I say “lockdown” but there are very much more people about now compared to just a couple of weeks ago. But masks, gloves and hand sanitiser are still commonplace and reassuring.

Last time I was busy fixing some minor cracking around the internal bulkheads either side of Rosie’s keels. I’d ground out the bad old matting that had come away since she had been lifted out.

I have progressed well in this area with the help of some west system epoxy, peal ply and some structural foam to fill the considerable gaps revealed by removal of the old matting. Next step will be removal of the peel ply, sanding away more of the paint to get a good grip for the epoxy and a small couple of layers of chopped strand mat in the areas I’ve prepared. Oh and finishing off the preparation of the starboard side joins.

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Since then though, Rosie’s old Volvo Penta MD11C engine has come out for some work, new gearbox and back engine seal as well as refurbished injectors.

While the engine is out of the bay it’s the perfect chance to get to clean up and repaint the engine bay. The part of a Centaur that is extremely hard to get into, especially with the older large Volovo engines.

As I was getting ready to begin my cleanup work the boss of the Yard paid a visit to tell me the engine was about ready to go back in. They would give it a clean up and treat any corrosion. Injectors were back, apparently they were not atomising at all – no wonder we had all those clouds of white smoke!

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Armed with gloves, de-greaser and kitchen roll I had hoped to do a simple before and after photo of the clean up and then paint with the new tin of grey bilge paint sitting ready.

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After making short work of the oily and slightly sea-salty mess I noticed that rather large crack. Cleaning a bit more another not-cracked but bad area further forward.

A bit of a dig in the area nearest me, because it was easiest to get to and perhaps less worrying than the other area yielded the result of some not very good fibreglass work..

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It was basically only held in place by paint, with my bare hands and no tools I was able to peel off the old bit of matting. It was still flexible!

As I’ve been told lots of times before, preparation of the surface is the single-most important factor in making a good fibreglass work. It’s pretty obvious that this was a recent bad job. I suspect this was added as a blockage to stop oily engine-bay water heading forward. But I can’t be sure. I can tell you that when I ground all this out again I encountered a layer of grey paint under this lot.

That said, I don’t think the “work” attempted here was for structural reasons. The outside damage was clearly from the lift out popping the classic osmosis blister, but the poor work could have trapped water here and made things worse but they do roughly line up so perhaps this area could do with a bit more strength.

What about that crack?!

When you are inside the boat, it’s not that easy to visualise where you are on the inside compared to the whole visual from outside. While sitting in here with the lamp on, cleaning all the grease and such away I was wondering if this had been there all this time. The crack is right beneath the middle of the place where the engine sits. Even with the best enthusiasm I’d never have been able to see this spot.

Accepting now this was going to be a much bigger job than just cleaning and painting I wanted to see if there was any evidence outside of a problem.

My initial thoughts were. Oh, maybe this is where the hoist was bearing the weight outside (I thought that was further forward).

Now, a Centaur can stand very stable on her two keels. They weigh between them around 800kg so the little boat wont easily topple forward of back. That said, she was propped up aft in the photo above. I’d have not thought this arrangement a bad idea myself.

Where the wedge is in contact with the hull is exactly where that crack is!

Fortunately, I’d taken the day off work for this. It was a Friday and the yard was humming with work going on. So, in a bit of a daze I rushed off to find the gentleman yard boss who said hello earlier. I showed him the damage inside and he quickly arranged for his lads to prop her up right.

I took the chance to visit the local DIY shop to get myself some sanding discs and wire brushes. On my return she was propped up better supported under both keels

The new aft “support” doesn’t bear any significant weight now. It is only to eliminate any chance of rocking forward or back.

How did this happen?

To get the engine out the yard needed to use a huge engine hoist – apparently it is a pre-1939 feature of the yard! To get it above and move the huge volvo beast out via the companionway Rosie had to be propped up differently. As a result of this re-positioning and the small army of lads required for that job it looks like far too much load had gone onto the aft “support”. Probably if the wedge of wood had been wider and spread the force out over a large area things would have been fine. But it wasn’t.

With the boat now not resting on this spot the crack had closed up, I decided to clean away the paintwork around the damage to get a clearer picture of the repair work needed.

With the paint sanded away and grease removed the depth of the damage was clear the black area is how far the oil from the gearbox removal work had penetrated through (when removing the old gearbox they found the rear seal had failed).

The crack ran all the way through! Going back in the water like this could have meant a leak, perhaps not fast enough to be obvious but I’m guessing enough to sink her after a couple of days!

You could imagine I was quite upset at this stage, but I kept my composure and went to fetch the yard boss again before he went home.

Between us we spoke of the things that needed to be done to fix this. We agreed that I would return for the next day where I’d have his attention for fixing up.

These folks arent’ cowboys, they’ve been running a successful yard as a family for about 100 years. They are masters when it comes to wooden boats of all sizes and have built a great many, including a large number of GRP broads boats. So, I looked on the next day as an opportunity to learn rather than one to get cross at the mistakes. The boss brought over tools that we’d need for the next day and I got ready to head home for dinner.

Day Two

I arrived a little later than planned after making a deatour to get some paint stripper (Do not get Nitromors for GRP work) and then taking it back to the shop after I’d read the “not for GRP” instructions. So, I had to sand the paint away instead.

I quickly set about grinding away the old paint with the loaned angle grinder and my trusty belt sander. The angle grinder was fast for the flat surfaces I could get to but just not nimble enough for the odd shaped cramped places.

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Yes.. that is daylight. Working on the premise that as a guide I needed to grid away the glass areas discoloured by where the oil had seeped in I started as far back as the crack began. You can see from above that I hit gelcoat as soon as the black marks had been sanded out. Gelcoat is not 100% water tight so yes, we’d have taken on water through here!

I’d originally thought this part of the hull to be extra thick and strong. Perhaps the hull material is shown better in this clip from just before I began to grind out the damage:

What struck me (apart from the huge scary crack) was how clear seeing through the fibreglass was. The crack was completely clean and straight. I’m no expert at this, but compared to other parts of the hull that have no paint on this looked different.

It was almost as if there was hardly any glass fibres there. In grinding away the damage I only produced that very fine powder you get from grinding resin away, there was little to none of that fluffy sort of dust I was getting while grinding away old matting elsewhere.

Grinding further forward, to the area where I’d first peeled off that terrible patch of fabric it looks like I uncovered the other side of the burst blister repair.

You can see from above I’m back through to gelcoat in this area too.

This whole area needed to be re-glassed. This was never going to be anything I could do myself, it was a major repair.

I soldiered on with cleaning and grinding. Removed paint away from the whole area where the repair would be needed. Almost on cue, the boss arrived to measure up the fibreglass we’d need.

The day before I had mentioned that I had some West System expoy but that I had nowhere near enough to do this. He right away said “No, don’t use west not here, she’s made o polyester. We’ll use my resin for the job.”

I don’t have any significant experience with fibreglass, I’ve only done a tiny bit of epoxy work and zero polyester based work, but he was certain.

Epoxy vs Polyester

The internet disagreed slightly, but not conclusively. My GRP repair book “The Fibreglass Boat Repair Manual – Allan Vaitses” was also not particularly alarming.

After a lot of googling, re-reading of my book and numerous YouTube videos I think I learned:

• Polyester bonds to polyester. Normally multiple layers of polyester are laid up before the bottom layer cures. The bond in polyester fibreglass is mainly chemical. You have many layers of glass embedded in one thick chemical layer of polyester resin.
• Polyester on top of Epoxy is generally thought to be sub-optimal.
• Epoxy “sticks” chemically and “mechanically” meaning if you have a rough sanded surface that epoxy would bond to it very well.
• Polyester does not “stick” as well on top of existing surfaces as epoxy does. It does stick to existing prepared polyester surfaces, but perhaps only about 80-90% as well as epoxy does.
• Doing multiple layers of epoxy means waiting for each layer to cure (you can’t lay too much because of the heat created)
• You get a bit longer to work with polyester than epoxy before it sets.

So, I’m happy I agreed with the choice of the experienced boat builder of polyester for this work. Epoxy is more rigid and sticks well, but given the cramped area and enclosed space it might have not gone well given the amount of fibreglass we need here.

There we go, a total of 3 overlapping layers of fibreglass the length of the engine bay, with an extra layer down the middle. (so 7 layers at the thickest overlapping part along the length of the boat)

The experience of doing this was a new one for me, I told myself to view this like a mini apprenticeship. Learn by doing!

Boss would whet out the glass in the cockpit on a huge sheet of old ply (looked like from another old boat) and lower it in for me to lay out the 1m length of the bay, doing whole alternate sides each time, overlapping the edge of the mat down the middle by about 3cm.

Over the hour or so we did this I was talked through each step, handed ready whetted sheets of matting and shown how to roll out the air bubbles and get the layers properly pressed in. Working against the clock, with little opportunity to re-position as we went.

As much as I wish Rosie had not suffered the damage here I’m happy with the resulting repair.

I took another photo with the flash off. You can see the two light patches. The bright dot is where I accidentally went through with the sander at the nasty crack. The light patch nearest the camera is where the osmosis blister was from the outside (paint sanded off outside already). If I’d not had to mend the large crack I might not have attended to this spot as well, probably only doing a basic repair from the outside.

Job for the next visit is to inspect the cured result and probably to grind the areas where I’d overlapped with still-painted places (don’t want anything to creep in at that bad interface) – we laid more glass than I anticipated. Then it’s paint the bilges and resume the original jobs.

Phew.