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A U-Boat In Ireland

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  • Not got that leveller, but the only time I've witnessed servo tremor with a pitch controller was on a unit that had insufficient damping on the output, and I found a digital servo tends to exaggerate that, as they have less deadband than many analogue models.
    DIVE IN! Go on, go on, go on, go on, GO ON!


    • Noted buddy, keep you posted when the servo upgrade arrives.

      I'm having a problem sourcing the material that Bob calls 'closed-cell construction foam' for submerged trimming.

      Does it have another name her in Europe/UK/ireland? Is there an alternative?

      ''We're after men, and I wish to God I was with them........!''


      • Blue foam board from the DIY store. Thatís what heís referring to. You donít want regular styrofoam because it absorbs water.


        • Google blue styrofoam. Unlikely to find it in a DIY store, as it doesnít get used for insulation like in the US. We tend to use the yellow polyurethane foam, which doesnít work as well for buoyancy.
          DIVE IN! Go on, go on, go on, go on, GO ON!


          • Thanks, have ordered some Blue Foam.

            Here is the budget and list of all suplliers that I used.

            U-boat Project Details
            Item Maker Cost
            U 47 Kit Robbe (Ebay) 380
            Piston Tank 900ml (Custom size) Engel 245
            Upgrade Kit (Deck, Conning Tower, Vents) Wikinger 169
            Bayonet Lock Norbert Bruggen 100
            Miscellaneous styrene, brass and steel strip/rod, glues, sandpapers, cable/wire, small switches etc. Various 100
            Pitch Controller Engel 70
            Piston Tank Controller Engel 60
            Sound module and Speaker Mtroniks 60
            Paint (5 spray cans, small tins of enamel) Halfords/Humbrol 60
            Couplings X 4 Cap Maquettes 50
            Servos (2 XStandard and 1 X Digital) Futaba (Ebay) 50
            Upgrade Kit (Flood holes lower hull) Wikinger 49
            Brass Vents (Lower Hull) SRS (B Nakropin) 45
            Batteries (2 X Zippymax 11.1v 3S) Hobbyking 40
            ESC (40 Amp- Lipo Safe) Mtroniks 40
            Props X 2 (Brass WW2 Pattern) 40
            Upgrade Kit (Deck thread patterns) Unkown (Ebay) 30
            Upgrade Kit (Wintergarden in Brass) Wikinger 29
            Periscopes Wikinger 29
            Waterproof Connectors X 3 12V Planet 15
            Prop Shafts Model Bits Uk 15
            Receiver Futaba (Ebay) 12
            Bluefoam (Ballasting) 10
            TOTAL 1698

            Interesting in that it ties in very much with Bob's estimates on his introductory page about the cost of building a sub.

            At around 250 hours construction time, this equates to 6.80 euros per hour, not even factoring in that once finished and used, that figure will be even less.

            Not as expensive as other hobbies I've had.

            The Boattrainman
            Last edited by The Boattrainman; 12-11-2018, 09:21 AM.
            ''We're after men, and I wish to God I was with them........!''


            • I'm setting the tower aside and starting on the hull tonight. I am going to try to address the problem with the shape of the bow, wish me luck!


              • Hi to the Boattrainman, i'm also Irish (galway) and i built the Robbe U47 back in 2004. i modified it's appearance quite a bit with some aftermarkets parts into a late war boat but without the snorkel. I think the conning tower came from a german company named dream arts which is long gone. i left it as a dynamic diver as it was my first and only rc boat, however i've taken it down from the attic this week and i've been looking into how would i turn into a static diver. I was thinking of a water pump and ballast bags. I see "mikes subworks" has some suitable ballast bags but he hasn't responded to my email as of yet. Anyway i'll post some Pics of my boat soon. your own project is very ambitious and inspiring. Keep up the good work.


                • I've got quite a few of the rubber bladders here that I'd be happy to let go for $12 each. If you're interested, pop me an email to "sales(at)" and we'll get you all hooked up! I also carry mini and micro air pumps that would be perfect to pair with them.


                  • Hi Patrick,

                    Great to see I'm not totally alone, there's at last two of us among the 4.5 million!!!!

                    I built the Robbe U47 way back around the same time you did, I made it as U203, however I didn't have the skills at the time to sort some of the issues with the kit. At that time I used the Accuarte Armour 1/35 Conning Tower (a resin kit) which is very heavy, and I undersized the Piston Tank, so while it looked reasonably well it never sat on the waterline properly. I sold it to fund other hobbies, but I always wanted to go back and do it properly, hence this build.

                    This forum is terrific, there's great support from other builders, plus Bob is a great supplier and very helpful also. I used his fittings kit for the Skipjack (Revell) and they were of superb quality. One tip which you probably know is to set up an AddressPal accout for the USA with AnPost, it makes the postage costs much lighter, plus the stuff will arrive faster.

                    I've got a Steam Coaster from Mounrfleet Models (2.5 years to build, I went back to original drawings and photographs to get it right), the Skipjack mentioned above with a scratchbuilt WTC, and I'm also working on a steam launch with a Cheddar Models Steam Engine that I got as a present recently. Hoping to get the first coat of paint onto U557 over the Christmas if I can get a quiet few days.

                    Best of luck with modifying your sub.


                    ''We're after men, and I wish to God I was with them........!''


                    • Anyway, this is my boat. The red anti-fouling paint isn't scale for a late war boat, but i thought it gave it some character. Also the net cutter on the bow is from an early war boat is a total NO-NO and i don't know why i put it on but i obviously thought it was cool at the time. I was shocked how basic and rudimentary the original Robbe kit was and in particular how poor the instructions were. That said it was basically sound and admittingly coming from an RC plane background i have been spoilt with cheap and readily available ARTF's (almost ready to fly). Building RC submarines, at least with static dive systems, really seperate the men from the boys.


                      • Perhaps you could start a new thread for this, Patrick.
                        DIVE IN! Go on, go on, go on, go on, GO ON!


                        • Yes, a new thread would be great, you did a great job Patrick, it would make a super static diver.

                          Check out the below for references, I've used this as a bible for this build (with one exception, I think he used the Laboe U-Boat 995 for drainage channels which are atypical):-


                          Per the authors research, no U-Boat ever had a boot strap or a red oxide lower hull, but you have that covered.

                          From my recollection, modifying the Tech Rack that came with the kit was a horrible job, that's why I didtched it for this build, plus by starting from scratch, I could squeeze in the biggest Piston Tank possible so it would sit on the waterline properly.

                          Happy building.


                          ''We're after men, and I wish to God I was with them........!''


                          • Great boat! So thereís two of you in Ireland now! Well,thereís two of us in Texas now too! Weíll have to form a Pan Irish - Tejano U Boot league ha ha. Yes start a thread! Maybe we can kick start Krick into re-introducing the kit under Romarine. Krick now owns all of the Robbe line and have been re-introducing it kit by kit. Just so you know Krick do have a lot of the spares, such as the WTC tubes and end caps, plus those wonderful Futaba F14 twin stick radios in 40 mghz.


                            • As the prep for painting continues, I'm fixing issues I ignored or where I made poor build decisions.

                              A major problem is the curvature and raised knuckles at the aft hull section near the rudders.

                              Click image for larger version

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                              I can't fix the overall issue, but I did remove the raised knuckles (shaded black), by grinding them with a small sanding disc.

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                              It removes the sharp raised bump but I can't fix the shallow raised section as it would removed a huge section of the hull.

                              I botched the attack periscope, especially the wire wrapping to remove water disturbance when on the surface, a single wound wire is incorrect.

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                              From photos it appears to have four windings that go around 3/4 of the scope and start straight at the bottom. I used waxed rigging thread with very thin superglue.

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                              I used the same for the fitting midway and at the top.

                              The 2.2cm gun brace, was just stuck to the tower deck, however it actually sits in a recess in the deck which I haven't made.

                              As the sub will always be 'travelling' I decided the brace should do it's job and secure the gun, so two small pivots of styrene were made and the gun brace glued in the fixed position.

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                              Finally, the two small compasses in their gimbals and the repeater were added using simple styrene tubes ..............

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                              ..........and the hatch gets a brass wheel, scratch built from brass wire.

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                              Back to the test tank this weekend for more trim tests.

                              The Boattrainman

                              ''We're after men, and I wish to God I was with them........!''


                              • So I'm looking for a bit of advice here.

                                I've managed to get the sub surface trimmed and also submerged trimmed (I skewed the main ballast keel forward a little so that foam was only required in the aft section for submerged trim, so the Piston Tank filling from the rear is counterbalanced by the increased buoyancy of the foam sinking below the waterline in the rear)...........

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                       it is just on the waterline and with the foam (high density, closed cell type) above the waterline.

                                But despite drilling plenty of vent holes, including a series along the keel........

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                                .......and some extra 2.5mm holes along the top of the saddle tanks (didn't want to do this but having extended the saddle tanks inboard air was def getting trapped underneath)......

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                                ................I'm left with a problem.

                                The sub refuses to re-set on the waterline after submerging!!!!!

                                On initially putting on the water, the sub sits fine on the waterline, dives level to periscope depth and on return to the surface sits around 10mm below the waterline. After a couple of spins around the lake on the surface, it's back on it's waterline, but once static dived again it will not re-set to the waterline. Are my vent holes too small (keel 4mm, saddle tanks 2.5mm)? Are more needed in other locations? Is this a common problem with saddle tank models?

                                The Boattrainman

                                PS .........and a Happy New Year to all!
                                Last edited by The Boattrainman; 12-31-2018, 03:02 PM.
                                ''We're after men, and I wish to God I was with them........!''