Here is a list of all the postings Gareth Jones has made in our forums. Click on a thread name to jump to the thread.
|Thread: A class yacht - Serica II|
I am thinking along those lines Bob. Ideally I would like to drill down from the top because the pilot holes are in the transition piece that fits above the lower keel. I think I will probably do as you suggest for the first bolt hole, which will be the aft one. Then I will fit that bolt through the transition piece and keel and drill the second hole down from the top using the transition piece as the pilot. I will post some pictures of my final solution.
Good idea Bob, I will bear it in mind if I ever make another keel weight. Unfortunately I could not easily do that with Serica. The position on the mounting bolts is already set in the hull as there are a pair of beams already fixed in the hull and predrilled from the original keel, made by John Gale but lost after his death.
The centre of gravity of the keel weight has to sit directly below the centre of buoyancy of the hull. The lead keel weight is over 60% of the total weight of the boat so if the two points do not sit in line, the hull will sit bow or stern down. I know where the centre of buoyancy of the hull is supposed to be because I have had a copy of the original BIll Daniels drawing and it is indicated on the revised keel weight drawings done by Jim Belton. However I was not certain where the centre of gravity of the keel weight would turn out to be until after it was cast.
I found the cg of the keel weight by balancing it on a length of aluminium rod laid on the workbench and was then able to mark it up on the weight itself. I then positioned the weight and the piece of wood that forms the rear of the keel on the transition piece between them and the hull and marked the position where the keel bolt holes need to be drilled.
Once I knew where those would go I marked and drilled the holes for the two dowels that locate the keel weight and the aft part of the keel. I did not want the dowels to end up crossing the path of the keel bolts.
The dowels will add to the strength of the completed keel, but probably more importantly locate the two parts together while it is being glued. Araldite makes quite a good lubricant when it is still wet so the two parts would slide all over the place and since the glue joint is on a 35 degree slope it would be almost impossible to clamp them together.
The two parts that make up the bottom section are now clamped up and drying on the boiler. You can see where I cut away the top section of the lead weight in the bottom right hand side. That gap will be filled with a length of 15 mm thick timber before attaching the whole thing to the transition section that fits on the bottom of the hull. The holes for the keel bolts have already been drilled in that so it will be used as a pilot for drilling through the bottom section. I will have to make some sort of fixture to hold the bottom of the keel upright and level under the pillar drill before attempting to drill the holes.
Edited By Gareth Jones on 22/01/2017 17:15:20
Its bigger than you think Ashley, it's next to a 15 inch ruler!
We collected Serica's keel weight from Bradford today. Here is a picture to give you an idea of the size.
As I expected it is too heavy, weighing in at 17.4 kilos. I have weighed the hull, the wooden parts of the keel, a similar mast and sails, radio gear, vane gear and guessed at the weight of fittings and I reckon I need to remove a kilo in weight from the keel. I have measured the area of the top surface of the weight and based on that I need to remove 15 mm from the top of the keel. I decided this is the best approach since it will keep the centre of gravity as low as possible and it will be relatively easy to do. A 15 mm thick wooden packing piece will replace the lead removed.
I have also measured the fore and aft position of the centre of gravity and it is about 20 mm further back than recommended on the drawing. I made allowance to be able to move the keel weight and the wooden section behind it fore and aft on the transition piece between it at the bottom of the hull. I plan to recheck the position of the c. g. when I have cut off the top section and position it accordingly.
Tomorrows job is sawing off the surplus lead, filing the top flat and then rechecking the cg. After that it is drilling the weight and aft section with a couple of 6 mm holes to hold a pair of stainless steel dowels that will locate the two parts together when they are glued. I then have some planing and sanding to do to get the transition piece to fit the bottom of the hull and top of the keel and then the tricky job of drilling holes for the 8 mm stainless steel keel bolts. I have ordered a couple of extra long 6 mm and 8 mm drills. in preparation for this task.
Serica's keel weight pattern has been taken to Monkmans Brass Foundry in Bradford and been cast in lead. We would have gone to collect it today but in view of the snow and ice this morning decided to put it off till next week.
In the meantime I have fitted the mast, the bottom section of which is a 2 metre length of 3/4 inch aluminium tube. The mast step is an unusual design, not one I have seen before, but infinitely adjustable over its range. This was the only metal fitting in the hull when we acquired it.
I did not want to sit the mast directly on this as I thought the relatively soft aluminium could be subject to some fairly big loads on its earth point. After hunting around various scrap boxes of stuff not to be thrown away because it might come in useful, I came across a brass hose end fitting that was a snug fit in the end of the mast. I filed a slot in it so that it locates in the step as shown in the two pictures below.
The flange on the end was then filed down until it was flush with the outside wall of the mast tube and the whole fitting glued into the bottom of the mast with epoxy. I then made up a slide to fit on the deck from sheet and strip brass and Serica now has a mast, or at least part of one, for the first time in her life.
I have got some dowel suitable for making the booms so I will make a start on that job prior to collecting the keel weight, hopefully next Friday. As you can see from the picture above our older sons bedroom has been partially taken over as a yacht and sail rig storage area
Edited By Gareth Jones on 13/01/2017 20:42:18
While Elizabeth was varnishing the deck of her Marblehead China Boy, she decided she would have some spare time and varnish to do the rudder for Serica and also the deck edge strips and hatch coamings. Both these items had only an initial sealing coat by John Gale when he finished the hull.
Serica is now sitting in the middle of the workshop, taking up most of the room, waiting for the varnish to dry before a further one or two coats is added.
Serica now has a rudder, made from 4 laminations of 2 mm thick mahogany sheet, glued together with epoxy. The rudder post is made from 3/16 brass rod and a pair of 3/32 pieces of brass rod are soldered into cross drilled holes to tie the whole thing together. Here are the component parts before being fully assembled.
The rudder bearing tube in the hull is 1/4 inch bore so a pair of brass tube bushes were fitted to locate the rudder post at the top and bottom of the hull, allowing the rudder to pivot with minimal friction. In a conventional servo driven rudder I would have used 1/4 rod for the rudder post but on a vane steered yacht, it is important that there is minimal friction in the rudder to allow the vane to drive it accurately.
The bottom bearing is made from a piece of brass strip screwed on to the bottom of the rudder skeg. A small hole in this strip is used to locate a triangular sectioned end of the rudder post, i.e. it primarily provides a pivot point to support the weight of the rudder assembly.
Here is the final assembly glued and shaped, ready for varnishing.
|Thread: Model Warship Turret Operation|
Thanks very much and a very happy new year to you too.
I did inform the world that I would not be taking up your challenge to battle Thor quite some time ago, the link is here. **LINK**
Maybe nobody explicitly said model boaters have no use or interest in Arduino as a control system but it was clearly the impression given by some of the posters, although not necessarily you, I hasten to add.
Ref the Mighty Thor challenge, I have been sidetracked by lots of other interesting projects in the meantime, but I would not rule it out one day. When would the Mighty Thor be ready to take on any challengers? Can we see some photos of the model as it is at the moment?
Can you tell me, is this Arduino thing that has generated 160 or so posts in a week on Mayhem, the same thing that people on here said was a one trick pony of no use or interest to model boaters?
Edited By Gareth Jones on 31/12/2016 19:29:53
Edited By Colin Bishop, Website Editor on 01/01/2017 13:55:25
|Thread: A class yacht - Serica II|
I have made a bit more progress over the last couple of days and finished the lower section of the keel that will form the pattern for the lead ballast
Here is a picture of the lead pattern about to be cut away from the rest of the lower part. I tried various way of dunking the piece in buckets and boxes of water to try and estimate the volume and hence weight of the final lead casting. Unfortunately the results were too variable to be usable, but I reckoned I was somewhere in the right parish and the shape matched the templates on the lines drawing that I have. I therefore decided there was no option but to cut it off and weigh it afterwards.
The picture also shows two of my Christmas presets, a new saw and a new top for my Black and Decker workmate. I have had this workmate for about 40 years and it has given sterling service despite being abused on many occasions. It was becoming slightly less usable as I had managed to cut a couple of corners off the top section when jigsawing a few years ago. I was planning to ask for a new one for Christmas but on reading the reviews on a well known website, most of them said the latest workmates are nowhere near as robustly made as they were in the past. However I found a company on Ebay who supply new birch ply tops to fit virtually any model of workmate so I ordered a set as a present to myself. They arrived just before Christmas and I fitted them yesterday. Its nearly as good as new now.
Here is the pattern which weighs about 1050 grams on the kitchen scales. Based on the relative density of the wood I used and that of lead, the keel should come out at about 17.5 kg, which is about half a kg over my target. I am going to go with the shape as it now and if the final casting is too heavy I will drill a few strategic holes and fill them to get the weight down. Hopefully the pattern will be off to the foundry in Bradford at the end of next week.
Over the next few weeks I am going to start making the rudder and some of the deck fittings, which will take me on to learning another new skill I have never tried before - silver soldering
Regards and best wishes to everyone for the New Year
That is a very kind offer. I will send you a pm later this evening.
I had not thought of using cast iron. I have found a small company in West Yorkshire who specialise in lead castings so we are planning to use them at the moment. I don't intend to tap the lead section of the keel, the studs will go all the way through and locate in a couple of stainless steel nuts bonded into the bottom of the lead and then filled afterwards. I am going to need to invest in a long 8 mm drill bit though. It will need a very careful lining up to make sure the holes come out of the bottom of the keel in the right place on the centreline.
I have done a bit more planing and whittling tonight. The keel is now looking something like, but still needs some material taking off as it's a bit fat in places. I have deliberately left it a bit long so that I can adjust the position longitudinally to get the cg in the right place.
I am also trying to think of some way of checking it will come out at the right weight before I saw the pattern off the rest of the keel. At the moment my thoughts are around the idea of submerging the lead section and measuring the volume of water displaced - somehow.
The other option is to cut it off and weigh it at that stage. I know the wood I have used has a specific gravity of 0.65 grm/cc and lead is 11.36 grm/cc. I could, at that stage temporarily reattach the front section and do some reshaping to get nearer the right weight if I am a long way off.
So to continue the story, we had a beautifully finished 84 inch mahogany hull, with no keel or deck fittings.
Making a keel was going to be a challenge, if the original Serica designer and builder could not get it right, there would not be much chance for us.
Fortunately David Bell had the original Bill Daniels drawing of Serica's lines and calculations plus a second drawing by a man named Jim Belton of a revised, lighter weight keel. Apparently Jim Belton built a plank on frame version of Serica using the modified keel. However what happened to it is not known.
Using the Jim Belton drawing I have started to make a new keel, laminated from 1 inch thick pine planks. When finally carved to shape, the lower front section will be cut off and used as the pattern for the lead casting, which should weigh in at around 17 kg/38 lb. Serica II should come out as a typical A class model of that era, around 55 inches waterline length, 60 lb in weight and 1570 square inches of sail area.
Here is the start of the laminating process for the keel with some of the pieces clamped up while the glue dries.
The next one shows the roughly carved block after a few nights work with a small plane. The piece of green card at the top is one of the patterns cut to get the profile correctly shaped. No 7 is at the joint between the bottom two pieces of wood. The diagonal line marks boundary between the lead and the timber in the final assembly.
There seems to be some interest in big model yachts at the moment so I thought I would start a new thread to cover the build of our A class hull, Serica II. It has not yet been completed and sailed, but it has connections with some of the most famous names in UK model yachting so I will start with its history. Over the next few months I will add some more photos as the build progresses and hopefully we will have it on the water next year, about 60 years after it was originally designed.
My wife Elizabeth is an enthusiastic restorer of vintage model yachts and sailing vessels. We saw Serica II advertised in the Turning Pole, the journal of the Vintage Model Yacht Group about a year ago. Elizabeth has about 20 models ranging from a 78 inch long 10 rater down to toy Star yachts so an A class would fill the hole in her collection at the large end of the class size range. With the help of the Vintage Model Yacht Group, of which we are both members, and in particular David Bell, we have now managed to trace the history of this particular hull.
Serica was designed in 1956 by Bill Daniels for Norman Hatfield, for the princely sum of 3 guineas. Bill Daniels was one of the most influential figures in British model yachting, being an active designer, builder and competitor from around the start of the twentieth century until his death in 1959. Here is a picture, courtesy of David Bell, showing Serica (registered K750) some time in the 1950's
Serica was build by Arthur Levison, another of the great names in British model yachting, The hull would have been built on the bread and butter principle then carved to shape, inside and out. Arthur Levison built many similar hulls in the 1950's, often modifying and developing designs to improve their performance. One of Arthur's other claims to fame is that he carved the figurehead of the Cutty Sark, now preserved in Greenwich.
Serica was not a success as it is thought that Daniels got his calculations wrong and the keel came out significantly too heavy. Under the A class rating formula this meant that it would not be able to carry the optimum amount of sail area and would be uncompetitive.
Arthur Levison built a second hull to the same or slightly modified design but this was never completed and abandoned in its roughly carved state. The reason for this is not clear but it is alleged that it was for an American customer who never took delivery of it. This hull was given to one of Arthur's neighbours and languished there, untouched, until after his death. His widow advertised the hull for sale and the advert was seen by David Bell, who lived nearby and suspected that this might be an Arthur Levison original.
David bought the hull but decided that there was too much work involved for him to complete the build so he passed it on to John Gale. John was also renowned for the quality of his wooden hull construction and had built many classic racing yachts up until his death in 2015. He completed the bare hull of Serica II, including a modified keel to address the over weight issue of the original design. After his death the hull of Serica II was offered for sale by his daughter, but in the confusion, the keel was separated from the hull and lost. In January of this year Elizabeth and I traveled down to London to collect the bare hull and start to plan its completion, 60 years after the original design was done.
More to follow, probably tomorrow.
Edited By Gareth Jones on 12/12/2016 20:38:05
Edited By Gareth Jones on 12/12/2016 20:43:00
|Thread: 4D Modelshop|
It's the only place I have found to get tee section brass strip in sizes big enough for model yacht shroud plates (6 mm x 6 mm). I found it on the web on Ashley's recommendation, never visited the shop though..
|Thread: Bellissima required ballast|
Serica II is definitely not a modern A class. It's a derivative of a Bill Daniels design from around 1956. We guess it will weigh around 60 lb (27-28 kg) when complete and it's 84 inches long.
One of the reasons it has begun to take priority over my Humber keel Spider J is that if we don't get on with it soon, we will be too old and decrepit to lift it in and out of the water.
Here's a photo as it is now, along with our hearing dog Sally for scale purposes.
I looked through the instructions here **LINK** and could not find any reference to any ballast in the hull so it seems reasonable to assume it is all in the streamlined bulb fitted to the bottom of the keel.
It is not too difficult to make up the shape in two halves using lead flashing, laminated together with epoxy adhesive. At least using this method you can trim the pieces and weigh them as you progress to get the right weight. In the ones my wife has made they have been filled with Isopon and sanded to shape afterwards, but take precautions against getting contaminated with lead dust in the process. There are plans of ballast shapes/profiles available on the web and I think, from the My Hobby Store plans service (or maybe it is the other lot)
I am currently making a pattern for an A class yacht keel weight. We are planning to get that cast professionally. I don't fancy juggling a pan filled with 17 kg of molten lead.
|Thread: A very tired pond yacht|
There are no wires in the seams of the sails, they are just hemmed to stop them fraying, attached to the mast or bowsprit and then tensioned using the lines and bowsies.
Here is a (not very good) picture of a bowsie on one of our yachts. (its a bit small, about 6 mm long and 2 mm wide brass strip with three 1 mm diam holes)
The line is attached to a corner of the sail off to the left hand side. It comes through the left and centre holes in the bowsie then goes of to the right, through an eye fixed to the deck or mast, then back to the third hole in the bowsie. By sliding the bowsie along to the left, the length of cord in the loop is increased and the whole length becomes tighter. The tension in the cord and friction in the bowsie stops it sliding to the right and slackening off. The tighter you pull it, the tighter it grips, within limits.
|Thread: TEV Wahine 1/35 Build|
I am glad to see the build is still progressing, you seem to be making faster progress than I am with Spider J.
I roughed up the back of the styrene sheets with 80 grade abrasive paper and fixed them on with slow setting epoxy (Araldite Precision), all over the surface including any overlaps. They were then taped and/or weighted down overnight while it dried. I did have some problems with voids and bubbles in some areas, particularly where there was a double curvature. The bubbles showed up particularly well when the model was out in the sun just prior to painting. My only option was to cut them out and fill them. In most cases you would not know they were there now and the model will represent a working sloop so a bit of surface imperfection here and there is quite normal.
Keep up the good work, it will be a very impressive model when its finished.
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