hull strengthening membrane?

hull strengthening membrane?

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  • #17628
    David Meier
    Participant
      @davidmeier28154

      Hi. I am building my first scratch built boat, a tenth scale of a 7 meter Italian fishing trawler. It is balsa planks on ply frames. I have had to use a fair bit of filler over the planks in places to get the hull form right (this is my first attempt remember). The filler I chose for its ease of sanding and similar hardness to balsa is PAL contract filler, interior & exterior.

      I would like to coat the hull with a strengthening membrane but am put off at the price of fibreglass cloth and resin. I have heard of people using tissue and dope (I assume it is paper tissue). Can anyone tell me of a low cost method that will put a bit more strength and durability into my hull? I would apreciate any helpful tips on how to apply the coating as well.

      Regards.

      David. 

      #17630
      Bob Abell 2
      Participant
        @bobabell2

        Hello David

        I would recommend you cover the balsa with 300lb cartridge paper plates of scale proportions using PVA…………….. with Fibre glass resin on the inside

        Have a look at my gallery……….Jeanie Deans at war……….that`s what I prefer!

        Bob

        #17631
        David Meier
        Participant
          @davidmeier28154

          Thanks for the help Bob.

          David.

          #17641
          60watt
          Participant
            @60watt

            Hi David.

            I’ve used epoxy with fine woven glass cloth to give a near invisible tough layer.It does away with a lot of filling but it showed every flaw. Unlike a coat of paint, there is no going back after coating with glass.

            Glass tissue soaked up a lot of resin and gave a very rough finish – no good.

            I would advise you to go ahead and buy fine weave/epoxy and do experiments beforehand.You would probably use it on every model thereafter.

            Tom

            #17650
            David Meier
            Participant
              @davidmeier28154

              Thanks Tom.

              Where do you source the fine weave cloth? and do you have an ounce rating that I should specify? When I have looked in hardware stores and auto shops they only have a heavy grade of cloth or chopped strand matt.

              David.

              #17655
              60watt
              Participant
                @60watt

                The only place I have seen it was my local model shop which stocked everything for model planes.It came as a Ripmax kit with a couple of metres of very fine translucent silk like cloth and 3:1 mix 24 hour epoxy.I think the wholesaler description was a "skin preparation" kit. An aeroplane forum would locate some.

                A square yard left weighs 12 gram – on a par with glass tissue

                I have used paper tissue with dope as well but it does not even begin to compare with possible finish or strength. I repeat the "experiment first"

                Tom

                #17656
                60watt
                Participant
                  @60watt

                  See page six

                  It goes clear on wetting and can be re-laminated when tacky.

                  Tom

                  #17662
                  David Meier
                  Participant
                    @davidmeier28154

                    Thanks Tom.

                    That looks like the way to go. I supose it is silly to skimp on this and compromise the model.

                    The PDF link is a good resource.

                    cheers.

                    David. 

                    #17663
                    60watt
                    Participant
                      @60watt

                      For scale effects I’d stick with Bob’s idea.At least you can start again if you din’t like the results.

                      Keep trying with the radio.I found faults came into the obvious and simple-to-fix category.

                      Tom

                      #17665
                      David Meier
                      Participant
                        @davidmeier28154

                        A smooth hull finish is what I am after so I will go with the fine glass cloth. As for the transmitter; not my strong point. I have looked closely with a magnifier and nothing stands out. Thanks for your help at least I have learnt something through the exercise.

                        cheers.

                        David.

                        #17684
                        Telstar
                        Participant
                          @telstar

                          Hi David     I covered a plank on frame 1meter hull by streaching material from a pair of tights over the hull and epoxy.  It gives a strong skin, that can be painted and finished as normal

                          Cheers Tom

                          #17695
                          David Meier
                          Participant
                            @davidmeier28154

                            Hi Tom.

                            I Like that idea, the tights would stretch and conform to the compound curves of the hull which are especially tight around the transom. Also this sort of approach fits my budget better.

                            Am I  right in thinking that the material you used was nylon as used in stockings and pantyhose or do you mean a thicker material?

                            cheers’

                            David.

                            #17696
                            Tony Hadley
                            Participant
                              @tonyhadley

                              Hi David,

                              The hull on my 1920’s replica vintage yacht was balsa planks covered with one leg from a pair of ladies tights. All as the method which Tom has suggested. I didn’t use any epoxy, just paint and varnish. Use fine denier tights as they wont take as much filler/paint/varnish to cover the weave.

                              Also flat areas can be covered in a very similar material, called knitted nylon (I obtained mine from a dance suppliers). Fine denier material is best.

                              http://www.modelboats.co.uk/wp-content/uploads/sites/5/images/member_albums/1858/Jenny_17.jpg

                              Regards, Tony

                              #17697
                              David Meier
                              Participant
                                @davidmeier28154

                                Thank’s for the extra info Tony. Your model looks superb, I will be very happy if mine finishes up to that standard.

                                Did you use paints that have a hardener with them or just turps based paint?

                                Cheers.

                                David.

                                #17700
                                Tony Hadley
                                Participant
                                  @tonyhadley

                                  Hi David,

                                  I used Revell aqua colour paints and Ecos varnish. Ecos is a domestic environmental water based varnish, and I have had no problems. I always use Ecos for all household diy painting as it doesn’t smell and upset SWMBO. Any domestic varnish and paints could be used, but I do find the water based/acrylic do keep the colour better. i.e the white does not yellow.This purely my personal preference, others will probably disagree.

                                  The problem I have had is controlling this yacht, on the water. She has a mind of her own!

                                  I am now building a Veron ‘Police Launch’ using the same method for covering the hull. i.e. balsa covered with tights. After covering I applied a couple of coats of varnish, finally trimming the tights off at deck level when the last coat was dry. The hull can be finished to your prefered choice.

                                  http://www.modelboats.co.uk/wp-content/uploads/sites/5/images/member_albums/1858/Police_Launch_with_tights.jpg

                                  Regards, Tony

                                  #17702
                                  Telstar
                                  Participant
                                    @telstar

                                    Hi David      As Tony says use fine denier ‘Nylons’ to give a fine finish, and light wieght.

                                    Hi Tony  Its good to know other builders use this material

                                    Happy modelling and a Merry Christmas Tom

                                    #17709
                                    David Meier
                                    Participant
                                      @davidmeier28154

                                      Hi Tony and Tom. Thanks for the very detailed and clear information. Useing acrylic enamel makes sense as I understand that acrylics dry from the base to the surface; whereas turps based enamels form a skin first and then the underneath hardens up.

                                      Here are a couple of pictures of the trawler I am building. One of the first planks going on and the other at the stage I am at now with the model. Still a bit more sanding and filling to do before I put on the nylons.

                                      /wp-content/uploads/sites/5/images/member_albums/4321/DSC_6366_%28Small%29.JPG
                                      /wp-content/uploads/sites/5/images/member_albums/4321/DSCN4438croped_%28Small%29.jpg

                                      #1800
                                      David Meier
                                      Participant
                                        @davidmeier28154
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