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R25 class Räumboot - building finally

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13 hours ago, robgizlu said:

Thrice Wow

Thanks Rob, I hope the finish is as clean as your builds always are.


Re the depth charge rack, it actually has a subtle difference in that the charge is held in a rocker rather than rolling down a simple slide.  Its an interesting design with added complexity that may have been to prevent accidental loss in bad weather





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Some time and plenty of sawdust later ⏰😷⏰😷 here is the hull about 90% right




As I've said in previous threads, sanding a hull really helps you get inside the head of the designer.  This hull looks simple, but the lines are actually quite complex and subtle.  There is a distinct hollow to the stern where the props are and a pronounced tumblehome.  Forward the lines fill out very quickly and sanding revealed that the frame 3 lines are slightly wrong as a slight hollow appears when looking diagonally from the keel up, more than should be there.  I've amended the drawing to deal with this and will correct the model with filler.


Note those prop shaft tubes are actually inner tubes, The final tube slips over them and will be smoothed in with filler


The knuckle on the bow is really hard to sand properly.  What I have to do is draw the knuckle line on the hull and use filler to perfect that shape, nothing is ever easy.  See the picture below to understand the challenge here.  Note the excellent finish they achieved considering this was wartime, impressive eh?




Anyway, here she is on the building frame




And back in the workshop with the deckhouse in place






Looking at these pictures, the block between frames 4 to 6 looks to be too full at the bilge.  All this can be sorted, just time, sanding and filler.  As always, fingers are the best tool for confirming the shape.  This is the beauty of this method of construction, it allows you to adjust lines before planking, very useful when not working from actual builders drawings.  As the lines I drew came from three drawings, I'm actually quite pleased to get this far without major adjustment


Next stage is to fit the deck so I get the sheer line right, then back to the hull final shaping before planking.  The deck will allow me to get the stern plan curve right before carving the round over stern.  I also need it to get the anchor scallop right 





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More progress on the hull.


The deck was cut out and glued in place after a lot of sanding to make the sheerline look right.  This time I opted not to fit a sheer strake between the frames, probably a bad call, much easier to use that to get the sheer line smooth




Cleaned up with the deckhouse in place




The bow is still lacking definition.  The line of the knuckle is tough to do.


In the end I taped it and filled to the tape to get is roughly right, then I added the base timber for the rubbing strake which sits on the edge of the knuckle.  This gave me a line to sand against, without that I would have been lost


Much filling and sanding later, its getting very close to right.  I've added a coat of sanding sealer to act as a foundation for the planking which I will glue in place wiht cyno.  The surface still has a few minor blemishes, but these are covered up by the planking.  As long as it feels smooth, it will work.  Note the bow blocks were jelutong not balsa, its a harder wood that is easier to get bow curves right




The stern lower hull picture shows the amount of filler needed between the frames.  There is a tendency to hollow between the frames when sanding as the balsa is so soft compared to the ply.  This is tough to avoid, but filler fixes the problem.  The prop shaft tubes have been faired into the hull with more filler




This shot compares the hull to the full size example above, not too bad I think




Lastly, the stern round-over was cut from a block of jelutong and glued in place.  It still needs a little filling to smooth it in place.  It seemed to me easier to round the stern (plan-view) first and the cut a block to match the curve, lots of compound curves going on here





Somewhere in my dim and distant past (~25 years ago) I bought a 1 ft by 2ft plank of 1 inch thick jelutong, I can't remember where.  It is still going strong as I use is sparingly.  Hopefully will see me out, goodness knows what it would cost today.  It is almost as good as boxwood when it comes to sanding or carving, wonderful stuff


The lower hull at the stern is an odd shape, very flat and actually a little hollow.  I'm guessing this was driven by the requirements of installing the Voith Schneider propulsion system which needs a flat bottom section.  Even though this vessel has conventional propellers, the lines were the same and that hollow is necessary to fit the prop size without a clash.


Overall, its nearly ready for planking, probably one more filling round needed as a last tidy up






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7 hours ago, Bertie McBoatface said:

The photos appear so neat and tidy and dust free

You should see the mess I made in the garage :bomb:, it's more or less a toxic area that now cannot be entered without a hazmat suit. 


My workshop is at the top of the house so dust levels are strictly controlled by the need to continue to be allowed live in the house :rofl:





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7 minutes ago, robgizlu said:

And all of a sudden.........Beauty

Cheers Rob , but just give me another day or so and you'll see it planked in cherry wood, now that's beauty, will be a shame to paint it.....





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43 minutes ago, Steve D said:

Cheers Rob , but just give me another day or so and you'll see it planked in cherry wood, now that's beauty, will be a shame to paint it.....






I was thinking that.........

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Starboard side planking complete  :phew: 


Now I admit to being lazy when it comes to planking as this is not going to be seen, it will have fine surface filler and paint applied.  Really I'm only planking the hull because:

  • I enjoy it; 
  • It covers the ply formers which have a nasty habit of showing through no matter how much paint is applied; and
  • No matter how careful the fine surface filling it, the odd horizontal line will still leave a faint shadow and given the actual hulls were fore-and-aft planking (as opposed to diagonal planked), this reflects reality in a soft way

So, back to being lazy.  Each plank should be tapered but life is too short and tapering 0.5 mm strip is simply a nightmare.  So I only tapered filling pieces.  The planking is in 5 mm and 3 mm cherry, the narrow strips used for the bow flare and the round of the bilge, areas where the curvature is high 


Here are the first strips laid in place around the forward rubbing strip




And this shows how I dealt with the expansion needed bilge, see lazy...




Strips are glued using cyno, held in place with masking tape


Gap filled




And done, sanded and a single coat of sanding sealer applied




This will be rubbed down and a second coat applied prior to primer.  The filler is added after the primer as this latter shows where is is needed


Back upright, love the colour of cherry wood




On to side two






and before you all suggest I leave it natural, I'm definitely painting :wink:



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This is a perfect demonstration of the technique that I thought I'd recently invented for my Bellerophon planking. It's so obvious really. The balsa infill makes the planking relatively easy and very very strong. Imagine doing it with just the frames! And yet that's what wooden sail boat modellers are served up in the kits. 


And she looks lovely Steve, as expected. 👍



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Second side and transom completed and one coat of sanding sealer applied




Note the bow has a flat profile, not the usual pointed shape, this is very clear on the photographs




Next, more work on the rubbing strips and side bumpers which are quite complex, looking forward to this bit


I also sent off the artwork for the stern deck checker-plate, more on that when it gets back from etching





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A few different things to report.


Firstly, I added the bumper strip fairings (not sure what else to call them) that (I guess) stop the rubbing strip catching on things (like quay-side rails).  Thhis was done by cutting the rubbing strip back to the planking and inserting a short length of 8 mm maple, I used a simple jig to get them all the same height




Once these were in place, I added the outer strip to the rubbing strip and the outer fairings, overall the rubbing strip sits 1.5 mm out from the planking (that's ~ 3 inch full size) and is "D" shaped.  Then the fairings were sanded to profile




Next the forward upper rubbing strips were added.  These are actually triangular, so I halved some 2mm square line on the diagonal and glued to to some 3 mm x 0.5 mm strip wood that was raised 0.5 mm above the deck.  This picture may help explain my tangled English




Those three short lengths of 0.5 mm thick strip are there to help me align the 3 mm under-strip.  Doing this gave me a land for the forward gunwale which sticks up ~ 4 mm from the deck at the bow and tapers smoothly down to a 1 mm kicker along the timber deck


Here you can see it before sanding to the smooth curve and the triangular shape of the forward rubbing strip (bit out of focus sorry)




The kicker was made out of 1 mm square lime, two high until the start of the metal checker plate rear deck section, 1 high thereafter.


Very careful study of this picture gives a good clue to the deck plating.




As I know how big the galley hatch is, it is possible to work out that the deck plates are 1 m square, laid on top of the timber deck as reinforcing for handling the sweep gear.  The anti-slip surface is a series of half round blisters ((like rivet heads) @ 70 mm centres.  From other photographs, it can be seen that the plates butt against each other on the square (so the joints form a cross).  I've drawn these and sent them to be etched in 0.38 brass, hopefully with me early next week.


The main deck will be planked in 2 mm x 0.5 mm maple strip-wood, but these is no point doing that underneath the brass, so a piece of 0.5 mm ply was cut and glued in place.




There is also a central metal strip running to the engine-room casing, these look to be 700 mm square plates.  The picture I cut out and mounted to the ply is incomplete but fine for this purpose.  You can see one of the access hatches marked out and also the space for the sweep winch.  The galley hatch sits where the gap is before the run to the engine-room casing


Here it is with the paper removed and sanded




You can see the gunwale kicker in this shot and the stern lower side rubbing strip


Lastly, this subtype of R25 class has an open scallop not a hawse hole for the anchor on the port side.  I was nervous of cutting this as a mistake would have ruined a lot of good work.  In the end it cut quite easily with a piercing saw an was sanded to shape.  Then the outer moulding was added and smoothed into the rubbing strip.  That moulding is in beech I think.  The dark areas at the top and bottom of the cut-out are where I've filled cracks with very fine sawdust power and thin cyno, simple and quick filler, I have a stock from emptying the disk sander.  This picture also shows the fo'c'stle gunwale's smooth transition back to the deck kicker.




Close to the end of the hull phase of the build (before painting in primer for final filling and more sanding of course...)


Overall, a good couple of days with no major mistakes.  Looking forward to seeing that rear deck in brass, special :cool:







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A bit of bitty progress.  I'm waiting for the planking for the deck to arrive so I've been fiddling with other stuff.  


First, the anchor scallop needs lining wiht metal, copper in this case.  A little bit of panel beating to get it into shape.  This leaves minor dents but I don't mind that, this part would get dented easily in service (I'll probably fill the worst).. The odd shape leads the anchor chain to the chain stopper.




Next I made the forward roller fairleads, just about the smallest rollers I can actually see to turn


Here are the frames before installing the rollers




and here afterwards (slightly out of focus sorry)




In the background is the breakwater made from brass wiht 0.7 mm brass wire forming th top


Here is is being soldered




And a better shot on the fo'c'stle.  This has flanges to the rear and braces forward, will be added after planking




Then the rear deck checker plate etching arrived :elephant:




The metal deck area has a strip that runs from the galley hatch to the deckhouse which I'd included in the etching but in the end decided that this wouldn't have been anti-slip so I've laid it with smooth brass and etched butt straps 


I also decided that the roll-over would be smooth, here the anti-slip surface would abrade ropes so I finished this in copper as it has double curvature.  Again the odd dent from my untrained hammering adds realism, it would get bashed a lot




I made this in separate sheets, could have been one piece of course but the real boat had sheets and the slight edge impressions look very like the real thing.  This reinforcement was added in the field not the shipyard and bolted in place, it would not have been perfect.  The gap in the middle is for the sweep winch to slot into.  The gap shape forward is for the galley hatch, I'll make up the wooden buck for that next





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14 hours ago, Bertie McBoatface said:

educational as always

Thanks Bertie, my goal with these threads is to explain how I build in wood and metal, hopefully to inspire others back to more traditional materials


14 hours ago, Dmitriy1967 said:

boldly you combine different materials

Cheers Dmitriy, I just use the easiest material I have to hand.  Persuading brass to take the right double curvature is well beyond my expertise, copper is so soft and once heated and quenched it can be made to do almost anything.  I should have said the copper sheet I used for the stern is 0.3 mm or 12 thou in old money* (inches).  The brass etching was 15 thou or 0.4 mm thick, half etched around the bumps.


* To explain that colloquialism, in 1971 the UK went decimal, so changed to 100 new pennies from the pervious 240 pennies to £1.  Hence for years afterwards, people would often talk about prices and then repeat the value "in old money", so 25p or 5 shillings in old money.  That stuck with me and it comes out talking about inches and mm.  Our move to the metric system was set to take place over a number of phases.  The story goes that when the phase came to deal with liquid measures for alcohol, Harrod Wilson (the PM) blocked the move as he didn't want to go down in history and the person who abolished the pint (beer)...  After that, it never got restarted so we are left selling petrol in litres but with cars that measure consumption in miles per gallon :doh:  I love it....





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