Members of Clontarf Yacht and Boat Club Club continue to lovingly build their IDRA14.
Below is the most recent update from the club.
It’s been a number of months since we updated you on the progress of our new IDRA 14, number 166. Not forgotten about, but sailing took precedence again this summer, and rightly so, with not only the usual club races, regattas at home and away, and the Nationals, but a variety of fun races this year including the Battle of Clontarf Viking boat rally, a night race and the fundraising and Bart’s Bash, the Guinness-world record attempt for the world’s largest sailing race.
Building never stopped, it just slowed down a bit! Probably the most significant building event was our change of practice to using a spile-board to create the plank shapes. Spiling is a method of transferring a template of the plank from the boat to the actual spruce. A spile-board is a light flexible board, typically 6mm plywood covered with masking tape, which is landed on the boat and clamped in place. Lines for the new plank are taken from the boat frame onto the spile-board. With the lines drawn on the spile-board, the Sitka spruce board is laid alongside. Lines can be transferred directly onto the spruce board to mark out the new plank. The spiling method has two advantages: it can be used again and again and; because of its flexibility it can be tweaked to ultimately get the finished board to hug the moulds. The spiling method has worked well for us especially with planks 8 – 11.
When we first set out to order the wood for the planks 18 months ago, we did so, without having an IDRA timber picking list to know exactly what wood was required and to what measurement. Usually part of a boat’s construction plans, there was none to be found with the plans we had, and although we looked high and low to find one, even putting a call out to RTE’s Seascape programme, none turned up.
From general advice we got, we then decided to use the timber picking list from the Mermaid class – the Mermaids use 10 inch boards to take their planks from. In hindsight, having seen how the planks fit together, we now know we would have needed at the beginning:
8 inch boards for the first 4 planks including garboard
10 inch boards for the next 4 planks
12 inch boards for planks 9,10, and 11, and
at least a 12- inch mahogany board for the sheerstrakes
We checked a number of the completed boats in Clontarf, and found that frequently the sheerstrake is spliced with
a scarf joint, i.e. two pieces of wood are joined or scarfed together to make a strong joint that bends in the same way as the rest of the board.
Scarfing has allowed us make up the extra width for planks 9, 10,11 and 12, which are narrow, at 10-inches, although we have only required very small scarfs hidden in the rebates of the overlaps. Plank 11 will be the largest of the scarfs.
Having ordered the ribs earlier in the summer, we recently routed 28 full-length ribs using a Festool OF 220 router (in a CMS table, with a CTL 26 dust extractor, to be exact). It took 28 minutes for the 28 Irish indigenous oak ribs to be routed on all sides. When ribs are bent, stresses remain in the wood, but by routing all 4 sides, it alleviates tension in the wood and stops them from splitting.
There are two approaches to ribbing: hot-moulding where the ribs are immediately riveted in place straight from the steamer and; cold-moulding, where the hot ribs are clamped in place initially and later riveted when cold. With hot-moulding the ribs will tend to pull to the shape of the hull, with hot-moulding the hull skin will tend to pull to the shape of the rigid cold ribs. We have decided to use the cold-moulding method believing that it will result in a better hull form. Our research has yielded this video which demonstrates the cold-moulding method.
Luckily with the boats not yet in for storage in the shed, when we did this job, we had ample space to set up and work away at the ribs one Saturday morning before a club race, and still managed to get out on the water in time for first gun that day. Next up will be building a steamer for bending the ribs. But that’s for next month!
Ruairi Grimes called in in early September to the shed again, this time to discuss the design features of the bow tank, triangulation, and how to calculate displacement necessary for a capsized IDRA, with a view to putting in underfloor buoyancy.
Ruairi has calculated the buoyancy needed to displace the weight of: two sailors, a boatful of water and the
160kg hull and rigging. He has given us two options, both of which feature a bow tank.
- Option 1 would be to put in underfloor buoyancy, with a bow tank. This might mean having the floor of
the boat raised 2-3 inches higher than is usually found in an IDRA.
- Option 2 would mean integrating side tanks into the bow tank, with the floor at the usual height.
Both options are still up for discussion but we are favouring option 1, which maintains the more traditional look of an IDRA.
We have continued to welcome visitors to the shed. In September, some of the team from our neighbouring club in East Wall, called in to see our progress during the Viking boat rally festival. They themselves have been building 2 Naomhógs (traditional Irish currachs) which they launched on September 21.
We finish September with plank 11, the last of the Sitka Spruce planks – both port and starboard planks prepared and ready, and below Plank 11 on the port side firmly in place.
We hope you enjoyed catching up on our summer progress! We’ll include bigger higher resolution photos on our Facebook page and on CYBC webpage, look out for them.
*** 4 June 2014 ***
As we head into this next bank holiday, we’re over half way along with the planking - we have put the 7th plank into place on the starboard side a while ago, while also doing last minute work to have our own boats ready to sail in the IDRA 14 Northern Championships in Rostrevor at the weekend.
Riveting and planking is going on steadily. We’ve been using the wooden laths or ribbons to help set out the spacing for each plank but after a recent visit from Martin O’Toole and Jim Boylan to the boat shed, we’re considering removing the remaining laths now and completing the planking using a spiling method. This should also work better for the remaining planks, as there is not so much steaming involved from here onwards.
The process of spiling involves using a spile-board, a piece of plywood similar to a plank, but lighter! The spile-board is placed on the boat where the next plank will be positioned. The lightness of the board allows it to be easily pressed into position providing a more accurate shape. It particularly facilitates getting the planks to hug the moulds on their way around the tumblehome zone of the hull. Marks are made on the board and transferred onto the actual plank, so that it can be used again and again.
Meanwhile, in early April, Nigel Young from North Sails Ireland came up from Cork to measure the sails of IDRA14/160, as 166 will be fitted out with new sails from North Sails. He spent about 2 hours on a Friday night, with Ronan and Lorraine, taking a series of measurements –
1. Taking note of the official class sail measurements,
2. Measuring an existing set of sails, and the spinnaker while laid out on the rig,
3. Finally, with an IDRA14 fully rigged, but lying on her side, he measured the sails with rig tension for tension on Light, Medium and Heavy Airs.
The measurements were sent to the North Sails Design Department for input into their system – we hope to have a computer design sent to us shortly.
Nigel’s father was a boat builder, building a Dayboat, a wooden dinghy not unlike the 14’s, that Nigel helped build and sail. Nigel has shown great interest in the project and had time after taking the measurements, to look at our progress to date.
The rig – Mast, Boom and Rigging – arrived to the shed in March from SUPERSPARS, who have been very generous, giving a great discount to help with the project. The rig has been safely stored, waiting its turn – a while to go yet!
*** 12 March 2014 ***
Planking has commenced! The starboard garboard was laid on Tuesday 7th January 2014. Steamed in a simple plywood box; held in place with sticks and clamps; glued with the mighty SP106. We are entering on a lengthy repetitive process. We have 24 planks to lay. Each will be shaped, steamed, sanded, rebated and sealed. Each will be tried for fit and adjusted. The Sitka spruce is beautiful wood to work with. The boards have tram-track grain and a honey brown colour. They are easy to sand but offer a greater challenge when rebating. Steaming has taken about 20 minutes before the plank is supple enough to get the twist needed to make the bend to the stem. When clamped lightly in place for 24 hours, it keeps the shape.
Although we are gluing the boat with SP106 epoxy resin we are also keeping to the traditional boat building method of riveting. Copper nails and rivets were sourced from Toplicht in Germany (www.toplicht.de) who incidentally has a wonderful range for anyone fitting out, renovating or building a boat.
The mast and boom are ready for delivery from Superspars and should be with us in the coming month. Thanks to Alan Henry for providing the spec to Superspars.
We are speaking with a number of sail-makers at the moment to decide on which company will dress 14/166 and will be back with news on this soon.
Ruairi Grimes is busy with the conversion of the drawings over to CAD using Solidworks. On a recent visit he showed us his drawing of a Mermaid. It was amazing to see the boat onscreen and be able to inspect any construction element in 3D detail. The software further allows the development of individual planks i.e., in-situ planks to be flattened showing their true shape. There may be an opportunity in the future to check a number of these full-size developments against our own templates.
Ruairi is undertaking a number of design innovations for 14/166, namely:
1. Bulkhead. We will be installing a bulkhead forward of the mast step where the centreboard casing ends. This is to prevent the forward rush of water in under the deck in the situation of a capsize and of course make it easier to displace the water to the back of the boat preventing the submarine effect. The bulkhead will be fitted with inspection hatches and as suggested by Alan Henry, perhaps a place to keep a beer cool and your sambos dry for between races!
2. Chain plates and Triangulation. A system of force-triangulation to strengthen the boat. This will incorporate the chain plates and mast-step using cables to take the load exerted by the shrouds and halyards when underway. The chain plate knees are also being redesigned making them longer to absorb more of the pressure; these will be laminated similar to the stem and transom knees.
3. Underfloor buoyancy. We are working on a way to fit buoyancy under the floorboards or a method of displacing the water from the bottom of the boat. Any thoughts on this topic please let us know.
We would like to thank Ruairi for the amazing work he is doing and we know the finished product will benefit generations to come.
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If you’re looking for us over the next month, we’ll be planking and riveting....
*** 22 January 2014 ***
A new year and lots to report from the last few weeks! Most importantly, in November, we passed the first of the measuring tests! Gerry Sargent was appointed as Class Measurer for IDRA 14/166 by the Class Association Committee. The first measurement of a timber IDRA 14 takes place when the keel is in laid and the building moulds are in place. Gerry came to the boatshed one evening in mid-November and spent over an hour and a half, meticulously checking that every measurement on 14/166 is as it should be to conform to class rules.
Not only did he give 14/166 a thorough and comprehensive inspection, but Gerry also showed us some of the original measuring forms so that we could see how we line up with boats made many years ago. The rules allow for a certain tolerance, of ½ inch all round on either side of the prescribed measurements, every boat must be within these tolerances. We were delighted to be in line almost everywhere, and only on the transom were we ¼ inch out, but still within the required range. We’ve passed the first stage of measuring with two more stages to go.
Follow the progress on Facebook See the 2013 reports here.
Any questions on our updates please contact Louise & Róisín Email: firstname.lastname@example.org