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Spider J

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Gareth Jones04/08/2014 08:51:47
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791 forum posts
1067 photos

Progress has been quite rapid on Spider J over the last week. I began to cut out and shape the canted frames which form the shape of the bow section.

spider 8.jpg

Initially these were just tacked in position with superglue. The edge which meets the first frame was angled on a disc sander and supported with a short piece of square section timber to hold it in place while the glue set. When all the sections had been added I checked that the edges all lined up on the profile where the skin will be attached.

spider 9.jpg

Superglue was then run down all the edges to finally glue the canted frames on to the main front frame.

Next it was into mass production of the 4 mm thick frames that make up most of the hull. These have come out muct more accurately and consistently than the ones on Shemarah. The reasons for the improvement are partly down to the production of the templates on computer prints, rather than tracing them off the plan by hand. I also now have the disc sander so it is much easier and quicker to trim the edges of the frames accurately and squarely rather than by hand sanding with a block and abrasive paper.

spider 10.jpg

I have also made a couple of changes to the way the frames are attached to the battens that fix them to the building board. On Shemarah I screwed the frames to the battens and then screwed the battens to the board. There were two problems with this. One was that when I came to screw the battens down on the MDF building board it tends to lift the MDF and the batten does not sit square and flat on the board. Hence it was necessary to remove the screws and effectively countersink the screw hole in the board, all time consuming and not helpful to getting the batten and frame in the right place. The second problem was that when it came to removing the battens from the frames, after the completed hull was taken off the board, it was really difficult to get to the screw heads because the frames were so close together. They are even closer on Spider J so an alternative method has been used.

spider 11.jpg

Firstly the frames have been stapled to the battens using 8 mm staples, good enough to hold them together during the build but easy to prise apart afterwards. Secondly the battens have been pinned to the board using panel pins, again good enough to locate the battens on the board but much quicker to fit and easier to get the frames accurately lined up on the building board. Hence progress has been very quick and, as I write I just have three more frames to cut out and attach. However these will need some adjustment as the plans show Spider T before she was fitted with a motor and propeller so there is some reprofiling required just forward of the propeller.

The brushless motor, speed controller, propshaft and propeller have all arrived so this week I am going to concentrate on testing the instalklation of the motor and proposed propeller in my TID tug before finally deciding on the installation in Spider J.

Next weekend we are off to South Ferriby on the other side of the Humber from where we live. The Humber Keel and Sloop Preservation Society are holding an open day to celebrate the centenary of Amy Howsons original launch back in 1914. She is one of the preserved sloops and there will be a gathering of keels and sloops in Ferriby sluice so there should be some good opportunities to get some usefull photographs and Spider J might also go along for a day out.

Gareth

Kimosubby Shipyards06/08/2014 15:53:57
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563 forum posts
272 photos

Hi Gareth,

you've lots more frames than I used for the Lady Daphne. Here's a quick view from all angles, you'll note in the "fish eye view" that I had already cut the slot for the keel and positioned the keel box too (profile image). And, for barge construction we find it easier to frame upright, as they would have been built, secure the frames with "runners" and remove from the building board before any planking.

No motor in her, and if there ever would be, it would be positioned on the stern quarter, port side of the stern post.

She'll be good and strong.

Kim

tbladydaph_ (014).jpg

Frames viewed from above

tbladydaph_ (015).jpg

Frames in profile

tbladydaph_ (018).jpg

Fish eye view.

Gareth Jones07/08/2014 08:32:22
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791 forum posts
1067 photos

Hi Kim,

You could be right about the number of frames. Every time I go into the workshop I see the structure of Spider J sitting on the workbench in front of me. The artist in me thinks it's a thing of perfect symmetry and beauty, it could be the skeleton of a whale sitting there. The engineer in me thinks it has twice as many frames as required and I should take half of them out.

spider 12.jpg

spider 13.jpg

After some thought last night, I have just about decided to remove 11 alternate frames from 12 to 32 in the centre section of the hull. They would not be totally wasted as they could be recycled into the frames for a Humber keel as the next potential project.

I am still considering making provision for a keel slot like you have in your Thames barge Kim. What's the purpose of the bigger square section at the front of the slot - is it part of the keel or the location of the mast?

Today its back to motor testing, it should be exciting, has anyone ever seen a Springer tug with a 425 watt motor?

Gareth

Bob Abell07/08/2014 08:53:55
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8921 forum posts
2810 photos

Hello Gareth

Don't be hasty!

The multitude of formers,makes your model look special and true scale and commands respect!

With less formers, your model will recede back into the nondescrpt modelling gloom?

Food for thought for the discerning modeller!,

Just my personal opinion

Bob

Dave Milbourn07/08/2014 10:20:04
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4011 forum posts
282 photos

Today its back to motor testing, it should be exciting, has anyone ever seen a Springer tug with a 425 watt motor?

>1/2BHP?? Open the taps and you'll not see it for long, Gareth. They are noted for going bow-down when power is applied!

Ref Spider J frames, I can see where the engineer in you is coming from but now you've plotted, cut and fitted them why take them out again? For once I agree with Bobbable.

Dave M

Kimosubby Shipyards07/08/2014 15:11:19
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563 forum posts
272 photos

Gareth,

now they're in leave 'em be! The configuration looks like an old cast iron radiator from my school days.

The square hole in front of the keel box is a mast box IF the mast penetrated the deck, but on a barge the mast steps in a tabernacle on top of the deck and can then be lowered by swivelling about the lower mast bolt. I've used a keel box from a yacht set-up because I had one.

I find creating the slot before planking enables the builder to get it supported and sealed whilst it can be seen and readily accessed.

I tried a 700 in a springer with a 7.2 pack, as DM says, she just went nose under, so I came back to the 545 on the same pack and decreased the throttle range to 80%. She's still speedy, but does not bury the head so much, and I've fitted wash boards across the bow too. Our Jason tried a 700 with an 11.2 Li-Po totally wasted and awash..........

Kim

Gareth Jones07/08/2014 20:50:10
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791 forum posts
1067 photos

It looks like the popular vote is to leave all the frames in so that's what I will do.

Motor testing went very well. I plan to write a short article for the magazine, Paul Freshney permitting, so I won't include all the details here. However in summary, the chosen motor was not up to driving a 55 mm diameter 4 bladed prop in my TID tug. The motor reached its 40 amp limit well before full throttle.

However it was very well matched to the 45 mm prop chosen for Spider J. At full throttle it pulled just over 25 amps, around 290 watts and generated around 3200 grms of static thrust. If you wonder what how fast a Springer goes with that much power the video below should whet your appetite.

 

Edited By Gareth Jones on 07/08/2014 20:51:09

Edited By Gareth Jones on 07/08/2014 20:59:49

Gareth Jones07/08/2014 20:58:39
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791 forum posts
1067 photos

Now that I have satisfied myself the video is working I should add the Springer was ballasted to be a bit tail heavy on the off chance that it decided to nose dive and do a submarine impression, Elizabeth was driving, and I took the video.

The motor installation in Spider J has been trialled in advance of the testing and looks pretty good.

spider 14.jpg

spider 15.jpg

spider 16.jpg

The next step is to reprofile the last few frames so that the planking will meet the skeg ahead of the propeller. The frame shapes used in the build were drawn before Spider T was fitted with a motor, i.e. when it was just a sail powered sloop.

Gareth

Bob Abell08/08/2014 13:05:24
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8921 forum posts
2810 photos

Hello there Gareth

Looking at your Brushless motor set up......Something is telling me that the flexible coupling is not right for this application?

Haven`t got a good reason, but a solid coupling may be better?

Bob

Gareth Jones08/08/2014 15:48:28
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791 forum posts
1067 photos

Hi Bob,

I dont know of any reason why the flexible coupling is not right for the application. The installation is identical to all my other models with the prop shaft as straight and true with the axis of the motor as I can achieve. At the moment the propshaft sleeve is a loose fit at frame 6, where it exits the cargo bay and in the skeg at the aft end. When I finally come to glue the shaft in, after all the frames are fixed in place, I will line up the motor shaft and prop shaft with a rigid coupling. The flexible coupling allows for any small discrepancies and also acts as a weak link in the power train if anything jams at high speed.

I don't think a brushless motor is any different from a brushed unit and should not be fitted with a flexible coupling. During the tests on the motor in my TID tug, the peak input power to the motor was 425 watts and allowing for the motor efficiency, I guess the coupling in the picture was transmitting close to 1/2HP to the propeller at the time.

You will need to come up with a good reason for me to leave the flexible coupling out.

Gareth

Edited By Gareth Jones on 08/08/2014 15:49:23

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