22 March 2023

Introducing the new rota-moulded Polyethylene International Topper

Roger Proctor, son of Ian Proctor who designed the International Topper, and the Designer’s Representative for Ian Proctor Designs who own the design rights for the Topper, explains the need for the change.

‘I first sailed the Topper wooden prototype in 1969, raced the first fibreglass boats in the early 70s becoming the first GBR National Champion, and then going on to sail the polypropylene boat, which I still do occasionally when my knees allow! I have been the Designer’s Representative since 1992, working closely with ITCA (World). So, I have seen manufacturing and materials changes in the Topper over the last 54 years, not least the various rig developments that have been introduced.

 As many of you will now know there is a new version of the Topper hull, and it had a great reception at the recent RYA Dinghy Show, with one RS parent telling me it was the best-looking boat in the show and that it was ‘like seeing the iPhone for the first time’! The show was also our chance to introduce the boat to the Royal Yachting Association in the UK, who were very impressed and welcomed the development.’



Topper International, in full consultation and cooperation with Ian Proctor Designs and senior members of the International Topper Class Association (World) committee, have moved the production technology of the Topper from injection moulded polypropylene to rota moulded polyethylene. This is the production method now used by the majority of boat manufacturers globally. This was necessary to do to in order to safeguard the future of the Topper. But why was this the case?

The reason it has changed is threefold, with the first reason being the most important:

  1. The deck mould was 47 years old, it had literally broken 20 years ago and been repaired at a huge cost, and was then damaged again 2 years ago, requiring replacement at a cost £1.5m. This clearly did not stack up financially because any return on investment would be over too long a period of time.
  2. Only 3 companies in the world can mould the Topper in polypropylene due to the size of the mould. All 3 moulders demand very high production runs and the German moulders were increasingly reluctant commit to specific delivery dates, making it impossible for Topper International (TI) to plan their schedules and deliveries.
  3. The cost per unit was constantly increasing, and the moulder required minimum orders of 500, so tying up Tl’s cashflow in an increasingly uneconomic way for the business.


Before the decision to move to rota moulding was taken however, extensive research was still done to see if a two-part polypropene deck solution could be achieved, but a feasibility study proved the work to be technically too difficult. Fibreglass was looked at but was quickly deemed not suitable.

The remaining feasible alternative was rota moulding in polyethylene, but the technology would be stretched by the demands of the Topper, particularly the welding edge which is an important feature of the boat. It would also mean that the floor would need to be raised a little and that the welding edge on the stern had to go because it would prevent the boat coming out of the new mould.

It was also logical to look at the boat anew, it was after all designed in 1974 and there was plenty of experience that suggested moving the self-bailer to the centre, having storage hatches (a necessity of the rota moulding process to insert the powder/material evenly during moulding) and, if we couldn’t have a stern welding edge, levelling off the transom so making it look visually as long as the polypropylene boat.

The Ian Proctor Designs brief was to make the new boat at least as fast as the old one. Having worked with my father and brother on this very matter on the Mark 3 Wayfarer, I know that this is an impossible request to guarantee to answer, even with a world-renowned designer such as Ian Proctor! Of course, the most important factor in any boat when measuring performance is the sailor themselves but weight, different materials under different conditions, manufacturing shrinkage, waterline length, centre of balance, etc, can all count. It is never an exact science and finding the right balance is difficult.

I hope this explains the logic behind the new hull and the reasons behind the key decisions we have made. But understandably there were some questions raised at the Dinghy Show and since:

Q: Have you tested it so far?

A: Yes, we have managed to do some testing, but that can only be done on a finished boat from the actual mould. Each testing has been in moderate to light conditions inland against an original polypropylene boat. We could see no visible difference in performance and the sailors did not report an appreciable difference, as they swopped from boat to boat to compare.

Q: How will the performance differences be tested/evaluated moving forwards?

A: More testing and comparison work still needs to be done. We are hoping that the ITCA (GBR) and ITCA (IRL) class associations will be willing to be involved in the testing and we expect that it will take at least a season, across all wind and sea conditions for proper comparisons to be made.

Q: How will the Class Associations at national events and international events ensure a level playing field?

A: Until the testing is complete it is difficult to say, but ITCA (World), Ian Proctor Designs and Topper International will work with the two largest Class Associations, to achieve this, but we strongly believe the differences in sailors body size and weight across the fleets in differing conditions ultimately can create greater variation in performance.

Q: Will all charter boats at the worlds will be roto moulded?

A: Correct, there are no polypropylene boats left in Topper International’s stocks.

Q: Can it be assumed that all international sailors coming to the 2023 Worlds will have new hulls?

A: Yes, as will some GBR and IRL sailors who have also bought the new boat.

Q: If a sailor with the new roto moulded hull wins the Worlds, will this make a 2-tier racing system?

A: At the end of the day, it is the sailor that makes the real difference. If a very good sailor sails in a new polyethylene boat and wins then is it the sailor or the boat? Alternatively, the best sailor may win an old polypropylene boat. People will have to make their own judgements on this, but we hope that this consideration will be made fairly and without prejudice. This is why testing is so important in order to give people confidence.

Q: In the absence of definitive performance data, the boat park may assume a perceived performance advantage from the new hulls and with that the residual values of injection toppers could fall causing difficulty in selling original injection hulls. What plans does Topper International have to prevent this happening?

A: Topper International have already spent £100s of thousands investing in the new moulds and the roll out, and so they cannot cushion owners from a fall in the second-hand value if that occurs, which is not yet ‘a given’. When you buy a car and then the manufacturer announces a new model, it can negatively affect the residual value. We hope that this doesn’t happen, but we can’t guarantee it. On the contrary, values of the Land Rover Defender have in fact rocketed since its production ceased!

Q: Will Topper International offer a favourable ‘Trade In’ scheme to allow existing owners to trade up to a new hull at a favourable rate, helping maintain residual values of the injection moulded fleet?

A: A trade-in scheme will not be available. After such a massive investment in new moulds, Topper International neither have the finance, manpower or space to facilitate part exchange boats and are operating at maximum capacity. A trade-in scheme could in fact create a drop in residual values, by inferring the injection moulded boats were now in some way outdated.

Q: The new hull would be considered a “Major Equipment Change”. Under normal class rules any major equipment change is usually put to a vote by the members of the class association. Will members get a vote or not?

A: We hope that, by working closely with ITCA (GBR) and ITCA (IRL) that won’t be necessary. We believe that it is vital for the International Topper to stay in production and continue to be a significant part of the world’s sailing scene.

Q: At the 2022 Worlds all boats went through a rigorous equipment inspection. Is the roto moulded hull automatically assumed to be class legal by national class associations and ITCA (World)?

A: The process will be the same as for the polypropene boats which was checking for equipment discrepancies introduced by the sailor. As long as the hulls, sails and equipment are in their original form as supplied by the manufacturer, then they will be class legal in the normal way.Q: Will the class rules need to be changed to allow a roto moulded hull to be raced alongside the injection hull?

A: We will be looking closely at any changes that may be required.

Q: Now that the shortage of supply won’t be a challenge, what plans for marketing and developing the class do Topper International have?

A: The focus so far has been on making the moulds and getting the first prototypes manufactured. There is a large backlog of orders from private buyers, schools, institutions and dealers, who are very excited about the development and feel that it will really help the Topper in its mission to expand its intermediate pathway status between the Optimist and Laser/ILCA.

Q: At what rate can the new boat be produced i.e. hulls per year?

A: To start with TI are planning around 30 to 60 per month.

Q: What price will the roto moulded boats be? 

A: £3,995 including VAT (ex delivery) for a fully kitted out 5.3 excluding covers and trolley. This is the same price as the polypropylene boat after a rate of inflation rise has been added, which would have had to happen. A hull only is available for £2,895 including VAT and the existing rigging and equipment can just be swopped over.

Q: Is it stiffer/more flexible?

A: It is stiffer, it has an outer plastic layer, then foam and an inner plastic layer. We realise that the fact that it is stiffer may be a benefit in a ‘sea’ but it is the nature of the new material.

Q: Is it heavier/lighter and what effect does this have on strength?

A: The later polypropylene boat came in between 45-47kg, depending on the moulders ‘shot’ weight which was influenced by production conditions at the time. Over time a polypropylene boat can reduce its weight to 43kg. TI will try to keep the new boat at a consistent 47kg. The new hull is strong and will take severe knocks. It does have a shinier hull which will be damaged like the polypropylene boat if it is dragged up a slipway.

Q: How does the centre of balance compare?

A: This has been measured and they are within 15mm of each other.

Q: How does it compare in length?

A: As part of the exercise we measured five polypropylene boats spread equally across sail numbers 25,000 to 49,000. There was a 20mm discrepancy between the longest and shortest boat in the test. From this, you will recognise that every polypropylene boat is different. The reason for this is that polypropylene will, over time and in different conditions shrink, so altering the hull length and weight. When a polypropylene hull first came out of the mould, they were longer than it eventually ended up over time.

The new boat is 15mm longer because we decided to make the new boat look as long as the polypropylene version which included the transom moulding edge. The reason this was done was because the polypropylene injection moulding rim couldn’t be retained due to the rota moulding manufacturing process and how the finished hull comes out of the mould.

One of the benefits of polyethylene is that it doesn’t shrink after manufacture so better at maintaining conformity than the polypropylene version as illustrated above. However, it is important to note that a rota moulded hull does shrink during the actual manufacturing process before it stabilises out of the mould. It is therefore very difficult to predict what that shrinkage will be prior to actual production using a real mould.

Q: Will it be easier to maintain?

A: Yes, many of the problem maintenance areas have been removed.

I hope this goes some way to answer many of the questions, and that you will all join me in supporting the new boat development and welcoming it into the class.

I will conclude by saying that I believe strongly that this is an exciting development born out of an unfortunate necessity. We wouldn’t have embarked on this enterprise if it hadn’t been absolutely necessary. Our judgement was that it was either preserve the Topper by using rota moulding or lose the boat forever, which would have been a tragedy for this design icon that has brought so much pleasure and experience for 100s of thousands of sailors worldwide.


Roger Proctor MBE FCSD FRSA

Director, Ian Proctor Designs Limited

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