|Gareth Jones||19/07/2014 09:29:53|
791 forum posts
This post marks the start of another epic building saga, although hopefully not as long as the Shemarah thread. The building board emerged from the workshop this week to be dusted off and have all the Shemarah frame positions sanded off.
The next project is intended to be a double bill with the same basic hull built twice, consecutively to save time. I plan to finish the first of these as a Humber sloop and my wife Elizabeth is going to do the second one as a Humber keel.
We have been into the Maritime Museum in Hull this week and photographed the drawings of one of the last keels to be built on the Humber, Spider T, which was launched from Warren's shipyard in New Holland in 1926. It was built for Mr. J. J. Tomlinson of Thorne whose nickname was Spider. Because many of the boats had similar names it was common practice to add the owners initial at the end to differentiate, hence Spider T.
Spider T is still sailing the waterways around the Humber, although not as a cargo carrying sloop. There is a link to its website here **LINK** However we are not sure yet whether to build the models as replicas of one of the surviving keels and sloops or just a generic model as they were when they were working vessels.
The body plan lines fit on a single sheet of A4 paper at 1:16 scale. I will print a sheet off, flip the original, print that drawing and then cut both sheets in half. Two halves will then be swapped over and joined so I have one A4 sheet showing the full outline shape of all the forward frames and a second showing all the aft frames. These will then be scanned back into the computer and printed out to give an accurate 1:16 scale set of drawings which can be used as the templates for cutting the frames from 6 mm ply.
The lines of sloops and keels were very similar and largely down to the choice of the owner. Sloops tended to have a longer 'run' which is the aft section that tapers from the rectangular box shape in the middle to the stern. This improved the handling qualities at the expense of some cargo capacity. Spider T has an exceptionally long run hull so should have the best possible sailing qualities. I am not too fussed about its cargo capacity, there should be plenty of space in the hull for all the 'gubbins'
Here a plan and elevation drawing of the hull
For those of you who have trouble understanding drawings here is what the final model should look like. This is the Humber keel Comrade, also still sailing the local waterways.
I have chose 1:16 scale as the biggest practical size for the model, which will be 46 inches long between perpendiculars, i.e. from the rudder hinge point to the prow. It will be about 48 inches high when rigged, but the mast will be able to be lowered as they were on the real ships. Sorry Bob, I am not going to make it 8 feet long.
In addition to having fully working sails and lee boards the models will be motorised, as were most of the sloops and keels from the 1930's onwards. To push forward the frontiers of model boating I plan to try a brushless motor for the first time in a model boat. I do have what may be a suitable motor in a model aircraft in the loft. At some point I will have to get it out and see what size and rating it is.
Thats all for now, hopefully progress will be fairly rapid over the next few months, unless some other interesting project take my fancy, or I get coerced into helping Elizabeth with her current project, the tea clipper Ariel.
Edited By Gareth Jones on 19/07/2014 09:32:40
|Bob Abell||19/07/2014 09:44:35|
8904 forum posts
All the best, Gareth and Elizabeth with your new model making venture
If they are anything like the Shemarah build, they will be lovely!......Despite being on the small size.....lol
Scale ribs we presume?......What choice of timber?........Something exotic like Lime and Pear?
Would be nice to see the models built simultaneously, then we could watch the fireworks at the same time?
Pleased to read that you will be fitting motors....Very sensible
|Tony Hadley||20/07/2014 15:03:24|
897 forum posts
Gareth, I can only endorse Bob's comments about your Shemarah build. It was interesting to see the model built to such a high standard, and the rust detailing at the end added to the model's realism.
Will be following the thread of this new build.
Did Elizabeth finish the tea clipper, Ariel.
|Gareth Jones||20/07/2014 17:35:02|
791 forum posts
Ariel is still work in progress. The radio gear and controls are fitted, the masts have been made, the deck has been planked and all the main deck components such as hatches and the cabin have been fitted. Elizabeth has just fitted the bulwarks but they still need capping rails and some stiffners. There is still a lot of work to do and I do not want to post any photos, as the model will probably be the subject of a Model Boats article some time next year. However it will be on display at Haydock Park next month if you want to have a look at the progress so far.
|Gareth Jones||22/07/2014 09:08:50|
791 forum posts
The frame sections have now been created as described above and here is a photo showing all the rear frames. I print them out on A4 sheets using Canon Easy-Photoprint, using the trimming tool to get them the right size. They only just fit on to the paper so its easy to judge the right level of magnification and get them all the same size, which is 290 mm across the extreme edges at the top.
I have cut the first couple of frames from a spare bit of 6 mm ply, as shown below.
I have made a few basic decisions so far but the design is still evolving. I have done a rough calculation of the weight of the model. A fully loaded keel could typically carry 80-100 tons of cargo and weighed around 30 tons, say a typical weight of 120 tons or 120 x 2240=268800 pounds. Since the model will be 1:16 scale the weight of the model should be 268800 / 16 x 16 x16 = 65 pounds approx. That is about the same as Shemarah so it will need removable ballast to be practical and, like Shemarah will have a built in carrying handle, hence the hole in the frame above.
Most of the remaining frames will be cut from 4 mm ply. However while the outside shape of all the frames is defined, the inside shape has yet to be decided. I plan to use the cargo hatches as access and the hold as working space in the model so there should be plenty of room for the control gear and ballast. However a major decision is should the model have an external removable keel, or can I get away with just ballasting it along the lowest point of the almost flat bottomed hull. It will not carry as much sail as a Thames barge so maybe some advice from one of their experts might help - Kim?
Edited By Gareth Jones on 22/07/2014 09:10:38
|Kimosubby Shipyards||22/07/2014 18:30:39|
563 forum posts
just spotted that question you posed, neatly done, and expert???
You witnessed a thames barge under extreme conditions at Onchan Park, when everyone (me included) expected a full capsize in those 20+knot gusts. You also know that I had let all sails fly and that I had on the small ballast (about 2.5lbs) about 6 - 8 inches below the hull bottom.
She stayed above water, though level with it on her beam ends, and because the lead battery was securely fitted on the keelson, she righted and I was able to sail her back in without any damage nor water ingress. A change of attire was almost needed though and yes, the pictures are on the web via our website.
The Humber keel has, as you say, much less sail, and a much shorter mast, of which there is only one, and only one sail to worry about. It is quite easy to add external ballast should it be needed, and in my opinion and if it were my build I'd have the option for it. BUT saying that, from your calculations above it would seem that you intend to float to near full capacity. Our thames barges are used for "racing" so are empty and sail as "in ballast" so the need for a keel. She'll probably then get away without external ballasting provided you get the mass low in the hull. I expect these Humber keels were as "stiff" in sailing terms as the thames barges, having all the weight low will make her stiff. They certainly operated out to sea so must have been weatherly too.
I'll have my new barge at Haydock, we'll have plenty of time to chew the cud, after all, who wants to come and see us old "Vintage Crew" with sailing stuff all about us?
A point to note as well, and I know you know but its important to get it in discussion, and thats scale and dimensions. A halving of scale for length is x 0.5, where as for area it's x 0.25 and for volume it's x 0.125. That's for each halving, so at 1:16 you have halved 4 times. So the sail area is a lot less, the rudder area severely reduced and the hull volume dramatically lost all in relation to each other. You will most certainly need to extend the rudder to get grip, and although you intend to operate the leeboards, their area will be too small to be effective at the scale, and making them bigger will ruin the actual visual impact. Its another reason we instal a keel - to stop leeway and permit the rudder to give some influence to direction (when as we all know its the sails that steer the boat being set for the required heading, the rudder is used to stop the stern crabbing away or when the engine is on.)
On that point I'll dig up an interesting photo of a barge under full sail and making her course, but the rudder angle is not what you'd expect. Remind me to bring the old barge DVD's too.
There, if you'd a pipe you could now smoke that, see you soon, Kim.
|Amy jane September||25/07/2014 08:18:57|
551 forum posts
Another interesting project, and no doubt will be a joy to follow!
All the best to Elizabeth, and her clipper project too.
|Gareth Jones||28/07/2014 07:57:41|
791 forum posts
Spider J's bricklike shape has begun to emerge from the sheets of 4 mm plywood that arrived last week.
I have done some research into brushless motor options and based on advice on the forum I have ordered a Turnigy 3548/6 as a first guess. This is rated at 790Kv, i.e it will do 790 rpm per volt applied so on 12 volts should do 9480 rpm and be able to deliver around 460 watts. Its 35 mm in diameter and 48 mm long and will allow the propshaft to be mounted low down in the hull of the model.
Based on some photos I have of various keels and sloops it appears that a typical propeller was around 30 inches diameter and had 4 blades. At 1:16 scale that translates into about 45 mm in diameter. The nearest I have in the database of models I have tested is my TID tug which has a 55 mm 4 bladed propeller and a Springer that I have run with a three bladed 40 mm propeller
The TID does 2140 rpm or 52% of the motor free running speed using a Graupner 720 BB torque with an input power of 54 watts.
It also does 3150 rpm or 48% of the motor free running speed using a Graupner 900 BB torque with an input power of 145 watts
The Springer does 3250 rpm or 45% of the motor free running speed using a Graupner 500E with an input power of 31 watts
Hopefully the brushless motor should be able to spin the 45 mm propeller at around 5000-6000 rpm or somwhere in the range of 50-60% of the free running speed. I am expecting that for the majority of the time Spider will be powered by its sails rather than the motor so there is no requirement for long periods at high powers, just the occasional blast to get the model out of trouble. My intention is to temporarily adapt my TID tug as a testbed for the brushless motor. If the results are interesting or helpful I might write them up in an article for the magazine - Turbocharging a TID tug is the provisional title that has come to mind. The information might help illuminate the dark art of matching brushless motors and propellers.
Now its back to the workshop for another session of cutting frames from 4 mm ply. So far I have made 9, only another 27 full width frames to go plus about a dozen canted frames at the extreme front and back ends.
Edited By Gareth Jones on 28/07/2014 07:59:40
|Bob Abell||28/07/2014 08:16:24|
8904 forum posts
9 frames plus 29 frames comes to 36 frames!
Did you not consider carving the hull from a solid block of wood?.....As there ain`t much fresh air left?
36 curved frames would look nice, but 36 bulkheads......Sharp intake of breath!
Looking forward to the build
|Gareth Jones||28/07/2014 08:44:47|
791 forum posts
There's plenty of fresh air in Spider J. The front three frames are full bulkheads, there are two in the middle and about half a dozen at the back end. All the rest are U shaped 4 mm ply. On the real Spider the centre section frames are spaced 20 inches apart which equates to about 32 mm on the model. I will put another photo up tonight when I have cut out a few more.
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