What if Insulation is NOT glued?

[J Clark H356]

DeepFRz is right about ventilation. By doing what I have recommended, you have basically moved the dew point to within the atmosphere of the boat and that is where you want it. Now you have to dehumidify the air. You can do that using a water to air heat pump with a condenser. The condenser takes the warm moist interior air and drops the temperature of it to the dew point and the resulting water falls off the condenser into a condensate pan. That's why you see a window air conditioner "sweat" in the summer or an ice tea glass get water on the outside. The condensate then must be routed to a point where it exits the boat.

In my boat, a Hunter 356 without any insulation, and a MarineAirr 16000 BTU water to air heat pump, I routed a drain from my condensate pan to my shower sump pump where it is pumped overboard, thus the moisture is removed from the boat.

We have been in 18 degree temperatures with 44 degree water and been reasonably comfortable after the first day. It takes time for the entire boat surfaces and materials to reach the ambient indoor temperature. Once that has been achieved, you have the thermal mass of the boat working for you instead of radiating heat off your body. After a couple of days we are able to maintain about 72 degrees with no insulation in the above conditions. The water to air heat pump is most effective at higher water temps, but ours has worked down to 40 degree water. Thats about as cold as the water gets where we are most of the time. When we are in those conditions, we get condensate off the ports and particularly the metal surrounding the ports. These are single glass/plexiglass so they have a very low R value. Until we have stabilized the internal humidity by running the boat a few days, it continues and we wipe it off with a towel occasionally. This is another issue you haven't discussed, but if you are going to insulate your hull, you should look at doing something to the ports too.

If you are constantly in cold climates, the cold air will not hold as much moisture as the warm air, so when you bring in cold dry outside air and heat it up, you lower the relative humidity and the dew point. You will introduce moisture through breathing, cooking and just naturally losing body moisture. That is how we keep our body temperatures regulated. That moisture will accumulate and be picked up by your HVAC system and condensate out if you have that kind of system, or you have to have air changes that will exhaust it to the outside. Showers and other moisture related activities do the same thing, so you should put some exterior ventilation in your shower area to exhaust that warm moist air so as not to introduce it into the interior.

[Benz]

Originally Posted by DeepFrz

Benz, ya but! You had your insulation trapped against the hull. Pretty much the same as gluing it, isn't it?

I thought so, and so do you, but the naysaying ragers didn't pick up on that. Still and all, gluing would be more secure, and carefully filling any air voids is well worthwhile.

[Benz]

Originally Posted by andrei_ca

I'm going to research it too but if you could recommend how to find kit hulls that'd be nice . Thanks,

Andrei

My kit hull came from the Cape George Marine Works in Port Townsend, WA. They have various sizes of the Cape George, and several years ago acquired the molds for the Bristol Channel Cutters.

Just across the border in Canada the Lyle Hess Falmouth 34--to me the ultimate medium-size cruising hull--was being produced and sold as kit.

When looking for kit hulls I found several available in England--the Heard 35 stood out, and the Cornish Crabber might be available as a bare hull, though you'll want to check.

Ben
zartmancruising dot com

[Suijin]

I have an insulation related question so I'll toss it out here. I have the headliner in my boat down for a deck refit and am going to put some sort of insulation up there, primarily to keep the boat cooler in the sun. I have 3/4" an inch between the coachroof layup and the ceiling panels, and was planning on putting two layers of Reflectix up there, cut to fit the patchwork of open spaces. However some Googling of Reflectix reveals that many consider it virtually worthless. Any better solutions for that 3/4" available space?

I know that no matter what I use the R value is going to be pretty low given the marginal space available, but anything would be better than nothing and I might as well use the most effective material possible.

[DeepFrz]

Years ago they used to build the Bristol Channel Cutters in Vancouver, BC. Great kit but the bronze castings must cost a bit these days.

[Pete7]

Originally Posted by Suijin

I have an insulation related question so I'll toss it out here. I have the headliner in my boat down for a deck refit and am going to put some sort of insulation up there, primarily to keep the boat cooler in the sun. I have 3/4" an inch between the coachroof layup and the ceiling panels, and was planning on putting two layers of Reflectix up there, cut to fit the patchwork of open spaces. However some Googling of Reflectix reveals that many consider it virtually worthless. Any better solutions for that 3/4" available space?

I know that no matter what I use the R value is going to be pretty low given the marginal space available, but anything would be better than nothing and I might as well use the most effective material possible.

Interesting, I was reading something similar the other night. the suggestion is that an air space is needed so the silver coating reflects the radiated heat away from the Reflexctix, as you would have if you put it on a wall behind a radiator at home. If you squash it in so the surfaces touch the underside of the deck and ceiling liner then conduction takes over and the heat transfers through.

I suspect this is why everyone in the tropics has a boom tent.

So an alternative effective way to insulate the ceiling void would be good.

Pete

[boatpoker]

23 years as a liveaboard between Toronto and the Bahamas. Most winters spent in Toronto with as many as 10 consecutive days of -30.

Entire hull lined with planks cut from 2" pink foam board tightly conformed to fit against the hull, All edges sealed with caulking then covered with a plastic vapour barrier. Any air allowed between the insulation and the hull will cause major problems. Winters in Toronto were spent under well vented shrink wrap.
We did nothing for added ventilation of the boat, normal leakage sufficed.

My wife had life threatening allergies so we simply could not afford a hint of mildew or mold.

[thinwater]

A few thoughts, in no particular order:

* Ventilation is not directly related to insulation. The total humidity must be controlled above the dew point of the coldest surface, and whether insulated or not, there will always be a few cold spots. Additionally, a well insulated boat will require less heating and thus potentially less water vapor will be introduced. Thus, in principle, a well insulated boat requires less ventilation. My boat was drier after adding insulation.

However, there is a caveat. If the heating system was NOT installed with a separate combustion air inlet (it should have been), then less heating means less fresh air drawn in by the heater. Thus a poorly insulated boat, with a heater that draws in fresh air through all of the leaks, is artificially ventilated and dried, and insulation will give the false impression of reducing ventilation. This, in fact, is why fireplaces are so well know to over-dry a house--they wastefully draw in air. My heater has a separate air supply. Electric heaters also do not draw air and will not induce ventilation.

* Ventilation to control humidity is not much of a plan in cold (-40F) climates. You need to keep the heat in. This should be... obvious. A dehumidifier is much better.

* Buy a boat with a thick cored hull. Less insulation is needed and mold is generally a non-problem.

* Insulation needs to be sealed to the cold surface, but it does not need to be glued. In fact, nearly all AC ducts are fiberglass insulated, which works because there is vapor barrier, and if properly installed, all of the cut ends are well sealed. But you have to be ruthless in the sealing.

* Don't try to install insulation once it starts to get cold. There will be a thin film of dew on the surface, no matter what you do, and the tape and adhesive will not stick properly. Even if they seem to, they will come off later. Do this when the surface is well above the dew point.

[boatpoker]

Just a further note .... Our heat and a/c source is a little different than the usual marine units. We have a Flagship Marine unit that has the usual reverse cycle air conditioning but the heat side of the unit is straight electric furnace forced air.

We have found this to be much more practical and efficient heat in the cold winter waters of Toronto.

[Stu Jackson]

My first season ever with snow on the boat. Before I got a heater, it snowed. Water 47F, deck with 2 feet of snow 32F, humidity 99%, no insulation, stock 1986 fiberglass boat.

It RAINED inside!!!

Once I got the heater, the rain stopped.

This is just a simple example of what everyone has been suggesting.

Insulation and vapor barriers are both a simple and a complicated subject. I am an HVAC engineer, I studied this stuff. It is complicated enough for you to do your own homework and research, because of some the questions you're raising are grade-school basics. It is simple enough that location, sealants, details and techniques have been recorded in basic insulation literature that is easy to find. Heck, I'll bet even Home Depot has a tutorial on it!

Good luck, study hard.