> I have made a couple of "light bars" which I can stand or hang
> in the area where I am working. I have used them as heaters many times
> with good results.

> I will often "bake" a kayak over night to drive out any dampness
> (leave the ends of the tent open abit and position the fan to vent the
> air) or to warm the wood prior to fiberglassing in the morning so I don't
> get outgassing bubbles as the day warms up.

> A plastic or blue tarp tent can be easily heated to room temperature on
> all but the coldest days. The tent should be big enough to allow the air
> to flow around the whole kayak. I use one of those small computer fans to
> keep the air circulating to eliminate hot spots.

> Basically the bars consist of an 8 foot 2x6 with light sockets, a dimmer
> switch and an extension cord. There is a mesh guard to protect the bulbs
> and two pieces of chain for hanging/positioning the bar from the nails in
> the rafters.

> Select the total wattage of the bulbs to suit the dimmer switch.

A nice idea. You can buy halogen work lights in 300 and 500 watt sizes, too. These frequently have their own low stands, so you just plug them in. Most inexpensive dimmers are rated for loads up to 300 watts, so if you have a lot of light bulbs in a light bar you may want to use several dimmers, or just unscrew a few bulbs once the temperature gets near where you want it.

I looked at a lot of small heaters and they all seemed to produce about 5000 BTUs for 1500 watts. Those with built in fans did not produce more heat, they just moved it more efficiently. You should get about the same heat output from any 1500 watt resistance load. This could be an electric iron, an electric frying pan, or 15 100-watt bulbs. I would not recommend using kitchen appliances for heating purposes, though.

If you use light bulbs for heat, spread them apart as evenly as possible. Light bulbs will heat the wood of the boat by radiant heat more than they will heat the air around the boat. The resin in contact with the wood will be warmed in turn, more by the heat of the wood, than the heat of the air around it. If you can put a reflector behind the lightbulb it will increase the amount of light ( and heat in the form of infrared light) that reaches the boat. Disposable aluminum pie pans are great for this. Cut a hole in them that is big enough to allow the neck of the light bulb to pass through. If you cut a hole big enough to allow the pie pan to fit around the socket, you can use your stapler to hold the pie pan to the same 2x4 that you have mounted the socket to.

For heating the air evenly, my favorite heating device is a cheap hair dryer. I can pick these up (used) at garage sales for under $5. They typically draw 700 to 1200 watts, which would provide about 2200 to 4000 BTUs, and they have fans built in. The heated air that comes out of these things is not an extremely high temperature, (don't want to burn the people using these dryers), so you could probably get away with not using a thermostat. I doubt you could ever heat a tented kayak much hotter than 100 degrees F. (about 38 degrees C.) with a single hair dryer, but putting a thermometer inside the tarp would be a good idea. I wouldn't use a good hair dryer for this. They are designed to run for a half hour or so. Running them overnight, or for a several hours straight is going to shorten their life.

Hope this helps.

Paul G. Jacobson