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  • This topic has 5,031 replies, 83 voices, and was last updated 1 day, 10 hours ago by ashley needham.
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  • #119886
    ashley needham
    Participant
      @ashleyneedham69188

      Hmmm..perhaps not rooster tails, however, what’s always missing in a model is the white water frothing you get from a real boat. The HSS should have two frothy white plumes from the 4 water jets at the stern.

      Ashley

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      #119964
      ashley needham
      Participant
        @ashleyneedham69188

        I have put in place wedges and splitter vanes. Test out tomorrow. If no good. I will have to make some sort of rudder arrangement.

        It’s a bit nippy, hope it is warmer tomorrow! Ashley

        #119979
        Richard Simpson
        Participant
          @richardsimpson88330

          Funny but over the years we tend to modify the way we look at things as our experience broadens our horizons and gives us a better balanced approach.  The way I see people has certainly changed but so has the way I see the wake created by various vessels as they pass through the water.

          I remember during our Naval Architecture lessons doing my ticket discussing the behaviour of wake and the way bulbous bows prevented the creation of bow waves and took away from that a very simple bottom line.  The way I see it, the hull that passes through the water with the minimum of disturbance is the more efficient hull.  When I look at modern craft such as lifeboats and many pleasure craft and I see large wakes, huge troughs at the stern as they pass, large piles of foam at the stern and big rooster tails, all I see now when I watch that is wasted energy.  It takes energy to disturb that water, which is therefore not being used to propel the hull.

          Just sharing a thought.

          #119988
          ashley needham
          Participant
            @ashleyneedham69188

            And it’s a good thought Richard

            Pictures of the new carriers sailing in formation with other supply and warships appear to indicate that the carriers have a much reduced wake.

            Apparently the Australian Jindalee long range radar ( I believe it was bounced off the ionosphere or something silly) could detect wake patterns in the ocean at massive ranges.

            Boating today, or rather not much boating. Massively windy and jolly cold. No point in even trying the HSS as it would have been blown all over the place. I took the two gp hulls and some tops, but again, with the tops not being sealed to the hull it wax too dodgy to put then in the water.

            Ashley

            #119992
            Colin Bishop
            Moderator
              @colinbishop34627

              Richard, that’s a bit of an apples & pears comparison. As I understand it, the maximum economical speed of a vessel is close to its theoretical hull speed which itself depends largely on hull length. Thus the express liners like the old Queen Mary had to be around 1000 feet long to achieve a service speed approaching 30 knots. By comparison the hull speed of a lifeboat operating as a displacement vessel might only be 8 knots or so. (just a guess!). However the lifeboat has to operate at 25 knots which requires far more power to achieve semi planing performance so it is operating very inefficiently from a hydrodynamic viewpoint but you will know a lot more about this than I ever will.

              Strangely enough, the bulbous bow is not a post WW2 invention, the Germans used it for their liners Bremen and Europa around 1930 and before that, the Victorians inadvertently invented it with the rams attached to the bows of their battleships.

              The effective hull speed can be usefully increased by hull design and refinements such as bulbous bows and anti friction coatings to improve economy. Most modern large ships seem to slip through the water with minimal wave disturbance which is a tribute to their design.

              Back in the 1930s the Queen Mary and the Normadie were pretty much neck and neck speed wise with QM having a slight edge but Normandie’s hull was far more efficient and you can see this in aerial photos with QM thrashing along while Normadie is clearly making far less wash. Normadie required far less power to make her service speed than QM despite being turbo electric drive but both ships had a very similar maximum hull speed. Of course it was all a bit more complicated than that as propeller design was also a major factor and both ships had big problems with their initial sets.

              Colin

              #119997
              Richard Simpson
              Participant
                @richardsimpson88330

                I think we are at crossed purposes Colin.  I wasn’t actually intending making any comparison, all I was saying is that when any hull moves through water, of any size or shape, any amount of displaced water detracts from it’s efficiency.  I know that is a wide and all encompassing thing to say but, as a very general rule, it is true.

                I was saying nothing more complex than any displaced water is a waste of energy, whether that is a bow wave, a wake, a wave at the stern, foaming or rooster tails etc..  They are all examples of wasted energy, which detract from the hull’s efficiency.

                What makes me smile is things like jet skis, flying around making unbelievable amounts of spray, wash and rooster tails as they try to impress everyone.  All I see is monumental amounts of wasted energy!

                #120003
                Colin Bishop
                Moderator
                  @colinbishop34627

                  Richard, yes, maybe I went off at a bit of a tangent but you got me thinking! It’s probably also true to say that wasted energy is the price you pay for pushing up the speed beyond economical limits. What make me smile is scale modellers asking about watercooling their motors and ESCs when they are simply addressing the symptoms where the true problem is a mismatched motor/prop combination. Also few people seem to appreciate the advantages of gearing (gears or belts) in bridging the gap between a fast motor and a slow prop to increase the efficiency of the installation and reduce current draw.

                  Of course water cooling can be needed when it comes to the fast racing boats as the priority is to get maximum speed regardless of the inefficiency consequences.

                  As an aside to my previous comments I looked up the liner ss United States which achieved 35 knots in service (and more on trials). Despite being roughly only half the displacement of the Queen Mary she needed 240,000HP as against 200,000HP in the QM. She also needed to be only slightly shorter in length than the QM (by 30 feet).

                  Today’s enormous cruse ships have much lower power plants as they usually cruise at 22 knots or less in service. I think there are always ‘sweet spots’ such as the 20/20 liners of the interwar and post war periods which were 20,000GRT (not displacement) and 20 knots service speed. Bigger vessels tended to have slightly higher service speeds.

                  Colin

                  #120008
                  Richard Simpson
                  Participant
                    @richardsimpson88330

                    I definitely remember discussions in those Naval Arc lessons about the relationship between speed and the length of the hull.  I always found the explanations a little vague though! I think one of the really interesting aspects that I saw time and time again was the exponential relationship between speed and power required.  Frequently in later years we could be pootling around with only two of the five engines running, one was required for house load so only one would be providing propulsion.  We could still be doing 12 knots or so.  Then, at the other end of the scale if we had four engines going at full load and put the fifth one on line we would probably only get an additional 2-3 knots out of it.  And the fuel difference would be enormous for that extra couple of knots.

                    Just an interesting snippet while we totally hijack Ashley’s thread, when the QE2 was a steam ship and getting across the Atlantic in five days she used to burn in the region of 700 tons of fuel per day.  She was around 80,000 tons.  Nowadays you can be looking at 120,000 ton ships going significantly slower but using only around 100 tons of fuel per day.  Adjusting itineraries to reduce speeds makes a huge impact on the cost of fuel.

                    #120033
                    ashley needham
                    Participant
                      @ashleyneedham69188

                      Didn’t the ss United States use a battleship propulsion system. Paid for by the government?

                      The thread is for general discussion. Hijacking totally allowed for interesting and informative discussion,!

                      I recall that the Island class OPV the RN used to have did about 14 knots on one diesel (it had one shaft) but only 16 when the other was added. The extra power is handy when going uphill of course….

                      Remember seeing one of the big models in Container house on the South Bank in London, and the bilge keel was curved presumably to match its cruising speed.

                      Ashley

                      #120042
                      Colin Bishop
                      Moderator
                        @colinbishop34627

                        ss United States used a powerplant designed for the new big US aircraft Carriers of the day – possibly the Forrestal class.

                        Colin

                        #120062
                        Richard Simpson
                        Participant
                          @richardsimpson88330

                          Interestingly that has come full circle as well as now the two new carriers use a diesel electric propulsion system with two turbines and four diesel engines to generate the power for the two main motors.  Almost all new large cruise ships built nowadays are also diesel electric.

                          #120069
                          Ray Wood 3
                          Participant
                            @raywood3

                            Hello All,

                            As we are talking things electric !!

                            My friends son just started running a Polestar electric car, goes like a rocket 🙂

                            His old diesel powered Merc used £200 of fuel a month for work travel

                            The new electric car costs him £500 a month to charge to do the same mileage !!

                            Food for thought, not mentioned in the adverts strangely 🙂

                            Regards Ray

                            #120074
                            The Long Build
                            Participant
                              @thelongbuild

                              I Just love it on a bank Holiday , cruising up to the Lakes, stopping off at a Service station passing the queue of 40+ Electric cars waiting to charge, the Electric car at the moment is a big white elephant, may improve in the future but at the moment infrastructure is useless an Probably in the long run makes no difference to the overall effect of the environment. Tesla laying of 14k of staff as sales are drastically dropping (according to the news_)..

                              bit like Model Electric boats, work at home but never at the pond !!

                              #120093
                              ashley needham
                              Participant
                                @ashleyneedham69188

                                Electric cars horribly ungreen from almost any standpoint. I am being green with my 20 year old Suzuki

                                Still passed ulez emission standard. I have not brought a new car for 15 years so have not ramped up new build or disposal emissions.

                                ANYWAY. I have a 1,/35 Amati J class yot kit to get rid of for a friend whose husband sadly passed away. Hull started on 20mm mdf build board. All bits in original box appear to be present. The chap who had it was quite meticulous. Pm me any interest.

                                20240423_14063220240423_14055520240423_140454

                                #120126
                                ashley needham
                                Participant
                                  @ashleyneedham69188

                                  Spent some time today soldering Dean’s connectors on my new Quicrun ESCs.  I bought 3 brushed and 3 brushless esc after saying for ages that I should get some. I am now well-stocked with relievers, esc and servos.

                                  ALso sourced a 6 foot picnic table to take to the Kempton show on 19th May. We had to ‘make do’ a bit regarding tables last year.

                                  Undecided on what to take exactly, will see what the weather is like. Bumpers for sure, perhaps Fireboat or the Ultimate.

                                  Hoping it’s OK tomorrow to test the HSS with its butchered rear end (in an effort to make it steer).

                                  Ashley

                                  #120131
                                  Chris Fellows
                                  Participant
                                    @chrisfellows72943

                                    Yes, over the last few months I’ve been stocking up on Quicrun and Seaking ESCs for my existing and planned builds. Also, motors, servos and servo horns. You never know if they will suddenly become unavailable as I found out with my favourite motor mount.

                                    Neighbour told me about the shortage of Hitec Rx following their decision to stop making Tx and gave me the nod on a supplier that had some. I was still one short though and only last week I found a couple of new ones on EBay so snapped them up.

                                    I only use Overlander motors in my builds and have noticed that the range of outrunners has reduced so I’m glad I bought what I need.

                                    Chris

                                    #120138
                                    ashley needham
                                    Participant
                                      @ashleyneedham69188

                                      Always worth buying more than you need. Had my hand bitten with the Planet T5…just as I made a foray into 2.4gig, they stopped importing them. I managed to buy another set and  few more rx.

                                      I splashed out on the new Planet 2+2, bought two sets p,us 10 rx.

                                      Wet here but as long as its not actually raining I need to test the HSS so will be at the pond.

                                      Ashley

                                      #120142
                                      Chris Fellows
                                      Participant
                                        @chrisfellows72943

                                        In theory I should stock up on spare motors as well for those that I can get, but that would be spending too much unnessarily as I can always use another make. I suppose I should get the Raboesch prop shafts I need as well though my future builds that need them are only slow so can use anything.

                                        Raining here yet again so off to my son’s flat again for some full-size painting and carpentry. Will get back to model building one day!

                                        Chris

                                        #120147
                                        ashley needham
                                        Participant
                                          @ashleyneedham69188
                                          1. Light rain since I posted.

                                          Spent an hour putting connectors on various esc I have, including two reversing brushless ones. I need to test them out properly as I trued one and thought that it wasnt that efficient. However. I should put it in something with an air prop and use the wattmeter.

                                          Snap. Handy positional vice with sift jaws to hold Dean’s connectors. A tip here is to solder wires on the tags with both parts of the Dean’s together to avoid overheating and also to keep the parts aligned (snap is post-soldering!)  I fitted fuses, very easy with blade connectors and fuses. White gunge on esc is silicone to provide some waterproofing. As the esc are never run at their max, any loss of cooling is minimal. Fuses 25A on the 30A esc’s.

                                          Ashley

                                          20240428_110801

                                          #120166
                                          ashley needham
                                          Participant
                                            @ashleyneedham69188

                                            We did a boat’n’tell today to test a few things out.

                                            Firstly the HSS. Wedges and vanes worked a treat and it steers like is has conventional rudders now. However there is vibration at high motor speeds which might be due to water flow or sumfing. I will smooth out the various internal contours and add skegs to stiffen the propshaft end. It didnt vibrate last time so it has something to do with the mods.

                                            Push-me,-pull-you ferry kept its nose up with a bit of subtle rebalancing and on reflection turns MUCH better that it would with just one prop/rudder, and going both ways! Despite the bluster and apparent shallow draft it was remarkable stable, although I have a pair of 20 ton lorries to go on the bow ramp.

                                            Hope you all liked the Mintanic…wait and see what develops over the next 18 months!!

                                            Ashley

                                            #120214
                                            ashley needham
                                            Participant
                                              @ashleyneedham69188

                                              It is at last a nice enough day to spray and I am in the middle of doing the ferry top in Halfords Appliance white…joy.

                                              Ashley

                                              #120225
                                              ashley needham
                                              Participant
                                                @ashleyneedham69188

                                                Bah humbug. I have a stinky cold, from who knows where, so will not be boating tomorrow.

                                                However, ferry  white paint is on ok.

                                                Various stickers arrived and look to be about ok.

                                                Ashley

                                                #120240
                                                ashley needham
                                                Participant
                                                  @ashleyneedham69188

                                                  It was really nice yesterday morning and I missed boating awfully,  but I did manage to spray the ferry bits white, and put a coat of LR Fiji white on the HSS. Trouble is, in the afternoon it got distinctly cooler so I had to stop…

                                                  I did paint the Blue and Turquoise bits on the HSS hull though and it looks very smart. I also pulled my finger out and made a box for it, a nice small 24×7.5×8 inches.

                                                  Today as its raining I have hinged the lid on, and glued a couple of non-detail strips of wood on the ferry top. The ferry box is a bit snug so the inside foam strips have been scraped off and after coffee time I will glue some strips of thick felt in their place. The snug fit was great but over time the rubbing will wear off some patches of varnish. Although the blue is gloss acrylic it’s not super shiny, so when I muster the courage to put the side p+o stickers on it will be sprayed with a gloss varnish.

                                                  Jobs for the afternoon will include painting the ferry top surfaces in green and a different green, and splashing some white emulsion on the box.

                                                  The biggy is of course the window issue, and I need to give this some thought. The graphics company that did the lettering could in theory print me rows of oblong black boxes…three sizes in varying quantities would sort out the window runs, and the various other openings..I like this idea a lot.

                                                  For the HSS, this only has basically a long panel window either side and a strip at the bow, so COULD be masked off and painted, or perhaps a simple strip of black painted paper could be fixed on?

                                                  Ashley

                                                  #120263
                                                  ashley needham
                                                  Participant
                                                    @ashleyneedham69188

                                                    <p style=”text-align: left;”>The painting is being a pain as usual. However the things that need spraying have been sprayed ok. Brush work for horizontal surfaces has been done, but having painted the area for the ferry lifeboats I find i am unhappy with the lifeboat look. They are too bulky and the top appears to be too big as well. I have sanded one down and the aspect is much better so I will sit in the sun and do the others. Afterwards I need to cut 6 covers in 0.8mm ply to give the appearance of a full lifeboat when viewed from the top.</p>
                                                    I also need to go to Squires garden centre where they have a large craft section and buy a couple of tins of their extra-gloss clear varnish. This goes on top of acrylic ok and is needed for the ferry sides and HSS below water section to stop watermarks…the blue acrylic is waterproof ok but does take Marks.

                                                    Patience now. I could stick some lettering on but am being good in letting the paint harden for a few days

                                                    Going to Trevor on Friday am and we are going to splash some paint on his big corvette. Assuming it’s a nice day. The deck needs doing and we need to mix some custom colours to do some cammo on the hull. The Plastic Warrior toy soldier show is on 18th May wot I will he going to, so I will be sourcing some crew for it, Airfix 1/32 British army support group figures, and rummaging in the boxes of figures just in case there is anything else that could fit.

                                                    Ashley

                                                    #120315
                                                    ashley needham
                                                    Participant
                                                      @ashleyneedham69188

                                                      Fantastically productive morning painting Trevors corvette.  Did the deck and marked out dazzle cammo on the hull.

                                                      And, having spent most of the morning doing fiddly deck painting, I spent half the afternoon fiddly painting the HSS funnel covers which are covered in corrugated card.

                                                      ALSO stuck the first of my stickers on. The P&O ones are possibly slightly large, but the picture shows the hull without the top so they will look smaller when this is on top. For the experts among you, the letters should be closer together, and the Dover lettering is very bold but the boat is based on a publicity model. HSS in foreground looks to be the same size but is 6 inches shorter. No lettering to go on this hull, the Stena wording goes on the lid.

                                                      Ashley

                                                      20240510_172104

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