Back in early 2009, I had this interesting discussion with noted sailor, designer and boatbuilder Derek Kelsall, related to his part in the early development and use of PVC foam core and polyester resin for racing monohulls and multihulls. Although not at the time directly related to 'small trimaran design', the work of pioneers like Derek should never be forgotten and his long, successful experience with foam and polyester also needs to be understood and appreciated, as this CAN relate to small tri construction after all —mike 2011
MW: Please tell readers a little of your background Derek.
DK: Sure. I grew up tough but happy, in a rural part of North Wales, without running water, telephone or electricity until called to National Service at 18, when I served in Kenya as a surveyor. This led to several years in oil exploration and I ended up in Texas for a while. But got restless and tired of office work and after some boat building and sailing in the Bahamas, I ended up doing 3 Atlantic crossings, including one that labelled me the first to officially race single‑handed 'across the pond' in a trimaran and much to the chagrin of 'the establishment', the first unballasted multihull. That was in the 2nd OSTAR (Observer Single‑handed Trans-Atlantic Race) in 1964—won by Eric Taberly in his slim 44' plywood ketch called Pen Duick II. I was 31 at the time. A couple of cats (both ballasted) were in the race too. I was doing very well when I hit something and lost centerboard and rudder a week out and had to limp back to Plymouth for repairs. My actual crossing was eventually 32 days, which would have been good enough for 4th in '64.
MW: So what got you building composite (foam) boats?
DK: The annual Round Britain race caught my imagination, so I designed and built the very first trimaran with PVC foam core and polyester resin hulls and 'Toria' surprised a lot of sceptics when I won the event. I'll email you some pics.
Here is 'Toria' (named after his daughter) both at her launching and then snapped by the famous Beken photographer, near Cowes in southern England. A boat way ahead of her time in both materials and form in 1966.
MW: And what did that lead to?
DK: I was then invited to build a boat for the new OSTAR race in 1968. This was to be for a Geoffrey Williams who had succeeded in signing up Lipton Tea as a sponsor—Geoffrey had the famous Robert Clarke design him a beautiful 60‑footer and we pushed way beyond the previous 45' limit of foam/glass use to create a boat that was really light but still strong. By pure coincidence, it seemed fitting that we built the boat in the town of Sandwich in Kent. 'Sir Thomas Lipton', as she was christened, won that OSTAR and took nearly 2 days off the previous best time.
MW: So what was your experience with building this huge hull?
DK: Well, things were very rushed. However, just three of us built the entire hull shell in foam and glass and had her all painted in just 700 hours ... ready to receive her interior bulkheads and deck. It was the designers' preference for plywood bulkheads and decking but this slowed construction and although we made the deadline, I was already becoming an enthusiast of foam, glass and polyester.
MW: So what came next for you?
DK: I built several other foam composite cruising and racing monos plus a few multis, including a 50' catamaran called Triana which was the first composite catamaran to be built to Lloyd 100A1 classification, but the next major challenge came from a boat built to enter the first 'Whitbread Around the World' race.
MW: And what was your involvement with that?
DK: Skip Chay Blyth had succeeded to get sponsorship from Jack Hayward, the person who had salvaged the first IRON ship 'Great Britain I', wrecked on the Falkland Islands. Jack had connections in high places and Royalty became involved when Princess Anne was scheduled to christen the boat. After I agreed to be a construction consultant, we went hunting for a suitable builder along the UK South Coast.
MW: So how did that work out and who was the lucky yard?
DK: That became a problem as everyone we asked was too busy to commit to meet our tight schedule! Realising that we'd lose the sponsor if we could not make the Royal launch date, I reluctantly agreed to get a work crew together and supervise the construction.
MW: But was this not another huge boat like the "Sir Thomas Lipton"?
DK: Oh quite a lot bigger again! She was to be 78 ft long, 17 ft beam with 17 tonnes of ballast and was by far the biggest sailing yacht of fibreglass composite to have ever been built at that date, so I was really diving in over my head with this one.
MW: So how did the work crew make out?
DK: Well it was somewhat of a joke, as we had to make do with whatever we could find. We were again building out in Sandwich, East Kent, and the area had not seen yachts of any real size built there for a decade. So I had to grab general carpenters, painters and labourers from all trades and train them on the job. In fact I did the lofting and frame building with help only from 'a model yacht builder' in an old sail loft! He was great though and went on to lead one of the work shifts.
MW: And what sort of time schedule did you have?
DK: It was already November and the boat was scheduled to have this Royal launch the next May! So we soon moved to a double-shift situation running from 6 am to about 9 pm, and I got little sleep as you can imagine. The team soon reached 16, but still no real boat builders and there was still tons to do. Chays' crew were chosen from the Marines and so we pulled them in to help build. Three shifts started, working round-the-clock. Ray (the model builder) now did 4 am to about 4 in the afternoon. I would take over usually about 2 pm and work through till 11 or 12 when I would brief the marine crew on work that could be done till Ray came in at 4 am.
MW: Sounds super hectic. No problem with materials?
DK: The most difficult problem I had in the later stages was getting the funds through in time. There was never any doubt that the cheque would come but there seemed to be an army of accountants between us and Jack, whose job was to delay payment for as long as possible. The next big hurdle was a gas strike. The fellow responsible for casting the 17 tonnes of lead keel could do nothing. He was also due to cast a keel for the current Prime Ministers' new 'Morning Cloud' so his reply to me was:
"If I can keep Ted Heath waiting, then I can certainly keep Chay Blyth or even Princess Anne waiting too!"
MW: So how was your workforce now working out?
DK: The Marines proved to be quite amazing and great to work with. They would do anything, as anyone not pulling their weight risked to be bumped off the crew list.
So I now had 32 motivated guys, that were doing an amazing amount of work. I finally had a secretary but there was still at least half a day of chasing this and that to find the thousands of items that go into such a boat. (From what I've read, it would now take 6–8 guys to handle all that planning, and I was also figuring out scantlings and things as we went along.) In those days, we built on a simple batten frame over stations, using foam sheets as large as we could get and lay on. We'd then finish by laying glass on the exterior using mostly UNI cloth—but there was a fair amount of external finishing. It was that work that later led me to develop the KSS system, where the topside gel coat and glass is all done flat on a table with a huge saving in finishing time, as well as visibly better results.
MW: So do you remember anything particularly memorable about the 'GB II' work?
DK: I vividly recall turning the hull. Eight tackles with supports from the factory roof beams and she went over with literally just a couple of inches to spare. I also clearly recall the moment when the hull and the ballast came together—two cranes and a howling gale at 2 am in the morning in Ramsgate harbour! The keel had eventually arrived but only with the steel blanks for the galleries still in place! So how do you remove 24 rectangular blocks of steel which have lead, close to a foot thick, cast around them? Well, by hand, slamming a very heavy rod of steel against the end to move a fraction of a millimetre at each impact, was the way it was done. These marines were great for this tough job and it took just a long weekend of very intense effort.
MW: So did you make the planned launch deadline?
DK: Yes we did and Princess Anne duly cracked the bottle on the assigned date and GB II slowly trundled down the old rail ramp, but due to the ballast delay, there was still lots to do. But she was now afloat in Ramsgate harbour and far less convenient to work on. However, I finally sailed her to Southampton and handed her over to Chay and his race crew.
MW: And how did she fare in the Race?
DK: Well our crazy effort was well rewarded as she was first to finish the Whitbread that year. Sadly, the victory was marred by a really unfortunate accident. One of the most enthusiastic and daring of the great marine crew, took one risk too many and was lost overboard.
MW: So how did the composite polyester, foam and glass hull stand up over time?
DK: GB II went on to race 4 or 5 more Whitbread races. But new refinements and weight savings for new boats made her no longer competitive with her 17 tons of keel. Ballast and scantlings dropped a lot over the next decade but GB2 was certainly very resilient. I met many past crew members over the years and the one common fact was that they all expressed tremendous confidence in the boat. At my last count, GB II had gone 6 times around the world and about 50 times across the Atlantic. Also she was raced by others under different boat names she sadly always seemed to be on budgets too small to sufficiently update her. But personally, I do not know of any yacht which could match the mileage she sailed, though I have lost track of her during the last ten years. As a boat built by men, of which not one could call himself a boat builder, I feel this is a record of significance which to me, is a powerful testimony to the materials and the build method. There can surely be no better test for a yacht than extensive long-distance racing in all sorts of weather over many years.
MW: In retrospect, is there anything you would have changed in the construction?
DK: As for the OSTAR boat by Robert Clark, designer Alan Gurney had persuaded us to use ply bulkheads in GB II. and at one stage, a bulkhead cracked and had to be reinforced. So there's one thing I would change as every time I have seen a foam sandwich hull with plywood, it is almost always the plywood which causes the problems. Bulkheads of the same foam sandwich as the hull and decks have always been 100%. From that boat on, I decided that for all my own designs, it would be foam sandwich throughout and I've never regretted the decision. Even today, we continue to use foam and polyester for most of our KSS designs and have no structural problems.
As far as GB II, at one stage it was noted that the coffee grinders were tilting and the deck waved slightly ahead of them. The dip in the deck was filled with filler and foam and more glass added over before refixing the coffee grinders. Apart from a couple of bubbles on the bow, due to outgassing of the foam, I know of no problems other than routine maintenance. Her dark maroon paint probably added to the outgassing.
MW: Well thanks a million for sharing this fascinating experience from the past and great to see that you're still actively designing and building boats…and still successfully proving that the combination of glass, vinyl/polyester resin and cross-linked PVC foam, is still a very good formula at relatively low cost—especially when used with resin infusion as now regularly done with KSS.
DK: You're most welcome and it's been fun to look back.
Good luck with your W22. Looks good.
This fine Kelsall yacht was appropriately named when considering its very focussed designer, who definitely knows how he wants things to be … "My Way"
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