A new Raidboat and Cruising Dinghy Design for the Home Builder

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • luckystrike118
    Power Kraut
    • Jan 2010
    • 154

    A new Raidboat and Cruising Dinghy Design for the Home Builder

    Hello!



    In this thread I will start to design a new Raidboat (or Fast Cruising Dinghy) for home- and professional builders alike. It will be on the simple, fast and cheap side of construction with as few parts to be built as possible. But it will be but not a „simple as can be“ design to allow all the features that make sailing and cruising live safe and comfortable.

    On the sailing side it will be a fast and lively boat with a good overall performance and balance, able to sail many miles a day. Easy Daysailing with your partner and one kid is also a design target as well as racing on club races.

    For me Lightweight construction and -displacement is the key to reach the targets and also allows easy trailering and -handling on the beach.


    Safety is another important topic in this design. Recovery from capsize, self bailing cockpit and getting back aboard ... I will turn attention to these topics



    Concept Catalogue

    General
    This boat is meant to be a singlehander for cruising and cruising raids and can take up to two crew and a kid for daysailing. When sailing in club races it shall not automatically earn the red lantern.

    Length over all will be two sheets of plywood long, meaning a little under 16feet. So it will be a long and light boat for a single hander and therefore a fast one due to the long waterline.


    Safety:

    A raised floor for a self bailing cockpit after recovering from capsize, no bailing out water when sailing in strong winds and waves, no need for Elvström bailers, no wet sleeping bag when sleeping in the boat.

    No side tanks (a la 470 or 420) to allow the boat to sink in a little when capsized. This helps to reach the daggerboard from swimming to re-right the boat. It also makes the boat roll back more slowly, so that you can climb back into the boat in one rush as the boat becomes upright. The boat will stay at 90° heel when the mast is nearly parallel to the waterline and will have no tendency to become 180°.

    A safety ladder for getting aboard after capsize as well for taking a bath when anchoring.

    A sea anchor keeps the boat with the bow into the wind while reefing or capsizing.

    Water ballast will calm the boat down when sailing in strong winds and inceases the stability. It also helps to re-right the boat. Off course the ballast tank is empty in light winds and regattas.


    Performance and Balance

    Sharpie hull with flaring sides. Sharpie hulls offer good performance when designed with care. In a modern design like this one they have a slim waterline for low resistance and good planing abilities. The center of flotation is slightly aft of the middle to allow an effective trim from the aft sitting skipper. The flaring hullsides increase the sailing stability when sailed heeled and dampen the tendence to capsize. They also make hiking out more effective.

    Lightweight construction. The lighter the boat, the faster it is … so simple. Even if this design is a cruising dinghy and has to carry a lot of stuff beside the crew, for me performance is important. Take out all the cruising stuff and have some fun racing on club regattas. Overall boatwheight ready to sail but without cruising gear should be well under 90kg.

    Effective sail plan. Cruising Dinghys need a sailplan with a low center of effort and the ability to reef easily to make sailing safe. Singlehanders are suited best if they have only one sail to handle. I have chosen to use the balanced lug sail with a large sail area as the standard rig for my design. It can be trimmed very good to balance the boat upwind and is very neutral and effective when the wind is coming from the side or behind. Mast will be free standing without the need for shrouds.

    I know that a lot of sailors prefer the yawl rig for cruising so this rig will be an option in the plans. On the downside of this rig I see the building effort of 3 to 4 more spars and the cost of two sails instead of one. And the loss of efficency of the departed sail area, the increased wind resistance and the wheight of the aditional spars.

    The rig of the OK-Dinghy or other singlehanded dinghys is another option. Even the sails from a windsurfer can be rigged, but this would be a experiment on your own risk. Windsurfer sails cannot be reefed.


    Comfort

    Side decks for comfortable sitting and hiking out over a long time.

    Sleeping inside the boat is possible on the uncluttered raised floor and unter a custom deck tent. This is important in my home country as „wild“ camping is not allowed in Germany.

    Dry stores are under the raised floor in the forward part of the boat, reachable through watertight hatches in the floor. Here are fixed places for the anchor, water supply and other heavy gear that will double act as ballast. A step upwards in the raised floor brings here a height of more than 30cm (1').

    High sides for dry sailing in the sitting area midships


    Construction

    Construction will be sitch and glue, the fastest and most effective construction method for plywood. Every part you build will also be in boat later. No need to waste time and money on a buiding jig or temporary moulds. Okume marine grade plywood with 6mm, 5ply will be used for all parts of the hull. 4 frames/bulkheads plus stem and stern will form the transvers members. Only one stringer will be in the hull sides, mainly to be the base for the raised floor.

    The Sharpie Hull is the fastest and simplest hull to build and with it's three panel layout also the cheapest one to put together. There is nearly no waste in the panels

    The round Mast will be made from wood in the birdsmouth technique and rectangular sections for boom and yard.


    As far as I can see it now you will need 7 sheets of plywood and 12 – 15kg of multi purpose Epoxy for glueing, sheeting and laminating glasfibres.
    Opposite to 5 sheets of ply for a „simple as can be boat“ of the same 16 feet lenght. In my oppinion it is worth the extra effort.


    That's it for now!

    I'am open for comments and incitements. If you have other topics and ideas to be minded let me know and I will try to incorporate them into the design.

    Have fun! Michel
    Last edited by luckystrike118; 07-01-2019, 05:11 AM.
  • luckystrike118
    Power Kraut
    • Jan 2010
    • 154

    #2
    Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

    Here is a first impession of the hull, raised deck and side decks are not included yet ... hydrodramatics first

    Raidskiff Radical hull and deck4.jpg

    Perspective view with sidedecks ... and still no raised floor.
    Raidskiff Radical hull and deck2.jpg

    Comment

    • FF
      Senior Member
      • Oct 2005
      • 1298

      #3
      Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

      I like your idea, but didn't Michael Storer do this already? Frank

      Comment

      • luckystrike118
        Power Kraut
        • Jan 2010
        • 154

        #4
        Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

        Hello Frank,
        yes, Michael Storer designed a raidboat a few years ago and two prototypes (as far I know) were built. They had serious problems, so Storer decided not to offer plans for the boat. His design was more a slim sailing canoe and built super light to be carried on top of a car. Afterwards he made no futher attempt to devellop a dinghy for cruising and raids.

        I focus on sailing stability and safety, in my opinion very important features in a cruising dinghy.

        Have Fun! Michel
        Last edited by luckystrike118; 06-29-2019, 10:55 AM.

        Comment

        • FF
          Senior Member
          • Oct 2005
          • 1298

          #5
          Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

          Michel, I meant the Goat Island Skiff. Joost Engelen used her with his wife in a 'Dorestad Raid, and earlier in the Great Glenn Raid. Don't know if she planed, probably not with the 2 of them aboard. Late rhe built a Storer canoe named Viola, and I think she is pretty succesful.
          Will you come to the Dutch Woodenboatshow in Den Helder next weekend? There will be raid people, and I would like to meet you.
          Frank

          Comment

          • luckystrike118
            Power Kraut
            • Jan 2010
            • 154

            #6
            Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

            Frank,
            of course I know the GIS, I have built one for a customer and sailed it too. To be honest ... on that GIS I have made my first experiences with a balanced lug sail. The Hull of the GIS is a very good example for a modern light displacement hull and the performance possible with the sharpie form. And of course she planed with two crew, not with all that cruising stuff on a raid, but while daysailing and a good wind ... sure she did!
            But the GIS is not designed as a cruising boat, it is a daysailer. It lacks all the details that makes sailing safeer and more comfortable, mentioned above in my first post.

            Next weekend I will meet my girlfriend in Wilhelmshaven. We live separatly and meet every second weekend. I will have to check first if we make a jaunt to Den Helder. Do you already know on which day(s) you will be at the festival?

            Even if I cannot visit the festival, we can chat about designs privatly and meet later.

            Have fun! Michel
            Last edited by luckystrike118; 06-29-2019, 07:35 PM. Reason: correction

            Comment

            • Joost Engelen
              Member
              • Aug 2016
              • 87

              #7
              Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

              Originally posted by luckystrike118
              Hello Frank,
              yes, Michael Storer designed a raidboat a few years ago and two prototypes (as far I know) were built. They had serious problems, so Storer decided not to offer plans for the boat. His design was more a slim sailing canoe and built super light to be carried on top of a car. Afterwards he made no futher attempt to devellop a dinghy for cruising and raids.

              I focus on sailing stability and safety, in my opinion very important features in a cruising dinghy.

              Have Fun! Michel
              One of the boats (the US one) was actually sailed by Michael Storer and I understand that the boat handled well and sailed fast. Two links to videos (in the second video Michael Storer is at the helm):

              Michael Storer's brand new Raid 41 seconds after it's first launch at the 2009 Texas200. It was built and is sailed here by Brian Cull.


              https://www.youtube.com/watch?v=I6aBw_-kmuc


              Michael’s comments were: “The boat was not a complete success. It was too hard to get back aboard after a capsize, but it is as nice to sail as the Goat Island Skiff, goes smoothly and quickly upwind and planes away downwind.”

              Due to the double floor, the sides became very high making it difficult to re-board the boat after a capsize. But perhaps some alterations (lower the sides and leave out the double floor) would have fixed this. That would have meant a big job (complete re-design!) and the project was shelved for not working consistently enough.

              Comment

              • Joost Engelen
                Member
                • Aug 2016
                • 87

                #8
                Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                I can confirm that the Goat Island Skiff readily planes, also with two persons aboard (and with light camping kit), when the conditions are right. I agree that there is limited space for carrying gear and that sleeping on board is very difficult (it has been done, but I would never consider doing this myself). Hence your proposition for a raised deck forward and the double floor, I guess, to take care of these 2 issues.

                To my eyes, the hull shown above shows much resemblance to the GIS save for the reverse bow, reverse transom and the reverse sheer. Obviously there is only so much one can do for a performance boat having a sharpie hull shape.

                Comment

                • luckystrike118
                  Power Kraut
                  • Jan 2010
                  • 154

                  #9
                  Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                  Hello Joost,

                  you wrote: your proposition for a raised deck ...

                  My design will not have a raised deck, my fault. I have chosen the wrong term due to a little confusion while writing the very long first post. The correct term ist raised floor, I have corrected this in the post.


                  you wrote: Obviously there is only so much one can do for a performance boat having a sharpie hull shape.

                  A designer once wrote: "Sharpie hulls are easy to build, but difficult to design"

                  This is true. I'am studying sharpie hulls for more than 10years now, for monohulls and multihulls alike. And you are right! If you want to transfer a modern, performance (planing) orientaded hull shape into a sharpie hull you are very limited in the shape of the all important bottom panel. You want to have a broad stern for planing, but the boat must behave like a sharpie in displacement mode (upwinds). That means the forefoot must be out of the water, otherwise you have massive resitance from turbulence around the chine forward. And there are half a dozen other design aspects you have to take care of and that must be done right.

                  Regards, Michel
                  Last edited by luckystrike118; 07-01-2019, 09:24 AM.

                  Comment

                  • Bill Door
                    Junior Member
                    • Apr 2019
                    • 8

                    #10
                    Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                    Originally posted by Joost Engelen
                    One of the boats (the US one) was actually sailed by Michael Storer and I understand that the boat handled well and sailed fast. Two links to videos (in the second video Michael Storer is at the helm):

                    Michael Storer's brand new Raid 41 seconds after it's first launch at the 2009 Texas200. It was built and is sailed here by Brian Cull.


                    https://www.youtube.com/watch?v=I6aBw_-kmuc


                    Michael’s comments were: “The boat was not a complete success. It was too hard to get back aboard after a capsize, but it is as nice to sail as the Goat Island Skiff, goes smoothly and quickly upwind and planes away downwind.”

                    Due to the double floor, the sides became very high making it difficult to re-board the boat after a capsize. But perhaps some alterations (lower the sides and leave out the double floor) would have fixed this. That would have meant a big job (complete re-design!) and the project was shelved for not working consistently enough.
                    I thought the problem was that he made the sides high enough to row comfortably without raised oarlocks. If making it a more pure sailing design, lowering the sides alone should alleviate the problem.

                    Comment

                    • Ben Fuller
                      Senior Member
                      • Jan 2000
                      • 4470

                      #11
                      Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                      There has been a Windmill design modification that meets most of the criteria that the OP posted. Michael Jones in St. Petersburg Florida who apprenticed years ago with Clark Mills. Boat is called MALU. http://www.jonesboatworks.com/malu/. A bit bigger and with side tanks as proven to work with Windmills, where the double bottom gave problems self rescueing.
                      Ben Fuller
                      Ran Tan, Liten Kuhling, Tipsy, Tippy, Josef W., Merry Mouth, Imp, Macavity, Look Far, Flash and a quiver of other 'yaks.
                      "Bound fast is boatless man."

                      Comment

                      • Joost Engelen
                        Member
                        • Aug 2016
                        • 87

                        #12
                        Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                        Originally posted by Bill Door
                        I thought the problem was that he made the sides high enough to row comfortably without raised oarlocks. If making it a more pure sailing design, lowering the sides alone should alleviate the problem.
                        Correct. But the raised double floor meant that the hull sides had to be made higher than normal as to maintain a normal rowing position. Leave out the double floor and the height of the sides can go down quite a bit.

                        Indeed if you would leave out rowing, the height of the hull becomes less of a consideration. But than again the Raid41 was conceived as a raid boat and rowing is normally a vital requirement in the sense of having solid secondary propulsion. Further a very wet boat does not make for a good Raid boat (not very comfortable on long sails).

                        Comment

                        • luckystrike118
                          Power Kraut
                          • Jan 2010
                          • 154

                          #13
                          Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                          Hello,

                          Malu is not relevant to this thread, it is designed as a daysailer, not a raidboat

                          *in this post I will use the term "raidboat", meaning raidboat and cruising dinghy alike, I think its the same breed.*


                          I agree that high sides are better for dry sailing and this is a important feature in a raidboat.

                          I think we are closing to main problems of raidboatboat design... (apart from secondary propulsion, important but not so impotant as...)
                          1. prevent capsize
                          2. recovering from capsize
                          3. self resuing

                          In my opinion and with my experiences in sailing dinghys...

                          1.1. slim boats like the raid 41 (well under 4' wide and with rectangular sections) capsize more easely and faster. A wider boat gives you more time to ease the mainsheet and prevent capsize. You also have more leverarm when hiking out, making hiking more effective.

                          2. 1. side flotation tanks let the capsized boat float high and make it more prone to capsize fully to 180° ... opposit to floating stable at ~90° when the hull partly sinks in.

                          2.2 The absence of side flotation tanks let the boat sink into the water to a certain point and the amount of water in the cockpit slows the motion when the boat is re-righted. This gives you more time to re-enter the cockpit immediatly when the boat becomes upright again.

                          3.1 A double floor makes the boat self bailing, I think this absolut important not to have to bail out the boat before you continue sailing. If it is all possible to bail out water, while you try to balance the boat and waves send you water in all the time.
                          https://www.youtube.com/watch?v=l6YZyY4e-H0
                          https://www.youtube.com/watch?v=8UoyhIJe_L0

                          3.2 If you are exhausted from re-righting it could not be wong if the boat floats stable (empty cockpit) and you have a boarding ladder at the stern.

                          Have fun, Michel
                          Last edited by luckystrike118; 07-03-2019, 09:50 AM.

                          Comment

                          • luckystrike118
                            Power Kraut
                            • Jan 2010
                            • 154

                            #14
                            Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                            Round 3 in the design spiral
                            further improvements in hydrodramatics and the double bottom is in

                            Raidskiff4.jpg

                            Comment

                            • Plyboy
                              Senior Member
                              • May 2016
                              • 441

                              #15
                              Re: A new Raidboat and Cruising Dinghy Design for the Home Builder

                              I'm just looking at the Bolger June Bug and thinking, "Heyyy, what if you scaled this up 10-15% for a beam more friendly to 2 sleepers...."
                              2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

                              Comment

                              Working...