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21-11-2024, 19:48
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#31
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Registered User
Join Date: May 2020
Location: SoCal
Boat: 35' Alden Design Cutter
Posts: 682
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Re: Old Wives Tales
Quote:
Originally Posted by MicHughV
I've gone fishing with some guest fishing people on my fishing boat, who discovered bananas in a lunch bucket fixed by my wife. They damn near threw me overboard with the bananas.
So whatever the curse behind it, for some people that is a serious no-no.
Fact or fiction, I don't know, but I don't have bananas on my boat anymore.
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Shoot, if my friends freaked like that, on the next fishing trip, they'd find a galley full of bananas, with banana smoothies and banana bread on the menu, and me wearing Banana Republic shorts, using Banana Boat chapstick, and wearing a Carmen Miranda hat.
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21-11-2024, 20:52
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#32
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Registered User
Join Date: May 2008
Posts: 3,751
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Re: Old Wives Tales
Silicone caulk sticks fine to silicone caulk. But nothing else does. Other caulks, paint, glue etc won’t stick to surface that once had silicone caulk. Even if you remove it the invisible residue will keep most materials from adhering. Only a very deep sanding will get rid of it.
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22-11-2024, 03:06
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#33
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Senior Cruiser

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 51,861
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Re: Old Wives Tales
Why would one apply new silicone, over old, if the old isn’t faulty?
Caulking over an old damaged* silicone bead, with a new silicone caulk WILL NOT WORK; and, in most cases, if you choose to apply new silicone over old silicone, any warranty is void.
* Dirty, cracked, mouldy ...
While new, freshly applied neutral-cure silicone can be applied, and will often bond to old silicone, if proper surface preparation is done; the bond is never as strong, as if it were applied to a clean, dry surface.
There are different types of silicones available, utilizing different cross-linking agents [cure type, vulcanisation]; and it’s important to match the chemistries, when applying silicone to silicone. If you know the make & model of the original silicone, use the same make/model for the new, and it should bond.
Applying a primer [adhesion promoter], specifically designed for silicone surfaces, can also improve adhesion by promoting better bonding between the existing silicone and the new sealant. This step becomes important when dealing with old or weathered silicone surfaces.
To further enhance adhesion, between silicone surfaces, it’s important to ensure proper surface roughness. By creating micro-roughness on the surface, we increase the contact area available for bonding, thereby improving mechanical interlocking [adhesion] between two pieces of silicones.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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22-11-2024, 06:30
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#34
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Registered User
Join Date: Jan 2018
Boat: 50ft Custom Fast Catamaran
Posts: 12,236
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Re: Old Wives Tales
Quote:
Originally Posted by GordMay
[SIZE=3]Why would one apply new silicone, over old, if the old isn’t faulty?
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because you missed a spot. Or maybe you put the part down and screwed up the bead.
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25-11-2024, 07:50
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#35
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Registered User
Join Date: Sep 2009
Location: New Bern NC
Boat: Searunner 34 Trimaran
Posts: 1,668
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Re: Old Wives Tales
[QUOTE=Chotu;3950931]"polyester and vinylester won't stick to epoxy"
well, after many, many cosmetic and not so heavily structural projects I have done this way, I can safely say this is a wives tale. It seems to stick as good as epoxy, although I have not done any destructive testing. I’m sure the bond is a little bit weaker, but it’s certainly pretty good.
"never use silicone on your boat. Silicone will not stick to silicone. You have to remove every bit of silicone to put new silicone on."
False. while, I have not really used silicone on the boat other than for some interior project, such as to Cosmetically fill a gap where a counter meets a bulkhead, I did use it on a side project that has to do with water.
I had put one pass of it on and it didn’t come out great. I missed a couple spots. I flipped the part over and kind of ruined the bead. so I had to either take all of that silicone off and start over, I just put a little more on. This little project has no cosmetic value at all, so I just put a little more on a few days later. Guess what? It’s stuck perfectly. It’s as solidly bound to the other silicone as it is to the rest of the material.
Response...
I have been a shipwright for 50 years, and have built my three cruising boat/ homes as well as worked on hundreds.
The "secondary" bond of epoxy over epoxy or polyester is still good, given good prep. The secondary bond of polyester over an epoxy glassed hull OR over polyester, is nowhere as good. Not even close!
Silicone caulk is ok if necessary to prevent damage to some plastics, but it should never be coated over with AwlGrip or more silicone. The bond is very poor! If I am re painting an area that had it, I remove 99.99% of the old silicone, and sand the surface to expose a new surface.
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25-11-2024, 08:43
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#36
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Registered User
Join Date: Jul 2016
Posts: 8
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Re: Old Wives Tales
The old wives tale has never been ‘Polyester or vinyl ester won’t stick to Epoxy’
The reality is simply that from an engineering perspective they both have a less than satisfactory bond to epoxy and are more likely to fail.
Small amateur repairs that are not under much structural loading might easily pass for satisfactory.
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25-11-2024, 09:35
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#37
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Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 10,284
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Re: Old Wives Tales
Quote:
Originally Posted by Greektherapy
The old wives tale has never been ‘Polyester or vinyl ester won’t stick to Epoxy’
The reality is simply that from an engineering perspective they both have a less than satisfactory bond to epoxy and are more likely to fail.
Small amateur repairs that are not under much structural loading might easily pass for satisfactory.
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Exactly. Long scarfs and double the bond area. I've used polyester for some large re-core jobs in low stress areas, and while there was no failure, I don't do that anymore. It's easier to work with, but the secondary bond just isn't as good.
I get Chotu's reasons and would probably do the same.
[Chotu: I'm sure this has been asked, but does MMA/Plexus work for you?]
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25-11-2024, 12:21
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#38
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Registered User
Join Date: Mar 2015
Location: Morrisburg, ON
Boat: 1976 Bayfield 32
Posts: 1,248
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Re: Old Wives Tales
Another boat repair "truism" I was told that turns out not to be true: That you can't repair carbon fiber with glass fiber.
I repair rowing shells for my bottom-feeding rowing club. We now get donations of old carbon fiber boats (mostly first generation 1980s-1990s), some with severe damage damage (large holes). They are easily fixed with glass and epoxy.
You get a better looking and probably a stronger job if you repair it from the inside, which usually means cutting a 4" hole to reach inside and putting in an inspection port. Most of these boats have hollow bow and stern floatation and are not made to be easily repaired.
You do need to protect your skin from the fibers though, they're sharp!
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25-11-2024, 13:51
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#39
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Registered User
Join Date: Jun 2009
Location: Annapolis, MD
Boat: Sabre 34-1 (sold) and Saga 43
Posts: 2,799
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Re: Old Wives Tales
Gougeon Brothers did a test a few years back (I'm getting old, a "few years" may really be "a decade or two"). They took several samples of epoxy projects, and gelcoated them. They then did some sort of bond test. I don't recall the details, but the end result was that gelcoat is a perfectly adequate finish. I can't recall if they tested it, but I'll bet dollars to donuts that gelcoat sticks as good or better to epoxy than other finishes, say Brightside or Emron. Adhesion in a paint film is a pretty low requirement!
This is one of those things where we find a theoretical advantage of one thing over another, and then decide that regardless of the real world implications, the better one is the only acceptable choice. Changing car engine oil ever 5K miles is obviously better than the manufacturer's recommended 7500 miles -- but who cares if either interval lasts longer than the car body or the head gasket or the rear main or most anything else that makes the car die?
I've been pondering this paradigm in regards to battery cables. There is a huge body of "knowledge" that asserts that battery cables must be carefully measured to fractions of an inch to prevent horrible unbalancing of paralleled batteries and resulting damage. Except I've never seen a single study or scientific calculation of the actual impact. Do batteries done this way last 30% longer? 20%? Even 5%? At anything less than 5%, it's noise, not meaningful. In my mind, even if they unbalance during a major charge/load event, they equalize out at the top or bottom, and the net available Ah are unchanged and the net charge time/energy is unchanged. But the logic makes perfect sense, even if the impact is irrelevant.
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25-11-2024, 17:32
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#40
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Registered User
Join Date: Jul 2007
Location: Florida
Boat: Swallow Craft, Swift 33
Posts: 297
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Re: Old Wives Tales
Quote:
Originally Posted by wholybee
Red light is the best way to save your night vision, and/or you should be using red lights everywhere at night.
Lots of studies on this. Dim white light is works just as well to protect your vision, and it is easier to see under dim white light.
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Naval aviation requires red lenses on everything on a flight deck at night. All aircraft instruments are red background illumination. Just the facts.
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25-11-2024, 17:37
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#41
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Registered User
Join Date: Jan 2018
Boat: 50ft Custom Fast Catamaran
Posts: 12,236
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Re: Old Wives Tales
The wives are certainly making their appearance.
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25-11-2024, 18:09
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#42
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Registered User
Join Date: Jul 2007
Location: Toronto, Canada
Boat: Luders 33 - hull 23
Posts: 1,846
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Re: Old Wives Tales
You have to replace your rigging every 10 years.
I heard that so many times, and yet, no one mentioned how much use was the rigging put thru.
Sounds like SS wire has an expiry date.
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25-11-2024, 19:47
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#43
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Registered User
Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 2,952
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Re: Old Wives Tales
Quote:
Originally Posted by sailingharry
I've been pondering this paradigm in regards to battery cables. There is a huge body of "knowledge" that asserts that battery cables must be carefully measured to fractions of an inch to prevent horrible unbalancing of paralleled batteries and resulting damage.
But the logic makes perfect sense, even if the impact is irrelevant.
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Now you will want to make sure that all the wires leading from the master to the individual detonators on the shell segments of your implosion "device" are of the same length.   
__________________
Beginning to Prepare to Commence
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26-11-2024, 00:38
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#44
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Registered User
Join Date: Mar 2012
Posts: 47
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Re: Old Wives Tales
Quote:
Originally Posted by cottonsail
Naval aviation requires red lenses on everything on a flight deck at night. All aircraft instruments are red background illumination. Just the facts.
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An observation: I think our wives might dislike hearing “wives tales” as opposed to “old wives tales”.
The night vision thing: the argument h is a not about how easy it is to see in dim white light vs red light. That answer is obvious. The point is about preserving night vision. In this case, red light wins. As for instrument panels, whilst red backlight makes sense in the preservation of night vision theory - that's good for me - BUT after lengthy passages on various newly built sailing boats, my advice is to avoid red digital displays. I simply can’t read them. I would now always specify blue for digital displays. But red backlighting on analogue gauges is good.
Sailing on a Friday? Steady on now. Don’t the sailors all get paid on a Thursday? Then they go ashore and energetically empty their purses into the barmaids’ grateful hands, and the following morning they are falling out of the rigging.
There’s always a hint of historical sense in old wives tales.
I wonder how many trawler men fell overboard after stepping on a banana skin?
Nevertheless, if my “mates” reacted so rudely at the appearance of a banana, I think I’d change my mates.
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26-11-2024, 06:49
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#45
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Registered User
Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 6,995
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Re: Old Wives Tales
Quote:
Originally Posted by guitarrich
The night vision thing: the argument h is a not about how easy it is to see in dim white light vs red light. That answer is obvious. The point is about preserving night vision. In this case, red light wins. As for instrument panels, whilst red backlight makes sense in the preservation of night vision theory - that's good for me - BUT after lengthy passages on various newly built sailing boats, my advice is to avoid red digital displays. I simply can’t read them. I would now always specify blue for digital displays. But red backlighting on analogue gauges is good.
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I agree, red digital displays do usually take a bit more effort to read. Orange can be ok though depending on the display in question and the size of the text. Analog gauges don't usually need a super precise read, so the level of detail you need to be able to see is lower.
Other than the tachs, I don't care that much about precision on my engine instruments, knowing that the coolant temp is showing "somewhere around the 180 mark" is good enough in most situations. So I only just barely need to be able to identify the marks and where the needle is pointing, anything more is a waste of night vision.
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