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Selection of Design
Selection of Design
I was more interested in experimenting with different rigs than trying different hull designs and wanted to get sailing quickly so decided to buy a fibreglass hull and complete this boat myself. There are however lots of different freely available designs here http://rg65.free.fr/start.php . The hull that I decide to get was a RG65 version of a Vanquish from www.rcsails.com. rcsails is based in Thailand and the service they offer was very good. Only 7 days after the boat and fin was ordered the it had been posed to me. It was a bit of a gamble placing an order with them because I had no idea of the quality of their construction or even the performance of the boat but as I was egger to get started I placed an order. The Vanquish 65 does however appear to be sailed with some success in Germany and is said to be a good heavy weather boat. There are several other suppliers in Europe who can supply boats but as far as i’m aware there is only PJ sails in the UK. There are some sailors from Rotherham developing a RG65 in conjunction with Dave Creed which I believe is going to be a simple to build Vac formed boat built around a central rib. This would have been my preference but in July 2010 it was on hold due to Dave been inundated with requests for Lintels following the success of this design at the Nationals.
Construction
Construction
When the boat arrived it was well packaged. On opening the hull looked well moulded and weighed only 65g. The fin was a different story however. It was thick short and not a good profile. This was disappointing and meant that I needed to either make a fin of my own or buy one. To build the rest of the componets in the hull I decided to use 5mm Depron foam sheet. This is available from my local model shop in a variety of sheet sizes. It is a light stiff material which is easy to cut with a craft knife and can be glued with epoxy and is very easy to sand. The problem with this material is that it is not very punch resistant ant you could easily push your finger through it. This is not ideal for a boat that will be sailed with and inevitably rammed by IOMs. To improve this characteristic I decided to try epoxy bonding some fibre glass cloth to the surface. This is quite difficult because it tends to delaminate but it dramatically improves the punch resistance and stiffness. The best results I found were to roughen the surface of the Depron with course sandpaper cover liberally with epoxy resin and carefully lay one layer of 165g/ m2 plain or twill weave cloth over the surface and smooth out any surface bubbles. Apply more resin then lay some mylar film over the surface and work all the resin to the edges using a flat edge. This gives a very smooth sheet which can be painted. If the surface is not going to be displayed it would be better to use peel ply instead of mylar because it would leave a finish which could easily be bonded to.
Construction Process
Construction Process
To complete the boat and get sailing I followed the process below.
Fit a Depron Fiberglas stern to the hull. When making any part such as the stern deck or central bulkhead which is symmetrical about a centre line I always make a pattern out of stiff card which can be folded on its centre line to ensure symmetry. The stern was bonded into the hull with epoxy thicken with micro fibres
Next I fitted 5mm x 10mm Depron gunwales. Using a long ruler as a guide a 10mm strip of Depron can easily be cut. This is bonded to the hull using 5 minute epoxy and is lightly clamped so that it is slightly higher than the side of the boat.
It is now possible to float the boat and find the position of the keel and fin. The hull can be put into a full bath with the keel inside the hull and the position of the fin found. I also put the sail and rudder servos and the battery in the hull to see if this altered how the boat sat in the water but surprisingly it had very little effect. One problem I had doing this was that the boat leaked like a sieve. I suspect that this is because I ordered the hull without any gel coat and there was insufficient epoxy to fill the voids between the strands in the glass fibre. The leaking was so bad that the hull sank completely in less than a minute. This problem was overcome by covering the hull in parcel tape which remained on for the rest of the construction to protect the surface finish from scratches and stray epoxy. Although this leaking may appear disastrous I was not overly concerned because the hull was going to be painted and later on and during the construction the inside of the hull was lightly painted with epoxy.
Making a strong light fin with a good profile is quite an involved task
. But I enjoy making fins and find it satisfying. There are commercial fins available and I believe that Dave Creed makes one which no doubt will be very well made and good value. The aerofoil that I chose was the NACA0008 profile. I decided to have a parallel fin because they are easier to make with a chord of 50mm. I chose a 50mm chord because this appears to be common for this class of boat. This meant that the fin needs to be 4mm thick. This appears to be slightly thinner than some of the commercial fins available. The fin was moulded following the “Moulding foils” process described in this article http://footy.rcsailing.net/awk/awk-article.pdf. The fin was laid up with one layer of 200g/m2plain weave carbon fibre cloth and two layers of 320g/ m2 unidirectional carbon fibre tape on each side. The inner void was filled with an epoxy micro balloon mix. I am quite happy with the fin because it is straight and strong and although it is a bit heavier and a bit thicker at 4.5mm than I would like I decided to use it because this is an area where excess weight is not too critical. The rudder was made out of two pieces of 0.75mm ply which were glued together around 4mm x 2mm strip to give an approximation of an airfoil. This was sanded and a 4mm stainless steel rudder post was glued in before the whole rudder was skinned in 200g/ m2 carbon fibre and sanded smooth.To make the fin box. The top half of the fin was covered in petroleum jelly before been wrapped in several layers of cling film. Once this is done wetted out fiber glass cloth is wrapped round the fin and the whole lot put into a vac bag and allowed to cure. This makes a very good fin box which fits the fin exactly.
Once the fin and fin box was made a hole was cut in the hull to accept it. This is a very hard task to do well and patience is required. The centre line of the hull was found by careful measurement form the gunwale on each side. I also found it useful use a laser level to project a line from the centre of the bow and the centre of the stern to confirm the measurements. Once this has been done the hull was cut with a Dremel and carefully shaped to accept the fin box. With the fin in the fin box it can be tacked into the hull lightly with thick cayno. To allow the alignment of the fin to be checked I put the fin in the fin box and clamped the bottom of the fin in a drill vice so that the hulls planned waterline is parallel with the work surface. If it wasn’t the fin box could be removed and repositioned .Once I was happy with the alignment of the fin box I fit the central bulkhead to the hull.
I like to have a solid bulkhead in my boats which divides the boat into two waterproof halves making it a lot less likely to sink in a disaster. The central bulkhead was made out of 5mm Depron which was glued into the hull on the forward side of the fin box using 5min epoxy. Once this is in place the fin box can be fixed to the bulkhead and the bottom of the hull using an epoxy micro fibre mix. The hull was also stiffened by adding several strands of carbon fibre tow along the length and around he hull. This dramatically increased the stiffness.
This boat has two decks. The lower aft deck and the main deck. The lower aft deck is fixed to the rear of the central bulkhead and the stern of the boat. The underside of the deck has local reinforcement made out of 2mm fibreglass sheet to accept the screws used to hold the servos in the boat. Before the deck was fitted to the boat it was skinned on both sides with one layer of 160g/2 glass fibre and epoxy. Once this deck was fitted a 6mm x 4mm carbon fibre tube was fixed using thickened epoxy to form a rudder tube. The upper deck has two layers of 5mm Depron at the bow. This was done to make the bow a little bit deeper to help the hull resist nose diving. I’m not sure that this is necessary but I like boats with a deep bow and many of the other RG65 designs have this feature. To make the upper deck I made a pattern out of hardboard and lightly glued the Depron to this. This allowed me to shape the sides of the deck to give rounded gunwales. Once this was done the Depron was carefully removed from the hardboard and both sides of the upper deck were skinned in 162g/ m2 cloth with 280g/ m2 carbon fibre been used on the underside of the deck around the mast and sheeting post positions. An access hatch made from a old Sudocrem container was fitted to provide access to the battery compartment.
This boat has a Hitec HS5245D Digital servo (Dimensions (mm): 17.0 x 32.0 x 31.0) which is used as an arm winch. It has been reprogrammed to give 160 degrees of rotation. This is a mini servo and only weighs 32g whilst providing 4.4Kg of torque. After testing it I did not think that the servo was powerful enough but during all the sailing to date it has worked perfectly even in strong winds. I would not however want to use this servo if the boat was conventionally rigged but there are loads of standard sized servos which would do the job. The steering servo is a Savox SH0257MG digital servo (Dimensions (mm): 12.0 x 22.8 x 25.4 ) this is a micro servo providing 2.2Kg of torque and weighing 14g. I used a Turborix 2.4 Ghz receiver and 5 AAA NiMh batteries for power.
The hull was painted with Plasticote spray paints. The hull was primed with a plastic primer before several coats of primer filler were applied. This was then rubbed back using fine wet and dry paper to give a smooth finish before three coats of gloss topcoat were then applied. The Plasticoat paints are easily available and spray well but the top coat takes months to harden. But once this happens the finish is very good and appears to be quite tough.
If I was going to congenitally rig this boat I would have put a mast tube 15mm in front of the fin but I really wanted a swing rig boat. I knew that the mast would have to be further forward than this because the jib is smaller on swing rigs but I was not sure how much. In the end I decided to put the mast tube 50mm in front of the fin and see how it sailed. I was prepared to tune the balance of the boat by altering the ratio of the jib and the main. The mast tube is a 12x10mm carbon fibre tube. It has 10x6mm stainless steel ball bearing in the bottom and a 10x6 flanged ball bearing at the top.
The rigs for this boat are made out of; 4, 6 and 8mm carbon fibre tube all with a wall thickness of 1mm. This is easily available from most model shops or the internet and cost about £7/m. The masts on the larger rigs are all 8mm. The smallest rig has a mast diameter of 6mm. The main boom and the spar are 6mm diameter and the jib booms are all 4mm. Although the class limits the number of rigs to three I have made 4 so far. The only rig I have sailed the boat in so far is the B rig (second from left) and it was apparent that the boat could carry much more sail so I decided to experiment with a taller rig. As you can see from the photo all the rigs are angular in plan have a flat top and full length jibs. I believe that the high jibs and flat top sails improve performance.The Swing rig block was made by gluing 2 pieces of 8x6mm carbon fibre tube to a 10x8mm tube and covering in 2 layers of 280g/m2unidirectional carbon fibre tape with the fibres parallel to the booms and one layer of 200g/ms twill weave tape on the outside. Once laid up it is put into a vac bag and allowed to cure. It is helpful to seal the ends of the tubes been used with play dough or blue tack to stop resin going into the tubes. Once the resin has cured the finished article can be cut and sanded to size
Rubber grommets are used for most fittings on this boat. They are easy to use but there flexibility does mean there is a bit of sponginess. The upper jib attachment is bound to the mast with cayno and carbon fibre tow. The head of the main is attached to mast with a piece of 1.8mm stainless steel wire which pivots freely in the top of the mast. I found that the best place for the up haul was 40% from the front of the sail
The sails on the rigs I have made so far are all have a single panel main sail with the mast inserted into a luff pocket and a three panel jib. They are all made out of 50 micron film. I think the two largest sails would benefit from been made out of a lighter material. I have been very surprised how well the single panel sails set. I originally only made a single panel main sail for speed and ease of construction whilst establishing the correct balance but I was so pleased with the shape that I decided not to use seams on any of the main sails. I originally thought that the top of the sail would have little or no camber because when I make sails with seams in I put the seams in to keep the camber in the sail all the way to top. I have also been surprised how little battening the sails need. The A, B and C rigs only have one batten at the top of the sail and the D rig doesn’t have any at all.
Developments
Developments
Since completing this boat I have only sailed it 4 times but plan to do a lot more. The initial impressions are very good and the boat appears to be; responsive, seaworthy and powerful. It is not as fast as an IOM but its not far off. It also looks very small on the water next to the IOMs but it sails well and appears fine in all the wind conditions I have frown at it so far. I am delighted with the speed which the boat can be rigged and the way the sails are exactly the same as the last time you sailed it. Hopefully I can find some local competition and even try and get a class race day to see how well it goes compared to others of the same class.
Conclusion
Conclusion
Although the boat is small the hull construction was no easier or quicker than building an IOM or Marblehead. I also found it difficult to get used to the small size and struggled to build everything light and small enough. I have learnt a lot building this boat and if I were to build another one I am sure that it would be better. I would however build it almost exactly the same way. I have enjoyed the freedom that the class allows and found working with Depron challenging and satisfying. The rigs were far easier and much faster to make than IOM ones with fewer components and no drilling. I believe that the sails could be improved with rounded Leaches and I would like to try sails without pocket luffs for comparison. I also want to try making some more sails out of different materials such as Icarex or Cellophane. I even have some more nonconformist ideas about trying; a balanced una rig, a gaff rig or even a solid or semi rigid rig using a KF aerofoil. The boat is very stable and when pressed had downwind can appear to trip up over the fin. It may perform better in strong winds with a shorter fin which I may try. I might even try a lighter keel to see what difference that makes.
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