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lenm last won the day on August 30 2017

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About lenm

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  1. Ocracoke 20 in OZ

    Yea, I'm liking the colour - Im thinking mid 60's Ford GT40 colours - Awlgrip sky blue topsides, burnt orange antifoul and teak trimming/deck.
  2. Ocracoke 20 in OZ

    Trowelable fairing compound today. Checkout the colour!
  3. Ocracoke 20 in OZ

    Thanks Due to availability reasons (local supplier) went with 1700 and 2100 variants (no mat). Need to be careful when rolling out though as the mat has an advantage of 'holding' the fabric together (as some people suggested earlier). Make sure you meet the 30oz glass recommended for the chine joints.
  4. Ocracoke 20 in OZ

    Thanks again to those who offered advise re glassing - great help. The final layer went down today and it all turned out superb! I've glassed heaps of surfboards, windsurfers etc in my time but nothing ever this big! Solo that is. If anyone is proposing to undertake a 20 foot + boat, solo (and is inexperienced in glassing) I'd like to offer a few observations/reiterate earlier advise by others.. - Get the slowest harder you can. E.g 2hr pot life with an 8hr open time. - Use a roller for the bottom. One with a long handle. Makes it easy to lap glass over keel line. - 17oz glass or lighter was easy to apply. 22oz is a lot of work to wet out unless you have help/someone working ahead of you. - Mixing up batches of epoxy around 1kg quantity at a time was nice and manageable.
  5. Ocracoke 256 hull #2 Build

    I've been hanging out for an update - looking really good! I like the clean interior edges. Is that teak on the comings? re the 302, are you also using 'awlfair' for the deeper depressions? can the awlfair go straight onto raw FRP or require epoxy primer underneath?
  6. OC20/B in Biloxi MS USA

    Onto the next project already! - your rate of progress is certainly making some of us look slow :-) Good luck with it and look forward to any updates.
  7. Ocracoke 20 in OZ

    Hi PAR, My gut feeling is that it was around 30% stronger than the others samples to shear. It's shear seemed a bit more dramatic than the other two samples. Once the fibres 'roll' it really lets go suddenly. I think a piece of ply in a double diagonal configuration would be a further improvement. The balsa was interesting. In particular the way the underside side skin looked 'punched' outwards, and delaminated after the initial impact. This was 'end grain' balsa, perhaps the grain orientation was transferring more impact/load to the underside skin? i.e less energy absorption?
  8. Ocracoke 20 in OZ

    Many thanks smccormick for the diagram - that is most helpful to me! Your method looks very well though out - some great ideas there. Re 'overbuilding' - I agree with your comments. I think it is human nature to want to beef things up a bit, however, in reality all the r&d has already been done by a good designer. 'Just follow the plans' has been my ethos for this project. My impact tests confirm (for me personally) that a layer of 12oz fabric over the ply is ample and comparable to other composites/sandwiches which I am more familiar with However (like you) I'd like a little more abrasion resistance on the bottom, and personally, something a little more subtle than a keel strip/guard. Murphy's law - if there is a wife or buddy involved at the boat ramp (launching) they are bound to scrape the bottom of the boat on the rocks in an attempt to avoid getting their feet wet. Over here in Australia, we have some rough 'corrugated' dirt roads that run for miles out to remote fishing spots. They test trailers and tyres and rattle suspension to death. I have seen a boat 'rubbing' on its trailer, the bottom of it wearing right through its polyester gel coat where the support pads are. I'll swallow the weight penalty and gain it back somewhere else on the boat.
  9. Ocracoke 20 in OZ

    'Tested' a few samples today in order to get an observation of how ply compares to other typical sandwich panels in an impact. Under 'uncontrolled' conditions, I dropped a 20mm, 1.5kg metal rod from a height of 2 metres onto 3 different configurations. 75mm wide panels were span 150mm (not clamped). 1) 13mm end grain balsa core with 18oz double bias each side 0/90 (vacuum bagged. 2) 15mm H80 foam with 18oz double bias each side 0/90 (vacuum bagged). 3) 9mm marine ply (meranti) with 12oz double bias each side 45/45 (hand laminated). Results 1) Balsa - large dent at impact site. Front/outside skin sheared. core fractured and sheared. large de-lamination of back/inside skin. 2) Foam - large dent at impact site. Front/outside skin sheared. core squashed and bent only. inside skin intact. 3) plywood - very minor dent at impact site. no damage to core. inside skin intact. Then took the panels up to complete failure (unmeasured) Comments 1) Balsa - inside skin holds structure from a complete shear. Core severely fractured in multiple places. 2) foam - inside skin holds structure from a complete shear. core severely squashed and bent. 3) plywood - Core layers separate completely. Wood fibres parallel to the shear direction 'roll' causing failure. fibreglass skins stay bonded to ply.
  10. Ocracoke 20 in OZ

    Smccormick, Thanks for taking the time to describe all this. Some great ideas, and if you have time to share your laminate diagram that would be much appreciated. I just spoke with the tech rep and looks like we can get hold of a hardner with a 2hr pot life and 8hr thin work time.
  11. Ocracoke 20 in OZ

    Thanks Capriosca, I'm hearing you re heavy fabric and tropical conditions. Did you use a single 1708 or 2208 on the 256? Currently proposing 2 layers of lighter fabrics (with no mat) due to their fast wet out and the way you can stage the pot life. Bottom done first then topside the following day. 1) Mash epoxy into wood with squeegee and wait till tacky. 2) roll out and epoxy a 8oz woven hybrid (0/90) basalt 3) squeegee and wail till tacky 4) roll out and epoxy a 12oz double bias (45/45) eglass 5) Squeegee 6) peel ply Alternatively, just 2 x layers of the 12oz double bias (45/45) As you mention, would be good to hear a more knowledgeable persons opinion, albeit, I've already asked a hundred questions already :-)
  12. Ocracoke 20 in OZ

    Thanks smccormick. Started glassing yesterday (glass tape chines). I dont have a helper so the rest of the hull looks to be a big job to pull off solo. Thats on the notion that everything is chemically bonded. It's got me thinking about breaking it up into smaller sections, with unfortunately, more mechanical bonding (will be mechanically bonding to a peel ply finish). Does anyone have any opinions re mechanical bonding or a good strategy to pull off hull glassing solo?? I cant say i have ever experienced a delamination due to a well prepared mechanical bond, apart from an incident where there was some some surface contamination.
  13. Aussie Open OB-20 #26

    looking great! should have lots of fun with this up in NQ.
  14. Ocracoke 20 in OZ

    Happy new year fellow boat builders and hope everyone has a productive 2018. We are ready for sheathing after a long interruption due to a period of calm oceans and hot ocean currents (great for fishing). Like the GulfStream in the US we get the East Australian Current - funnelling warm water from the Coral Sea along the East coast of Australia.
  15. Utah OB20

    Further to PAR's suggestions regarding peel ply, I agree with his recommendations re whether to bother with it. I've used it extensively in the manufacture of epoxy windsurfers These boards typically receive a sheathing of 2 layers of 6oz fabric. Be aware with peel ply you can end up with tiny 'pin holes' in the final laminate depending on your methodology. Ie. little voids between the fabric weave. They are a pain to fill and are often invisible until you start laying down paint. I've even had an instance where a pin hole let water into an underlying sandwich core. In summary, be cautious using peel ply if you are going for a thin sheathing layer.

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