Working with Epoxy

Only the bowsprit to varnish

I’ve been involved with epoxy resin, rather too closely for my liking, for about thirty years and have developed something of a love/hate relationship with it. Fortunately it hasn’t caused any other issues, which is a little surprising, because before I became as fully aware as I now am of the risks a fair amount of it found its way onto my skin. There is currently a surging interest in working with it, not just for boatbuilding, but also making cabinets, musical instruments and so on. I thought it would be helpful to offer some tips and advice from an experienced but lay perspective.

The advantages

The curing process involves the coming together of the two components without requiring a third factors, such as moisture or air. This means that it does not shrink during curing and can thus, subject to the addition of suitable fillers, be perfectly gap-filling. In fact joints can be made a little loose and still be strong, something that infuriates traditionally trained craftsmen and women.

Over the years I've tried various other glues that were said to be gap filling, but it seems that none truly was. But I have at least one boatbuilder friend who will disagree with this.

The main advantage is simply that a joint made with epoxy, if properly protected (see below) will be far stronger than the wood it is joining. 

The disadvantages

The main one is the risk to health. We are told that epoxy resins and the relative hardeners are not carcinogenic but I'm not anxious to be the person who proves that wrong.

Demonstrable os the fact that exposure to the components, probably the hardener rather than the resin, results in people becoming sensitised, so that any time they are newer to epoxy they come out in red blotches and feel weak. I once knew an old retired boatbuilder who could not even sit in the cabin of a boat built years earlier with epoxy without this happening. 

Less important is that it's one of the most unpleasant substances to work with, sticky of course but in a rather special, nasty way.

It's also very sensitive to ultra-violet degradation and must not be used as an unprotected external coating, however née it looks when fresh. This is a very good reason for avoiding brightwork altogether, just giving the cured surfaces several good coats of gloss paint to keep the light out, saving heaps of future maintenance work in the process.

Finally, it's usually more expensive than other glues.

Next I'm going to describe briefly how I use epoxy and in the process explain how to capitalise on the advantages and minimise the downside and save money.

Gloves or no gloves?

Personally I prefer not to wear gloves, because I believe it's better not to get my fingers sticky in the first place.

When building a community skiff a few years ago we had to adopt the industry standard of providing boxes of surgical gloves and requiring people to wear them. In fact two pairs must be worn, as it's almost impossible to get them off without getting glue on one's skin. I suspect that wearing gloves gave some people a false sense of security and made them careless, because most of the glove could not be used a second time. If you get a hole in the end of a finger you're in real trouble.

When you get glue on your hands, which of course I do, wash immediately in warm water with conventional soap. In no circumstances use acetone - it removes the natural protective oil in the skin and facilitates the passage of toxins into the body. Doing this forced a career change on a man I used to know, from modern boatbuilding to the manufacture of fake antiques, the latter more profitable but not without risks, only judicial ones rather than to his health.

Use weighting scales rather than pumps

I've yet to find pumps that were accurate ad have given up using them, since portable digital scales and so cheap. Protect the scales with plastic film.

This enables very small quantities to be mixed accurately and saves money and mess. By the way I've been told the correct West mix is 100:17, not 5:1!

Use disposable containers

Washing out and hoarding the pastil cartons that supermarkets insist in using is a sure sign to one's partner that another boat will be along on a year or two, if he or she hangs around that long.

I like the wee yogurt ones, because the corner suits my thumb and ensures that I pick it up the same way each time. The bigger soup and cream ones are great for larger mixes.

Read the Instructions (as Mother always said)

The best companies provide instruction manuals and sell ranges of mixers and fillers for all purposes to produce the best joints, coatings, space fillers etc. Buy those and use them. Using sawdust to bulk out joints may seem to save money, but may result in a glue starved joint.

Use Clingfilm

For example, laminating inwales from long strips of softwood involved mixing ore glue than I like to work with and unavoidable handling of these bendy, slippery strips.To cope with this I got a big commercial roll of plastic film  and covered the bench with it, then a second layer on which the strips were placed. Once they were coated (leaving a couple of inches at each end dry, to enable them to be lifted and cut off later) I flipped the glued faces together and folded the film over to enclose the workpiece totally. It was then easily transferred to the outside of the hull and left to cure. Later it would be lifted off, cleaned and fitted permanently to the inside.

Use heat

I read a lot about jobs being halted during periods of cold weather, but think a lot of this can be avoided if the glue starts out reasonably warm. I keep mine (in an old feed box, to avoid mess) in the boiler room in the house. Heat guns are handy, too.

To Pre-wet or not to pre-wet?

This is one of the new religions taking over the World. The Gospel according to the Gougeon Brothers says to do it, but it doubles the spreading time. There's no doubt the first coat of epoxy disappears into the dry timber by the time you apply the second coat with the fillers. Adding some filler with colloidal silica renders the mix less runny and so less inclined to sink in, so just use one coat? On the face of things this should save both tie and glue.

I won't disclose my preference, my beliefs in this field are personal, but just say that I've yet to have a joint that failed and the basic trick is to use plenty of glue.

As Captain Pete said, the time to worry about whether you used enough glue is not when you're five miles offshore in a gale!

In her cowshed

An early trip

More about the joys of Skiffing (not the Lonny Donegan type)

Imagine sporting events taking place with hundreds of participants, thousands of spectators, police and ambulance people about but no arrests and no injuries! In Scotland! Welcome to the World of Scottish Coastal Rowing.

Ullapool 2013

Imagine over 400 rowers in a total of 75 traditional rowing boats racing from Dumbarton to the Glasgow city centre, again nobody got arrested or hurt, apart from a few blisters! Welcome to Clydebuilt Festival 2017, due to be repeated on 15 September 2018.

Anster's finest at full stretch

There was even time to launch couple of new traditionally built boats. Glasgow's great Lord Provost Eva Bolander, herself a rower, wearing the gold chain.

Spot the mystery man in the crowd

From quiet beginnings a few years ago skiffing has grown and grown, been exported world-wide, become the major keep-fit exercise for thousands of people, many of whom never imagined they would ever take up an oar, linked communities through common interest and gentle, occasionally strenuous, but always good-natured competition, with virtually all funding raised within the communities.

Perhaps because we don't make constant demands for public funding, don't use carbon fibre, don't buy our boats from the boating industry, have fun, row to coastal pubs, have picnics on islands, invite strangers along to join us, we are virtually ignored by government agencies such as Scottish Rowing, the self-proclaimed "governing body for rowing in Scotland". The annual subscription to that outfit, with its team of sport administrators and experts, would be twice the total annual budget of my home club, Isle of Seil Coastal Rowing! No thanks.

The top image is of our crew battling it out in Ullapool at the skiffieworlds in 2013, a few weeks after we launched our Selkie, an event hosted by the always innovative Ullapool Coastal Rowing Club.

Musical skiff Sephira in the foreground

We were represented at the 2016 event in Northern Ireland with the help of some wonderful rowers imported specially from the United States, although our resources didn't stretch to taking the Selkie over.

We are now working towards the 2019 Worlds in Stranraer and hope to be there in force with the skiff Selkie and a mixed crew of Seilachs and friends from near and far.

Clarification for younger folk, Lonny Donegan did skiffling, not skiffing!

Two Lovely Sisters

Above is an image of the beautiful sloop Delight, designed by Olle Enderlein for a member of the Danish Royal family and launched in 1955. When I was over in Travemuende in 1999 visiting my sailing friends at the Freundeskreis Klassiche Yachten I spent a nice afternoon sailing on her. The Baltic is an utterly great place to sail and our German friends respect and look after their classic yachts much better than we do. I attribute the partly to the fact that they lost so many after the War, the bigger ones officially when the British Army took them as "Windfall Yachts" and the smaller ones when they were simply pinched by some of the officers who wanted boats.

Shortly after my return I got a message from my host asking if I knew of anyone in the UK who might be interested in Delight's sister ship the Sara Moraea, which had spent her life in Stockholm. I immediately thought of my friend the lovely Jimmy Houston, who sadly passed away last month. Jimmy had owned a number of very nice yachts including Enderlein's Dione and it occurred to me as an outside chance that he might be interested. The following message resulted from that:

And the next thing I heard was that Jimmy had booked flights for himself and Hilary for what he told her was to be a cultural weekend away. The owner of the Sara Moraea was connected with one of Stockholm's orchestras, so this wasn't entirely misleading.

Sara Moraea then made the journey by road to Scotland and a couple of years later I crewed Jimmy in the 2003 Fife Regatta. As you'll see Summer on the Clyde was a wee bit rougher and colder than the Baltic.

We had a cheery time following the fleet around and found that we could keep up quite easily with most of the bigger boats.

What impressed me was the ease with which the Sara Moraea could be worked, everything beautifully balanced, a nice light helm (not that I got it that much), sails of smallish size as these Scandinavian boats and have light tall rigs over slender, easily driven hulls. In fact they're the opposite of the equally narrow but heavily ballasted and canvassed boats that were typified by the rest of the fleet. 

Jimmy was at that time regularly sailing her single handed, with a light steering device that enabled him to make his tea on his trips across to Arran. I was sorry to learn a few years ago that he had reluctantly sold her, having turned down numerous offers over the years. I believe that she's now in good hands down South.

For those interested in the design I'm copying a couple of pages from the article that appeared in Yachting World in April 1955.

One from the archives

Right now I don't have time to construct new posts, so here is one from the archives, posted to Woodenboat.com in 2005:

Canoe Yawl Sonas by David Ryder-Turner

I built my first boat in 1988, a Nutshell pram, having confined my efforts before then to maintaining Stroma. In 1990 I built the Swampscott dory, a sixteen foot racing dory to a design from about 1880 redrawn by John Gardner of Mystic Seaport. In 1992 I built an eighteen foot Quincy boat, another old American design.

In the late eighties Stroma had been difficult to maintain because I could not get her under cover in winter in Argyll. I feared that rot was getting a hold and was conscious of her historical significance. The Scottish Maritime Museum offered what seemed a good deal. I would lend them Stroma, they would renovate her professionally and she would be available for me to sail as a working exhibit. I did not then know that they had no carpenters among almost one hundred employees, but that is another story. By 1992 I no longer possessed Stroma and the boats I had built could not sail outside of Loch Melfort. Stroma and I are now re-united, but that is a story for another day.

In 1992 I was acting for one of the people involved with Kentra on the Clyde. There was a flurry of litigation of enormous complexity and I got to know my American client very well. Having built some American designs I had decided to build Joel White’s Haven class. My client persuaded me to look closer to home. He told me about David Ryder-Turner’s design number 41, which he had admired. I had never heard of D R-T.

A few weeks later D R-T clumped up the drive at Kilmelford very early one Saturday morning. He must have left the Clyde before dawn. He had under his arm a loaf of bread which he had baked, a bottle of wine and a set of drawings. Number 41 was a little centreboard canoe yawl, very long and slender. The lines and sail plan were pinned on the sitting room wall and studied in great detail over the next few weeks. After the visit we kept in touch by phone. The design became number 42.

Design number 42 was basically Sonas. D R-T was offering to supply drawings and help if I would build two boats, one for each of us. It was drawn in three sizes and the largest was selected. This meant the boat would not fit in my workshop. A redundant industrial unit was found, which I could rent for one year before the owners needed it. This meant that many parts would need to be prefabricated. By October 1992 I was persuaded to make a start.

Over the winter moulds were made, the stems laminated and D R-T got on with the drawings. I started working out the building schedule and wondered how to build a boat while keeping on top of a demanding day job. Eventually this led to shifts of 8.00am to 4.00pm in the office followed by 5.00pm to 11.30pm in the shop a couple of days per week and two full shifts at weekends. D R-T was to visit, do some work and supervise. Early on he decided against having a boat of his own. This meant that the overhead got a bit heavy for one boat, moulds etc were only used once, but saved on the amount of work involved.

Sonas was to consume about two thousand hours of work, from me mainly but also D R-T himself and the late Duncan McKay, who scheduled his work as a taxi driver to allow him to attend eventually almost daily. Boats have that effect on people. With the experience I now have I could build the hull very quickly, but finishing would always take a lot of time. As the man said, building a boat is ninety percent sandpapering.

The bow and stern stems were laminated Douglas Fir, an excellent wood used for the keelson, beam shelves, deck beams and much else besides. The stems were set up on a ladder, which supported the blockboard moulds. The beam shelves were temporarily slotted into the moulds and protected by plastic to stop them becoming glued in. The moulds were taped up for the same reason.

Originally the hull was to be covered with mahogany veneer and I bought enough for two hulls from McGruer. I should have realised they were only selling it because they had machined it too thinly and it was useless. I was left with enough wood to make model boats for about two centuries. However experience is a valuable commodity. The hull was eventually planked with red cedar from Joe Thompsons of Sunderland. This was machined 18mm thick with a concave/convex profile, a product now largely replaced by Speedstrip. The strips were glued with Balcotan, as the prospect of mixing epoxy hundreds of times was daunting.

Western Red Cedar had the advantage of being rot-resistant, very light, long-grained and strong. It glues beautifully with Balcotan or epoxy. Thompsons’ product was very mixed in quality. A lot had been machined with no regard for the grain and was discarded. It is poisonous and if you get a little skelf you really feel it a few days later. I think it was probably used for arrow heads at some point. Thompsons’ strips had a lot of splinters. Doing the job again I would use Douglas Fir or Honduras cedar and get it specially milled with straight edges. These could easily be planed, or epoxy squeezed into the spaces. Of course this would also be heavier, but you could reduce the dimensions to compensate.

D R-T insisted that the individual strips be scarf-jointed to get the complete lengths, most needing to be about 27 feet. To do so I built a scarfing box through which I could run a portable circular saw. I also made a jig in which I could glue up five at once. D R-T called sometimes and condemned a joint here or there. About 150 joints passed his test and were used. This work was quite unnecessary. Butt joints would have been quite adequate. Planking up should have taken about 100 hours and took about 300 because of this.

At the end of 1992 the hull was complete, epoxied, glassed and faired while upside down, then left to cure over the Christmas break. In January 1993 I held a turning over party to get the man and woman power to lift Sonas safely. She was so light she nearly flew up to the roof.

I had glued MDF boards to the outside of the hull, octagonal in shape, to facilitate turning over. I found that I could roll the hull over unaided, which meant that later I could do all sorts of jobs single-handed. For example, drilling for keel bolts was done with the boat on her side, checking the drill bit with a spirit level.

I decided to build the floors from scrap Bruynzeel ply stacked to form blocks, which were spiled and fitted. Had they been shaped when the moulds were set up a lot of time would have been saved. The inside of the hull was cleaned off (horrid work) epoxied and the bilges glassed. D R-T instructed that the glass should be fitted between the floors. Doing it again I would glass throughout, then fit them. This would be easier and I think stronger. What was done has proved very strong however.

The beam shelves, which had been only loose-fitted originally, were now freed from the building moulds, finished and glued into the hull. They are massively built and much over strength. The boat was set up dead true to her waterline and the sheerline faired down, a process which took lots of time and was enormously satisfying.

The ring frames were cut from 25 mm Bruynzeel ply, spiled and fitted. Again they should have been fitted and shaped earlier. Spiling added about 50 hours.

I found a single log of ancient yellow pine, not in the sawmill’s inventory, which I bought and got machined for deck-planking. It was epoxied in strips on top of 7mm ply giving a finished deck thickness of about 16mm.

Covering-boards and kingplanks were made from mahogany, as were seats and other internal furniture. After some experiments with machines these were hand-sanded.

The keel was cast in Cornwall by Henry Irons from a piece of lead cut from Kentra’s old one. William Fife’s wonderful creation of 1923 was losing a little weight to balance the installation of modern equipment. Thus Sonas has a physical connection with her inspiration. The new keel was delivered to Scotland on the back of a Cornish cream lorry.

The bronzework came from a variety of sources and some was quite indifferent. I would never again buy bronze fittings without inspecting a sample. I suspect there are gentlemen out there who think that if you can cast bronze at all you are a craftsman. This goes for some very big names in the trade.

The blocks came from Harry Spencer and were a delight. They seem too nice to leave out in the rain.

The spars came from Collars and were beautiful. D R-T had supplied a spar drawing in great detail and this was complied with. The mast later proved so light that it had to be rebuilt. The lesson in this is not to tell the expert how to do his job. Had I asked Mr Collar for a mast to do the job and left the dimensions to him there would have been no problem.

Gayle Heard made the sails. They are pretty good.

The name Sonas is Gaelic for a type of happy experience and was the name of one or two famous boats in the past.

The boat proved very strong and virtually maintenance-free. She is extremely fast and must be reefed in strong winds. This was a deliberate part of the design as I did not want to bother with a spinnaker and our winds are usually light. She will scare the unwary and should be treated as a fine piece of sports equipment rather than a serious yacht. Her looks are quite outstanding and when you are on the water you had better be ready to have your picture taken.

With the experience gained in sailing Sonas I suggested to D R-T that he should draw out the design to twentyeight feet, widen the hull by nine inches and include a centreboard. This would have increased the displacement and made her more sea-worthy, as well as increasing the cockpit space. The centreboard, which I had discarded because we have plenty of deep water, would have made her easier to handle out of the water and enable easier transportation to sailing events. You could also explore shallow coves and picnic places more easily.

D R-T had originally suggested the yawl rig and I had rejected it, because I considered it fussy in such a small boat. I am now convinced that it could be very useful, as it would enable you to sail home comfortably under foresail and mizzen when the wind got up. 

The UK yachting press showed no interest in Sonas, probably because there would have been nothing in it for the commercial interests that dominate our publications. Oddly she was written up in Classic Boat in June 1993 before she was built. Wooden Boat ran an article on the modified design.

Ewan G Kennedy, Kilmelford, Scotland, April 2005.