I continued to fillet and fibreglass all of the seams. When doing the front compartment, I need to use a length of timber as a spacer to hold the correct shape. However, once the fillets and the fibreglassing was complete in this section the compartment held the correct shape without the spacer. I also epoxied a thin batten of Tasmanian Oak along the full sheer as an inwale which also helped hold the shape even without the internal moulds.
I added a piece of tassie oak across the top of the front bulkhead to provide strength and give me something to use to attach deck to when I come to put it on.
To finish off the front compartment I added a king plank that I had carefully shaped to fit snuggly in the bow and I cut a hole to fit a hatch that I bought from the local chandlery. Once I have added on the deck pieces, this will become a watertight (hopefully!) compartment that can be used for stowage. Since the taking the following photo, I gave the entire compartment a couple of coats of white paint which look good.
With the forward and rear compartments complete, I then added in the smaller bulkheads that will create the 2 seat ‘plinths’ and the 2 mirage drive housing. As with the other compartments, I filleted and added fibreglass tape to each of the seams. I didn’t worry about neatness in the spaces as they will be sealed up once completed and so I did the minimum amount of sanding. The following picture shows one of the mirage drive compartments fully completed and waterproofed with epoxy, awaiting the mirage drive housing and the top.
Below is the rear seat plinth awaiting the top to finish it and the rear mirage drive compartment with the top on temporarily to ensure the sides where in the correct alignment while the epoxy set. I had also laid out some masking tape around the seams to be filleted in the area between the seat plinth and the rear bulkhead. This is the first area that will have exposed fillets in the finished boat and I thought the masking tape would help keep the fillets neat which would reduce sanding. Unfortunately it did work very well and so I didn’t bother with it on any of the other sections – I will just have to do a bit more sanding to get it to look neat!
I finished off the mirage drive housings by epoxying the 2 halves together. I then gave the outside a light sand and wrapped the outside with a single piece of fibreglass to ensure that it was strong and resilient.
I used sandpaper to shape the bottom of the mirage drive housings to ensure they fit reasonably tightly to bottom of the boat and then glued them into place with a thick layer of well thickened epoxy. I made sure that some epoxy squeezed out from around all edges and used a paddle pop stick to create a watertight fillet.
The final picture shows the current status of boat as of today, 24/06/2017. Tomorrow I plan to complete the last of the fillets which will be a big moment – it is definitely not my favourite job! And then I need to sand them all …
This weekend I started by adding in the transom pieces and using cyanoacrylate glue to align the planks and ‘kicker’ to set it off instantly whilst I held the planks in exact alignment. I just needed the glue to hold the planks together so that I could cut out the stitches before I apply the epoxy. I was worried that the glue wouldn’t be strong enough but when placed in drops fairly regularly, it seems to be plenty strong enough.
I also added in the rear bulkhead which all fit together perfectly. Once I had temporarily glued the entire rear section of the boat, I cut some fibreglass tape and lightly sanded the inside of the compartment ready for the first of the fillets.
I laid in fillets of thickened epoxy (West System) along the first 2 chines and all around the transom and bulkhead joins. I was a bit rubbish at making a fillet – they were definitely not the neatest but luckily this is going to be fully enclosed and so will not be too visible. While the fillets were still wet, I laid on the 50mm fibreglass tape I had cut previously and wet it out with unthickened epoxy. I used a disposable chip brush to smooth and wet out the tape, which also assisted in smoothing out the still wet fillets which was an added benefit.
The joints between the 2 garboard planks and the 2 upper strakes were too flat to add a fillet. So I first painted epoxy on the 50mm strip around the joint and then used this to tack up the tape while I went back and wet it all out. All in all, it seemed to be pretty successful.
When I worked on the design of this boat on the computer, I got a Rhino file from Nick of the Ripple III hull – which is based on Mack Horton’s original Ripple build (see side bar on home page for links these guys). Nick had first created a smooth ‘ideal’ hull shape but then worked out where the plank lines should run and cut the model into the 8 strakes. When I was designing the rest of the boat, I used these plank lines to cut my pieces. This has worked perfectly in the rear of the boat where the pieces are all naturally flat. But towards the bow, the ‘ideal’ hull in the computer has more curve across the plywood plank than can be achieved in reality. This mean that I had to manually cut off some of the curve to straighten the worst bits. I only had to cut off the 2 sections of the front bulkhead where they met the garboard. After this, I could get a good enough fit for the rest – and as always, the epoxy will take care of the rest.
I finished this weekend off by cutting and attaching some 25 x 16mm Tassie Oak stringers to the inside of the sheerline at the bow. I need this inwale to attach the hull top to and to help hold the shape and strength of the boat. The plywood had a funny wriggle in it up at the bow that was ruining the smooth lines – but the addition of the hard wood stringers sorted that out. Unfortunately I forgot to take any photos – I will have to do that next weekend.
I used the extra day off on the ANZAC day weekend to start the build properly. I started by screwing together some structural pine to act as a strong back. My car port is on a slope and the tiles are not particularly even. My original intention was to level the strong back with some blocks of wood – but in the end I decided that it probably wasn’t necessary using stitch-and-glue and moulds at 1m intervals.
Then I measured out the spacing for the moulds and centred them on the strong back and attached them with some angle brackets.
The whole set up only took a couple of hours and I was able to lay the garboard planks in moulds and stitch them together with zip ties through the CNC drilled holes.
The planks went together really easily – apart for when I accidentally tried to attach one of the planks backwards! I got through quite a few stitches before I noticed that something was not right. Luckily it is really easy to cut out the stitches, correct the plank and start stitching again. By the end of the day, I had basically stitched together the entire hull – and it looked like a boat already! When I built my previous boat, it took me a year before I had the hull complete, so this was a pretty massive advantage in using this method of building.
I added internal moulds to hold the correct shape. I had cut triangles at the top centre so that I could use them to adjust the alignment of the boat to keep the hull true – but I didn’t have to – it was exactly true from the start.
Just after this photo, I zipped up the bow of the boat – this was the bit that needed the most contorting and encouraging – but it all came together remarkably well and there are only a few small gaps between plank that will be easily taken care of when I add the epoxy fillets. It was all very satisfying to see it finally coming together.
Having spent months learning to use Rhino (a blog in itself!) I finally had the files ready to get Ripple 3 cut out at the CNC router. I purchased and delivered 4mm Joubert Oukume marine plywood for the boat kit, 12mm structural plywood for the moulds and 30mm foam for the Mirage drive casing. The CNC routing company cut the kit for me and delivered it to me about a week later.
It took me a while to get started but finally I pulled out the pieces for the first planks and pressed them together. I found that the design of my joints was not the best – the straight edges of the ‘fingers’ crested some potential that the pieces may not be fitted together precisely. But with care I think the will fit together tightly enough. I used drops of Gel type super glue to permanently stick the joints together.
Using this technique it only took me about 15 minutes to get the first couple of planks together which I pretty pleased with!
Unfortunately, it was at this stage that I hit a snag! Some of the pieces were missing from the cut pile! I went through all of the parts carefully and worked out that 3 of the plank pieces were missing. I figured that the CNC routers had accidentally thrown out the pieces with the scraps – until I checked my DWG files to discover that the mistake was mine! 😦
Back to the computer. I still had half a sheet of plywood left over – carefully planned when I was laying out the pieces on the computer the first time. Unfortunately it was a short fat shaped half which would not fit the 3 missing pieces on – grrr! So I had to purchase another whole sheet of plywood and take it to the CNC router again and another week later I had the last pieces of the kit – and another 1/2 sheet of plywood, long and skinny this time. I am sure they will come in handy at some stage in the project 🙂
In the meantime, I decided to start on the mirage drive casing. The CNC router had cut these from the 30mm foam. I had designed them to be an open half that I could glue together and fibreglass the inside. I had been warned about the difficulty of trying to fibreglass the inside of the casing when it was all together – so we will see if this is an improvement.
The 6mm dowel was designed to slot through all of the pieces to assist in aligning them and to provide some additional strength etc. I used thickened epoxy (West System) to glue 7 of the 30mm thick pieces together for each half of the 2 mirage drive casings.
Next I cut the fibreglass sheet to size and wet out the sheeting with more epoxy. This was the first fibreglass work I had done and so far it seems to look pretty good. Once the first coat of epoxy had dried, I trimmed up the daggy bits of fibreglass and gave them another coat to fully fill the weave.