Replies

1. 
   Steve_G | Dec 22, 1998 09:52am | #1

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   Tom--try this URL-- http://www.island.net/~butler/
   These folks have a bunch of plans, at least two of them for hot tubs. I have ordered reprints of magazine articles on several of their projects, and they seem very well thought out and executed.
   They use plywood and expoxy instead of redwood, but you could probably adapt the plans to redwood. They seem to be founded in shipbuilding techniques, so it should hold up well in this application.

2. 
   Tom_Pace | Dec 23, 1998 12:32pm | #2

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   I need help with plans on building a wood hot tub. Does anyone
   know where I can access plans ?

   I especially would like the formula for determining the angle for the slats of the tub.

   Thanks in advance,

   Tom

3. 
   Guest_ | Dec 23, 1998 12:32pm | #3

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   Tom: I've built a couple of hot tubs for myself over the years - both fixed and portable (I've got a 120-pound outfit that's gone on camping and snow camping trips). I'm a strong proponent of the taller, smaller diameter redwood-style tubs as opposed to the low profile, reclined seats jacuzzi ones. I find it more comfortable, easier to carry on a converstion with someone when you can look at them (instead of the sky), and easier to give a massage in. But I've never built out of redwood. Rather, I used fiberglass or plastic because it was cheaper, quicker, far less maintenance, and much more energy efficient. Energy efficient because you can insulate the outside of a plastic, fiberglass or epoxy-coated plywood tub but not a coopered redwood tub. The redwood has to breath. So your only insulation is the 1.5 inches of wet wood.

   Look at http://www.island.net/~butler/ but you can do better and avoid the corners. Use 1/8 marine plywood wrapped in a circle, and coated inside with epoxy resin (System Three is good). Use fiberglass tape on the seams and back the seam with another bit of plywood. At this point you've got a very floppy cylinder. Place it on an oversized circular plywood bottom and epoxy in place, reinforcing the bottom seam with fiberglass tape. Then build a stud wall around the outside, 16 inches on center and insulate with fiberglass batting. Wrap in 1/8-1/4 plywood (or T-111 and you're done) and side with shakes or vertical siding. Like building a little, circular house.

   It will still seem a little floppy until you fill it with (2000 pounds of) water. That will essentially nail it to the ground.

   Cheapest heat to operate is a natural gas hot water heater ($119 at Home Depot) and if you can locate it below the tub, it will thermosiphon with the need for a pump. Setting the thermostat of the hot water heater will control the rate of thermosiphon and maintain a steady (+/- 1 F) temperature but will need seasonal adjustment.

   Cheapest heat to install is the element out of an electric hot water heater ($8). Epoxy in a 1-inch female pipe thread fitting and screw in the element. I like to use 240-volt elements at 120 volts. You get 1/4 the power (1000 watts instead of 4000) but the element doesn't get as hot and you can use a normal circuit. (Or plug it into 240 when you are in a hurry). Spiffy, precision thermostat in the 100-105F range aren't cheap ($100-150). I either modify a $20 digital thermometer with alarm to trip a power relay or just put the 1000-watt element on a lamp timer (those things to convince the burgulars that you are still home). Just get a high wattage one and adjust it seasonally for as many hours of operation as needed (e.g. 2 hours/day summer, 9 hours/day winter).

   Epoxy-coated plywood is versatile stuff. I trust my 39 pound sea kayak in the ocean off Alaska and it's a single 1/8" thickness of mahogany plywood encapsulated in 6 oz fibeglass cloth and epoxy resin ($260 of materials).

   A 6-foot diameter tub holds 17 backpackers (max), but no clothes, and there was very little water left when they all got out. My next hot tub will be as described above, but elliptical, 3' x 5' for four adults.

   Happy soaking,
   David