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Bobcat · 19-08-2015, 11:01

My question is, should I be using fiberglass on the interior before installing the insulation? First thought in my mind is that it would be nothing but good, but I am not sure and want to understand pros and cons. I will be insulating with two layers of Reflectix and separated by polyethylene foam. Just not sure what this would do for condensation between the hull and the first layer of Reflectix.

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I have yet to do mine since my previous boat was made from marine ply, it wasn't necessary. However, I am now in a similar position to you with my subsequent old GRP cat. Anticipating this problem, I spoke to friends who have been that way as recently as last winter (2014/15). It seems that anything flexible that is foam backed is a no no unless you wish to repeat the exercise in not too many years time - the foam disintegrates and leaves a horrible mess to try and clear up in 10-15 years time, possibly less in warmer climates when it might otherwise have helped keep your boat cool.

The vinyl alone (no foam backing) does a great job and seems to last forever. It is best glued to thin plywood, even that as thin as that which is put on top/bottom of good quality ply to save damage whilst in transit. This can be obtained quite cheaply if you get to know your local plywood stockist. The plywood with vinyl glued to it can be formed in panels for easy access if you wish to get to the electrics or fix leaks in the future but most importantly the plywood itself is a great insulator.

It can be fixed eg screwed to small pieces of timber glued to the fibreglass hull etc to provide yet more insulation by way of an air gap or cavity. So, you have three layers of insulation as well as the fibreglass ie air cavity, plywood and finally the vinyl sheet. Friends in the relatively warm if not positively hot Mediterranean have used this technique as well as those sailing in the cold and wet of northern Britain.

A friend from Sweden (up near the Arctic Circle) had some kind of structural or insulation foam sheeting a couple of inches thick between the ply and hull - however, it was structural or proper insulation sheets not the stuff they glue onto vinyl fabric. It may have been the spray on stuff used for insulating piggeries I'm not sure but it was durable.

Interestingly, he also had a sauna up in the fo'c'sle under a hatch ... if you knocked on the bow to attract his attention, he often appeared as if an apparition within the steam which issued from the open hatch! He also had a massive freezer/icebox made from the same foam sheeting. He built the boat himself - beautiful! I met him in the Med - it kept his boat cool as well down there! Hope that helps.

msh_sailers · 19-08-2015, 11:06

Quote:

Originally Posted by Steady Hand

I haven't found the link yet, but while looking came across another I want to suggest you visit. It is a long list of important boat projects related to another brand of boat, but the info is comprehensive. If you read those pages, I believe it will help you greatly.

"101" Series - Quick Links to "Popular" Topics includes "Electrical 101"

Already found a topic I can use some reading up on from there "Head Odors". I swear the holding tank hasnt been messed with in two years and the odor in the V-birth strangely smells like ****. So, I will look into what they say there. Probably PO left his bag of fun stored in there and over the years it has just been........ sitting....... i guess? lol

Steadman Uhlich · 19-08-2015, 11:13

Found it!

First, go to this page. Look over the topics or list of projects. The owner, a nice CF member, has done an outstanding job of documenting his projects. While his is not an islander, there are similarities and methods that apply to most boats.
Highly recommended reading! It offers many hours of free lessons on refitting a 1980s era sailboat.

s/v Stella Blue To Do List

On that list you will see he chose to paint his headliner.

Painting the Headliner

Also....

On the top list look for the Deck Hardware links. Look for the windlass replacement post. That, as I recall, details how to use epoxy on holes in cored decks.

You have to dig into his site, as there are many topics covered deeper within major areas. Have fun reading!

Steadman Uhlich · 19-08-2015, 11:16

Quote:

Originally Posted by msh_sailers

Already found a topic I can use some reading up on from there "Head Odors". I swear the holding tank hasnt been messed with in two years and the odor in the V-birth strangely smells like ****. So, I will look into what they say there. Probably PO left his bag of fun stored in there and over the years it has just been........ sitting....... i guess? lol

Yes. That link list has posts or articles written by Peggy Hall, a very nice CF member, who literally wrote the book about marine heads. She is an expert. Read her advice and take notes. Her complete book is on Amazon. I will buy a copy of the latest edition when I buy my boat. Highly recommended.

jwcolby54 · 19-08-2015, 11:59

Quote:

Originally Posted by msh_sailers

I will be insulating with two layers of Reflectix and separated by polyethylene foam. Just not sure what this would do for condensation between the hull and the first layer of Reflectix.

Just an FYI Reflectix is good stuff however you need to use it correctly or it is almost useless.

It is intended to be used inside of air gap walls. The air is the insulator and is trapped and therefore cannot move. Air is a somewhat decent insulator.

The numbers that Reflectix claims for its insulation value includes the insulation value of that air layer. All by itself, it has an R value of about 1. Not useless but not particularly useful either.

So if you were to use two layers of Reflectix and a layer of foam, your total R value would be 2 (the two layers of Reflectix) and the value of the foam, whatever that may be.

Unless you intend to use Reflectix in the manner that it requires you would be better off leaving it off and just going with a good foam sheet.

If you want to use Reflectix , you need to placer a layer, build up stringers to create the air gap, then staple a layer of the reflective on top of the stringers to create the air gap between the two layers etc. You MUST create the air gap, and it MUST BE AIR, or you will simply end up with the R1 value of the Reflectix (plus any foam).

Google Insulating sail boats. I found a couple of decent articles, which I thought I had saved, but apparently not.

msh_sailers · 19-08-2015, 12:12

Quote:

Originally Posted by jwcolby54

Just an FYI Reflectix is good stuff however you need to use it correctly or it is almost useless.

It is intended to be used inside of air gap walls. The air is the insulator and is trapped and therefore cannot move. Air is a somewhat decent insulator.

The numbers that Reflectix claims for its insulation value includes the insulation value of that air layer. All by itself, it has an R value of about 1. Not useless but not particularly useful either.

So if you were to use two layers of Reflectix and a layer of foam, your total R value would be 2 (the two layers of Reflectix) and the value of the foam, whatever that may be.

Unless you intend to use Reflectix in the manner that it requires you would be better off leaving it off and just going with a good foam sheet.

If you want to use Reflectix , you need to placer a layer, build up stringers to create the air gap, then staple a layer of the reflective on top of the stringers to create the air gap between the two layers etc. You MUST create the air gap, and it MUST BE AIR, or you will simply end up with the R1 value of the Reflectix (plus any foam).

Google Insulating sail boats. I found a couple of decent articles, which I thought I had saved, but apparently not.

Since I am new to the boating community, I am trying to create a mental picture of "giving air space" between the layers with stringers. But I am not exactly following. Any chance you know of a image on google that can show me this? Thank you so much for your insight. I have already bought the Reflectix but not the foam. Any info would be great. I need to move the boat in two weeks and Id hope to get most if not all of this done by then. Thank you once again!

msh_sailers · 19-08-2015, 12:14

I looked into exactly what air gap walls are and I think I am following you better. Should I just stick one layer to the actual hulls surface and the next to the paneling, so that once I put them up (velcro them), there will be that gap that you are referencing?

Like this in a way since there is obviously a gap between the reflextik and the later applied paneling.

jwcolby54 · 19-08-2015, 12:23

yes, if you wish to use it at all. Or justy do away with the stuff and put a layer of foam in there.

Strait Shooter · 19-08-2015, 13:30

Contact cement and armaflex

http://www.armacell.us/home/

Bobcat · 19-08-2015, 14:37

It is intended to be used inside of air gap walls. The air is the insulator and is trapped and therefore cannot move. Air is a somewhat decent insulator.

The numbers that Reflectix claims for its insulation value includes the insulation value of that air layer. All by itself, it has an R value of about 1. Not useless but not particularly useful either.

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Insulation values are great but how long will the product last - manufacturer will probably have the answer to that but do check.
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So if you were to use two layers of Reflectix and a layer of foam, your total R value would be 2 (the two layers of Reflectix) and the value of the foam, whatever that may be.

Unless you intend to use Reflectix in the manner that it requires you would be better off leaving it off and just going with a good foam sheet.

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But does it biodegrade and if so after how long in a marine environment? Ask the same of any foam product you are thinking of using ie how long does it last in the environment it will be placed in!
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redsky49 · 19-08-2015, 14:57

Quote:

Originally Posted by jwcolby54

Just an FYI Reflectix is good stuff however you need to use it correctly or it is almost useless.

It is intended to be used inside of air gap walls. The air is the insulator and is trapped and therefore cannot move. Air is a somewhat decent insulator.

The numbers that Reflectix claims for its insulation value includes the insulation value of that air layer. All by itself, it has an R value of about 1. Not useless but not particularly useful either.

So if you were to use two layers of Reflectix and a layer of foam, your total R value would be 2 (the two layers of Reflectix) and the value of the foam, whatever that may be.

Unless you intend to use Reflectix in the manner that it requires you would be better off leaving it off and just going with a good foam sheet.

If you want to use Reflectix , you need to placer a layer, build up stringers to create the air gap, then staple a layer of the reflective on top of the stringers to create the air gap between the two layers etc. You MUST create the air gap, and it MUST BE AIR, or you will simply end up with the R1 value of the Reflectix (plus any foam).

Google Insulating sail boats. I found a couple of decent articles, which I thought I had saved, but apparently not.

Reflectix is snake oil in a roll. This is one of the most over-hyped deceptive products I have ever encountered. It has the actual insulating value of a couple sheets of aluminum foil. You find it at all the Harry Homeowner locations, not in commercial or professional applications. It is marketed to the well intentioned, but ill informed. It is a scam.

As a mechanical engineer by profession, one of the tasks I performed on a nearly daily basis was energy analysis and heat loss calculations. This issue is indeed in my wheelhouse.

For every surface, whether horizontal or vertical, there is a heat transfer factor known as the "surface air film". This can range as high as 0.68 R Factor. This factor exists on both sides of any surface, whether indoors or outside.

In the insulating claims that Reflectix make on their packaging, they indicate not what the insulating value of their product might be, but only show the total R value for whatever assembly they are quoting. There is very little insulating value to Reflectix and that is a fact! Yes, there is an insulating value for an air gap (if still air), but you can hardly claim credit for that because of your shiny product. A simple 6 mil plastic sheet will perform as well, and frankly, until the air gap exceeds about 3/4", it doesn't add an appreciable amount of insulating value.

I am sure someone will post some miraculous anecdotal information to the contrary, but facts are facts.

The PO would be far better off to use a semi-rigid or board insulation, something like extruded poly or one of the isocyanurate products. Sheets of Armaflex, a material similar to that used in wetsuits, would also work well. It will be more work to install, but you will at least get your money's worth. They (rigid board insulation) also come with a bonded reflective surface if so desired. Score the back side and you can easily form simple curves with it. Heck, even recycled styrofoam coolers would work better than this Reflectix.

If it sound too good to be true, it likely isn't. And in my opinion, Reflectix isn't!

jwcolby54 · 19-08-2015, 18:36

Quote:

Originally Posted by redsky49

Reflectix is snake oil in a roll. This is one of the most over-hyped deceptive products I have ever encountered. It has the actual insulating value of a couple sheets of aluminum foil. You find it at all the Harry Homeowner locations, not in commercial or professional applications. It is marketed to the well intentioned, but ill informed. It is a scam.

A little harsh but I wouldn't spend any time trying to dispute it. You are pretty much right on all points. The "reflective value" is real. That is also used (and for the same purpose) in plain old aluminized fiberglass batten. Beyond that... not much there.