Old Wives Tales

[Chotu]

"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.

These are two wives tales that I have run into. Wives tales do you have?

[wholybee]

Originally Posted by Chotu

These are two wives tales that I have run into. Wives tales do you have?

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.

[rslifkin]

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.

Isn't that one task dependent? IIRC, red light is easier on the eyes if both lights are at equal brightness, but some tasks can be done under significantly dimmer light if it's white instead of red, so the advantage goes to white light in those cases.

[thinwater]

Originally Posted by rslifkin

Isn't that one task dependent? IIRC, red light is easier on the eyes if both lights are at equal brightness, but some tasks can be done under significantly dimmer light if it's white instead of red, so the advantage goes to white light in those cases.

Not from the studies (military and aviation) that I have read. EVERY task can be done with a lot LESS white light than red light.


The only value of mono-chrome light is that folks understand the purpose of dim red light. But just as often the dim red night lights are WAY to bright. We found that typical safe red night lights on head lamps, for example, were about 20 times too bright for mil spec night use.



The trick is rigging white lights that are dim enough. Covering the light with athletic tape is usually about right, sometimes two layers. Really dim. Other wise your eyes don't adapt.


Note that white paper in moonlight is almost 100 times too bright for full dark adaptation.





https://www.practical-sailor.com/saf...ering-us-wrong

[thinwater]

Climbing ropes are sacrificial, and quickly lose energy absorption capability after an impact load.

In fact, climbing ropes have a much greater fatigue life than any other nylon construction. Climb ropes used to catch ordinary climbing fall typically endure thousands before being retired, and failures due to anything other than cutting over a sharp edge are virtually unheard off. I never heard of one nor have I read of one in accident digests. The source of the tale is a complete misunderstanding of the UIAA impact "fall rating" scale. The test is designed to destroy ropes, and no non-climbing rope can pass all of the requirements at all. It is a very extreme test.

[rslifkin]

Originally Posted by thinwater

Not from the studies (military and aviation) that I have read. EVERY task can be done with a lot LESS white light than red light.


The only value of mono-chrome light is that folks understand the purpose of dim red light. But just as often the dim red night lights are WAY to bright. We found that typical safe red night lights on head lamps, for example, were about 20 times too bright for mil spec night use.



The trick is rigging white lights that are dim enough. Covering the light with athletic tape is usually about right, sometimes two layers. Really dim. Other wise your eyes don't adapt.


Note that white paper in moonlight is almost 100 times too bright for full dark adaptation.


https://www.practical-sailor.com/saf...ering-us-wrong

That article does mention preferring red for moving around even though it's not good for looking at charts, etc. That's the kind of differentiation I was thinking of.

[SailingHarmonie]

Pretty much any advice that includes the words "ALWAYS" and "NEVER".

Because it always(*) depends on the situation.

It is a necessary fact that most people's boating experience is very limited. Most people do not own very many boats in their lifetimes, and do not sail in very wide geographic regions. Despite this, some of these people somehow feel qualified to offer unqualified advice to anybody, with any kind of boat, anywhere. Some people just do not know what they do not know.

This also applies to almost all advice offered on a forum like this that is offered without asking a lot of questions first. Very, very few people present questions here, especially complex ones, with enough background to actually formulate a reasonable answer. That's how experienced people can help most, by asking the questions needed to get a useful answer.

(*) Yep, I said it...

[thinwater]

Ethanol gas is only stable for a few months.


This is true, and at the same time, entirely untrue. I have stored sealed samples for years with no degradation (lab tests). If anything, it is more stable with regard to gum formation than traditional gasoline. However, ethanol gas does have a strong tendency to absorb water from the air, which results in a weak electrolyte that promotes galvanic corrosion within the carb (brass and aluminum together are bad), which leads to clogging. The sludge is corrosion products, not gum.


Keep your gas very dry and use anti-corrosion additives, such as Biobor EB or Stabil 360 Marine (blue, not the red stuff, they are different).

[pcmm]

I've been making that argument about Polyester over epoxy for ages. I can one up it. I've had zero issues getting Gel-coat to stick to epoxy long term! I closed in 15 thruhulls on my boat 9 years ago and there were a few that were in the topsides just above the boot stripe. Very close to the water. I closed them up with epoxy and 1708 and then as the last coat covered them with gel-coat and blended them into the rest of the topsides at he waterline! The only reason I know they are their is because I have pictures from when I did the repair.. The gel-coat has had no issues at all staying adhered to the epoxy repair at or just above the waterline for 9 years! Like everything else, its all about prep!

[thinwater]

Originally Posted by rslifkin

That article does mention preferring red for moving around even though it's not good for looking at charts, etc. That's the kind of differentiation I was thinking of.

The article was cut for space. Moving was also tested (blacked out basement and boat on pitch night). White was always better. It seems, there are no tasks where some level of color discrimination does not help. Your brain is used to processing in color and uses even slight differences in shade as clues. The brain evolved navigating with moonlight and starlight.



Try it your self. Stay up late, black out the basement on a moonless night, and try both. You will need to sit in complete dark for ~ 20 minutes first.

[noelex 77]

Originally Posted by thinwater

Not from the studies (military and aviation) that I have read. EVERY task can be done with a lot LESS white light than red light.

The luminous intensity is largely inconsequential as it only accounts for the human photopic spectral sensitivity curve.

The reason red light is more effective in preserving dark adaptation is that our rod receptors are highly insensitive to red frequencies. Consequently, we can utilize our cone receptors to perceive relatively moderate detail without compromising the receptors responsible for our deepest levels of night vision.

This principle has limited practical applications, but one such instance is sailing, where the provision of dim red light is helpful in some situations. The efficacy of red light in preserving the deepest levels of night vision is not a myth.

[grantmc]

That you have to have an iddy biddy little toilet. I've never understood that.

This is my toilet, it stands proudly and is full size with a good size handle. This is a model was used in submarines.

[Iron E]

Bananas

[JPA Cate]

"Never leave on Friday". Utter bollocks. Leave when the weather's propitious.

[skipperpete]

Originally Posted by Iron E

Bananas

Bananas “ talk to each other”, as soon as one in a shipment ripens, the whole shipment follows suit.
Bananas will make other fruit ripen ie a hard avocado will quickly ripen if placed in a paper bag with a ripe banana.