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Seamaster Refloat

A Dark Night Fix Up

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Nick Cripps03/10/2020 22:02:24
113 forum posts
65 photos

The Seamaster was designed by Ken Willard and first appeared as a plan in RC Modeler magazine. Ken was a prolific designer with dozens of published plans, many of which are waterplanes, and you’ll find examples of the Seamaster at most waterplane events in the same way as you will see Wot 4s at the flying field. With a thick, parallel chord wing, large tail areas and simple layout, the Seamaster will fly as slowly and gently as any trainer, but wind up the power and increase the control throws, and it will aerobat with the best sports models. Like the Wot 4, the Seamaster has been copied by many and has been produced in a number of forms and sizes: as a kit by Ace R/C, as an ARTF by Thunder Tiger, and in many other versions with various names such as Lochmeister and Neptune (the latter still available from Maxford). Plans can be found on Outerzone or from RCM magazine if you fancy your own model - a Seamaster is the perfect first waterplane.

My own particular version was bought in September 2015 from Lancaster Models & Hobbies on the way back from a Windermere Model Waterplane Flyers meeting at Ullswater. The model was scratchbuilt, and is itself a clone, and came complete with 4 Futaba servos and an old OS40FS for the princely sum of £85. Its first outing was at Billing Lake near Northampton where the LMA/BWA hold their monthly meeting, on a fine, late-Autumn, November day later that year. As the day edged towards a close the wind dropped, giving perfect conditions for such a lightly-loaded and somewhat low-powered flying boat. The photos below were taken that day, the late-afternoon sun perfect to show off the Seamaster.

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Unfortunately, the model met its demise the following year when I spun it into the lake, breaking the fuselage but leaving the wing intact. The Seamaster will tolerate a lot of abuse but too much elevator on a low level, downwind turn was pushing it too far.

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I couldn’t bring myself to scrap the model so it was left in a corner of the garage while I decided what to do with it (even surviving a house move!). Salvation came in the form of MattyB’s suggestion to recycle rather than build a new model (link) and this gave me the impetus I needed to tackle the repair described here.

By the way, there’ll be no Haribo-eating reprobates or French-speaking plastic mannekins helping here, and definitely no rivet counting, so you’ll just have to be satisfied with my inane rambling and crude balsa bashing…

Nick Cripps03/10/2020 22:08:27
113 forum posts
65 photos

My first thought on assessing the damage was that a complete new fuselage and tail unit would be required. However, as I think it was Peter Miller once said, it’s always less work to repair a broken model than to build a new one, I thought I would have a go and see how it went.

The first task was to remove all the Solartex covering from the fuselage so I could clearly see the extent of the damage. The left hand side of the fuselage was broken at the trailing edge bulkhead with the right hand side sheared off at the leading edge. There were also a few broken fuselage fragments (and a few missing!) and the impact with the water had collapsed the base of the motor pod due to the weight of the fuel tank. The wing bolt mounting plate had also loosened and I was concerned that this might be difficult to repair with adequate strength. There was nothing to do but try and piece it all together and see where we get to. I can always revert to plan B and build a new fuselage if all else fails.

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It was clear that the model had originally been built by a very competent modeller, using a good choice of balsa grades in much thinner section than I would have expected for this size of model. For example, the fuselage sides are only 3/32” balsa with the top and bottom of the rear fuselage sheeted in 1/16”. There was evidence of a previous repair to the left hand side and stripping back the covering had also revealed some water damage to the lower rear sheeting which had swelled and buckled in places.

I decided to start with the motor pod where, in addition to the damaged floor, the sides had split away from the motor mount and rear panel. I’ve never been a great fan of cyano for general building work, preferring aliphatic glues, but it was the ideal choice in this case, especially as there was some fuel soakage in places. Apart from one piece missing from the left hand side, the sections were easily coaxed into position and held by hand while medium cyano was wicked into the joins. A triangle of scrap 1/8 “ balsa was used for the missing fragment which was again cyano’d into place and the motor pod was put aside before tackling the next task.

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Next up was the wing bolt plate. It looked like this had also been repaired at some point so I cleaned off some old glue, smothered it in epoxy, clamped it all up and hoped for the best. Luckily it seemed to work ok so I moved on to the challenge of joining the 2 fuselage sections together.

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Trial fitting the 2 fuselage sections showed that a jig would be needed to keep them reasonably well aligned. The spray rails on the bow section ahead of the step were too wide for the jig so it had to be supported by an old battery while the remainder of the fuselage was clamped in the jig. After tacking in some odd fragments, the 2 sections were offered together. Superphatic was wicked into the joints with spots of cyano in strategic places to help hold it all together while it dried overnight.

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Nick Cripps03/10/2020 22:31:50
113 forum posts
65 photos

I was pleasantly surprised this morning to see how successful my attempts had been. It’s not a perfect job by any means but it will look fine at 50ft away on the lake.

The hole in the right hand fuselage side ahead of the step was patched up by splicing in some scrap 3/32 sheet. Some filler was mixed up from balsa dust and aliphatic glue and spread around the major fuselage joins.

To strengthen the motor pod, I mixed up some laminating epoxy and laid some 4oz glass cloth on the inside of the bottom sheet, overlapping the left hand side and rear bulkhead by approximately an inch.

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While this was hardening, I cut away a section of water-damaged sheet from the lower rear underside and replaced it with more scrap 1/16” sheet.

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With most of the structural work now complete I started to think about how to cover the fuselage. I found some matching red Solartex which was the remnants from the Hi-Boy trainer I built some 30 years ago. Unfortunately there isn’t enough for the whole fuselage so I will have to either change the colour scheme to blue Solartex to match the wing trims or use red nylon.

Not sure how well the old Solartex would adhere after 30 years in the loft, I thought a test would be a good idea, alongside seeing how well doped nylon would cover surface imperfections left behind after removing the original covering. I know Derek Hardman worked hard to make sure his products stuck to a model but it does make refurbishment difficult at times!

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At the top left is Solartex ironed onto the ply underside and balsa spray rail (not great adhesion) and on the right is Solartex on fresh balsa (works well). At the bottom is dampened nylon doped onto the ply surface. Tomorrow I’ll check how well each method worked as I tackle the next stage of the repair.

Edited By Nick Cripps on 03/10/2020 22:38:00

Nick Cripps04/10/2020 19:46:41
113 forum posts
65 photos

As predicted yesterday, the Solartex patch on the existing woodwork did not adhere too well but on fresh wood it is fine. The nylon appears to be stuck down well but did "bloom" a bit and looked more pink than red. A further coat of dope should sort that out. Given that there's no more Solartex available, and trying to remove the patches of red adhesive is a lot of work, I think I have no choice but to go with the nylon covering, hoping it will match reasonably well. If not then I'll have to spray it red and then fuelproof.

Still feeling a bit unsure of the overall strength of the repaired fuselage, I decided to put a layer of 1oz glass cloth on each side, overlapping the repaired areas. It doesn't show up too well on the photo but gives you the general idea.

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alex nicol04/10/2020 20:14:25
avatar
419 forum posts
17 photos

Hi Nick,

Watching with interest, keep the pictures coming.

I've bent a couple of models (land based) and ended up with a 3 piece fuselage, snapped at wing le and te. for what it's worth Ive employed very similar repair method, Jig it, cyano everything and then glass over the repair. It's worked well for me.

Good luck with your repair

MattyB04/10/2020 20:51:09
avatar
2418 forum posts
47 photos

Great stuff! Am really glad the DNFU Challenge was the nudge you needed to get this done, I’m sure it will be a great flyer once mended. smile d

McG 696904/10/2020 21:04:05
avatar
3522 forum posts
1338 photos

.. sjeesh... you will have done with your refurb before I even start mine.

Great progress, Nick.

Cheers

Chris

Nick Cripps04/10/2020 21:42:27
113 forum posts
65 photos

Thanks for the comments, guys, really appreciated.

It's good to get some feedback, makes all the effort in taking the photos and doing a write-up worthwhile.

Nick Cripps05/10/2020 21:44:57
113 forum posts
65 photos

The epoxy cured well overnight so this morning I sanded the fuselage all over and brushed on a coat of full strength cellulose dope. Once dry, this was lightly sanded again and a 2nd coat of dope applied.

I then started the covering process with the motor pod and pedestal. The nylon was dampened with a spray mist of water and then thinners was brushed through to adhere the nylon to the doped surface. Looks ok so far, if a bit pink, but it should look better once dry and after a further coat of dope.

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I'd forgotten how powerful the smell of dope was having not used it for a few years now after a steady diet of ARTFs. I can't believe I used to cover combat wings with nylon in my bedroom as a teenager back in the 70s. No wonder my Mum complained about the smell!

Nick Cripps06/10/2020 21:02:41
113 forum posts
65 photos

I realised today that it must be over 40 years since I last covered a model with nylon and the techniques I'm using are from what I can remember from back then. I also realised that I'd missed out an important step in the process so thought it might be useful to describe it here for others not familiar.

First the basic raw materials: cellulose (nitrate) dope and corresponding thinners. The dope tin was from Perkins and was bought when I did some tissue covering some years ago. The same technique can also be used for tissue covering by the way. The thinners was from a local motor factor - you don't need to buy the best quality for this task, the cheapest works fine. You will also need a decent pair of scissors to cut the nylon (I used some decorators scissors) and a cheap brush with either a metal or wooden handle ('cos a plastic one would dissolve!).

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As mentioned yesterday, the 1st step is to brush on a full-strength coat of dope and lightly sand it when dry, followed by a second coat of dope. The nylon is cut to size, dampened with a mist of water from an aerosol bottle such as used for perfumes, etc., and laid onto the doped surface.

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Decant some thinners into a clean jam jar and then flood the nylon with thinners, smoothing it down, brushing it out to the edges and carefully removing any wrinkles...

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... which then gives this once the edges are trimmed to suit.

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The step I forgot yesterday, but remembered in time today, was to run another brushload of dope onto the overlapping area so that the next piece can be covered in the same way by just brushing thinners through as before, resulting in this:

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Nick Cripps06/10/2020 21:16:20
113 forum posts
65 photos

Next up was the side pieces and, wanting to cut the nylon closer to the final shape, and also to minimise wastage, I used a dressmaking technique I'd seen my Mum use years ago. I made up a template from newspaper and pinned it to 2 layers of nylon before cutting round it to produce 2 identical sides.

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After doping the overlapping edges again, the 2 sides were doped into position as before.

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I finished off today by adding the top covering to the nose section and left it all to dry out overnight. Tomorrow's job will be to cover both sides of the fin and the top fuselage deck at the rear.

One slight frustration has been how the nylon has frayed when rolling it around the edges. You can usually get away with it when using tissue, as long as you are careful not to tear it, but nylon seems to be a bit more of a problem. I'm not aiming for a concours finish on this model so I'll just live with it.

Nick Cripps07/10/2020 21:19:11
113 forum posts
65 photos

I suddenly realised last night, while working away on the Seamaster, singing along to the music from my favourite playlist, just how much I was enjoying myself. I've always considered myself an aeromodeller, rather than just a model flyer, as I started out building control-line models from kits and plans as a teenager. While in the last few years I have mostly been putting together ARTF models instead of building from scratch, I've always wanted to get back to the traditional skills. This repair has reminded how much fun it can be using the old techniques and has given me the appetite to do more.

Talking of traditional skills, the next stage this morning was to trim back the covering along the edge of the top deck. Digging down to the bottom of my toolbox, I unearthed a hard-backed razor blade which is ideal for this job.

Helen Mirren looks inscrutable under that mask but I'm sure she's impressed really smiley.

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The fin was covered both sides and then the final piece of covering was doped in place on the rear deck.

I then made up a 50/50 dope/thinners mix to seal the covering in place. The blushing (from trapped moisture) you can just make out on the fuselage side was also present on the bottom of the hull but has now disappeared with the 1st finishing coat of 50/50 dope. I'll go over the rest of the model during the next couple of days with 2 or 3 coats of dope as required to give a good surface.

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I found that the rudder had warped a bit and was showing signs of water damage so that was cut away and a new rudder prepared. I'm adding 1/32" ply doublers each side to support not just the control horn but also a water rudder (hence the oversize doublers). This will be free to pivot down below the actual rudder with the aid of a light wire spring but will also allow it to hinge up out of the way if it hits an obstruction. More on that another day...

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Nick Cripps08/10/2020 19:35:31
113 forum posts
65 photos

Not some much time to spend on the Seamaster today but some progress was made.

A cope of thinned dope was applied to the rest of the fuselage which has all but cleared up the blushing present in some places, as you can see from the partially-doped front section below, and the wider picture below that. I think it will need at least one, maybe two, more coats before it's ready for fuelproofing.

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The dope also stiffens up the whiskers of thread that have come from trimming the edges and these can be simply removed by a quick wipe over of fresh sandpaper.

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Next was some further work on the new rudder. The ply doublers were glued either side of the rudder and left to dry overnight so they were ready for their initial coats of dope before covering.

I was also able to spend a bit of time working on the parts for the water rudder. In the photo below are a piece of thin piano wire wound into a couple of coils for the return spring, the rudder itself and the 2 bolts; one for the pivot and the other to retain the end of the spring and act as a limit stop.

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Doctor Chinnery08/10/2020 20:18:37
131 forum posts

Nick - just a suggestion from the dim and distant past ( the early 70s ) - when my young ( then ! ) Wife saw me struggling to cut the blue and maroon nylon to shape to cover my Impala -- she gently moved me aside and marked the nylon with her thin triangle of dress-makers marker ( dunno the proper name but it's a sort of waxy chalk ) - now the cunning bit: Di cut the nylon with Pinking Shears*, the fabric doesn't try to slide away from you as you cut, and the edges won't unravel when handled, doped etc. unless seriously provoked. So so easy, when you have the right tool for the job. Most definitely a Lightbulb Moment.

* Look it up.

Nick Cripps08/10/2020 22:08:06
113 forum posts
65 photos

Thanks, Doc, always best to use the right tool for any job.

I'm aware of pinking shears - my Mum always used them when cutting out material for dressmaking and they are always used for covering material on full-size aircraft - I just don't have any.

I'll pick up a pair next time I'm in Hobbycraft, I think.

Nick Cripps09/10/2020 21:27:53
113 forum posts
65 photos

No photos today, just a quick update on progress.

With 2 coats of dope on the fuselage, I lightly flatted back the surface with fine wet & dry paper and applied a 3rd coat. There was still some evidence of blushing once that had dried so a 4th coat was brushed on. Hopefully that will be enough and I can set the fuselage to one side for a few days to let all the solvents gas off.

The next job was to cover the rudder. This went much better as I had learnt a few lessons from the earlier covering efforts which helped me avoid getting any frayed edges; the odd strand being quickly removed with the wet & dry paper once the dope had dried.

Tomorrow, I'll look at what needs to be done to get the engine and radio back into the model.

Nick Cripps10/10/2020 21:21:55
113 forum posts
65 photos

The original engine was a rather asthmatic OS40FS, pre-Surpass version. It was barely adequate but it was fun to fly the model "on the wing" rather than haul it round the sky, however, I think a bit more oomph would be beneficial. Fortunately, I picked up an OS48 Surpass at a swap meet last year which has the same crankcase width and therefore fits the existing engine mount. As usual with 4-strokes, the carb position is somewhat problematical and the '48, with a longer inlet tract, moves the carb further down the crankcase to a position where it is close to one of the mounting bolts. There's just enough space if I pull the engine forward on its mounting bolts so I hope the carb doesn't rub against the bolt.

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As you can see, the throttle servo has been installed but I've not yet made up the new linkage to the throttle arm - always a pain to get a good mechanical arrangement, I find.

I've also installed the rudder and elevator servos on the existing bearers and put in a 1/16" ply plate to carry the rx battery. I will probably install the receiver itself in the rearmost bay, under the wing bolt plate, suitably waterproofed, which I will show later when I get to that stage.

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dave windymiller11/10/2020 22:14:33
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160 forum posts
163 photos

Looking good Nick!

Is that the one i had a go on several years back?

Last time i used nylon was for a warlord combat wing in the late 70s. Handy as you have a ready made bag with the bits already in when it gets stuffed into the deck.

It looks like rip stop nylon your using? never thought of that being used for a covering.

That long abandoned kids kite that hanging up in the garage is now being seen in a different light!!

Cheers

Dave windy miller

Nick Cripps11/10/2020 22:28:45
113 forum posts
65 photos

Thanks, Dave.

Good to see you and the guys at the field today.

MattyB12/10/2020 11:28:02
avatar
2418 forum posts
47 photos

Excellent stuff, it's looking very neat and tidy. Looks like it will be cutting a new wake very soon indeed!

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