Sailing/rowing/motor sailing dinghy decisions.

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  • BOI
    Senior Member
    • Jul 2015
    • 282

    #31
    Re: Sailing/rowing/motor sailing dinghy decisions.

    Originally posted by James River Rat
    I have a Dyer 12.5 that is a Rhodes design.
    Originally built in cold molded ply.
    Dyer still makes this boat.
    Rows superbly for a bigger boat. sails great.
    Two position mast so cat boat or sloop at your option.

    Powers only so so due to rocker at stern allowing the bow to rise with added power. [ATTACH=CONFIG]25578[/ATTACH]
    I don't sail, so look at Paul Gartside's lugsails for lugsail ideas; they are highly peaked. They do have a boom, but a crutch attached to the side of it so the boom locates on the mast without either a vang or preventer. Todd Bradshaw has described this feature as "underused". On some of his rowboats Paul Gartside also has boomless dipping lugs for offwind sailing; they are meant to be boomed out with an oar.

    About your hull:

    I like the boat in the picture above a lot and it gives you a clue as to how to design a chine boat with a chine that runs high in the bow and peters out before you get to the bitter end. There is a very similar boat called Martha's Tender, drawn at ~9' or 10' has been successfully lengthened to 12".

    To me this is a vast aesthetic improvement over that prominent chine low at the bow, but they say beauty is in the eye of the beerholder.

    Without even knowing about this Dyer 12.5 I've come up with a similar design (also using Freeship) to be built at 10' length in origami stitch and glue technique. So far a 1:8 scale model made from 1.5mm plywood has proven the concept, but the bow was a bit of a struggle. The full size panels out of 4mm Meranti plywood are lying scarfed up on my basement floor, not yet together. A 12' boat of similar proportion could probably be built out of 1/4" or 6mm ply, if not the 5 layer marine ply (stiff), then the "Home Depot" 3 layer ply, sheathed in fiberglass on both sides. I totally get Paul Gartside's ideas about saving tropical hardwoods, expecially for an experimental boat.

    Don't use underlayment to test the shape; I've got a cheap streak and worked with enough of that stuff to know that it rarely has the veneers approaching anything like equal thickness. This makes it bend quite differently from ply with more even veneer thickness.

    Just buy a couple sheets of 1/4" good one side fir or whatever, make sure it has waterproof glue, cut the front 8' of the boat, drill, zip tie it up. If the shape comes together take it apart, scarf on the last 4', make it your boat. If it doesn't work, go back to Freeship for a redesign.

    In that style of hull here is plenty of curvature in the bottom panel, both rocker and twist, and is should be plenty stiff. If this forum is to be trusted, the glass inside and out will confer better abrasion and impact resistance than one layer on the outside alone.

    Some high density plastic wear strips on the bottom wouldn't go astray if you are planning on dragging it on the ground. So far I've used that stuff only on dog sled runners but it will go on any boat I build for use in the real world, they call this island The Rock for a reason.

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    • WI-Tom
      Seaside Expat
      • Jan 2009
      • 15902

      #32
      Re: Sailing/rowing/motor sailing dinghy decisions.

      Originally posted by Andrew2
      The Drascombe range mostly have boomless mains and also have a reputation for poor windward ability.
      Tortoises have four legs and also have a reputation for poor land speed ability.

      Tom
      Ponoszenie konsekwencji!

      www.tompamperin.com

      Comment

      • Edward Pearson
        Senior Member
        • Dec 2015
        • 2208

        #33
        Re: Sailing/rowing/motor sailing dinghy decisions.

        Booomless sails work perfectly to windward, provided you have sweated the sheet lead position, rigging, sail cut etc. Just look at a jib/ genoa: it's doing most of the work to windward. Correctly set, you will have the perfect blend of foot and leach tension/ twist. Additionally you don't have the weight or turbulence of the boom. Nor flattening of the bottom of a laced on sail. A standard mainsheet is a compromise position for the sake of simplicity: upwind you are getting disproportionate leach tension as you sheet in. You should also be able to extend the sail down a bit if your looking for area, as there isn't a boom to hit you. I would consider stays on the mast - that allows a lighter mast, and enables a taught sail. If you want to get to windward, you want a taught luff - as a mast bends the luff looses tension.

        Fundamentally ultimate power to windward is a function of luff length and that's the compromise if you don't sail a stayed bermudan sloop rig, and take benefits from another rig. Since a boomless mainsail like on Ilur is a fit and forget item, you could argue that you may as well make it out of reinforced shaped mylar rather than 'adjustable' dacron, it's just the asethetic doesn't match!

        An alternative approach on a boomless sail is to have a squared off clew with a clew board with three diagonal positions for the sheet attachement. That gives you three different sheet angles up for low, medium and high wind speeds: to alter the foot to leach tension proportion. The self tacking jibs on high performance dinghies do this. It's simple, cheap and easy for the days wind.

        Two sails are more efficient than one, and a jib is especially efficient to windward for its area, but for a simple boat and simple solo pleasures (not to mention less cost) I'd favour a single mainsail, at 12ft. A mast that ends up a bit longer than the boat makes a good cover ridge pole, but if it must fit in and be boomless, also look at a sprit rig: it's got the shortest spars for an area. If you must have a jib, sheeting an unstayed sprit in simultaneously tensions the forestay for upwind work, which is clever. I wouldn't worry about reefing - just don't over canvas it and at 12ft your body weight adds alot of weight on the rail. A simple small boat will likely only be used in ideal weather conditions. One reef would be more than enough.

        If you do use an engine, make sure you have a long tiller extension to fit it, as you will need to get your weight well forward to compensate for the aft engine. On that score the top of your transom at the engine mount will be defined by your engines immersed leg requirement - you will need to find out your shaft length/ look in the manual at the design stage, and consider engine trim angle. You would only need a light low power unit.

        Your optimum 12ft'er for sail, row and motor might be something like an Oughtred Gulliemot with the brailing single standing boomless lug fishermans sail option - it would be straight forward from a plank kit. I know you want to design your own boat single chiner, just sayin! It's nicer to own and easier to resell a beautiful thing.



        Also be aware that if you're not physically size limited to 12ft, a 15ft boat requires no more scarfs per plank in construction from 8ft sheets.
        Last edited by Edward Pearson; 11-02-2018, 05:48 AM.

        Comment

        • skaraborgcraft
          Banned
          • Jan 2010
          • 12824

          #34
          Re: Sailing/rowing/motor sailing dinghy decisions.

          The loose footed sprit main on my old snipa, was well positioned for going upwind, in that the beam of the boat aft was rather narrow, but that meant the sheeting angle was wrong for off wind work. After trying a balanced lug rig (with boom) on the same mast, i never went back. Not suggesting its perfect, but good all-rounder.

          Comment

          • marujo.sortudo
            Senior Member
            • Nov 2009
            • 207

            #35
            Re: Sailing/rowing/motor sailing dinghy decisions.

            With a boomed sprit there is a simple emergency reef where you remove the sprit and it top of the sail flops over in the lee. Boomless sprits with brailing lines are wonderful when it comes to putting sail away quickly without shifting weight forward. Of course, the main benefit of a sprit would be shorter spars. I think you'll probably be very happy if you go with the lug for all the reasons mentioned.

            Comment

            • 109jb
              Member
              • Sep 2018
              • 37

              #36
              Re: Sailing/rowing/motor sailing dinghy decisions.

              I've been doing a lot more thinking, making up sail plans, researching and I think I've settled on a sail plan. Well, sort of.

              First off, I decided to just keep the mast as short as possible, but if it winds up to long to store inside the boat then that's just how it will have to be.

              In regard to boomless lug sails, There are a lot opinions about them running the gamut from "they're great" to "they suck". Most of the "they suck" opinions seem to come from those who desire the utmost performance from their boats, and the "they're great" crowd favors ease of use and are willing to sacrifice a little performance. I guess I don't mind sacrificing some performance, and see enough of the pros that I want to give one a try. I may not stick with boomless, but I at least want to experience it.

              The 3 sail plans below all use the same mast, yard, and mast location. The plan on the right uses a scaled version of the boomless standing lug sail Todd Bradshaw designed for an Argie 15 builder with the addition of a small jib. I'm going to start with this rig initially to decide if I like it. If I do it ends there.

              12 Dinghy 11-3-18.jpg

              If after sailing the boomless lug I decide it isn't for me, I can move to one of the two plans on the left. The only real difference between these two is the main sail area. I think for a little boat like this, the 67 sq ft main shown in the center should be enough, but the a main in the one at left is a little bigger.

              As for the jib, I'm going to try running it without mast shrouds at first. I think it may work based on the laser pico which has a similar sized jib on an un-stayed mast. Time will tell. If it doesn't work I'll just add dyneema shrouds.

              My plan is to first build using lumber store plywood so that if this thing is a turd I don't have too much invested. For that one I'm going to use a centerboard box that allows me to shim the centerboard either forward or aft within a 1 ft range to allow for the different CE from each of the sail plans and to find the best location for it. I'll be able to hack on it and try it out with the motor, and oars, etc.

              Getting back to the hull, I originally designed it with the V-hull cross section in the picture below, but am considering re-designing it with a flat bottom cross section similar to the one shown. I would use the flat bottom all the way to the transom. I'd like to hear opinions on which one would be better. Some experimenting in Freeship indicates that I should be able to get a better shape on the bow.

              cross section.pngFlat bottom.jpgFREE!ship linesplan.jpg

              Comment

              • 457277
                Member
                • Dec 2012
                • 36

                #37
                Re: Sailing/rowing/motor sailing dinghy decisions.

                The flat trapeze bottom is the best choice. I use it on all my plywood designs.

                JS
                sassdesign.net
                www.sassdesign.net
                I'm not lost, I'm just uncertain of my position.
                I'm still confused, but on a higher level

                Comment

                • Woxbox
                  Senior Member
                  • Feb 2006
                  • 9923

                  #38
                  Re: Sailing/rowing/motor sailing dinghy decisions.

                  I like everything in the plan except the fact that the leech on the jib will forever tangle with the yard. A longer bowsprit?
                  -Dave

                  Comment

                  • 109jb
                    Member
                    • Sep 2018
                    • 37

                    #39
                    Re: Sailing/rowing/motor sailing dinghy decisions.

                    Originally posted by Woxbox
                    I like everything in the plan except the fact that the leech on the jib will forever tangle with the yard. A longer bowsprit?
                    I was so focused on getting the main worked out that this slipped through the cracks. I took a quick jab at it as shown in the picture below. I lowered the head a bit, extended the foot, and put some hollow in the leech but left the bowsprit the same length. I think this would work and only lost about 1 sq ft, which I could get back by extending the bowsprit just a few inches.
                    jib mod.jpg

                    Comment

                    • amish rob
                      Emperor For Life
                      • Mar 2010
                      • 24274

                      #40
                      Re: Sailing/rowing/motor sailing dinghy decisions.

                      The five panel boat looks dope. Five panel boats work pretty well, for how simply they are made.

                      If the loose footed sail doesn’t work out, you can always just clap a sprit boom on her, like a sharpie sail. Nothing to adding one except a snotter...

                      Peace,
                      Robert

                      Comment

                      • Canoeyawl
                        .
                        • Jun 2003
                        • 37705

                        #41
                        Re: Sailing/rowing/motor sailing dinghy decisions.

                        Originally posted by Andrew2
                        The Drascombe range mostly have boomless mains and also have a reputation for poor windward ability.
                        Having fitted a Drascombe boat with a proper boom, I think the poor windward ability can be attributed to the flat steel plate centerboard and rudder.
                        That and they are handicapped by waterline length.

                        Comment

                        • mohsart
                          Senile Mumbler
                          • Mar 2014
                          • 1066

                          #42
                          Re: Sailing/rowing/motor sailing dinghy decisions.

                          Originally posted by WI-Tom
                          [...]also easy reefing (which the spritsail doesn't do).[...]
                          I have yet to see an explanation of how that is so.
                          It is often stated as a fact, but I have, despite explicidly asked for it, never seen any proof.
                          Fact is that one reef can be taken in on a sprit sail quite easily, under way; I have done it several times and it takes less than a minute.
                          As for simplicity, there is a huge misconception that a sail needs to be hoisted, with a small boat the sail can be laced permanently to the mast and the mast and sail taken down together. With a larger boat/sail the sprit sail can be belayed to the mast instead of taken down.
                          Personally I can not see how it can be any easier.

                          /Mats
                          sigpic
                          Diagnosed with autism. Sorry, not much I can do about it.

                          Comment

                          • mohsart
                            Senile Mumbler
                            • Mar 2014
                            • 1066

                            #43
                            Re: Sailing/rowing/motor sailing dinghy decisions.

                            I should add that I am genuinly interested in why lugs are supposedly so much easier to reef/handle than sprit sails. I am by no means advocating that sprit sails are superior.

                            /Mats
                            sigpic
                            Diagnosed with autism. Sorry, not much I can do about it.

                            Comment

                            • mohsart
                              Senile Mumbler
                              • Mar 2014
                              • 1066

                              #44
                              Re: Sailing/rowing/motor sailing dinghy decisions.

                              Originally posted by marujo.sortudo
                              With a boomed sprit there is a simple emergency reef where you remove the sprit and it top of the sail flops over in the lee
                              A boom is not needed for this.

                              /Mats
                              sigpic
                              Diagnosed with autism. Sorry, not much I can do about it.

                              Comment

                              • WI-Tom
                                Seaside Expat
                                • Jan 2009
                                • 15902

                                #45
                                Re: Sailing/rowing/motor sailing dinghy decisions.

                                Originally posted by mohsart
                                I should add that I am genuinly interested in why lugs are supposedly so much easier to reef/handle than sprit sails. I am by no means advocating that sprit sails are superior.

                                /Mats
                                I've sailed both, but have far more time with lugs and they sure do reef easily. I think the problem with reefing spritsails is that as the sail is reefed, the heel of the sprit eventually gets low enough to hit the foredeck or otherwise cause problems. You can rig it to get around this, but it's an added complication compared to lugsails. I can see how taking one reef in may not be enough to cause that problem, but it's not unusual for me to sail with 2 or 3 reefs in.

                                I'm aware that spritsails don't need to be hoisted; I always kept mine laced to the mast as you describe.

                                It can also be a little pesky to keep the tip of the sprit attached to the sail while reefing or deploying the sail.

                                I have never heard of anyone who has sailed both spritsails and lugsails who finds spritsails easier to handle. But I like spritsails. I just like lugsails a lot more.

                                Tom
                                Last edited by WI-Tom; 11-04-2018, 07:23 PM.
                                Ponoszenie konsekwencji!

                                www.tompamperin.com

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