Seb, originally from Portsmouth in Hampshire, is the Sales Supervisor for the Gael Force Marine Megastore in Inverness.
He has agreed to write a series of posts following him and the restoration of his 26 foot, 54-year-old fibreglass yacht.
This series of blog posts so far can be read here.
Estimated reading time: 8 minutes.
BLOG POST #5: Rudder Surgery (Part 2) & ‘Bringing Her Home’
Before we get back to the rudder, there’s the small matter of transporting the boat overland to her new home – my driveway!
I moved house last month (hence the lack of an August blog entry) and before all the boxes were unpacked, I was organising transport for Sunfire to take her overland from Hopeman harbour to a nice little spot just outside my front door.
The Invicta 26 isn’t a particularly large or heavy yacht, but my nerves were still shot as I helplessly watched her suspended several metres in the air, cradle and all.
Getting to this somewhat precarious point took a couple of hours – we had to shift her around in the cradle and adjust all the side supports before lifting her.
There were a couple of touch and go moments – at one point I think most of her weight was on the side supports – but ultimately we got her on the lorry without any damage other than some frayed nerves and I was delighted to see her arrive safely at the other end.
Sunfire weighs about two and a half metric tons, which incidentally is the limit of the lorry’s crane when fully extended. The shape of the driveway meant that the boat had to be craned off the back of the lorry, as opposed to side-on, which required the crane to be… fully extended.
It was a cool and overcast day, so when I saw a bead of sweat appear on the crane operator’s brow I knew it was the ‘maximum load’ alarms and not the weather that was making him sweat.
In the end, the crane held strong and the boat was carefully positioned into the perfect spot. When I look out my bedroom window I can now see Sunfire lying comfortably in her new home!
Now, back to the rudder.
Recapping quickly, in my last blog we saw how I cut out a huge section of the side of my yacht’s rudder with reckless abandon. The reasoning behind this was that I’d discovered that the entire thing was completely hollow and would fill up with water as soon as it was submerged.
I wanted to fill it with a rigid, closed cell polyurethane foam to add stiffness, strength and to reduce the volume of water that would ingress into it once back in the water. Making that first cut was one of those ‘no turning back now’ moments, but after discovering what lay inside, I’m confident it was the right thing to do.
There were lumps of what appeared to be old, rotten core material inside and a thin layer of powdery stuff covering all the inner surfaces. It may sound strange, but these little lumps of crud actually made me very happy as they implied that many years ago there was indeed a foam core in this rudder.
There was also glassed-in plywood around where the pintles were, which would have been for re-enforcement but was now completely rotten.
As always before attempting any repair, the first thing was to remove all the rot and clean all the surfaces.
Removing that rotten plywood was no easy task. I tried using a rotary tool with a small grinding attachment to grind it out, but the wood was so saturated (even after two years ashore) that it didn’t work. In the end, a good old chisel was the most effective.
With the rotten wood removed and the surfaces cleaned up I was finally ready to start rebuilding. Roll out the epoxy!
Epoxy is a very versatile substance and can be mixed/thickened with a variety of additives and powders in order to change its properties to suit any particular application.
West System has a range of epoxy products that will cover just about every kind of repair you can think of on a fibreglass boat. It’s also used for many bonding and re-enforcing applications on GRP or wooden boats.
I contemplated going into great detail about all the different epoxy products and how to use them, but that would itself span several blog posts and there are tons of helpful how-to manuals already available on West System’s website.
It’s important to note that whenever using epoxy, gloves and protective eyewear should be worn. You really don’t want this stuff on your skin!
Before I could think about putting in the new foam core, I needed to re-enforce the area where I’d removed the rotten plywood.
To do this, I wanted to fill the area with thickened epoxy and new plywood. I first cleaned the entire area with acetone and then coated it with a thin layer of un-thickened epoxy. The next batch of epoxy was thickened with 402 milled glass fibres and squeezed into all the nooks and crannies of the cavity.
I filled the entire void like this, adding in some plywood to bulk it out, and then glassed over the top to the repair with biaxial glass cloth to finish it off. I’m confident that it’s now stronger than it was and also that any points of water ingress around that area have been blocked up.
After this, I applied a thin mix of epoxy and 404 high-density filler along all the inside seams of the rudder, where the two halves were originally bonded together, to seal up any potential leaks.
This probably wasn’t necessary, but with the innards of the rudder so exposed, it was an opportunity I couldn’t pass up. The thinness of the mix allowed it to self-settle along the seams.
With the epoxy all fully cured and any amine blush (a waxy substance that forms on the surface as part of the epoxy curing process) washed away, I was ready to start pouring in the new foam core.
The two-part polyurethane foam I used was designed for this purpose and is much more rigid than the ‘builders’ expanding foam you get in a spray can.
The two parts must be mixed together at exactly the correct ratio – I used some electronic weighing scales – and when combined you only have a few seconds before the reaction starts. If you don’t pour the mixture quickly enough you’ll soon have a foamy disaster on your hands, literally! Again – gloves and eyewear should definitely be worn.
I started by pouring the foam in all the edges of the rudder then set about building it up in the middle.
The great thing about this foam is that it’s easy to work after it has cured. It didn’t take me long to cut and then sand it to a profile I was happy with. I bevelled the edge around the cut-out to give a good surface area for the new sheets of glass to bond with.
West System recommend a bevel of twelve times the thickness of the laminate you’re working on. In my case, the laminate was 4mm thick so I made a bevel of 50mm.
I was using a heavy tri-axial cloth for rebuilding the side of the rudder and I calculated that 4 sheets would give me the correct final laminate thickness.
The first sheet would be the largest – going slightly beyond the outside edge of the bevel and the last sheet would be the same size as the hole I cut out. I used the section that I cut out as a template to mark out the glass cloth.
Before laying up the glass, I stabilized the surface of the foam core by spreading a thin layer of thickened epoxy over it. When laying the glass, I used a roller to spread the epoxy around and into the glass cloth as I lay each piece down. It’s important that the glass is fully impregnated with the resin and no air bubbles are trapped underneath it.
I’d not glassed an area this big before, but I think it went well overall. I might have underestimated how much epoxy this heavy cloth could soak up though so I may have ended up with a laminate that is a little heavy on glass and light on the resin.
Before the epoxy cured, I covered the whole thing with peel ply. Peel ply is a cotton weave cloth that epoxy doesn’t bond with. Once the epoxy has cured, the peel ply can be ‘peeled’ off, taking any amine blush with it. This process leaves the surface underneath perfect for the next step – fairing.
Fairing is the process of smoothing out any unevenness in your fibreglass layup and getting the surface ready for painting. In this case, I spread epoxy thickened with 410 microlight over the entire work area then sanded it down with my home-made flexible sanding board.
The sanding board is just a 3mm strip of plywood that I glued a couple of handles onto one side and then a sheet of cork and some sandpaper onto the other side. It’s great when you need to sand a curved surface as it conforms to the curve.
My initial mix of the fairing compound was a bit thin and sagged away from the centre, so after sanding it back there were quite a few low spots which needed more compound.
I mixed up some ‘peanut butter’ consistency epoxy, spread it on, waited for it to cure, washed off the amine blush and waited for that to dry. And that’s where I am at the moment. Sanding is thirsty work however and I’ll have to leave the next session of sanding bliss to the next blog!
Coming Up Next Time: I’m hoping to wrap up the rudder next, I mean literally wrap it in glass fibre, so join me then!
If you have any questions for Seb regarding this post, please feel free to comment below.