing experts to help with the PBO Project Boat

After the 2020 sailing season was largely lost to lockdown, Maximus had been ashore at Dell Quay in Chichester for two years when my wife, Ali, and I took her on.

Our surveyor, Ben Sutcliffe-Davies, had identified that the topsides of our 28ft Maxi 84 were very flat and dull, and could use a good compounding before being protected with wax. He also advised that boat polishing should be done before we reapplied the antifouling, to minimise the risk of cross-contamination.

Having never compounded a yacht before, and last polished a car over 20 years ago, I needed to take a crash course in how to do it!

I talked to a couple of experts, delved through the PBO archives, and took in a healthy dose of YouTube tutorials. However, it wasn't until we called in the boat polishing experts that we achieved the finish we really wanted.

Article continues below…

Few things irk me more than dirty, chalky and stained gelcoat. Like an engine that is corroded – or lines…

Everything you need to know to make an invisible gelcoat repair, from preparation and filling to topcoat and polishing

Maximus is a 28ft boat with off-white gelcoat. We applied a three step system for the purposes of this article. I was working at the top of the ladder for most of the time, which adds to the fatigue of the process, especially when using a 2.2kg electric polishing machine.

On top of that we took photos and video clips of our progress, so the time we took should only be taken as a very rough guide– in most cases it can be done more quickly.

Thoroughly remove grime and dust using boatwash. Frequent washing prolongs the life of the gelcoat by removing contaminants before they have a chance to bond or etch to it. Remove stains with a proprietary stain remover.

Time: 4 hours, including decks and topsidesProduct: 1L Clean to Gleam boatwash (£20), brush and sponge

Use a rubbing compound to abrade the gelcoat. This typically contains aluminium oxide, which does the ‘cutting back’. For mild oxidation, you can skip Stage 2.

Time: 6 hoursProduct: 1L Farécla Profile Select (£30) or 1L Farécla Profile Premium Paste (£48); Farécla G Plus electric rotary polishing machine (£172); Farécla 8in G mop twisted wool pad (£20); Farécla G Plus spurring brush (£15)

Use a fine compounding liquid to remove light marks in the gelcoat left over from Stage 1 and increase gloss.

Time: 4 hoursProduct: 1L Farécla Profile Finish Liquid (£24); Farécla rotary polisher (£172); Farécla 8in G mop lambswool pad (£20)

For best results wax 2-3 times a year to stop UV light attacking the surface.

Time: 4 hoursProduct: 1L Farécla Profile Polymer UV Wax (£30); Farécla 3-pack G Plus finishing cloths (£12)

Total cost of tools & products: £279 (1 stage using Profile Select) to £341 (2 stage using Profile Paste).Typical cost of cut-back, polish and wax at boatyard @ £13/ft: £750-£1,000

Prices obtained from a range of online suppliers. These may vary. Compound, finish and wax products by Farécla.

You’ll definitely notice the difference after a cut and polish

When the surface of your gelcoat loses its lustre, and starts to take on a chalky appearance, it's time to think about boat polishing.

This is because the marine environment is a harsh one: oxidisation, UV damage and environmental pollutants cause the gelcoat surface to degrade, become more porous and take on water and airborne dirt.

In ‘polishing’ the topsides, we’re actually removing the degraded gelcoat polymer, to expose the fresh polymer matrix, with its original glossy lustre and pigment.

So as well as a big improvement in the cosmetic appearance of your yacht, boat polishing is essential in maintaining the structural integrity of the gelcoat as a barrier against the elements.

Maximus's off-white gelcoat was dull and chalky

We spoke first to David Johnson of Wessex Resins and Adhesives. "We’re asked a lot of questions about GRP maintenance at boat shows," he says. "Boat polishing is a fairly tedious job that requires concentration. It's lots of work and there's no gold medal!"

David owns a 30-year-old cruiser and points out that since lockdown the supply of new yachts has dwindled and more people than ever are buying second-hand – and a lot of those owners will be keen to make sure their hulls sparkle.

David explains that you can do a lot of the boat polishing work by hand to start off with. Buy a roll of microfibre towels, dip them in water, put compound onto them and keep working it with a lot of elbow grease.

By dampening the towel you maintain the cutting action. You need one cloth for applying the compound and then two other cloths – one for getting the residue off the compound, then another for getting the gloss back up. You have to throw away the saturated ones, and will use a dozen or more at least.

"Once you’ve got a good sheen, before it dries up, use a proper polishing mop, but only rotate slowly," he warns. "No more than 700-800rpm. If the rpm is too high you’re going to burn the compound off right away."

A boatyard drum proved a handy platform for the 3M polishing kit

If you’re not sure whether a polish is worth doing, David suggests testing a patch of the boat with a tube of toothpaste first. Rub it onto the hull with a cloth and see what kind of a gloss you can get. You might be surprised how it lifts the finish.

Yellow patches are common on old boats. Maximus has these, as well as some cleaner white patches. David explains that a lot of boatcare products will bleach out oil or rust. "I suspect someone's used a white stain remover on Maximus," he said, giving a possible explanation for the white patches.

"Oxalic acid bleaches out the yellowing from oil stains. There's a product called Y10 – it's a gel. You brush it on and that removes the oil stain, then you go back to compounding."

The underside of the boom was especially dirty

As I had a large area to cover, I decided to buy a polishing machine, along with the 3M Perfect It compounding system. This was: Hard compound, Medium compound and wax, and 100% Wax.

I also bought a lambswool bonnet for applying the hard compound and a medium sponge head for the medium compound and wax.

I then went to Machine Mart in Portsmouth to pick up a polisher/sander. I chose the Clarke CP150 as it had the variable speed control I needed for both polishing and sanding.

Being a beginner, I specifically opted for Clarke's ‘dual action’ (DA) machine with a hook system on the pad for the interchangeable attachments.

The DA polisher rotates in a figure of eight action, and is less aggressive than a rotary machine, where the disc rotates 100% in one direction.

My research had suggested that it was easier to damage the polished surface with the rotary machine, as it's more aggressive, and builds up heat more quickly.

However, we’ll see later that my choice of machine probably wasn't the correct option for compounding and polishing.

James polished the transom and port side hull using 3M products

I had to call Clarke International for the rpm for each setting, as this was important for the polishing and it wasn't stated in the manual or tech spec. They advised the settings ranged from 500rpm at 1, through to 3,500rpm at 3 and 6,000rpm at 6.

Different compounding products require different rpm settings on the polisher you choose, so it's important that you can vary the speed settings if you haven't chosen your compound or polishing product yet!

Most compounding and boat polishing systems seem to require between 1,500-2,000rpm, but if I want to use the machine for sanding, I’ll need the top 6,000rpm setting.

Farécla products were used on the starboard side

Lastly, I took along some lint-free rags that I’d made from old t-shirts for buffing after finishing the boat polishing. It's also easy to buy lint-free buffing cloths from the chandlers or a hardware store.

I persuaded my friend Phil to help out and on arrival at the boat we set up for two days of work, which is what we’d both secured from work and parenting.

My main job for the day was to prepare the topsides for compounding and polish. We’d jet washed the decks previously, but being right next to a tall hedge, and still having the mast stepped meant the deck was very dirty from leaves, blossom and bird droppings.

James used Clean to Gleam boat wash on the grubby decks, hull and rigging

The last thing we wanted was to wash a lot of this muck onto newly polished topsides. Based on the principle of starting at the highest point of the deck, I started on the coachroof with a bucket of water and 100ml of Clean to Gleam boatwash.

This was effective when applied with a sponge and wiped away, though some of the more persistent stains required a mildly abrasive sponge to clear.

After the coachroof was cleaned, I worked my way back from the forestays. This was quite time-consuming – more than I’d allowed for – and it took a couple of hours at least.

Having applied the boat wash, some of the dirt was still loose on the deck, so we used a hose and soft bristled broom to clear the remaining dirt. Very satisfying!

The next step was to clean and decontaminate the hull topsides. I could then start by applying the Clean to Gleam boatwash to the topsides with a sponge, before using a rag to wipe down.

It's important to choose a biodegradable product if the run-off is filtering directly into a waterway, rather than into the drains.

We’d hoped to start the compounding that day, but time was ticking on as we’d had to travel to Chichester from Bournemouth, picking up the materials on the way.

We wanted to be able to do the stern of the boat in full initially, as it was the first time either of us had compounded a boat.

So we tidied up and prepared to start again early the next morning. We pitched our tent at a nearby campsite and went to the local pub for a pint.

Small gouges were filled with the wrong colour filler – but looked better after sanding!

The next day, Phil began by prepping some of the gelcoat marks we’d made when removing the antifouling, and applying a gelcoat filler.

I also asked him to fill a few small marks in the topsides gelcoat, only to be told later by the boatyard that this was a mistake, as it was both the wrong colour and the wrong product (I’d found it on the boat).

What's more, the boatyard said they were reluctant to take over someone else's repair, so it looks like that one's on me! I decided to apply the full 3M Perfect It system to the stern of Maximus to get comfortable with what the process entailed.

We started by masking off the boat name decals and the top of the antifoul strip, to prevent the former peeling and the latter cross-contaminating the compound material. We were later advised it would have been easier to remove the decals altogether with a heat-gun and buy new ones

Starting with the 3M Hard compound, I used a lambswool head on a polisher at 2,000rpm and worked in 2ft x 2ft areas, to ensure the compound material remained easily workable.

I used a jam jar to put the compound into, using a half inch brush to apply it to the topside surface in a series of large X's. I used the polisher head to spread the compound liquid before bringing the polisher head up to speed.

Working in the 2ft area, I started in the top left corner, and polished right to left, left to right until I reached the bottom right corner. I then continued to polish bottom to top, top to bottom as per the diagram (below). I polished each area for approximately 60 seconds.

Pattern for the polishing machine

The most helpful boat polishing tip I was given was to let the polishing mops do the work, and to apply minimal pressure to the polishing surface. As such, I used my second hand to gently guide the polisher head with my fingers, rather than ‘push’ it around.

The Hard compound is lightly cutting into the surface of the topsides, so it was important to ‘go easy’. Once I’d completed the stern and rudder with the Hard compound, I changed the polisher head to a medium ‘sponge’, which was used for the 3M Medium compound, which included an element of a wax finish.

Having researched the 3M Perfect It system, it is possible to just follow these two steps, as there is a wax content in the Medium compound.

However, to achieve a better gloss, and better protection for the topsides, I was advised to use the 100% Wax third stage in the process, which is also applied using the same medium sponge polisher head, also at 2,000rpm.

The boat polishing process itself is relatively straightforward, but as I was working 2m up a ladder and applying a three-step system, I was soon fatigued. The polisher itself weighs 2-3 kg, and the more tired I found myself, the more difficult it was to apply a consistent pressure to the polished area.

When polishing a large area, I also found it was easy to over-extend my reach, which led to an inconsistent finish and having to re-treat the area.

To keep track of where I’d got to I ended up using two little bits of masking tape loosely stuck to the rubbing strake to define the area I was working on, or using ‘waypoints’ on the hull such as the stanchions or fixing screws in the acrylic windows.

After finishing for the day, we’d done the stern and starboard side of the hull. There was a visible improvement to the finished section when compared to the port side of the hull, but the gloss was no way near as shiny as I’d hoped, and nothing like one of the neighbouring boats that had been polished recently.

I took a few pictures and resolved to do some more research before I returned to Maximus the week after.

Christine Foster and Romain Ostermann from Farécla gave James a hand and some valuable boat polishing tips

A few second opinions confirmed that the gloss finish I’d achieved with my first attempt at compounding and polishing the topsides was definitely short of what was possible.

I’d been telling myself that this was because we were starting with a grey/off-white gelcoat, which was never going to come up as glossy and lustrous as a deep blue, but alas my initial efforts were still below par!

Luckily, a few phone calls led me to Romain Ostermann and Christine Foster from Farécla. On hearing I was struggling with the PBO Project Boat, they came down to Maximus the very next week to show me how to achieve the perfect polish.

Romain (left) explains why the rotary polisher is more suitable than James's dual action machine

Romain reviewed the areas I’d polished on my previous visit. Whilst the finish I’d achieved was fairly consistent across the stern and port side of Maximus, he was instantly able to tell that the compounding hadn't been aggressive enough in removing the oxidised gelcoat surface, and cutting back to create a fresh, glossy surface once more.

It wasn't the 3M Perfect It system that was at fault: Romain identified that a rotary polisher is much more effective when cutting back the gelcoat surface. I’d chosen the Clarke DA machine specifically because it was more forgiving for a beginner, but the level of oxidation on the hull of Maximus required a heavier touch!

Romain uses a spurring brush to get rid of any excess fibres from the mop

Equally, I was using a lambswool bonnet, and Romain advised me to use a twisted sheepswool bonnet instead, to increase the cut further. Romain did say, however, that a dual action machine is perfectly good for fine polishing of topsides that are in relatively good condition.

Maximus's topsides are an off-white gelcoat. Is this as pleasing as deep lustrous blue, black or red gelcoat? Possibly not, though beauty is in the eye of the beholder!

In fact, according to Farécla, white gelcoat is great for keeping down the maintenance required to keep it glossy. The spectrum of colour isn't as deep, so you don't need to work as hard to achieve an acceptable finish.

Romain explains how to use the liquid polish and the rotary polishing machine

Either of Farécla's Stage 1 compound products featured in this article can be used as a standalone treatment on white gelcoat, but for coloured gelcoat Farécla always recommends using the second stage finish.

I sanded back the gelcoat filler, starting with a coarse 80-grit roll of paper, and getting progressively finer, through 300-, 600- then 800-grit. Actually, once finished, the patches didn't look nearly as bad as before.

1. Centre the mop on the polisher: sheepswool for Stage 1, lambswool (pictured) for stage 2.

2. Paint the compound, paste or liquid, onto the mop to prime it.

3. On the lowest speed (700rpm) spread the product evenly with the rotary polisher.

4. Crank it up to 2,200rpm for Select Liquid or 1,500 for Select Paste and go right to left, up and down.

5. After one minute lower the speed to 1,100rpm to reduce the heat generated by friction.

6. The white powder on the mop is the gelcoat oxide that has been polished off.

7. Wipe down the completed area with a microfibre cloth.

8. Remove excess fibre and powder from the mop with a spurring brush.

9. Work in 1m square sections. The masked off area is now ready for a final coat of wax polish.

It was time to put Farécla's products to the test on Maximus's port side, which had been previously cleaned and decontaminated. As we were testing two different Stage 1 products, we masked off three sections:

Farécla recommend using a twisted sheepswool mop to apply both of the Stage 1 products on test. When using a new mop, it's important to use a spurring tool to remove any loose fibres before you start – a bit like hoovering a new carpet after it first goes down.

Liquid (right-hand panel) vs control: This can be used as a single stage system for boats with white gelcoat. And the results back that up; we’d estimate an 80% legibility from our label reflection.

Romain and Christine explained that boat owners have been using a paste to compound their boats for years, and seem reluctant to try this newer liquid compound which feels smoother to the touch, with less of an obvious cut. It would be interesting to see the results.

Applying the Profile Select Liquid first, we primed the pad with around double the usual application, in order to ensure good coverage from the start of use. We applied the compounding liquid to the pad, and spread onto the panel at 700rpm initially, before increasing to 2,200 rpm for the majority of the time.

After 60 seconds or so, we slowed to around 1,100rpm to take some heat off and bring up the gloss. We used a microfibre cloth to quickly wipe down the area; the panel came up really nicely after just one application.

Paste (left-hand panel) vs control. Paste can be used as a single stage process for boats with white topsides, but on Maximus the gloss achieved was not as good as that achieved by the Select liquid.

On a separate patch, we used the Profile Premium Paste for comparison purposes. After priming the pad and spreading the paste at 700rpm, we increased the polisher speed to 1,500-1800rpm, slightly slower than the Select liquid. It was notable that there was more spatter from the paste, which is a thicker, grittier product.

Nonetheless, the Premium Paste achieved a nice finish after a single application, though to the naked eye it was clear that the level of gloss was inferior to that of the Select liquid after a quick buff with the microfibre cloth.

Sadly, we didn't have access to an actual glossmeter (an instrument to measure the specular reflection of a surface) but that's not to say we can't give you some gloss test results!

In the absence of a meter, the PBO patented gloss test is simply to hold the compound product label up to the freshly compounded topsides. You then take an estimate on the % legibility of the label in the reflected image.

It's obviously not a precise art, but it acts as a yardstick for the finish you’ve achieved. We’ve tried our best to photograph the difference, but the boats are very tightly packed in at the yard, so we couldn't get far enough away!

Liquid (right-hand panel) then Finish. We’d achieved a good level of gloss from the single Select treatment, but the Finish application did improve the gloss effect further.

Farécla recommend using the same Stage 2 product for both the Select and Premium treated areas; Profile Finish Liquid. It's a fine compounding liquid; there's a small amount of cut to it to remove light marks in the gelcoat left over from Stage 1, but its primary purpose is to increase the gloss finish.

To increase the buffing effect at this stage of the system, it's recommended to switch to an 8in lambswool mop, rather than the twisted wool mop used for both Stage 1 treatments. Again, use a spurring tool on the mop before use to remove any loose fibres.

Paste (left-hand panel) then finish. The gloss achieved from a single application of Premium paste lagged behind that of the Select liquid, but the Finish application brought them visibly closer.

We changed the bonnet on our rotary polisher to the Lambswool 8in. As it was the first use of the mop, we primed it with around double the usual application of the Finish product.

As we’re interested in increasing the gloss in this stage, the recommended speed setting on the polisher is lower, around 1,100rpm. Again, it's still important to use your second hand to guide the polisher head, rather than apply any pressure. We’re letting the machine do the work, as Romain liked to remind me!

The application method for the Finish product is the same as for Stage 1, and indeed for my initial efforts using the Dual Action polisher. We again spent around 60 seconds polishing each panel, and were careful not to over-extend the area worked on at any one time, to maintain consistency of finish.

Once finished, we used a microfibre cloth to rub down the panel, increasing the gloss and removing any polish residue.

For a boat of Maximus's size a machine is best for waxing

Whether you settle for a one or two stage compounding system, you’ll want to protect the glossy finish with a coat of wax.

The wax layer will bring both water resistance and UV inhibitors to your gelcoat finish, maintaining the lustre of your newly polished topsides for longer. Farécla recommend two similar wax products:

James applies the wax finish

Unless you have a small boat, a machine application is preferable given the surface area involved. Maximus is 28ft so we opted for the Farécla rotary polisher, using the Polymer UV Wax product.

Farécla recommend the use of a 8in sponge finishing mop, at 1,000-1,500rpm. The wax can be applied directly to the surface, or onto the mop head, depending on your preference. The boat polishing technique is exactly the same as for stage one and two, followed by a wipe down with a clean microfibre cloth.

If you prefer to apply the wax by hand, or a machine application isn't practical, the Polymer UV Wax product can be applied directly to the surface of the topsides, and buffed by hand, using a microfibre cloth.

Rub down afterwards with a microfibre cloth

The two Farécla wax products are interchangeable so it's fine to apply the initial coat by machine in the boatyard, and top up the wax coat by hand later in the season when you are on the water.

It's fairly clear in my mind what approach I’ll take when I next polish Maximus's topsides. While the initial outlay for boat polishing tools and products is not a great deal less than paying for a professional job (see costs) you obviously get to keep the equipment and use it each season, so it saves a bit of money the first year, then more as the seasons go by.

Next time I would use the Profile Select Liquid compound. It's easier to work with than a paste, with less spatter, and achieved a good glossy finish with just one application.

After a lesson from expert Romain James has another go

In fact, the Select treatment was so good that I’d happily forgo the second stage Finish treatment and move straight onto protecting with the wax product. This should mean you can start and finish the compounding in a single long day, as long as the topsides are already clean. And spend more time sailing!

I’ll definitely also keep a supply of the UV Wax in a locker for regularly topping up the wax layer every few months, especially if it saves me from a couple of days polishing my boat perched atop a step ladder every winter.

Dell Quay Marine, Osculati, Raymarine, Shakespeare Marine, TruDesign, Screwfix, Coleman Marine Insurance, MDL Marinas, Premier Marinas, seajet, Marine & Industrial, Clean to Gleam, Dometic, West System, Farécla, Navigators Marine, Lewmar, RYA, Aqua Marine, Ecobat, Victron Energy, Scanstrut, T Sails and XP Rigging.

This feature appeared in the January 2022 edition of Practical Boat Owner. For more articles like this, including DIY, money-saving advice, great boat projects, expert tips and ways to improve your boat's performance, take out a magazine subscription to Britain's best-selling boating magazine.

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