Another write up by Arne Kverneland

  • 08 Jun 2020 18:58
    Reply # 9023211 on 869421
    Anonymous member (Administrator)


    A new rudder for an Athena 34

    Since the matter of rudders has been up on the forum recently, and since it rained yesterday, I collected some photos and diagrams from when a friend of mine built a new rudder for his Athena 34. Hope you find it useful.


    I suggest that any comments are placed here, on the ‘General rudder endplate specs’ topic.
    I let you have the draft already, and will try to straighten it up during the coming days.

    Arne


  • 27 Mar 2020 23:25
    Reply # 8863221 on 8853366
    Anonymous wrote:

    David,
    the first link indicated that a dish towel would work quite well, so now I made a mask from it. I feels very similar to those I made from my roll of cotton canvas. In both cases I double it with a patch in the front (this time fitted on the inside).

    Arne


    PS, 24.3.20: I have opened a new topic and hope to continue the discussion there.





    1 file
    Last modified: 27 Mar 2020 23:28 | Anonymous member
  • 24 Mar 2020 20:13
    Reply # 8854575 on 869421

    On a more serious note, a couple of weeks ago when surgical masks suddenly became unavailable, I pulled one apart and examined the three layers – the water resistant (coloured) layer which goes outside, the moisture absorbent inner layer – and the almost unnoticeable middle layer which combines the two conflicting properties of (a) breathability (b) filtration.

    I then went to Spotlight (our local fabric supplier) to look for materials which most resembled the above, with a view to doing some fooling around during the expected period of self-isolation and travel restrictions (which is now upon us).

    The nearest I could find for the outer layer, which looked good, was a non-woven microfibre cloth that comes in various weights, I think used for stiffening inner layers, in the garment trade. The one I bought is polyester and I put it under the tap - it is water resistant, though not quite as good as the outer layer of a surgical mask.


    I think if I were going to make a Arne-type DIY mask I would put a throw-away replaceable layer of this on the outside, as a first-line defense against droplets.

    I think the main purpose of the mask is to lower the likelihood of transmission rather than protect the wearer. (A surgeon doing an appendix operation does not wear a mask because he/she is afraid of catching appendicitis). That being the case, Arne’s mask, with a water resistant outer shield or an improvised celluloid visor (see below), might be as good as any.

    The problem is, the high-tech spunbond middle-layer filter in surgical masks does not seem to be readily available, so trying to make a true surgical mask is probably not a DIY task. I bought a pack of vacuum cleaner bags to cut up, thinking this might make the best available inner layer for filtration – but have not yet had time to test “breathability”.

    Then googled and saved what seemed to be the best information (and top of my list was the same site as the one on the top of David’s list – recommended reading.)

    By far the most practical I could find, on the subject of DIY masks was this one, put out by Hong Kong Consumer Council and including a recommended DIY design from Shenzhen and Hong Kong University Hospital: https://www.consumer.org.hk/ws_en/news/2020/covid-19-diymasks

    This is the one I would follow for a simple DIY surgical mask which does not require sewing – augmented by a transparent visor shield made from transparent file-folders which is attached to one’s glasses. The transparent shield and the DIY mask made from household materials, as described in the link above, might be a good option

    The New Zealand file folders seem to be a little opaque, but light, stiff cellophane (celluloid?) is readily available by the roll at the local stationery warehouse.

    In the meantime, surgical masks are available again in NZ though you have to hunt around for them and take pot luck. I agree with Arne, the high quality dust mask which allows unfiltered exhalation may be a protection for you, but does not protect others and so is not a good choice.

    (PS I bought a Hepa filter too, with a view to trying out a "Darth Vader" style, but after looking at Arne's modelling photo's I decided it might frighten the public - though as Arne points out, that does achieve the goal of "social distancing"!)

    One more point: Arne's mask, and the cloth type in David's No. 3 recommended website, are presumably intended to be sterilised and re-used. Don't bother tryjng to sterilize a surgical mask, it destroys them. They are throw-aways and nothing wrong with that in these circumstances, as long as they go straight into a lidded bin. Where they are in short supply and have to be re-used, a Chinese friend has told me people leave the surgical masks in direct sunlight when not in use, which may help a little to sterilise, without destroying the middle filter layer.

    I'm waiting for some lateral thinking from Howard.

    Last modified: 24 Mar 2020 21:19 | Anonymous member
  • 24 Mar 2020 11:47
    Reply # 8853395 on 8853295
    Graeme wrote:

    I was going to make a split mask but I was told it wouldn't work.

    This probably won't work either:


    One Users' DIY air pollution anti-virus mask
  • 24 Mar 2020 11:24
    Reply # 8853366 on 869421
    Anonymous member (Administrator)

    David,
    the first link indicated that a dish towel would work quite well, so now I made a mask from it. I feels very similar to those I made from my roll of cotton canvas. In both cases I double it with a patch in the front (this time fitted on the inside).

    Arne


    PS, 24.3.20: I have opened a new topic and hope to continue the discussion there.

    Last modified: 24 Mar 2020 22:24 | Anonymous member (Administrator)
  • 24 Mar 2020 09:57
    Reply # 8853295 on 869421

    I was going to make a split mask but I was told it wouldn't work.

  • 24 Mar 2020 09:55
    Reply # 8853293 on 869421
  • 24 Mar 2020 09:01
    Reply # 8853272 on 869421
    Anonymous member (Administrator)

    Yes, David,
    Now I only wait for someone (down under?) to come up with a clever shelf foot version. I actually have a couple of very good dust masks; 3M 9914. Unfortunately, what makes them particularly good as dust masks, makes them useless as virus masks: One breaths out through an un-filtered valve.

    My guess is that the filtering effect can be increased simply by doubling or tripling the layers of cloth.  Thanks to the wide area of such a full-face mask, the air speed and pressure get very low.
    Anyway, my mask has proven to have a great side-effect: People back off when they see me coming...


    Arne


  • 24 Mar 2020 08:34
    Reply # 8853268 on 869421

    Aha! The Cambered Panel Virus Mask! I have absolutely no doubt that broad-seamed and shelf-foot models will appear in due course.

    I have reserved two FFP3 dust masks that I bought for GRP-grinding, in case I need to protect myself against others, or others against me.

    But if I needed to make a mask, I still have some Ventile cloth that I used to make outer clothing in my mountain-going days. This is very densely woven long staple cotton, that is very breathable but almost waterproof.

  • 24 Mar 2020 00:25
    Reply # 8851529 on 869421
    Anonymous member (Administrator)

    Corona-speculations

    Hi Folks!
    Since I have put myself  more or less in ‘inner exile’, I got the idea to make a facemask to protect the surrounding against me, in case I were infected  by the Corona virus (I’m feeling just fine). With no facemasks available anywhere, I thought that this is the only way, if I want one.

    Here is how I did it. After a bit cutting and trying, I think I found a quick and easy way. After the two first ones, I think I now can make one in about 15 minutes or so.
    I don’t think a facemask makes that much difference  -  keeping a distance and washing one’s hands frequently is still very important. Even so, I hope that the facemask may be a supplement.

    Arne


    Last modified: 24 Mar 2020 00:26 | Anonymous member (Administrator)
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