The Rondar Prototype Squib April 14 th 2016.

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1 Page 1 of 17 The Rondar Prototype Squib April 14 th The prototype was first seen by the technical sub-committee on 28 th October 2015 along with a representative from the RYA. Since then it has undergone many performance trials and many people within the class have seen and sailed in her. This process has thrown up many comments about difference in feel, for example, and many theories have been produced and questions raised. In this document I have tried to examine objectively the prototype and where possible to make comparison with other Squibs. In the main I have used my boat No96 as a bench mark. I know its pedigree and feel it is typical of many other boats of the same vintage and having been completely rebuilt in 1994 is carrying 20Kg of correctors and is typically when weighed at Nationals and inlands 685Kg (5Kg overweight). The original design concept of Rondar was to build the boat as simple as possible, take out all of the wood and time consuming structure. The boat would consist of 3 mouldings in foam sandwich simply bonded together, the floor raised to make it self-draining, and the seats being part of the central moulding giving greatly increased buoyancy. Rondar were asked by the NSOA to make a prototype to prove the concept worked, but it must not be faster than the current boat. See Appendix 1 (Rondar proposal Oct 2014 presented at Rutland). When the technical sub-committee first viewed the boat it was obvious that the different construction methods, including vacuum bagging, had resulted in the finished boat being too light. It was agreed that Rondar should add as uniformly as possible to the inside of the boat glass fibre matt and resin to make the boat achieve the class rules of 680Kg all up weight. To do this 20Kg was added in the area of the rear tank, 20Kg in the front tank and 20kg each side between the inner moulding and hull. The resulting boat when finished was 4Kg over weight with no correctors, weighed by the RYA. See Appendix 5 for cross section of the Prototypes construction. The performance testing of the boat has been well reported, and I will not go into that other than to say so far the boat has met the NSOA s requirements that it shall go no faster than the current Squib. The various issues that have surfaced are: 1) It feels different, 2) It s stiffer 3) Its weight distribution is different, weight in the middle not in the ends. 4) Its bow down on the lifting strops, the weight distribution is different. 5) The foam sandwich hull will be easy to damage, not as tough as the current Squib. In order to try and establish facts I have done tests, whilst at Weymouth and more recently I have had the prototype in my shed and made several measurements, and obtained information where relevant. The details are contained in the appendix 1 to 4, but these are précised below. 1) It feels different. It does and it sounds different I agree. However so do many other boats I have sailed during the trials. It s quieter in waves.

2 Page 2 of 17 2) The boat is stiffer The panel stiffness will certainly be stiffer as the 3 mouldings are foam sandwich, but as much of the structure that makes the current Squib stiff has been removed, (appendix 5),is the assembled boat different? how can we quantify if the full assembled boat is stiffer? Some boats build a space frame structure around the mast heel and shroud points to stiffen the boat so that it is capable of more rig tension. Stiffness equates to the boats ability to accept rig tension without distortion. The details of my tests are in appendix 2. However the tests I did show that the current boat is very stiff and comparable with the prototype. The wires in the rig account for virtually all measurable movement of the boat. 3) The weight distribution is different. The way the boat was constructed this is unlikely as all care was taken to ensure the boat was of even weight distribution. The recognised way to test this is to check the inertia of the boat rotating about an axis a little above the centre of gravity (often referred to as the Lamboley test). The important aspect of any test of this nature is that the rig and methodology are the same. The test I made shows the Prototype is 4.5% greater in inertia. When you consider the prototype has no correctors and No96 has the original teak seats and correctors totalling 40Kg virtually on the C of G this accounts for any difference seen in the test (See Appendix 3 for details). 4) Its bow down, the weight distribution is different. Measurement under the floor soon revealed that when the prototype was made the bulkhead under the crew floor coincided with the normal keel fixing bolts holes. Rondar had to drill 2 more holes further aft for the keel fixing bolts, thus the lifting points are also 120mm further aft. As a consequence when using normal Squib strops where most of the weight is on the aft lifting eye the boat does hang bow down. I did measure the position of the C of G and it is actually 48mm further forward than No96. (See appendix 3 for details). In the production boat the bulkhead will be moved forward so that standard keel bolt hole positions can be used. 5) The foam sandwich hull will be easy to damage. Indeed this has long been the view on foam sandwich construction, but in 30+ years it has become common construction in dinghies and yachts and is now the norm for build. Many builders do not build anything else, and viewing the boats at the Dinghy show it was very hard to find anything constructed not in foam sandwich. The squib is a keelboat with a hull weight of nearly 300Kg. Most dinghies are less that 1/3 rd of that.

3 Page 3 of 17 The table below shows the probable final laminate spec of the Rondar Squib to make it fit the class rules 680Kg carrying the legal max of 30Kg correctors, and with a constant laminate from stem to stern. Alongside this is the laminate spec of other boats Rondar make. Boat Squib Viper firefly K6 Enterprise 505 Resin system Polyester polyester polyester epoxy epoxy epoxy/carbon Gel coat layer yes yes yes yes yes yes 1st layer in from gel 300 gm2 CSM 300 gm2 CSM 225 gm2 CSM 300 gm2 Biaxial 200gm2 Twill 100gm2 WR 2nd layer in from gel 600 gm2 Biaxial 300 gm2 Biaxial 300 gm2 WR 300 gm2 WR 300gm2 Biaxial 180 gm2 Biaxial 3rd layer in from gel 600 gm2 WR total of glass 1500gm2 600gm2 525 gm2 600gm2 500gm2 280gm2 foam core layer C mm 4mm above WL foam core layer C mm 8mm 8mm 6mm 6 mm below WL 1st layer inside foam 600 gm2 biaxial 450 gm2 bi axial 225 gm2 CSM 180 gm2 Biaxial 2nd layer in from gel 600gm2 WR 300 gm2 WR below waterline 3rd layer in from gel total of glass 1200gm2 450gm2 525gm2 600gm2 500gm2 180gm2 Vacuum bagged yes yes No yes yes yes If you look at the thickness of the glass laminate outside of the foam it is 1500grm/M 2 you will see that it s three times that of the Firefly that is built as a team racing boat. Additionally much of the glass fibre is in the form of Biaxial glass (cloth) and woven roving, which has much more glass and less resin that the current Squib Hull per Kg. See Appendix 4 for Rondar s assessment of the way the Rondar Squib hull will be built relative to the Bruce Parker Squib. I can confirm that I could detect no damage to the hull from its testing so far, and it is thinner than the production proposal outside the foam core. My conclusion In terms of stiffness I can detect no overall difference between No96 and the prototype, and find to my surprise that the rigging wires are by far the most flexible component in the Squib. The weight distribution is very similar in terms of inertia, and C of G 47mm forward. The measurements conform with the class rules (with the obvious exception of the raised floor) in all but 2 respects. The Mast step is 8mm higher than class rules, but 13mm higher than was wanted, and the shroud plates slightly too far aft. The laminate spec for the foam sandwich hull will make a hull far more resilient to impact damage than any other class of boat in the market place built with this technique. The boat meets the spec in terms of performance and construction. Malcolm Blackburn

4 Page 4 of 17 Appendix 1 (6 pages 4 to 9)

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10 Page 10 of 17 Appendix 2 (3 Pages 10 to 12) Squib Stiffness testing April 2016 The perception of the Rondar Squib is that it is stiffer than the normal Squib. The foam sandwich construction will result in increased panel stiffness, but the fact that virtually all of the wood structure of the Squib has been deleted leaves the question, does increased panel stiffness change the overall stiffness of the assembly? So I came up with a plan to try and measure the lack of stiffness of my floppy old Squib No I set up a laser to point at various places in the boat, namely the forestay plate, shroud plates, and mast. The laser was sat on the helmsman floor well away from any stress area from the rig. 2. I then clamped a piece of wood to the side of the shroud plate at the level of the top bolt. I did this each side. 3. I then attached a piece of whipping twine so that it sagged slightly and added a 6mm nut to the middle to keep the string straight. 4. I put a straight edge across the top of the wood blocks and fastened a ruler to it to measure the sag. I thought that if when loaded up the boat deflected the sag in the twine would change thus measuring the bend of the boat. The simple triangulation calculated that for a 60mm sag in a span of 1.8 metres then a 12mm change in sag indicated a movement of the shroud plates inwards 1mm per side. 5. I tightened my shrouds as much as possible and pulled on the rig tension until I measured 400Lbs on a Superspars rig tension gauge. I could just detect some movement. The laser showed no change to these points on the boat, but the twine sagged 3mm which is equivalent to the shroud plates moving inwards 3/12 = 0.25mm. When at Weymouth I repeated the same exercise on the shroud plates on the Rondar Squib This time I had to contend with the boat being floating, so it was more difficult to measure such small amounts. The corresponding change was about 2mm which is a change of 0.167mm This change was much smaller than I expected. In fact I had expected to see far more movement on No96. However this does backs up something Alan Johnson had told me some years ago when they experimented by putting a strut between the shroud plates. They found that when sailing the strut never loaded up and came under compression.

11 Page 11 of 17 When applying this amount of rig tension there is a significant movement of the Jib halyard, so I though it significant to compare the movement of the halyard on the 2 boats. I set up a small rig tension setting of 130Lbs (10 on my rig tension gauge) then increased to 20 on the gauge, (200Lbs) then 25 (285Lbs), then 30 (400lbs). The picture on the left is No96 and written on the mast is the rig tension gauge numbers. i.e. 10 (130LBS) Ruler 0 20 (200LBS) Ruler 26mm 25 (285LBS) Ruler 43mm 30 (400lbs) Ruler 80mm Corresponding for the Rondar. 10 Ruler 122mm (0) 20 Ruler 150mm (28) 25 Ruler168mm (46) 30 Ruler 202mm (80) So from this test the boat and rig stretches by 80mm when the load is increased from 130Lbs to 400Lbs. The jib luff wire was the same on both tests. The rig tension gauge was the same. The Rondar had a Superspar mast No96 had a Canopus, both boats had 3mm jib halyard (flexible) and shrouds 1 x 19 stiff 3mm. Thus these tests suggest that both boats have a very similar stiffness.

12 Tension Kg Page 12 of 17 Further to these measurements I conducted a calculation of the rig to see what stretch you would attribute to the rig alone. The starting point was to measure the elongation of a 3mm diameter 1x19 stainless wire. The measurements gave. 3mm Luff wire 5Metres long Elongation mm From zero Triangulating all the shrouds then the calculated elongation measured on the jib halyard for increasing from 130 to 400Lbs shroud tension calculates to be 78mm. Calculation of the compressive load in the mast under 400Lbs shroud tension is 1177Lbs (534Kg) Under this load the mast compression calculates out at 1mm. The conclusions I draw from this is that the both Squib No96 and the Rondar Squib are very similar, and in reality virtually all the movement is associated with stretch of the rig and by comparison the hull is extremely rigid. Malcolm Blackburn

13 Page 13 of 17 Appendix 3 (2 pages 13 to 14) Measurements of the Rondar Squib. 05/04/2016 Having had the opportunity to have the Rondar boat in my Toy Shed I performed various measurements to ascertain where the boat fits in relative to my benchmark Squib No96. Centre of Gravity It was reported that the boat was very bow heavy on the crane and I confirmed that when we put the boat in the water at Abersoch. Looking at the keelbox area it is clear Rondar have struggled here as this piece of the mould was missing from the moulds Tony managed to recover from Bruce Parker, and Rondar have had to make up a temporary mould to make this part. The keel bolt holes and pads moulded in are about 120mm too far aft. Rondar redrilled the keel and thus the lifting eyes are 120mm too far back. The measurements that I took on No96 was that the C of G of the bare boat without rudder sails boom etc was exactly on the line of Section 6 which is pretty well between the jib cleats and spinnaker sheet cleats on the deck coming pad. The Rondar boat was 47mm further forward. To relate this to understandable terms, if the Rondar boat was sailed by a 100Kg helm it would have the same C of G as No96 with a 80Kg helm. It is always noticeable that when launching the Abersoch Squib fleet all with the same strops there is variation in the attitude that the boats lie on the crane. No96 does have the original half height rear buoyancy tank from the day she was built which will account for some of the 47mm difference. Moment of inertia Rather than going through lengthy calculations I did a simple comparison. I set up a rig that allowed the boat to rotate for and aft about a point approx 450mm above its C of G. The measurements were all the same and the technique the same other than the C of G being 47mm forward on the Rondar. No96 did 10 oscillations in 33 secs, the Rondar did 10 in 34.5secs. (4.5%). As frequency is proportional to inertia the Rondar is 4.5% higher in fore and aft inertia. The impact of No96 having 40Kg in seats and correctors close to the C of G and the Rondar having the weight evenly spread probably accounts for much of the difference. Curvature of the deck During the Rondar build process it was realised that our current class rules have no control upon the height of the top of the deck and the hull measurements. Thus by curving the deck more or less could change the allowable position of the internal structure and mast step. The table below has the measurements of 3 Squibs I could get hold of. Boat number Sect 9 Sect 6 Front of mast hole Class rule measurement front of mast hole to top of tank ( mm) Rondar The 645 measurement as we know is out of class. I measure this as only 8mm too high, but as the deck is 5mm higher above the sheer line than 878 the total above the sheer line the mast is 13mm high. As we know for the trials 18mm was cut off the mast to make the rigs equal height. Mainsheet track length When Rondar were building the prototype I suggested a height for the track below the top of the deck of 281 to 331. It is fitted at 288mm (currently the rule positions it from the floor which can no longer be a datum). Consequently the track was fitted into the buoyancy tank rather than on top. Thus the track length was restricted to 593mm rather than the class rule of 610mm. Not a major problem, but I think we should let it be fitted on top of the tank, iin which case the measurement would need to be 230mm.

14 Page 14 of 17 In reality with today s measurement rules if the floor was max height and track max height above this you could have the top of the track at 220mm below the top of deck. Mainsheet track position The aft position for the track has a dimension from the aft vertical of 1.720mm to the aft side of the track. If the track was mounted on top of the buoyancy tank we could let this be a more variable position. Personally I did not like the track forward, but I know there are many that would like it forward. Maybe we could allow a dimension of to (others can decide this one!). Floor height The measurement rules will need changing to allow the higher floor, however for interest these are the measurements. Section 9 Section 6 Current rule Tolerance mm mm Actual 480mm 510mm Mast Hole Recently there have been a few problems with measurement and at the Lowestoft champs we found that the mast hole had moved towards the back of the tolerance band sometime between 811 and 819. The Rondar is 3445mm against a tolerance of mm. Typical for newer boats with this deck mould. An observation and I have no answer, the drawing in the class rules shows a dimension from this feature of 3460+/-10, yet written in the rules it s 3440 to Keel Position Measured from the Aft Perpendicular the aft edge of the keel where it meets the hull is 2204mm The tolerance is 2204 to Base line to underside of keel is 600mm, tolerance is 588 to 618mm. So the keel is as far back as possible and in my experience most boats are that way. Shroud plate position I need Salty to confirm this, but I measure the shroud plates as 385mm forward of the Section 6, the rule requires these to be mm. The impact of this is obviously that the boom will not quite go out as far, I doubt if any real impact is made upwind sailing. No96 and 789 are bang on mid tolerance. Seats / Buoyancy tanks For completeness these are the various measurements. Top of Deck to top of seat / tank. Sect 6-322mm, Sect 9-230mm Width between tanks, Sect 6-585mm, Sect 9-605mm, With of moulding on top of seat, Sect mm, Sect mm Other than that I did not go into great lengths to measure all the hull, but the bits I did from base line to sheer line the boat comes out OK. No surprise as it comes out of the same mould. Malcolm Blackburn

15 Page 15 of 17 Appendix 4 (2 Pages 15 to 16) Production Squib Laminate and build details ( from Rondar). Laminate thicknesses of the other boats we make is attached. The proposed Squib layup is what we would like to do based upon where we think it will need to be at given the overall weights we need to get to. The original layup was 2250 gm2 of CSM, and 600gm2 of WR, so a total of 2850gm2 of glass, matched to approx 5000 gm2 of resin. Ours is approx 2700 gm2 of glass, plus approx 250gm2 of foam, using approx 3000 gm2 of resin. In other words the same weight of reinforcement but structurally better placed, with more of the fibres running in directions that there are loads, plus 2kg per metre2 less weight of resin, which gives us the weight to create the internal moulding. More importantly, chopped strand mat is a labour intensive mat to put into a moulding, as it has to be wet out on a bench first, and then worked with the roller until the mat breaks down, and then it has to be worked and washer rolled to eliminate all the air that is inherently trapped within the mat. As a result you need to put it down in thin layers, as opposed to thicker ones, otherwise getting enough resin into the mat, and getting the air out becomes a major issue. There is a lot of styrene in the atmosphere, because of the resin to glass ratios being higher, so there is more resin curing, and as there is more resin, the laminate is going to shrink back more, and the heat will be higher which potentially sets up micro cracking in the laminate. As a result of a mostly chopped strand mat laminate, BPS had to use a double gel, and long curing times and then leave the boat in the moulds for a couple of weeks and so on, all of which reduced the shrinkage, allowed the slow cure without under cure and so on, but is not how we run our workshop, and the Squib has to fit in. We prefer bi-axial mats and woven rovings, as they are far easier to wet out, do not trap air, and they are significantly quicker to get into the mould, which is important when we need to get a vacuum bag down before the resin goes off. They are more expensive, but structurally better, and the end result is a stronger laminate, with a higher strength to weight ratio, a lower propensity for damage in the event of a collision, and a lower prospect of water take up over the years it is in service.

16 Page 16 of 17 Boat Squib Viper firefly K6 Enterprise 505 Resin system Polyester polyester polyester epoxy epoxy epoxy/carbon Gel coat layer yes yes yes yes yes yes 1st layer in from gel 300 gm2 CSM 300 gm2 CSM 225 gm2 CSM 300 gm2 Biaxial 200gm2 Twill 100gm2 WR 2nd layer in from gel 600 gm2 Biaxial 300 gm2 Biaxial 300 gm2 WR 300 gm2 WR 300gm2 Biaxial 180 gm2 Biaxial 3rd layer in from gel 600 gm2 WR total of glass 1500gm2 600gm2 525 gm2 600gm2 500gm2 280gm2 foam core layer C mm 4mm above WL foam core layer C mm 8mm 8mm 6mm 6 mm below WL 1st layer inside foam 600 gm2 biaxial 450 gm2 bi axial 225 gm2 CSM 180 gm2 Biaxial 2nd layer in from gel 600gm2 WR 300 gm2 WR below waterline 3rd layer in from gel total of glass 1200gm2 450gm2 525gm2 600gm2 500gm2 180gm2 Vacuum bagged yes yes No yes yes yes

17 Page 17 of 17 Appendix 5 Construction of Rondar Prototype with detail in red