Jump to content

Designer

Members
  • Content Count

    1,525
  • Joined

  • Last visited

  • Days Won

    87

Designer last won the day on December 23 2018

Designer had the most liked content!

Community Reputation

177 Excellent

1 Follower

About Designer

  • Rank
    Advanced Member
  • Birthday 01/01/1

Contact Methods

Profile Information

  • Gender
    Not Telling
  • Location
    Vandemere, NC

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Designer

    Core Sound 20 Mark III #3 "Jazz Hands"

    Steve, I think that I figured out why the enlarged view gave the 4" measurement. The enlarged view was scaled by 2 and the dynamic dimensioning turned the 2" into 4". We have had some issues with sprits being too short. We have been adding hardware along the way to make rigging quicker and each link we add requires a few inches more sprit. Because the sprit slopes down aft at about 30 degrees, if the snotter is higher on the mast or the sail is not hoisted to the top, it makes the sprit angle down more which requires a longer sprit. I think that we had lengthened the sprits by the time that plan sheet was drawn. I would finish rigging the sprits as you have them and go sailing. If you cannot flatten the sails enough, I would just scarf some wood on the aft end.
  2. Designer

    Core Sound 20 Mark III #3 "Jazz Hands"

    Steve, Good catch. I did not see the 4" but I did see the 2" and commented that it should be less. I like to put the clew eye strap as far aft as I can as long as the aft fastener cannot pull out of the end grain,.There is no point in carrying around extra sprit for nothing. The exception is Carlita's mizzen sprit that was extended for the mizzen sheet to clear the wind vane. By moving the eye straps as far aft as possible will give you as much sail adjustment as the sprits will allow.
  3. Designer

    dutch OB 20

    Jan, I like that thin layer of glass on the inside of the planking. It helps to prevent water from getting into the ply and it adds stiffness to the skin and adds to the impact strength. Yes the 120cm wide fabric will be perfect. Hightechmarine brings up an important point. I do not know what radius your fabric will wrap around without bubbling so I would do a test sample. I tell everyone that the round of a pencil is the minimum that you need. It is really annoying to see bubbling on either side of the chine corner. If it does happen, I have been able to save it with peel ply. If you do not have peel ply some clear plastic is worth a try. It does not always work but when it starts to bubble there is nothing much you can do but repair it later and wished that you had made a bigger roundover. The down side is that the sharper you can make that chine edge the more efficient and drier it will be. I build the rounded over chine corner back to a sharp edge with colloidal silica thickened epoxy. If you have any milled fibers, I would add some to the mix. The rounded corner allows the water to wrap around the chine instead of breaking away clean. Dave, My guess is that being about half the weight and thickness, the ding resistance will be about the same as 10 oz glass. While we are on the subject, sheathing the outside does not add much to the stiffness to the planking. Glass on the inside does and adds to the impact strength but does nothing for ding resistance. The reason is that the forces are generally inwards putting the planking under tension. Glass fibers have much more tensile strength than wood fibers. Sheathing on the outside will be in compression and the thickness of the glass is quite thin so does not add much extra thickness to the planking. Thickness increases stiffness in all materials.
  4. Designer

    dutch OB 20

    Oyster makes good points. I have never had much trouble wetting out carbon but the thing that bothers me is that it does not change color like glass and you never know for sure if it is properly wet out as it is still black. I just over work it to make sure that it is done. fortunately at 5oz it wets out easy.
  5. Designer

    Dawn & Paul’s CS-20 MK3 #16

    Maybe Chick missed the point. These are copies and are not printed on B&B printers. But on the other hand Chic has already received the help on his previous boats without the formality of a coupon.
  6. Designer

    dutch OB 20

    Seeing that I designed the boat and specified the sheathing material I thought that I should comment. There are three main considerations that I wanted to meet for sheathing the hull as well as the cost and weight and availability. I specified 10 oz (400 g/m2) finish cloth which meets all three points adequately. This does not mean that is the only choice. I see that our builder has gone up scale and bought a more exotic cloth. I do not have the mechanical properties for it except that it is half the weight and we know that it is stroger thickness for thickness. My guess is that it will be strong enough. The most important part is the chine joint which holds the boat together. I specified two layers of 10 oz glass (400 g/m2 inside and out over the chine joint by 2 1/2" (6cm) including the chine flats. This gives an adequate safety margin allowing for the variables of home built and qualities of glass and epoxy. I felt that it would be practical if the bottom was glassed 2 1/2" passed the chine first, the edge sanded to a taper and then the sides were glassed down over the chine and chine flats br 2 1/2". Laying the glass this way would meet the strength requirement of the chine and have no seams to fair and later print through on the shiny sides. I see that the spec. sheet shows that the fabric is a meter wide. It is just a bit too narrow to reach 6 cm up the sides and lap the keel in the center of the boat, I would lap the chine by 6 cm and patch the gap at the keel line. The second consideration is ding resistance. I think that this fabric should as well as the 10 oz glass. The third factor is keeping the moisture out of the wood. Wood does not rot if the moisture content is kept below about 22%. Epoxy is the best vapor barrier that we have but it is not 100% vapor proof. With all semi permeable membranes more thickness is always better. Keeping the wood dry under the epoxy also reduces movement of the surface which reduces print through in the paint. So how does our carbon kevlar fabric stack up against our low tech glass fabric? I think that it is equal or maybe a bit better in 1 and 2 and is lighter which is always a good thing. I think that glass comes out a bit ahead in three. It does cost more but some of this is offset by using less epoxy. Kevlar does not feather well, it just fuzzes up when you grind it. Fortunately it is not too thick and you may just have to fair it just with fairing compound. If I inherited this boat I would be happy with the choice. If I was building the boat I would choose glass. I agree with the previous post and lay the fabric dry and wet out through the fabric. This allows you to keep the thread lines nice and straight which is important foe maximising the mechanical properties. It is easier because the fabric is perfectly and trimmed in advance so that once you start mixing epoxy it takes less time and there are no distractions.
  7. Designer

    Dawn & Paul’s CS-20 MK3 #16

    Chick, Yes the coupon is valid and will be honored by B&B for members of the family which includes you. You just need to present a valid coupon printed on a B&B printer.
  8. Designer

    Building a Two Paw 8 for Trailer Camping

    Don, I use anything that will hold the panels in place until I can get some epoxy into the joint. Just because we show the ties nicely spaced, you do not need to put in a tie if you do not need it. We will double up the wires in the forward most holes in the chine where there is a lot of force. The transom to bottom joint has no force at all so anything that will hold it together until the epoxy dries is good. Just use your judgement.
  9. Designer

    Island cruise

    Bill, You are making us jealous, it has been cold and wet over here. I was just thinking about Petunia the other day and wondering if you were back in Baja.
  10. Designer

    Core Sound 20 Mk. 3 #22 - Essex Fells, NJ

    You are welcome. I would rather you ask these questions rather than guess wrong and mess it up. It also helps us to see where we might need more clarification. We agonize over wording and where to put emphasis. I am like most people that if an instruction is too wordy or difficult to understand I will try to work it out for myself.
  11. Designer

    Core Sound 20 Mk. 3 #22 - Essex Fells, NJ

    You are way overthinking this. Dowels will be on the neutral axis when there is any side loading on the joint and therefore do not contribute much. In fact I can think of situations where dowels are weaker. The two layers of glass contribute way more strength to the joint. The object of the thickened epoxy is mainly to hold the lead tip and the board together so that you can work on it. It also fills any mynor gaps or voids. Because the lead surface being bonded is smooth, it is always a good idea to sand the surface to improve the bond. You have to glass the wood part of the board, it is no extra work to carry the glass about 4" or 5" past the lead joint. You could call it done and you should be fine but we added the extra 6" wide layer just as a safety factor. The exact overlap is not critical, just make sure that bottom edge of the glass sheathing is about an inch below the 6" tape lower edge. In case you are skeptical, Southern Skimmer has used that same centerboard joint in many Everglades Challenges and many other sails. The joint looks as good as the day it is done except that the leading edje shows a history of hitting the bottom. This is why you should not glass all around the tip like a footie. Lead makes a wonderful chafing or wear tip whereas glass is not very good. When I bond the lead to the board, I clamp the board vertically so that the lead can sit on top. I clamp 2 pairs of small pieces of wood vertically, one pair forward and one pair aft on the board so that they stand up past the lead. The lead is tapering and the wood temporary clamps will not fit tight to the lead but it makes sure that the lead cannot fall over or move out of position but more importantly you can measure the gaps between the wood clamps and the lead on each side to make sure that the lead is straight. Just be sure to put some tape or plastic on the wood clamps near the joint so that you do not glue them to the board. Clean up the squeeze out. The only other tip I can think of, be careful if you use a grinder to shape the lead to the wood after it is bonded. I did this once and the transfer of heat into the lead was instantaneous, the epoxy softened and the tip fell off. This should not be a problem for you as I recall that your lead is a pretty good fit. If there is any mynor fairing to be done at the joint, it is better to hand sand and or fair the joint with epoxy. Good luck with the project.
  12. Designer

    Core Sound 20 Mark III #3 "Jazz Hands"

    Congratulations Steve. It is great to see her outside at last. What people do not understand is that if you have what it takes to get this far you surely have what it takes to get the boat out. At the beginning, it reminded me a little of that old British song from the 60's, just kidding but it is fun.
  13. As has often been seen in this forum, many of the builders share their mistakes unabashedly with the world. In most cases it is just a matter of making a few adjustments or redoing a job and at worst, some time and materials have been wasted. It does help to educate the builders who follow and it is well taken by experienced builders who have made their share of mistakes with a “brother’s in arms” attitude and often share some of their mistakes. In the spirit of sharing information here is one of my screw-ups. As a professional, we don’t make mistakes! I wish that that was true. We just make different mistakes. One of my short comings is being too familiar and do things for myself that I would never do for anyone else. I am currently redoing my inside port rings on Carlita. I love the design and they have worked perfectly and look really good. For some reason our marine wholesaler who supplies most of our marine fasteners does not carry #10 x 32 flathead machine screws. They have to be that size to fit the rivnuts already installed. I did not get around to outsourcing the screws until I was rushing to get ready for the Everglades Challenge. I asked Carla to pick some up for me at the local Ace hardware and installed them. By the time I got back from the EC I noticed that a couple of screws were starting to rust. I replaced them in time but last year I noticed some more were rusting and put it on my mental list to do. While rushing to get ready for my Port Townsend trip I forgot to change them out and planned to do it when I got back. The screws kept nagging at me and I finally got serious about them before the last messabout and discovered that I could not unscrew four of them. I put it off until after the messabout because I did not want to risk putting her out of commission. I tried to unscrew them again last week without success. I sicced Alan onto them with the same result. My last resort was to remove all of the willing screws and pry out the ply rings forcing them to break at the seized screw and then grab them with vicegrips. It worked well until the very last screw which twisted off. Luckily I made the original cut files for the ports and it was only a matter of putting some 9mm scrap on the CNC machine and I cut out a new set of rings. They now need their inside edges to be rounded over with 5/16” roundover bit, sand them and epoxy coat and varnish before installing. I still have to solve getting out the sheared screw first. I ordered up some 316 grade machine screws because I do not want to do this again. We magnet tested the old screws and the rusted screws jumped to the magnet. The rest of them were mildly magnetic. Of course the new 316 grade screws were not attracted to the magnet. Had I bothered to magnet test the original screws, I could have taken the bad ones back and had them replaced. You can see the two left screws were steel with the lower one sheared off. The right screw was also steel. The next pictures shows one of the original with a new 316 grade screw. The other picture is the broken out ring. I do not know why so many screws were bad but they were in self service bins and perhaps some steel screws were returned and put in the wrong bin.
  14. I have been wanting to do this for a long time to speed up my packing up and unpacking the boat but other jobs had priority. I watched Jay packing up his rig and he inspired me to get it done. I measured the gap between my two masts in their trailing position which turned out to be 1 1/4". The main mast being in the tabernacle puts the track down and head aft. I elect to stow the mizzen mast with the track facing up and head forward. This makes the masts about level athwarts where the crutches need to be for stowing the sprits even though the tracks are on opposite of the mast. This is because the mast diameters are apposite where each of the sprit crutches need to be. I made the crutches out of 3/4" ply and it takes about 3 feet of 1/4" shock cord for each crutch. It takes just seconds to move the loop of shock cord under the masts while gathering the rigging and passing over the top of the sprits and putting the loop into the slot. There is no tendency for the crutch to fall over and the setup is very firm when both shock cords are secured. Like Jay and Chick, I leave all of the lines attached except for what I need to undo to remove the sails. Where I differed is not pulling the sprits up the masts but let my snotters go to the stopper knots. This puts them on the deck making the masts easier to lower. If anyone wants I can email them a pdf of the crutch shapes, they can adjust it to their mast stowage setup. I have not sealed them yet. I will pad the bearing surfaces when they are coated.
  15. Designer

    dutch OB 20

    Hi Jan, Welcome to the forum. You are doing very nice work. Thanks for sharing the pictures. I am looking forward to watching her grow.
×

Important Information

By using this site, you agree to our Terms of Use.