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Old 29-01-2016, 11:47   #16
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Re: Un-ownerizing a Cal-20, and making it better

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Epoxy is an adhesive. Polyester resin is not. Polyester resin can form a molecular bond if applied to polyester resin that has not fully cured. That's how several layers of fiberglass become a solid hull. Add another layer years later & it may stick or it may not but it will never become part of the hull. For a mechanical bond an adhesive is required for a structural connection & epoxy is typically the adhesive of choice when it comes to boats.



Why WEST SYSTEM® Brand epoxy? All epoxies are not created equal.

You use the term adhesive as if that were the beginning and end of the discussion. Epoxy gets that adjective because it bonds well to a wide variety of others materials and polyester not so much. But the question here is not how many materials the resin can bond to but how well it bonds to an existing polyester substrate specifically.

Just because epoxy bonds to existing polyester better than new polyester doesn't make the P-P bond poor. It would be poor if it had 50% of epoxies bond strength but it doesn't, it's about 80% or so, better if you prep the surface well.

With a bond strength almost 90% of epoxy's does spending two or three times as much for epoxy make sense to get the last 10%? Depends on expected loads on the repair and how deep my pockets are and how comfortable I am depending on something that isn't the absolute best it could be.

In addition to resin costs, epoxy requires special mat with binders compatible with epoxy and greater safety measures are required working with epoxy so there are additional costs there.


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Old 29-01-2016, 12:09   #17
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Re: Un-ownerizing a Cal-20, and making it better

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You use the term adhesive as if that were the beginning and end of the discussion. Epoxy gets that adjective because it bonds well to a wide variety of others materials and polyester not so much. But the question here is not how many materials the resin can bond to but how well it bonds to an existing polyester substrate specifically.

Just because epoxy bonds to existing polyester better than new polyester doesn't make the P-P bond poor. It would be poor if it had 50% of epoxies bond strength but it doesn't, it's about 80% or so, better if you prep the surface well.

With a bond strength almost 90% of epoxy's does spending two or three times as much for epoxy make sense to get the last 10%? Depends on expected loads on the repair and how deep my pockets are and how comfortable I am depending on something that isn't the absolute best it could be.

In addition to resin costs, epoxy requires special mat with binders compatible with epoxy and greater safety measures are required working with epoxy so there are additional costs there.


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I'm not sure what you're basing your calculations on but by my calculations polyester's bond strength is 28.7935% of polyester's assuming it's applied at high tide. It is true that epoxy costs more than polyester resin but that just proves that epoxy is better.
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Old 29-01-2016, 12:16   #18
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Re: Un-ownerizing a Cal-20, and making it better

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Originally Posted by Scout 30 View Post
I'm not sure what you're basing your calculations on but by my calculations polyester's bond strength is 28.7935% of polyester's assuming it's applied at high tide. It is true that epoxy costs more than polyester resin but that just proves that epoxy is better.

I got my numbers from Don Casey (http://www.boatus.com/boattech/casey/polyster-epoxy.asp). Where'd you get yours?

Extra cost proving better quality is a logical fallacy. Just look at D.Trump for an example.


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Old 29-01-2016, 12:36   #19
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Re: Un-ownerizing a Cal-20, and making it better

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I got my numbers from Don Casey (BoatUS – BoatTech – Polyester or Epoxy Resin? by Don Casey). Where'd you get yours?

Extra cost proving better quality is a logical fallacy. Just look at D.Trump for an example.


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Donald Trump is a perfect example. He used to use polyester resin to hold his fiberglass hair down. He has since changed to West Systems epoxy & it now never moves.
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Old 29-01-2016, 12:38   #20
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Re: Un-ownerizing a Cal-20, and making it better

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Donald Trump is a perfect example. He used to use polyester resin to hold his fiberglass hair down. He has since changed to West Systems epoxy & it now never moves.

Very good riposte!!!


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Old 29-01-2016, 12:51   #21
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Re: Un-ownerizing a Cal-20, and making it better

Thank you. I accept your apology.
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Old 29-01-2016, 12:56   #22
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Re: Un-ownerizing a Cal-20, and making it better

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Thank you. I accept your apology.

Oops! Another logical fallacy: assuming that any concession to the other side's argument is tantamount to capitulation.

Try again.


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Old 29-01-2016, 13:27   #23
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Re: Un-ownerizing a Cal-20, and making it better

Besides what do I have to apologize for? Disagreeing with you? Boy aren't you special


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Old 29-01-2016, 14:04   #24
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Re: Un-ownerizing a Cal-20, and making it better

I have a free Cal 20 in my yard, here on Vancouver Island, B.C. It's been stripped to bare bones, but hasn't been butchered like the boat you are going to resurrect. It has a bulb keel, with freshly rebolted/stainless nuts. A cleaner palette, and yours if you want it.

Best of luck with all of your plans!

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Old 29-01-2016, 14:08   #25
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Re: Un-ownerizing a Cal-20, and making it better

Simple question. If you have it all figured out, then why post such on here? Perhaps other than to gather attention, & incite controversy?
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Old 29-01-2016, 17:17   #26
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Re: Un-ownerizing a Cal-20, and making it better

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Besides what do I have to apologize for? Disagreeing with you? Boy aren't you special


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Another feeble attempt at humor due to two too many years of watching The Colbert Report.
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Old 31-01-2016, 08:18   #27
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Re: Un-ownerizing a Cal-20, and making it better

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He also removed the chain plates, and out the mast step in the cockpit to accommodate the mast being raked forward like 20 deg and ran 3 headsails, almost cutter style, with no boom and main, bizarre if you ask me.

that may seem bizarre and unusual but it's not unique. it's been done. that kind of rear mast/ sails attached to the forestay set up has a few benefits. no boom so gibes are fairly gentle. no spar to interrupt air flow over the luff. that's a biggie. have you tried sailing it that way?

there was an interesting boat I saw on a youtube video a few years ago (I believe he called it a universal hull). it featured an odd hull design with the bow being angled backwards towards the top, like a cow catcher on an old steam engine. but the coolest thing it had was a rig set up like you describe; only with a single sail. having multiple sails would make it more versatile.

before you redo the rig (but, after you do something about the mutilated hull/deck joint ), you should sail it and see how it does...then post here to tell those of us who may be curious about it.

I had forgotten all about that rig type. thanks for reminding me. essentially, it's a completely staysail driven rig. without any boom, I should think down wind would be less efficient...
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Old 31-01-2016, 10:06   #28
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Re: Un-ownerizing a Cal-20, and making it better

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I agree that that an oar or a pair of oars are much preferable to an outboard especially an unsightly one mounted on the transom.

Paul
Oh yes...

An OB hanging on the back of this boat would totally clash with all of the other modifications....
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Old 31-01-2016, 11:15   #29
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Re: Un-ownerizing a Cal-20, and making it better

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Oh yes...

An OB hanging on the back of this boat would totally clash with all of the other modifications....
Forgot to say the PO had a 4d battery hooked up to 40 1watt solar panels, and a positive and negative stud rigged up right by the motor well so he could have unlimited juice for his Minn Kota
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