S2 6.7 Junk Rig Conversion

  • 28 Jul 2019 23:05
    Reply # 7800664 on 6872873
    Anonymous member (Administrator)

    I see no reason for turning this into rocket science.

    The mast steps (all from plywood) of my first three boats were just primed with West epoxy resin, and then glued together after the coating had set. I never worried about that waxy ‘blush’. None of those mast steps has come unstuck yet. I guess the very big glue surface makes it strong enough, even if the strength of the glue joint should turn out to be only 30% of that of a correct joint.

    When making Ingeborg’s mast step, I ‘moved up’ a little: After the coating resin had hardened, but before gluing the whole lot together, I wiped the surfaces off with water with some household ammonia ( known as Salmiakk here) in it. That got rid of the waxy feeling, for sure. I guess a light sanding after that cleaning, would not hurt, but I can’t remember I did that. Even Ingeborg’s mast still stands upright.

    My main focus has been on avoiding water penetration anywhere at the mast step.


    Last modified: 28 Jul 2019 23:06 | Anonymous member (Administrator)
  • 28 Jul 2019 22:20
    Reply # 7800621 on 7798242
    Scott wrote:

    I will be using small paper cups and never putting more than two pumps in at a time (using West System 300 mini pumps). As Annie says it is not so bad to run out of epoxy in the pot and need to mix more. It is much worse to have the whole thing become a hot and urgent situation.

    I am not sure how thick I need to make these sealing coats of epoxy on the mast step layers. Do I need to have it thick enough that the piece looks like it is encased in smooth glass? Or is it OK to end up with a thin coat that is still a little rough?

    I believe the purpose of this sealing coat is to prevent starving the joint when I bond the mast step layers to the hull and layers below. Is a thin, rough, sealing coat enough to ensure that the wood will not soak up too much epoxy when I glue it into the boat?

    I tend to use containers with a wide base - I have an everlasting supply of yoghurt pots from which the set glue breaks out easily - because the smaller the cup, the more likely the epoxy is to warm up while you are mixing it.

    I wouldn't put a sealing coat between each layer and let it partially cure.  My own method would be to clear up epoxy on the top layer down to a smooth base, and then coat the bare wood of both faces before mixing up the glue mix.  That way you don't need to worry about amine bloom, sanding or how far the epoxy has cured.  My rule of thumb is never, never to put the glue mix directly onto the wood unless it's a really runny mix; and then I make sure there are plenty of microfibres to wick the epoxy to dry places.

    I rarely have a problem with amine bloom from slow - 206 - hardener.  It's the 205 that causes the problems and sometimes the coating is positively slimy.  I try to avoid using fast hardener.  But washing with fresh water with a drop of ammonia in it sorts the problem.

  • 28 Jul 2019 16:02
    Reply # 7800252 on 6872873

    Scott, no it does not have to look like glass. Just as many coats, maybe two, to keep the plywood edges from soaking up the final bonding mix will do it. As you know when West System epoxy has cured beyond fingernail hard, one must make sure to remove the amine “blush”before applying another coat or bonding. That is the only thing I don’t like about West S. compared to some others. In addition to the other suggestions of ways of slowing the process, keeping the mix less concentrated or more spread out helps. Ventilation is most important of all. Don’t let the mix go off  where you can breath the fumes.  If working inside I set cups with unused mix outdoors to solidify. Also if you go from plastic to paper cups avoid the waxed ones

  • 26 Jul 2019 16:18
    Reply # 7798242 on 7798200
    Scott D wrote:

    Well, at least your cup didn't melt.  I've done that a few times.  

    The epoxy wasn't wasted.  It was the basic overhead cost of learning.  

    The worst part is that I am re-learning this. The last time I did any epoxy work was around 2015. I used a red plastic solo cup to mix up some epoxy. First I almost burned my hand, then the cup started melting and separating before the whole thing suddenly kicked into a solid block of plastic.

    I will be using small paper cups and never putting more than two pumps in at a time (using West System 300 mini pumps). As Annie says it is not so bad to run out of epoxy in the pot and need to mix more. It is much worse to have the whole thing become a hot and urgent situation.

    I am not sure how thick I need to make these sealing coats of epoxy on the mast step layers. Do I need to have it thick enough that the piece looks like it is encased in smooth glass? Or is it OK to end up with a thin coat that is still a little rough?

    I believe the purpose of this sealing coat is to prevent starving the joint when I bond the mast step layers to the hull and layers below. Is a thin, rough, sealing coat enough to ensure that the wood will not soak up too much epoxy when I glue it into the boat?

    Last modified: 26 Jul 2019 16:25 | Anonymous member
  • 26 Jul 2019 15:45
    Reply # 7798200 on 6872873

    Well, at least your cup didn't melt.  I've done that a few times.  

    The epoxy wasn't wasted.  It was the basic overhead cost of learning.  

  • 26 Jul 2019 09:10
    Reply # 7797761 on 6872873

    The only time I would ever dream of mixing up a batch of epoxy that big is when I'm coating or laying down fibreglass.  Why would you?  It takes about 15 seconds to pump the epoxy and one minute to mix it.  I cannot see the point of 'saving time' when it means that you are putting yourself under pressure to get the mix out of the container and on to the wood.  If you run out of glue half way through the job, it's vaguely irritating to have to go and mix up some more; if the epoxy starts going off it's a recipe for disaster. As you pointed out, the first thing that goes through your mind is the cost of wasting it, so you are inclined to use it anyway, even though the pot is getting hot and the mix thickening while you use it.  The cost of this pot of epoxy (which is actually, a lot cheaper in real terms than it was 40 years ago) is nothing compared with your peace of mind after the event (did you achieve a decent glue joint?) and, in the worst case, the piece of wood that has to be removed as there are big gaps in the joint because the epoxy had gone hard before it squeezed out.

    I am not renowned for throwing money around, but even I will ditch half a pot of epoxy rather than risk a sub-standard joint.  However, the secret of success is, when in doubt, mix less.  Frankly, I think it's easier to mix another batch than to faff around with iced water, which I would undoubtedly tip all over the wood I'm about to glue!

  • 25 Jul 2019 23:44
    Reply # 7797374 on 6872873

    With the temperatures you are experiencing are you using the slow hardener for your mixes of epoxy?

    Another trick is to have a bucket of ice and keep the mixed epoxy container seated in that. It will not go off until it warms up.

  • 25 Jul 2019 17:48
    Reply # 7796935 on 7796586
    Anonymous wrote:mistakes with epoxy. With the temperature back to a more reasonable dry 68 Deg F yesterday I thought it would be OK to mix up four 'pumps' of West System epoxy at once. I was wrong! About half of it 'went off' in the cup and turned rock hard while I was spreading epoxy. I am trying not to think about how many dollars worth of epoxy I used to make this cup-shaped yellow disk. I will make smaller batches and spread them thin as soon as I can in the future.
    An icecream bucket of ice to put your mix bucket inside may help. Also, using a more bowl shaped mix container helps (to keep the epoxy spread out thin to stay cool). I have used a take out salad dish for a lot of stuff like this. I have also seen people put the epoxy into paint trays (there are cheap paint tray liners that can be tossed when there is too much hard epoxy in them to be used any more) to keep things cooler.
  • 25 Jul 2019 13:43
    Reply # 7796586 on 6872873

    I am still trying to make progress every day. Some days this is just cleaning up the mess from yesterday to get ready for tomorrow. On other days I spent hours in the boat using a hand plane/rasp with temperatures around 90 Deg F and a dew point around 74 Deg F. The result is 7 layers of 1/2" mast step that fit nice and snug against the hull and the layer below. With this done I am sure I could do it again much more quickly and with much less error and rework. Maybe I will test that idea in the future.

    I am moving forward from making mistakes with plywood to making mistakes with epoxy. With the temperature back to a more reasonable dry 68 Deg F yesterday I thought it would be OK to mix up four 'pumps' of West System epoxy at once. I was wrong! About half of it 'went off' in the cup and turned rock hard while I was spreading epoxy. I am trying not to think about how many dollars worth of epoxy I used to make this cup-shaped yellow disk. I will make smaller batches and spread them thin as soon as I can in the future.

    Three layers are coated.

    Progress, I think?

    Last modified: 25 Jul 2019 13:47 | Anonymous member
  • 13 Jul 2019 01:19
    Reply # 7777636 on 7777553
    David W wrote:

    [...] The additional area of bond created by the fiberglass is also an addition to your safety factor.

    All the best with the project, David.


    Thank you for taking the time to respond. Thanks also to David T. for the details regarding Weaverbird.

    I will think about fiberglass between layers, running up the hull, and large fillets at the top.

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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