The Melatelia: light wind dinghy

Discussion in 'Boat Design' started by laukejas, Mar 20, 2015.

  1. tdem
    Joined: Oct 2013
    Posts: 130
    Likes: 5, Points: 18, Legacy Rep: 41
    Location: NZ

    tdem Senior Member

    Hey Laukejas, really enjoyed reading that. I think your writing focuses on the important and interesting parts, without excessive detail. Very good.

    One thing I'm still wondering is, do you know if you met your target weight?
     
  2. laukejas
    Joined: Feb 2012
    Posts: 766
    Likes: 19, Points: 18, Legacy Rep: 128
    Location: Lithuania

    laukejas Senior Member

    Thank you for your compliments, tdem. As for the weight, I really do not know yet: I haven't been able to find a way to weigh the boat. Surely it could be placed on a standard scales for people, but somehow I didn't come across them.

    However, judging from the ease of carrying the boat, I'd say the weight must be pretty close to 30kg. There is absolutely no difficulty carrying and car-topping the boat with a helping set of hands. For it's size, the boat feels like being made out of cardboard - light as a feather. Even if I did go overweight, it can't be more than a few kg.
     
  3. sharpii2
    Joined: May 2004
    Posts: 2,246
    Likes: 329, Points: 83, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    I also liked your articles. And I agree they were quite interesting and to the point.

    A particular point of interest to me is the transom failure. I take, from reading the article, that you hit the rudder while diving overboard to rescue a fellow sailor, who's boat capsized, and the blow was transfered to the topsides/transom joint.

    I'm wondering. Did the glue joints fail? Or did the wood at or near the glue joints fail?

    I'm surprised the Tyvek sail performed as ell as it did. It enabled you beat a few other boats even.

    Good to hear from you.
     

  4. laukejas
    Joined: Feb 2012
    Posts: 766
    Likes: 19, Points: 18, Legacy Rep: 128
    Location: Lithuania

    laukejas Senior Member

    Thank you for your compliments, sharpii2. Indeed, as I was jumping out of the boat, hoping to splash in the water, I tripped and landed on the rudder box instead. All my weight (80kg, wet clothes and life vest) plus movement inertia. Something was bound to break. The thing is, the rudder box is made like a tank, it is so strong I think it could almost survive a car driving over it. And the rudder hinges that attach box to the boat are made from gate hinges, that is 3mm thick and 5cm wide steel, with hinge diameter of 13mm. I know that is grossly oversized, but with no sailboat hardware to buy in my country, this was the next-best option.
    So, the weakest link in the chain was the transom. As you can imagine, landing on the rudder created a pivoting force, pulling the top of the transom away from the boat. Since I never intended for the transom to suffer such impact loads, the joints between transom, chines and side decks were made only with epoxy fillets, no woodscrews. There are several wooden pieces running along on the outside of the side decks (you can see them in photos), but they feature no woodscrews either (due to hard accessibility to install them). I could have at least screwed these to the transom, but somehow that slipped my mind during the building.
    When the transom failed, epoxy stayed intact. It was the wood that failed, right at the glued joint. If you zoom in on one of the photos, starboard side, you'll see what I mean.
    When I repaired the transom, I dried it out (since a lot of water rushed in to the cracks), poured unthickened and thickened epoxy inside (as much as I could stuff in) and then clamped the whole thing with clamps and woodscrews. I think it worked, though there were deep cracks that are impossible to access (even with epoxy-filled syringe). Basically, there is no way to fix them except to remove the transom altogether and replace it. But I don't think that's needed. It should be plenty strong anyway, unless I land on the rudder again. :D

    The sail - well, as I said, I really did sweat at that thing. Except for the material, it is made as a real sail should be made, no shortcuts. And several adjustments to counteract the stretchy nature of Tyvek. At the end of the season, it didn't perform well anymore (leech has started flapping, the bag at the yard became worse, some seams opened up, and finally leech unfolded), but it was still a competitive sail.
    For the next summer, I'm converting to balanced lug (since handling boom vang is a pain in the a**), increasing area from 6.34m^2 to around 8m^2. I will re-make spars to handle increased loads, I already gathered new fabric (4oz resin-coated polyester, very similar in properties to Dacron, only slightly more stretchy), and I'm now in a process of reviving an old sewing machine to make it all work. If this deed is successful, Melatelia will be a rocket in light winds. With an insane SA/D ratio of 23 (or 32 if sailed single-handed), no factory boat will be able to compete with her in these wind conditions.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.