Topic: Severn Class in the Workshop - a 1/72nd Lifeboat build and R/C conversion (Read 30893 times)

Canterbury Coxswain · « **on:** January 03, 2016, 12:38:58 pm »

Never thought I would be doing this! I blame Craig [Craggles] and Ned [Netleyned] - the former for showing the start of his Speedline 1/12th Severn build and the latter for his pick-up on my comment on Craig's thread.
So, here we go. Like a lot of folk reading this my workshop is full of lifeboat 'projects' - at 1/12th scale an Arun, Trent, Solent, Mersey, Atlantic '21; at 1/10th scale an Atlantic '75; at 1/16th scale the FCB2 [EffSeaBeeToo] Shannon Prototype; at 1/32nd scale an Impact [RNLI] Severn conversion; at 1/72nd scale the aforementioned Severn and a German DGzRS 46m 'Hermann Marwede'. The Arun was my first, not finished, but on the go for some 15 years! I hope this will make some folk feel better for having read this - print it off and show 'the other half' that there is someone worse than you!
To the nub of the matter. I bought this kit some years ago, wanted to convert it to radio control, started it, put it down when a 'hic-cup' occurred. Painted the hull when I wanted 'an in build' display on my Lifeboat Enthusiasts' Society [LBES] stand at a Show, and then recently - having already bought the shafts and propellers from PropShop - decided to get on with my twin shaft conversion, as there were a number of single shaft 'Deans' versions appearing. I wanted something that could be put on the 'calm' water of a pool at an indoors Show like Brighton Model World [February
I hope this will encourage a few to have a go for themselves. It is small, just about viable, can be made in a very limited space and does not require a workshop [only to store all the other lifeboat projects] and is relatively inexpensive. I will try a few 'posts' over the next few days to start to catch up the build.

Canterbury Coxswain · « **Reply #1 on:** January 03, 2016, 12:44:08 pm »

Sorry Reader,
Meant to say in the opening narrative above - Brighton Model World [February 19th - 21st 2016] and the 'Warwick' International MB Show. I got distracted by comments from the kitchen regarding Sunday lunch!
Kim

jarvo · « **Reply #2 on:** January 03, 2016, 02:40:13 pm »

HI Kim

Will be watching this closely, i have 2 of the ready to run models, tank stear type that i am going to covert to "proper control" will be interesting how you do the conversion, good luck

Regards

Mark

Netleyned · « **Reply #3 on:** January 03, 2016, 02:58:37 pm »

Just had a look at the one I have, kindly donated by
a member on here.
I was waiting for the upgrade version of the drive
from Dean's that seems to have disappeared.
Twin screw would be heaps better.
I have the hull together with no holes yet
so ready to look and learn.
Congrats on 'Full' status and thanks for the beer

Ned

Canterbury Coxswain · « **Reply #4 on:** January 03, 2016, 03:05:18 pm »

In case you decide to build one of these I'll go back one step to the hull build - it needs to be done carefully and utilising the deck as a dry fit 'in-fill', this keeps all in shape while it dries and leaves no problems later on.
Also to be borne in mind are the size and therefore the 'all up weight' to keep it on the actual boats waterline. The model is just under nine and a half inches long [OAL] or 238mm and has a width of three and one eighth inches or 79mm. The length on the waterline is eight and a half inches long. The weight to bring it to the waterline, once the shafts and their outer casings were fitted, plus the propellers, 'A' frames, rudders and their shafts were in place was 42 grams. This is at the point where I have constructed the wheelhouse in such a way [not as per the plans] that it can be taken on and off as a whole, easily, and that will allow the removal of the interior - as should it be required this is another saving of 12 grams! As I am writing this now some time after this part of the build the electric speed controller [ESC], forward only, has arrived from Hobby King in Hong Kong. The internal controls and electrics come out as:

3.7 volt single cell LiPo battery - 14 grams
ESC - 3 grams
Receiver [Rx] - 4 grams
motors x2 [with gear boxes 3 grams] - 6 grams
shaft couplings - 2 grams
servo for rudders - 9 grams

All of this equals 38 grams, leaving some 4 grams for the extra plastic parts of the kit, paint [do not forget this as the weight is considerable on this tight tolerance build] and the wiring. So I might need that interior detail section out when on the water. I'll take a photo of these items later today or tomorrow and post, obviously some of the wiring and plugs will be reduced or taken off once the set-up has had a 'dry run' off the boat. This will save some valuable weight as it is included in the figures above.
The photo of the deck area will show how I have assembled and then cut out the wheelhouse floor to leave an up stand [which will need to be raised a little at the bow end to repel water from the forward deck area] and adding the back wall of the wheelhouse as an integral part that can be lifted off - not as per the plans. Trust this all makes sense, so far.

Canterbury Coxswain · « **Reply #5 on:** January 03, 2016, 11:54:51 pm »

The shaft outer tubes supplied by PropShop I reduced by 20mm, having cut through and gently tapped from the inside the end bearing, then I faced off the cut end on the lathe and re-inserted the bearing. Later, when all fitted in place I also took about 15mm off the shafts too. I drilled one hole through the hull from the outside, starting small and then progressing up through the sizes to 3.5mm, then finished off with a round file to get the elliptical shape to allow the tube to sit low in the aperture. Once I was satisfied I did the same with the other side and then made a couple of spacers for bth ends of the shafts with a 25mm separation. Normally I would make discs to replace the propellers on the outside part of the shafts with a 3mm x 2 [allowance for clearance over the 12mm diameter] - here I used Blutac and to position them before 'spot welding' with Superglue [CNA] and then boxing on the inside and using 24 hour Araldite resin glue. All seemed to go OK. When hardened, removed the spacers and fitted the shaft and propellers. Satisfaction so far. Next session the 'A' frames.

jarvo · « **Reply #6 on:** January 04, 2016, 12:46:25 am »

Great work, like the tube supports in the last picture

craggle · « **Reply #7 on:** January 04, 2016, 08:43:31 am »

Looking great Kim

I knew I should have bought one of these while I had the chance for inspiration on my 1:12th version. Just had a look for one and they seem hard to find again?

Be good to see the progress so keep up with the updates.

Craig.

Canterbury Coxswain · « **Reply #8 on:** January 04, 2016, 05:55:43 pm »

Thanks Craig - glad to see you have actually tracked one down and purchased it, as you say it will acquaint you with the boat a little.
On with the 'A' frame build next. I started by using a little bit of etched brass 'sprue' from my Speedline Trent parts, so it is a little oversized, but I was happy with that. I then soldered the required size tube inside the bend and then 'chain drilled' the slots, having broken off the already assembled plastic ones. Then I pushed these through the slots, bent them over [not very pretty at that stage!], before boxing them on the inside of the hull and then filling with 24 hour Araldite resin glue. During this process the paintwork has got scratched, but it has to all be rubbed back before completing the hull paintwork. For those wondering, I use the Halford's spray paint for this, being the Ford Balliol Blue - the nearest match to the actual BS numbered RNLI paint. When fitted and hardened off I then fitted the shafts back and with a small amount of reaming on one side they both spin freely, however, I have noticed one shaft is now about 1/32nd of an inch out of line! Next I'll concentrate on the rudder build / conversion and their shafts.

Canterbury Coxswain · « **Reply #9 on:** January 05, 2016, 12:57:50 am »

It was at this point I decided to plug the two rudder shaft holes with Blutac, and with the shafts and propellers in place, weight the model to the water line, including the wheelhouse and interior - job done - now to take off the wheelhouse and weigh the extra weights [three 3.7 volt LiPo batteries], inside a large amount of water!!

Silly boy to use batteries as weights - let that be a learning curve for others, but no damage appeared to have been done when they were very quickly dried off and allowed to dry 'naturally'. I was fortunate, if you have not used this type of batteries before it is well worth looking up the safety side of things and the method to use [sand and salted water] should a mishap occur. The ingress was through the underside of the bow thruster tube on the hull's bow. You can see I dammed one side with a small 'V' of styrene card and then infilled with Araldite resin glue - when dry a second test in the ubiquitous washing up bowl and all was well.

On with the rudders. I had decided to use the original kit ones and modify slightly in both the thickness and length [an extra 2mm], but so they still 'look' in scale. To this end I utilised 1mm [.95mm] stainless rod [from PropShop], styrene card and a dentists' drill I acquired cheekily some 53 years ago from my dentist Alan Vogt in Trinity Road at Wandsworth Common! I was a young lad heading for the teenage years making Airfix kits [as you can see, still am!] and Stanley gave me a handful, which I still have and use - if only he could know! I bent the shaft to a right angle, drilled out a 'cavity' [excuse the pun] to accept this shaft, glued it with Araldite, then covered with that side with a template of styrene card to the new depth, adding a small piece on the original side. This was then all shaped and polished with those nail file emery boards [from Boots the Chemist] that go down to the 12,000 grade level and ladies use to polish their nails - superb. Then the outer rudder tubes were added when cut to length, inserted and glued in place, using a small length of styrene tube on each to re-inforce. Then, later adding a small rectangle of 1mm carbon fibre sheet profiled and fixed to the stern / transom hull to prevent flex when the servo is connected. Next will be the deck support plates, as I mean to be able to screw the deck into place on the hull.

derekwarner · « **Reply #10 on:** January 05, 2016, 01:35:24 am »

Well done CC....those rectangular and square encasements for epoxy grouting the prop shaft casings & A frames are simply good design & workmanship

...if they do it in real vessel applications, there is no reason why we should not follow the same path .......

Yes, that displacement check & estimation or calculation's are also good practise

.....Derek

boat captain · « **Reply #11 on:** January 05, 2016, 09:16:21 am »

I have one on its way £15.00 plus £4.00 postage Antics website also found some for £60.00 a bit overpriced!

Joe☺☺☺

craggle · « **Reply #12 on:** January 05, 2016, 09:47:29 am »

That's a good price too.

I found mine on a website from a company called Kingkit who deals in previously owned and end of line model kits. I have used them before and always been impressed with what I have received but as it is a pre-owned kit there is a chance it is an older release but he does guarantee they are complete and un-started unless otherwise stated. He has 10 more in stock if anyone else is interested.

Paid £18.50 for it, will let you know what it looks like when it arrives.

Will make a useful reference I think for my bigger, 1:12th scale kit.

Craig.

timbo · « **Reply #13 on:** January 05, 2016, 03:21:08 pm »

Got one ma self fro Antics

had the same idea Craig! I am going to use it as an aid to my 1/16 build that I have on the bench.
Tim

Canterbury Coxswain · « **Reply #14 on:** January 05, 2016, 04:14:57 pm »

There's certainly a 'rush' on the Airfix 1/72nd Severn kit now - should push the prices up! I wonder what the economy would look like if you took out all the model kit world production, purchases and postage costs?
I said I would take a shot of the internal electrics bought so far. As also said, some of the plugs will be taken off and items 'hard wired', also the lengths of cables reduced to what is required. I am having second thoughts on the 'forward only' ESC, so have ordered two units from a Chinese gentleman in this country that have reverse also, but a 'with brake' mini-switch too. A little more weight, but worth the try - I'll only be using one, much as I would love to have one on each motor!! Talking of which, when the battery is connected to the little geared motor unit [and it's on full speed] I have tried to stop it turning with my fingers and gave up with the heat and pain caused! Seemed quite powerful, I think they are used for mini quad-copters. Regarding the servo and weight, I am also thinking of milling out some of the blue plastic case if required - but not my first choice.
Off to Canterbury Choral Society rehearsal in a short while [Haydn's Nelson Mass and Vivaldi's [popular] Gloria - RV 589] for a Concert in a few weeks time in the Cathedral, so I'll try and post the deck support panels installation when I get back later.

Allnightin · « **Reply #15 on:** January 05, 2016, 04:38:08 pm »

It will be interesting to see how performance of a more scale like two prop version compares with the simplified single shaft one that Dean's Marine did with their forwards only Mini RC set a while back

https://www.youtube.com/watch?v=MIfbJcBrs4Y

Canterbury Coxswain · « **Reply #16 on:** January 05, 2016, 05:26:53 pm »

Thanks for this video clip 'ANI' - it was a reminder that the HiAb could overbalance the model to the starboard side, so when putting the electrics in, a slight compensation for that ought to help with the final outcome. Ron's also went very well and a comparison, although not what I intended, will be interesting to see. I just wanted something that could go on a couple of indoor small pools at Shows and on another small 'project' I have whirling around in my head - like we do! I also wanted it to look scale-like when off the water and on the stand's display area. Interesting, it handled better than I could have imagined, so might be able to venture further afield, but, I must 'walk' with it [get it on the water to the right level] before I can 'run' with it [send it out into the deep at those type of speeds!]. Kim.

Big Ada · « **Reply #17 on:** January 06, 2016, 04:40:17 pm »

I am on Board Kim, don't let me get wet!

Len.

craggle · « **Reply #18 on:** January 07, 2016, 01:18:49 pm »

Well, My Airfix Severn has arrived today, very pleased with it.

It is, how shall we say, small though.......

I was expecting it to be a bit smaller than my 1:12th version bit it's tiddly! I can see now that radio controlling it isn't as straight forward as I first thought so carry on with your build Kim and I'll copy once you have worked out all the bugs.

Craig.

Netleyned · « **Reply #19 on:** January 07, 2016, 01:49:09 pm »

Kim,
Can you give us a link to the esc supplier?
I think I have located the motor/gearbox at Hobbyking.
It gives the weight as 1.9g so I assume its the right one.
40000 rpm seems a bit high?

Ned

timbo · « **Reply #20 on:** January 07, 2016, 05:27:44 pm »

Mine came today to

Your right Craig its certainly going to be fun trying to rc it.

Tim

Big Ada · « **Reply #21 on:** January 07, 2016, 06:07:03 pm »

Kim brought along his build so far, to our Club Meeting last night. Yipes it is small!!, time to get your eyes tested and an upgrade to specs. After my 19ft build this looks so tiny and he talks in Grammes and even peeling labels off to reduce weight.

Len.
Scale Secretary, Model Boat Association Dover, Kent UK.

craggle · « **Reply #22 on:** January 07, 2016, 08:27:40 pm »

Just in case anyone is looking at this and thinking "seems a lot of effort" I noticed today that the ready to run Severn is in the sale items on the RNLI web shop for only £40. I was tempted but think three Severn's in the house may be a bit over the top.

It claims to be 1:20 scale as well but it's not. The drawings I have are 1:20 and it's a decent size but looking at the dimensions on the RNLI shop page I reckon their model is closer to 1:35 scale.

Craig.

17-09 · « **Reply #23 on:** January 07, 2016, 09:06:55 pm »

Your correct Craggle, this mistake was pointed out to the RNLI back in 2007 when the model was first produced, they failed to correct it in their brochure then and it is still being advertised as 1/20th scale 9 years later!
The boat is basically accurate however and runs very well when converted to full R/C.
17-09

jarvo · « **Reply #24 on:** January 07, 2016, 09:35:13 pm »

Hi Ned

Can you give the Hobbyking code number for the motor/gearbox you found please

Mark

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Author Topic: Severn Class in the Workshop - a 1/72nd Lifeboat build and R/C conversion (Read 30893 times)