Archive for March 2015
Today I placed the last two planks at the bow on the starboard side of our Did 40 Cr to complete the plywood skin of the hull. It has taken eight weeks to complete the skin from go to whoa which is a little longer than I anticipated at the beginning. A lot of time was taken fairing stringers for the first layer of the radius chine and a lot of time was taken tidying up the rebate on the 12 mm plywood where the second 6 mm layer of the radius chine lands. I did a little planing of the first 6 mm layer at the transitions to the 12 mm flat sections and a little torture boarding of the first 6 mm layer to ensure there were no hard spots that would show in the final layer. I think I have achieved the finish I was expecting at this stage. The shadow on the second layer indicates that the hull is quite fair and this can be compared with a similar photo in an earlier post of the first layeer.
As the planking has progressed the temperature under the overturned hull has become more moderate demonstrating the insulation properties of the timber.
The second 6 mm layer of plywood on our Didi 40 Cr is complete right to the bow. The photo shows temporary cleats holding the plywood hard against the radius chine.
The shadow on the second layer of plywood on the radius chine of our Didi 40 Cr shows that the hull is quite fair before sanding.
Our twilight race result was rescued by one good move at the approach to Humbug. By sailing wide to leeward of the fleet we escaped the wind shadow of Greenwich and sailed away for a third fastest and second on handicap.
The forecast was for light winds and after the black fleet not finishing last week they were sent out on the same course around Goat Island as the white, green and blue fleets.
At the start we were out maneuvered by French Connection who made sure we did not have room to tack or gybe in front of them to return to the start line so we were 20 seconds late at the start. While we were late we were in the right position and powered up so by Humbug we were up near the front of the pack. Worlds Apart hug the north shore while we looked for breeze mid channel. Agrovation mid channel in front of us did best, was never headed and went on for a well deserved first and fastest. On the work to Goat Island we observed Agrovation on the right side of a couple of good lifts which complemented her good boat speed. Worlds Apart powered through our lee on the approach to Long Nose and French Connection did better mid channel than we did in Snails Bay so by Goat Island we had a bit of catching to do. Wide around Goat Island worked this week and we poled out for the long run home.
Jackpot and Soundtrack from the black fleet overtook us but had trouble getting away on the run home. French Connection and Gwhizz were closer to the bridge while we went just a couple of boat widths wide of Long Nose on the way home. The run was very square and at times over square which gave us clear air with which we were able to keep just ahead of French Connection and Gwhizz.
At Greenwich Point the four fleets merged into one large one and as they each tried to protect their breeze they went higher and closer to the wind shadow. Gwhizz had a good squirt of breeze and charged purposefully into the wind shadow. We slipped away to leeward of the whole pack and had Worlds Apart in our sights.
It was deadly light in Humbug, so light that the fleet was becalmed for long enough for us to get a ten minute break.
Last night was our chance to turn the tables on Izzi and Saoirse who were left out on the course in light air. We have been there before so we know they will come back.
Zig zagging in light air on the way to Goat Island
I am looking forward to placing the last plank on the second layer of the radius chine of our Didi 40 Cr. Three days of perfect working conditions should see the finish of this stage and then I can move on to planing the flat on the “V” of the keel. There are only seven more planks of 6 mm plywood before I move to a double layer of 3 mm plywood for the tight radius at the approach to the bow. The 3 mm layers are easy to bend for all but the last plank and I will try to do them together as I did on the first layer.
Yesterday started out warm and sunny so I could clean up the glue from the first layer on the port side ready for the second layer. While the tarpaulins were off I took this photo of the starboard side which is still to be prepared.
The starboard side of our Didi 40 Cr still to be prepared for the second 6 mm layer of plywood on the radius chine at the bow.
By the time the preparation was completed the wind and rain came after gluing just one plank. As rain threatened all afternoon I went under the hull and started preparing the inside of the water tank for the epoxy glass join of the top of the water tank to the newly formed radius chine hull. That is ready to do now the first time I need an inside job. I have a mental list of lots of inside jobs still to do like fitting the last two shelves in the quarter berth and fitting for later installation the fronts to these shelves. There are still 20 mm triangle cleats to be fitted to the front edge of these shelves and to the ones in the saloon and if these jobs run out I can do some of the filleting of the hull to the frames on the near vertical edges where gravity is not much of a factor. The rudder stock and associated bearings and stainless steel is in manufacture so that should arrive in good time to be fitted and then completing the rudder will be another good inside job.
Wednesday evening was the slowest race of the year and the dying breeze produced some unique results. Every fastest time yacht also won their division on handicap. As the evening wore on and the prospect of finishing within the time limited dimmed more and more yachts called in on channel 73 and announced their retirement from the race. None of the black fleet could complete their course and the late night made for a smallish attendance at the BBQ and presentation.
We made a well timed start to leeward of the fleet but Agrovation higher on the start line reached across our bow to give us all their dirty air. This was particularly damaging against the incoming tide and we lost a lot of ground pinching to round Onion Point. Gwhizz showed the fleet a clean pair of heels but on the run through Humbug we poled out our big genoa and blanketed the fleet. This left us a bit high into the wind shadow and we saw Worlds Apart to leeward nose into the freshening breeze to make a handy break on Izzi and Agrovation.
On the work to Goat Island we were pinching into a big incoming tide immediately behind Izzi. I tacked away chancing a bit of tide against stronger breeze in the middle and in the process lost ground on Izzi and Agrovation. Izzi got away while there was breeze and left us to play with Agrovation for the rest of the race. In the end they went a bit too close to Greenwich Point and languished in the wind shadow. They were unlucky as the wind had swung south and the Greenwich shore was almost the windward shore but once into Humbug the breeze swung back reestablishing the wind shadow. We were never more than a few metres in front but with the incoming tide abating and with no wind the speed across the ground was down to .3 knots and a few metres takes a long time. For the last 200 metres to the line we hooked the boom up with the boom topping lift to get a bit of twist in the sail and that seemed to help us get home in the dark. We were 18 minutes behind Worlds Apart and Agrovation finished 15 minutes behind us which is quite a feat seeing we were in touch at the entry to Humbug.
Fourth fastest and fourth on handicap was a fair result from ten starters and a fair reward for the crews tireless efforts to get us to the finish line.
The lightest night of the year, so far.
There is 152 planks to be shaped and glued into place to form the round bilge on our Didi 40 Cr. After reality sank in I set a target of eight planks a day thinking that I might better it on a good day. Well by that measure there are few good days. As hard as I try one plank an hour seems to be my production rate. On the first layer a lot of time was spent fairing stringers progressively so I thought the second layer might go a bit quicker. That has not proven to be the case because there is still a lot of preparation work. I have to tidy up the 6 mm rebate where the top layer of plywood overlaps the join with the 12 mm plywood and do some fairing of the first layer.
After some experimentation I have settled for 18 mm 8 gauge metal threads to hold the two layers together while the glue cures. Smaller screws provided enough holding pressure but the larger screws have a larger diameter head which gives more driving power with the battery operated driver and it is easier to clear any glue from the slotted head.
Today I worked ten hours on the hull and managed ten planks for the regulation one per hour but it is hard to find days where the conditions are right for one to work such hours. It cannot be too hot or be wet and I must have all the materials needed and make no mistakes.
With a large part of the hull now planked with the two layers of 6 mm plywood I have tried my hand at fairing the radius chine with the torture board. What tiny bit I have done looks good but there are a lot of screws to remove and a lot of hull that will need the treatment.
Progress on the second 6 mm plywood layer on the radius chine of our Didi 40 Cr
In the photo you can see how much of the second layer is completed. Since I took this photo on Saturday afternoon I have added another 16 planks and at a rough guess the radius chine section is 70% complete.
Well that was a slow week for boat building. A very hot Monday restricted work hours to the late afternoon and and with rain threatening all Friday I have completed just 24 of the 76 planks on the second layer. I completed the interior glassing of butt joins in the side panels today and tried my hand at filleting the ply skins to the transom. Between the epoxy fillets and the few shelves still to be installed inside I figure there is plenty of work ahead for many rainy days.
There is little difference in the appearance of the hull with the second layer so I have not bothered with photos. Also I have kept the covers on all but the work area each day in case of rain. In lieu of a photo I will show a drawing of what she might look like on the water. I am still thinking about the name and Passion X is one possibility. The sketch shows the bow sprit, longer spinnaker pole and cabin top traveller. Also the shape of the stern is modified ever so slightly.
Off site work has started on my rudder stock so in a few weeks I will be able to fit the rudder bearings.
This is how I propose to finish our Didi 40 Cr. Note the removable bow sprit, the long spinnaker pole and the cabin top traveller.
Wednesday night provided a spectacular light show when a storm cell moved up the Parramatta River and engulfed the Greenwich Flying Squadron twilight fleet just as they were crossing the finish line. In the calm before the storm places changed and the race for many was lost in the confused wind.
The wind forced out of the storm cell was in the opposite direction to the prevailing wind and rose from zero to thirty knots in a matter of five minutes. In the dark and gloom it is a wonder that the finishers were able to place yachts as they crossed the line.
For our part it was a bit of a dud race. We made a good start and were first into Humbug but the newer faster yachts in the fleet are able to take our wind on the run through Humbug to pass Cockatoo Island to port. Around Cockatoo Island we were forced to go too close into the wind shadow to protect what wind we had from the following yachts while to leeward Saoirse found wind and powered away to beat us over the line by 16 minutes. So far ahead of the fleet were they that they finished before the storm cell took away the prevailing wind. Worlds Apart, Gwizz, Izzi and Agrovation were all in the mix for second place and the navigation mark on Goat Island there was not a lot between them and us.
On the way we might have done better if we could have tacked onto port on Long Nose and were not driven well past the point by a starboard tacker and the earlier fleet returning from Goat Island. But for that delay we might have sailed around Goat Island in breeze instead of drifting around it in dead calm. I thought we were doing the sensible thing going wide around the Island while the foolish ones who were hugging the shore would sail into nothing. Well we all sailed into nothing only we did it the long way and the fleet was well gone by the time we emerged from the Bermuda Triangle. I thought everyone passed us but had not counted on Tartan who was well back waiting for the storm front to sweep them home for a good place on handicap. By luck we managed to sail past Avanti who did the regulation wide arc of Greenwich Point while I played the dying prevailing wind running away with the stronger puffs. That did not stop us all waiting in the lee of Greenwich until it swapped from lee shore to windward shore. In the switch we were able to pass French Connection and then sail until we had her clear astern to recover some dignity for the evening.
Fickle winds ahead of the storm
The meal after at the club was well attended and I particularly liked the mint flavoured fruit salad. We were able to take a tub home for the modest donation of a $2 gold coin so we could enjoy it again today.
Courtesy of a few yachts that did not return for the meal and results announcements we were able to take home a bottle of wine from a surprising sixth place on handicap one second ahead of Worlds Apart who while second fastest was becalmed in the approach to the finish line.
Today with more help from friends we passed the half way mark on skinning the radius chine on the Didi 40 Cr. Now all the stringers are hidden under the first layer of 6 mm ply. Already I have fitted four planks of the second layer to check my construction detail and now I can go full steam ahead.
First layer of the radius chine completed on our Didi 40 Cr
On the first few planks where we used two 3 mm layers of ply to achieve the 6 mm we have temporary cleats between the stringers. Forward of that the stringers are close enough to not require additional cleats.
With help from the crew we have almost finished the first 6 mm layer on the radius chine of our Didi 40 Cr. I was able to use 6 mm plywood up to 2.4 metres from the waterline entry at the bow. Beyond that the sheets would snap when bent to the required radius. Dudley calls for 4 mm ply from there but I opted to do the first layer in two layers of 3 mm plywood. A single sheet of 3 mm ply was enough to cover the last 2.4 metres in two layers so it is both a practical and economic option. In the penultimate 1.2 metres we used cleats between the stringers to make sure the 3 mm layers were pulled together but for the last 1.2 metres the stringer spacing was so close as to not need any additional cleats.
The other minor variation was for the last 2 metres to take the two 3 mm layers across the tangent stringer to the keel centre line. This makes it easier to hold down the end of the plywood and also gives avoids a join across the tangent stringer doubler.
At this stage I stopped using the 12 mm ply cleats to hold down the plywood planks to the tangent doubler and started using 19 mm silicon bronze nails which have amazing holding power in the tough dense meranti keel timber. Right at the bow a lot of nails were needed to hold the last plank to the tight curve.
Tomorrow I will true up the centre line with the rebate plane and try to complete the starboard side. After that it will leave just 72 planks to go (counting the 2 by 3mm planks as a single 6 mm plank)
I am going to use the 2 by 3mm planks an extra metre further back from the bow on the second layer so that the external skin is not so highly stressed. We have found it almost a quick to do the two 3 mm layers together as to do a single 6 mm layer and with the solid 6 mm layer as a backing a few silicon bronze staples should hold down the 3 mm plywood between the stringers without the need of extra ply cleats.
Using the 12 mm plywood cleats held down with three 10 gauge 32 mm self tappers has proved to be a great success. Once I started to use a large screwdriver to torque up the self tappers to the maximum the joins have been finished flush and square to the tangent line with remarkable consistency and accuracy. The hull side of the cleat is covered with packaging tape which acts as a mould release so the glue joins look like fine furniture.
On our Didi 40 Cr the glue joins after removing the ply clamping cleats are of high quality.