any advase in insulation materior

I'm refiting a 49' metal hull shoonner
My next estep will be insulation.
Does any one have used blue board from Dawn?
Or there is something better, besides spray on foam [ to messie]
I would apresiate very much your comments

 

Closed cell foam, flame retarded . Dont use fibreglass house insulation. Generally you will need to shop around, prices vary considerably for similar materials depending on scale.


You might want to check your Coast guard regs and recommendations. some insulations like Polystyrene are too flammable, but we can get panels wrapped in alloy foil which are ok to use.

Cheers

 

I have tried the blue styrofoam. It is good but time consuming to install all peices need to be cut to fit snug otherwise air will get behind it and you will have condensation where you won't see it. If you do use it put it on in a couple 1'" layers (makes for a better fit on the hull contour) bonding it to the hull first then each succeeding layer. You can also use glue on pins the same ones you would use to put soft accoustic foam up in an engine room. They come in all different lenghts for different thickness of foam.
A neat thing to do is build it up to the thickness of your longs then go over all the exposed edges with another layer. Makes for a very clean looking insulation job.
Personally I favor spray foam even with its drawbacks as it covers well, fills all the voids and is less expensive especially when you count your labor.
When we sprayed Balto we went the extra mile and used 3lb roofing foam. This applied very nice and made for a very even coat. When we were done you could stamp up and down on it as hard as you can and it would not dent. pretty amazing stuff.

Dan

 

The rigid polystyrenes, as Dan says, will prove very tedious to install.
They also have the two big problems of not liking fuel, and being a good fuel.
Armaflex/Armacell flexible closed-cell foam http://www.armacell.com/ is reportedly becoming popular in new metal boats, or so I've been told, and it looks pretty easy to use in a retrofit situation. Some spray-on insulations are popular too but you need to be careful to ensure water can't pool or get trapped on or near them. (That goes for any insulation, really, but especially with the foams because if water gets trapped behind them, you get a rust problem.)

 

I am in the proccess of fitting out my 30ft steel yacht and i am getting the inside sprayed with a special foam that is foam proof and will seal the hull against moisture egress after application

 

air flow idea

I too am having the foam vs. panel debate as to my 34' Golden Hind project

Forgive me if this sounds ridiculous, but modern home design now recognizes that to prevent condensation in the attic area (and consequent ice-dam problems in our Buffalo winters), the living area is super-insulated and fresh exterior air is allowed to circulate under the roof to prevent condensation by equallizing the temperature, pressure, humidity etc. on both sides of the roof.

I also believe that Saab automobiles manage to rust so slowly because they have air channels that circulate air through the front of the car, the front, rear, and door panels, ultimately exiting out the trunk. The constant airflow removes any pooled moisture.

Therefore, could I square off the interior of my boat with firring strips leaving a couple of inches between the well-insulated interior cabin wall and hull, leave the steel well-primed and painted, but open to circulating air, and arrange for positive ventilation by drawing fresh air the length of the hull interior from the bow and venting it from the rear engine room?

I believe with sufficient airflow, this would make the exterior and interior surfaces of the hull close enough in temperature to prevent condensation in any climate, the constant moving air should keep things dry and provide lots of fresh air to the Kubota diesel and the Dickenson stove.

Any insight would be most appreciated. I know this plan will give up much internal space but I think it would solve many problems as well.

 

Whizbang, you are certainly right about ventilation being a good thing, but the problem is very different on a boat hull than in an attic or the exterior walls of a house.

A house can have vents at a low level that feed in cool air that heats in summer and exits at a higher point, like at an attic vent. This convective flow is very important to carrying off the moisture that is collected, and simply works in the opposite direction in winter when the exterior is cooled.

You don't usually have the advantage of a low point flowing to a high point on a boat, however. I think you could get this effect by using a solar collector to heat some plates and effectively force the ventilation, or you could go with a forced air system using a fan of some sort, but these approaches are either complex or will eat a lot of power. Another consideration is that too many vents in your hull can also lead to too much water in your hull under certain conditions.

The simpler solution is to seal the insulation to the external plate so that moisture is physically excluded. So, for example, a closed-cell foam can be glued directly to the inside surface of the hull with a fairly heavy mastic of some sort (or epoxy paint, or whatever) so that no water can get in between the hull and the foam. A job that must be done carefully, obviously. The foam itself, though, being a good insulator, will not cause condensation . . . so the problem goes away. The foam will help to keep things quiet in the hull as well.

BillyDoc

 

yes this is possible

Yes to allow air to circulate will prevent any damp pooling.We have a yacht in greece that has teak strips with a 1cm gap between,these cover the entire side areas of the boat before any internal fixtures were added and allow for air circulation. However i live and sail mainly in Ireland, where the moisture content is quite high, so with this boat i am shot blasting the interior,sealing it then while still dry i am spraying it with foam insulation so that no moisture can get near the inner steel thus i hope permanently preventing internal rust problems

 

Thanks for the feedback.

My idea was to put air intakes [closeable in bad seas] through the top bulkhead of the externally draining chainlocker and have the air drawn the length of the boat by selectable vents [mutually exclusive] ie.
- A vent in the back of the cabin exploiting the vaccum of the diesel stove,
- A vent exploiting the vaccum of the diesel engine when under motor,
- A fan driven external vent in the engine room driven by alternative energy, solar, wind, etc.

I keep reading horror stories about corrosion under sprayed foam. Then I see stories about laid in panels failing to stop the condensation. Since I am building new, I have the advantage of building in full access to all parts of the interior hull. Problem is, what's the point if all I can do is inspect the foam instead of the rust.
Maybe I should focus on reliable condensation prevention first and add R-value as needed.

Anyone have experience with these?

SUPERTHERM multiceramics coating-"10 dry mils thick. controls cold and heat from traveling through it providing a controlled zone that avoids conditions conducive to condensation."
http://www.supertherm.net/home.htm

AP/Armaflex Sheet and Roll Insulation - "used to retard heat gain and control condensation drip from chilled water and refrigeration systems.R-Value 8 at 2" wall thickness."
http://www.armacell.com

all ideas most appreciated

 

Whizbang,

Sounds to me like you definitely understand the problem, and I'm with you about the sprayed-on foams. Too dangerous a practice for my tastes! I've also read that the urethane-based spray-on foams actually break down to form acid in sea water. So you get the usual corrosion from any sea-water in the nice oxygen-starved space --- plus acid effects!

You haven't said what metal you will be using (or i missed it) but either aluminum or steel can have this problem.

Here is what I tentatively plan on doing, with an aluminum hull. After all the welding is done I will clean everything as well as I can and prep all the internal surfaces exactly like I will be doing the external hull below the water line. Then, I have two ideas I want to explore, but haven't yet. The first is to simply paint the interior with two-part epoxy, very much like I will be doing the outside of the hull. Perhaps several coats. But I haven't played with this stuff yet so I'm not familiar with how well it adheres, etc. The other approach I am familiar with because I've used it a lot, and that is to use some product like Devcon(R) Flexane(R) 94 Liquid 15250 to paint the internal surfaces with. This stuff is a two-part, fast curing urethane rubber material and is extremely tough. It is used to line the insides of rock-hoppers and for conveyor belt surfacing. There is also a "primer" for this material that makes it bond to metals very well. The downsides to this stuff are: it is expensive, it is a shiny black in color, and the stuff cures and can no longer be painted in about 5 minutes. So, you have to mix up small batches and paint like crazy until your brush locks up. Oh, and forget about cleaning that brush, it's a gonner!

Actually, I'm hoping to find some other brand that is, at least, white.

AFTER the inside of the hull is waterproof, then I'll lay down a closed-cell rubber foam for insulation and mechanically fasten it down. The more I think about it, the more I think I'll avoid glueing it down exactly because I don't want to trap water under it. I'll also probably only use the foam down to just above the bilge as well, but will use the Flexane in the bilge. Actually, I was planning on using the Flexane to fasten my lead ballast "ingots" down in the bilge as well. I definitely don't want any electrical contact between the aluminum hull and that lead! I have other places planned for batteries.

BillyDoc

 

My 34' Golden Hind project is in wellprepped steel and has lots of layers of highbuild industrial primer on it.
The SUPERTHERM multiceramics coating [www.supertherm.net/home.htm] seems too good to be true. I am thinking if the stuff works, I'll paint the inside with that and then slap on 4 inches of the AP/Armaflex Sheet Insulation [www.armacell.com]. In theory achieving a total R value of 26.
Really skeptical re: SUPERTHERM. If it does what claimed it would be on every boat on the planet.

 

I agree, Whizbang, the supertherm sounds way too good to be true. You should ask them for a sample, but two things occur to me right off: first, they claim that the stuff is "hard as a rock" which might not be such a good idea on a boat hull that flexes slightly, and the "ceramic" insulation sounds a lot like ceramic microspheres to me, which are about a third the price of glass microspheres, and those are cheap. The ceramic microspheres are a byproduct from coal-fired power plants and used to sell for a few cents a pound . . . and a pound was a pretty large volume since they are mostly hollow. They are used industrially as filler. It's conceivable that you could just get some epoxy paint and mix some ceramic microspheres in and have the same thing at much less cost. Any flexure will crack it though if the epoxy is too stiff . . .

BillyDoc