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.