S2 6.7 Junk Rig Conversion

<< First  < Prev   1   2   3   4   5   ...   Next >  Last >> 
  • 12 Dec 2019 23:30
    Reply # 8259382 on 8211324
    Annie wrote:

    You might find a multitool is a good choice for this job, Scott.

    I do not like spending money on tools and finding some place to keep even more stuff.

    But -- the multitool was a very good idea. It is amazing how it will cut through wood with just a little pressure but at the same time if you accidentally bump your hand it doesn't do any damage. I should have started with this. The de-coring part of the work is moving along much faster and with better results now.


  • 09 Dec 2019 18:05
    Reply # 8226190 on 8211324
    Annie wrote:

    You might find a multitool is a good choice for this job, Scott.

    Go for the oak, Scott, as long as it is seasoned.  (a) we are just talking trim here (b) John Guzzwell recommends it in his book (c) Tystie is trimmed out in oak and has had no problems with bits falling off. It supposedly has a reputation for not gluing that well: so has teak.  I've never (touch wood!) had a problem with either. 

    To ease your mind, just be more than usually scrupulous in ensuring that both surfaces are well wetted out first and maybe even wipe it with solvent.  If you look here, you will find more about gluing it from the Gougeon Bros.  But don't forget, you are not using it structurally.


    Annie,

    I am working on borrowing a multi tool or maybe buying one if I have to.

    The Epoxy Works Article that you shared was the same one that convinced me not to use oak and epoxy for structural work on the deck core.

    This is from the article:

    " [..] two factors, dimensional instability and high density, interact to result in the unpredictable performance of an adhesive bond. The grain strength of the oak is about the same as the adhesive strength of the WEST SYSTEM 105 Resin-based epoxy. When the oak changes dimensionally, there is a “tug-of-war” between the strength of the wood and the strength of the epoxy bond. Sometimes the epoxy holds and sometimes it doesn’t. [The flexibility of G/flex epoxies is what allows them to maintain their bond with oak—Ed.]"

    Scott.

    Last modified: 09 Dec 2019 18:06 | Anonymous member
  • 08 Dec 2019 07:56
    Reply # 8212144 on 6872873

    For major GRP cutting jobs, a blade edged with tungsten carbide grit is best. They can be found for both multitools and hand saws, and a store that sells ceramic tiles is a good place to look. For small jobs, you may get away with a HSS blade, but it will blunt quickly.

    I was assuming that the boat has some trim already, and you'd try to find something that was near to a match, or at least, pleasing to your eye. Species such as maple and poplar will need a good coat of epoxy, as water ingress would turn them black.

    For replacing the balsa, douglas fir will do fine.

  • 08 Dec 2019 05:52
    Reply # 8211324 on 8209644
    Scott wrote:

    I will plan to do this as well. I found my tiny hack saw. I think it should work for squaring up the corners.

    I started working on getting the core out with a chisel. Balsa is more difficult to break apart than I expected. I am happy it is not plywood.

    Do you have a recommendation for a hard wood to use? My first thought was oak. Then I read on the West System website that oak should never be used with epoxy. I can't seem to find any ash boards. Poplar looked good, but then I found people online saying it is no good for boats due to poor water resistance.

    The price of maple terrifies me. Hickory I have only found as flooring sold by the case.

    At the moment I think Douglas Fir seems like the best option for 'hardwood strips' even if it is not really hardwood. 

    You might find a multitool is a good choice for this job, Scott.

    Go for the oak, Scott, as long as it is seasoned.  (a) we are just talking trim here (b) John Guzzwell recommends it in his book (c) Tystie is trimmed out in oak and has had no problems with bits falling off. It supposedly has a reputation for not gluing that well: so has teak.  I've never (touch wood!) had a problem with either. 

    To ease your mind, just be more than usually scrupulous in ensuring that both surfaces are well wetted out first and maybe even wipe it with solvent.  If you look here, you will find more about gluing it from the Gougeon Bros.  But don't forget, you are not using it structurally.


  • 08 Dec 2019 01:52
    Reply # 8209644 on 8175658
    David wrote:

    I would also cut away the radii in the corners. If the corners are square, it will be easier to bond on pieces of hardwood trim to cover the messy edge.

    I will plan to do this as well. I found my tiny hack saw. I think it should work for squaring up the corners.

    I started working on getting the core out with a chisel. Balsa is more difficult to break apart than I expected. I am happy it is not plywood.

    Do you have a recommendation for a hard wood to use? My first thought was oak. Then I read on the West System website that oak should never be used with epoxy. I can't seem to find any ash boards. Poplar looked good, but then I found people online saying it is no good for boats due to poor water resistance.

    The price of maple terrifies me. Hickory I have only found as flooring sold by the case.

    At the moment I think Douglas Fir seems like the best option for 'hardwood strips' even if it is not really hardwood. 

  • 04 Dec 2019 15:28
    Reply # 8175658 on 6872873

    I would also cut away the radii in the corners. If the corners are square, it will be easier to bond on pieces of hardwood trim to cover the messy edge.

  • 04 Dec 2019 02:24
    Reply # 8170666 on 8163493
    David T wrote: I would rather chisel out the core to a depth of 1 1/2" all the way around, bond in hardwood strips in to fill that cavity, then bond and bolt the plywood on top. Having done that, an extra two squares of thick plywood of smaller size, surrounding the tabernacle, will transfer the load satisfactorily, to the larger square.

    Thank you. This seems to be a very good plan. Hopefully after I chisel out 1.5" I will have solid dry core all around.

    Your help is very much appreciated.

    Scott


  • 03 Dec 2019 08:54
    Reply # 8163493 on 6872873

    Both skins of the deck are clearly structural. It's not the same as having a thick deck, some core, and then a thin headlining inside. So the question is, how to get a strong join to it? For fastening on deck fittings, the usual way is to make a large hole through one skin and the core, fill the cavity with a strong epoxy and filler mix, then drill through that solid plug for a bolt. That would work, to bond and bolt a thick piece of plywood (18mm or 3/4") over the hatch hole. However, I would rather chisel out the core to a depth of 1 1/2" all the way around, bond in hardwood strips in to fill that cavity, then bond and bolt the plywood on top. Having done that, an extra two squares of thick plywood of smaller size, surrounding the tabernacle, will transfer the load satisfactorily, to the larger square.

  • 02 Dec 2019 21:44
    Reply # 8158580 on 8153183
    David T wrote:

    I think we need more information and pictures to be of specific help to you, Scott.


    Hi David,

    Thank you for taking the time to respond. I will attach all the photos I took when I was at the boat. 

    I am not sure what information to provide. The tabernacle will be buried in the deck approximately 890mm. For selecting a mast I came up with a target yield strength of 1753 kpm. I would like to determine what sort of deck structure I need to ensure that the deck will not crush or collapse if and when the mast really sees that 1753 kpm load.

    If I understand all those numbers correctly then I think the deck will need to withstand a force equivalent to 1970 kg applied sideways. I am not sure where to go from there.

    13 files
    Last modified: 02 Dec 2019 21:50 | Anonymous member
  • 02 Dec 2019 09:33
    Reply # 8153183 on 6872873

    I think we need more information and pictures to be of specific help to you, Scott. Generally, though, mast partners on a GRP boat can be made by stacking up layers of plywood locally, not all the way out to the deck edge. A plywood deck beam will help stiffen the whole area, if the boat is lightly built.

    1 file
<< First  < Prev   1   2   3   4   5   ...   Next >  Last >> 
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software