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#1 Knot Me... maybe

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Posted 24 May 2019 - 08:52 PM

Any cunning buggers out there with enough clues to suggest a laminate for me?

 

My boom has more holes in it that your average tea bag so I'm going to build a new one. I have a mold (female 2 piece) that's 170mm high x 130mm wide x 5mts long (I need 4.4) round figures.

 

I've been asked by 2 other boats if I'd build them one as well...... errrrrrr...... we'll see.

 

My laminate dude is somewhere in Belize trying to cuddle a Whale Shark.... I hope it's only cuddle. 


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#2 chic014

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Posted 24 May 2019 - 08:58 PM

https://www.optimum.co.nz/


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#3 Island Time

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Posted 24 May 2019 - 09:16 PM

Bad Kitty's Mrs, Nina. http://cleverfoxproj.../our-engineers/


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There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats


#4 Myjane

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Posted 26 May 2019 - 07:55 PM

Just reading you question do you mean a ,glass laminater it’s a class boom ,
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#5 Maté

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Posted 26 May 2019 - 08:39 PM

Best advice I can give you for a critical part like a boom especially given the amount of work involved is to go to a professional and get one designed. The alternative is to do it by guesswork, educated or not,  which involves a lot of luck. It might work out fine but one of the main reasons to do this this is to save weight and possibly money, the amateur approach is to overbuild which may work fine but offer no weight or stiffness or cost advantage over good old alloy. 

 

An alloy section is pretty cheap and reliable, but if you were splitting the cost 3 ways on the design then a carbon boom would be my pick. 


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#6 Knot Me... maybe

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Posted 27 May 2019 - 09:17 AM

Just reading you question do you mean a ,glass laminater it’s a class boom ,

Someone to suggest what the laminate should be.

 

 

An alloy section is pretty cheap and reliable, but if you were splitting the cost 3 ways on the design then a carbon boom would be my pick.

Cost is not a input, it's about learning, upskilling and using your hands to do more than shift paper around a desk. The word cathartic comes to mind.


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#7 waikiore

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Posted 27 May 2019 - 02:53 PM

I designed and built a couple of carbon/ wood booms in the eighties because the sparmakers price frightened me, they didnt break, and were lighter and way cheaper than off the shelf ally, so I guess successful not counting my time of course. That Nina would be my pick  for a proper spec though.


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#8 Hurts

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Posted 27 May 2019 - 04:08 PM

Engineering for yacht bits is a funny science IMHO. They do all these impressive calcs working out the theoretical loads but then seem to add in some pretty major fudge factors like "make it 4 times stronger than it theoretically needs to be" which make it all seem like a guess. The fudge factors is massive butt covering but takes care of the real world crazy loads caused by you:  
  • catching your topping lift on a boat on the other tack as it goes past, 
  • having 12 drunken people on the rail in a rum race with massive sail area up etc, 
  • Big seas, 
  • chinese gybes, 
  • using your boom as a crane to lift your engine out etc etc. 
 
Best approach in my somewhat unconventional view is get the laminate specs off some other dude who's built a similar boom that has stayed in one piece successfully and adjust if you feel like it. Otherwise if you still have the alloy job as a spare and it's a learning exercise then just puzzle it out yourself; greatest load at mainsheet attachment, 3 to 1 ratio of Unis and DB - if it breaks you built it too light otherwise it was too heavy :-). Maybe keep people away from having their heads too close to the boom for the first few races... 
 
Write down the laminate for future reference...

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#9 Knot Me... maybe

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Posted 27 May 2019 - 05:07 PM


Best approach in my somewhat unconventional view is get the laminate specs off some other dude who's built a similar boom that has stayed in one piece successfully and adjust if you feel like it. Otherwise if you still have the alloy job as a spare and it's a learning exercise then just puzzle it out yourself; greatest load at mainsheet attachment, 3 to 1 ratio of Unis and DB - if it breaks you built it too light otherwise it was too heavy :-). Maybe keep people away from having their heads too close to the boom for the first few races... 
 
Write down the laminate for future reference...

 

Lovin the style, one I employ myself frequently.

 

I have 3 to make now so No.1 can go to Mr Guinea and No.2 to Mr Pig, I'll take the 3rd one :thumbup:


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