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I'm with you there Skydive 👍What Boatshed means is the part of the rudder in front of the stock. Thinks: are you building an Offshore Power Boat or a scale Lifeboat? If the former then follow Boatshed's recommendation. If the latter and the rudder is 'scale' then leave it alone. Any braking effect, which usually is only significant in a fast racing boat model or other fast planing types, can be diminished by reducing the rudder servo throw at the TX. One should also consider how the original behaved, maybe they did 'dig in' maybe not. There has to be a reason why such rudders were developed, and surely not just to annoy modellers 😁 One more minor point that struck me - Ouch 😭 Your prop struts! "not that it provides a huge amount of support but adds to the scale appearance." Even in a model they can be important. To help reduce potential whipping of the propshaft, especially if the model is overpowered. Actually in the originals they were vital, especially in larger vessels. The purpose of these struts, in larger vessels 'A' frames, is to provide support to the end of the shaft which carries the prop weighing several tons and, more important, to carry the bearing for the outer end of the shaft! Actually in the originals the shaft tube, or 'Stuffing Box' would not extend significantly beyond the hull. Thus the strut or A frame was vital for the shaft end bearing, fitted immediately in front of the prop for maximum stability. Attached pics of my HMS Belfast (sorry don't 'ave nutt'n smaller with this feature🤔) show the arrangement. Have witnessed such construction in various shipyards around the world. Last one in UK was the first T45, quite an experience! 😲 In the end she's your boat, if it feels good do it! 😉 I would leave the rudder alone if it is 'as fitted'. 👍 I make my struts and A frames from brass sheet and tube. Cheers Doug 😎 PS Stick with the brass Donnie! 👍
So, managed to get all the glass clothing done at work at the weekend! So far, 1 coat of resin followed by 2 thinned coats to come. Today has seen all the fenders/rubbing strakes added. It took some careful measuring to get positioned correctly but well pleased with the outcome. It paid to pre-shape them prior to fitting. I’ve added filler where needed and a couple of coats of sealer, all seems to be faired in nicely. May need some touch up after priming. Also fitted the rudder mounts as today’s final job. Tomorrow should see the prop shafts fitted, motors mounted and will make the shaft struts. Postie arrived with some RNLI resin crew figures that will add a great touch when painted.
This is not a build but a modification of a cheap Chinese boat just for fun, I got a bit bored of scratch building projects as they take so long especially as I am not retired yet. The NDQ 757 Coastal Brother 1:25 Radio Controlled Racing Power Boat cost about £25 from Amazon. These boats have a basic 27mhz radio and two 380 type motors which have forward and reverse and you steer by powering one motor or both for straight ahead. I bought two of these boats as they are light and about 24 in long, one to convert/upgrade radio, esc and brushed motors the second was to upgrade radio, esc for brushless motors. The brushed motor version I put in two higher rated motors (390) with cooling fans built in, but same motor diameter but longer body I had to modify the mounts, kept same couplings and shaft/propellers. I did remove trim tabs (fixed) and replaced the straight running adjuster for a racing rudder. The brushless version is the same but has brushless motors 2x 2845 2600KV sensor less Specifications: KV(RPM/Volt): 2600KV RPM: 50000 Max Current: 42A
I placed the rudder servo forward of the gear box. The folks at dumas wanted it placed. Against the coaming that runs along the opening of the hull! I found this angle troubling! The servo would be on a 180 degree angle. Which would be hard to get to. What if I don't have a screw driver. that's small enough to get to the screws! So, the servo has been placed next to the gear box! On a 90 degree angle which makes it extremely accessible. I have also placed the receiver. On the coaming using double sided tape. I placed the aerial on a piece of wood. I placed on a 90 degree angle! On my last Tug I put the receiver. On the motor mount floor. And the aerial against the coaming!
Evenin' Gerry. OK understood. So I assume you have no electrical equipment, experience or components available. Correct? For an 'electrics novice' I am inclined to recommend you start with standard brushed motors and NiMH batteries. Cheaper and easier to manage for a novice. In which case 3 x 380/385 motors with 3 x 25mm 3 blade screws would be a good start. Can send some info on a suitable dual+1 ESC and rudder mixer tomorrow, getting late here in Munich now 😲 Don't worry there's lots of clever (been there dun that) guys here who'll help you through 😉 More later when I've cogitated a little 😊 One final thought: don't finish planking/skinning the hull until the motor mounts and prop shaft hull breakthroughs are sorted out and trial fitted for alignment. Doing that on a completed sealed hull is a pain in the you know where🤔 cheers Doug 😎
Have added a few more planks over the last couple of days before and after bed as on nights. Gaps should be closed by Friday? Have also marked exit points for prop shafts and marked and drilled rudder mounting holes.
Many thanks Dave and Brian, I guess Brian's craft is much bigger and heavier than mine; 56x30 cm. Spec says weight 1.3kg with motors fitted but without batteries and RC gear. It came with a 9cm diameter 3 blade ducted fan, 13x? two blade thrust prop and a pair of 400 size brushed motors, the mountings for which limit me to 28/30mm diameter brushless. When I hauled the kit box down from an upper shelf to investigate I found the packing list and spares price list in both Deutschmark and Euro, i.e. circa 1999/2000!! Planning well ahead for the retirement 😉😉 In mine there are no rudders! The whole motor/prop mount is turned. Will see how it goes with that and maybe mod it later with rudders depending on how easy it is to control - OR NOT😲 many thanks for the tips 👍 Doug
At this point I decided to fit the rudder tube, water pick up and skeg. I was able to mount the boat in the machine vice by gripping the keel; this ensured that the holes are drilled absolutely true and square, 2 x 8mm holes are needed to take both the rudder tube and water scoop. I purchased the rudder assembly from a well-known supplier but I didn’t like any of the proprietary water scoop tubes on offer so decided to make my own. Whilst the boat is in the vice I also decided to machine the slot for the skeg to fit in. This required drilling a series of 2mm holes and then opening them up into a slot using a long series slot drill again giving an accurate slot which the skeg can locate into. Water scoop Having dealt with the woodwork, I turned my attention to metalwork. To bend the ¼” brass tube successfully it has to be annealed, (cherry red and quenched in water), then inserting a tight fitting spring inside the tube to stop any kinking I gently pressed it round a former to the correct shape. Springs removed I filed the end to the correct angle which gives an oval opening, but the end didn’t look finished, so I machined a thin spacer and then squashed it to suit the oval end and silver soldered it to the end of the tube, this gives a much better visual appearance.
I am currently building a skimmer (Dave M will be very familiar with the type). I propose to mount the motor as a pusher on the single pylon. To minimise clutter I was thinking of a single rudder, mounted centrally behind the motor. Most skimmers/airboats I have seen have two rudders, but do I really need two? Any thoughts? Thank you Steve
Hi Mate and welcome to the forum, (mad as hatters!!!) I have built the 46" and before you get to far in you need to decide if your having single or twin motors, and rudders, that way you dont fall foul of bulkheads, and shaft mountings, mine has Graupner 700bb motors on 3s lipos, but i am up-grading them to brushless soon, have the new ESC,s and the motors are on order. Great model to build and sail, attracts a lot of attention. Mark
Hi Steve Sorry, no I did not take photos of the build. If you have the Mobile Marine hull then I built a vertical wooden plate up through the top and strengthened with wood plates beneath the top moulding. If your rudder snake runs over the top make sure you allow for this when deciding how high to mount the motor/prop!! This works but flexes when power is applied so if I did another I would mount the upright to the base and make a slot in the top to allow it to pass through. I would also provide support, below the top, to the upright behind and right up to the hull sides. The force from the motor is truly awesome and plastic mouldings tend to (and do) flex. I use two rudders as other members have found they work better than one. I used 1/8" welding rods for the cage and did have some hard black netting at one time but have had no problems with just the frame. If I sailed in an area where the public had access then I would provide a cover. Just get the mount and prop sorted before you finalise as mine was too small!
Ok Is the weight and dimension the same as the Siren or 507? Looking at the rudder this looks like an after fit and does seem to be differently mounted (more vertical) than those on the website. The keel looks flat on the bottom. Has it been chopped in half? This would make the model very sensitive, especially in a gust. I'll wait for your response before adding more thoughts.
Hi All I was told to use plumber's tap silicon grease, which I have used for 3 years and only regreased once each year. I have added oiler/grease tubes to my rudders as well. Also you can get a silicon spray like WD40, but, with the silicon spray it crawls up the shaft. With the shaft out and the tube cleaned out(pipe cleaner works well for this) a shot of silicon grease in each end of the tube(only small amount). Hold your finger over the other end and install the shaft, this stops the grease coming out as the shaft comes through. A shot of silicon spray down the oiler tube and seal silicon fuel tube sealed off at one end. Canabus
This time I will try to remember to put in the ‘source’ information on the bits and pieces I use........... In the most recent piece I should have included exciters/transducers are Dayton Audio DAEX 25VT -4, 4 Ohms – 20 Watt pair, obtained from Sound Imports Netherlands and very quickly as well. The sound unit is a Mtroniks Digisound 5M diesel sound, available all over the place. Now to look at where I am at. Exciters are in place as high up the Hull as possible, but remembering the Deck level. Used the adhesive pads as supplied after wiping that part of the Hull with Meths and Silicone adhesive to keep in place as well as using the wiring tidies from Modelsport Ltd., for the cabling. (Pic 1+2) Before I start the motor and controller wiring I changed the platform ‘up front’ (pic3) with a piece of thin ply which I have given a couple of coats of varnish to waterproof. Then I thought to myself “why am I waterproofing this when, if it gets that wet, it will have gone to the bottom and be useless anyway”! (Pics 4) However, the platform gives a little more choice in terms of layout of other components and my plan for them is not really settled yet. I am concerned about the stern and possible swamping, but it currently seems the best place for the upgraded battery. (Pic5 ) Whilst talking batteries, I have gone for a separate battery supply for the receiver and hope to use the Bec supply for running other less critical items. Also the fitting of the battery in the stern bay drew my attention to the rudder servo for a couple of reasons. First is I am still considering increasing the size of the rudders and I am assuming that will increase the strain on the servo. The servo supplied is a standard issue and not water resistant so I have gone for an upgrade as shown(Pic6) That gives torque increase of 17Kg/cm over the Hobby Engine S1040C and has metal gears, metal control arm and waterproof for 20grams extra weight. Second is the closeness to the new battery position. So I was going to alter the servo arm setup anyway and the new metal arm suits this well. Maybe my ‘tutors’ will consider all this to be a little ‘over the top’ but I do so enjoy messing......................... New Servo DS 3218 by AYANI from Amazon. (Pics 6/7 ) Following that distraction, back to the front end and the Motor/Mixer placing and wiring. Now a little time ago I drew a plan to see what could go where and it came out that most of the ‘bits’ would go in the front bay with motors to be wired once power was brought forward, followed by the Esc/Mixer. (Pic 8) At that time I bought a P94 dual esc/mixer from Action Electronics and got the 20 amp version to be on the safe side................. My ‘guardians’ did point out this was ‘over-kill’ but I had already got it. Now, when placing the unit on the mounting board I found that the heatsinks made it too high to fit in the Hull! So being a spoilt brat only child I ordered the 10 amp version and as usual it came very quickly from up here in Bangor. ( Will keep the other one for the next project............Happy Hunter??) Unboxed it and it looked just the same, heatsinks and all. (Pic 9/10 ) So at that moment there was a bit of a set-back so I rang Component Shop at Bangor, they said “take the heat sinks off and you have a P94 lite”! Such a simple answer and such a nice chap. (Pic 11 ) Now a quick 'measure up' before I have a glass of wine (Pic 12) and does it all fit...? Well it appears to at the moment! (Pic 13) Next time really going to screw down the components under the forward hatch and wire it up. NPJ
[Score: 9/10] 35"/4500g CG-40564 Capable of 15mph and a runtime of 45mins Twin Propellors (4 Blade 50mm) Direct Drive to a 775 JOHNSON-TYPE 6-12V (4 Blade) Powered by NiMH (8.4v) 3Amp/h Batteries Controlled Through HOBBYWING (15Amps) ESC - Comments: DUMAS 1:14 USCG 40' UTB. REPRESENTING US COAST GUARD UTILITY BOAT CG-40564, WHICH CAPSIZED DURING A RESCUE ATTEMPT ON THE COLUMBIA RIVER BAR ON 17 JAN 1961. HER CREW WAS FORTUNATELY RESCUED. SHE WAS ASSISTING CG-52301, A 52' TYPE F WOODEN MLB, WHICH FOUNDERED WITH THE LOSS OF ALL HANDS. IT REMAINS THE WORST SMALL BOAT RESCUE DISASTER IN COAST GUARD HISTORY. THIS IS AN UNUSUAL SCALE BALSA PLANK-ON, COVERED BY 2 OZ FIBERGLASS. I USED MINWAX POLYURETHANE FOR AN ALTERNATE TO RESIN, WHICH TURNED OUT WELL, AND CAN BE DONE WITH MINIMAL VENTILATION. WITH BIRCH PLY DECK & CABINS, 1/8" SCRIBED SHEATHING COVERS THE DECK BOW TO STERN AND MAHOGANY TRIM LEFTOVER FROM ANOTHER DUMAS KIT IN MY SCALE SHIPYARD. STOCK D/C FITTINGS WITH SOME SUPPLEMENTAL PREMADE AND HANDMADE ITEMS. SHE FEATURES TWIN RABOESCH 4-BLADE WIDE FLUKE WHEELS AND MATCHING RUDDERS; WORKING HATCHES WITH STOWAGE AREA FOR ANCHOR & TOWLINE, LIGHTHOUSE 9V LED NAV LIGHTS AND FLASHING LED LAW ENFORCEMENT BLUE LIGHT (RC CONTROLLED). I'M ADDING A MOUNT FOR A SCALE BROWNING M2 50 CAL THAT I WAS ABLE TO PRODUCE ON MY 3D PRINTER. THAT'S AN ADVENTURE IN ITSELF. THIS WAS MY FIRST REAL PLANK ON BULKHEAD, AND BALSAWOOD CAN BE A LIL TRICKY, BUT WILL ALWAYS BE THE STANDARD OF WHICH I COMPARE ALL MY SUBSEQUENT BUILDS. MY FATHER BUILT RC AIRCRAFT, AND ALWAYS PREACHED THAT YOU SHOULD OVERBUILD IN ORDER TO SURVIVE A CRACK-UP AND FLY ANOTHER DAY! THAT'S MY CREED WITH BOATS. OVERBUILD!!! THANK YOU DAD! BTW-FYI-MR. ARNOLD PALMER WAS A US COAST GUARDSMAN (YM3) 1950-53