Wooden Diving Board
Dr. D asked me to look into building a wooden diving board yesterday. I started by reviewing a bunch of patent documents online as well as the info at various websites (woodendivingboards.com, etc.). Here's what I came up with.
93" length x 17" width x 3" thickness
Ipe (pronounced ee-pay) is a tropical hardwood sold as decking in the US. Also called "ironwood".
(7) 1" x 6" x 8' ipe boards
$400 @ $5.75/lineal foot for 1x6 decking (3/4")
Estimated Cost to Build (Wood only)
Time to Build (Shop labor)
One week if wood is readily available and acclimated to install location. Eight weeks if not.
Buy lumber + fabricate 13 wood parts + drill holes + epoxy lamination/glue-up + plane flat + add epoxy hardware + sand smooth + varnish/oil finish + connect wood parts + transport to site + install wood assembly on base + install at site or have trusted contractor do install.
Stainless 316 marine grade fasteners; Carriage bolts w/ nylock nuts and ~50 Screws.
West System G/flex 650 Toughened Epoxy (32 oz. bottles, 2-part mix).
Steel Base Unit
Fabricated bent stainless steel can be custom made or a pre-made base (S.R. Smith) can be ordered from supplier online. Configuration of mounting holes is important, both from base-to-substrate and from board-to-base unit. Expansion bolts may be needed. Rough dimensions of base = 15" wide x 12" tall x 24" long. Steel thickness = 0.13". Base unit should provide the desired amount of elevation above the water surface. If it does not, a secondary base (concrete pad, etc.) may be needed. Hole spacing for board-to-base connection: Three rows of three holes spaced on 8" x 4" grid, grid centered on base. Additional anchors through flanges on base to concrete or wood substrate.
a.) Sikkens "Cetol Filter 7 Plus". Flexible, UV-resistant, semi-transparent, medium build, satin varnish.
b.) Possibly consider using spar varnish such as Epifanes "Wood Finish Gloss" or "High Gloss Clear Varnish". Make sure to follow thinning/application/sanding/dry time instructions on can. There are other spar varnishes out there that would work fine, too, but Epifanes is one of the best, most durable varnishes used for exterior brightwork on boats. $60-100 (1-2 quarts)
c.) Another oil finish of your choice.
Breathable sail cover fabric with high UV protection is appropriate (i.e., Draylon. Sunbrella Marine Grade, Top Notch 9, Sur Last). There are cheap diving board covers available online, but may not fit well. Consider having a custom cover made at a sail shop. When not in use, the board should be covered. Cover fabric needs to be reasonably breathable and reasonably water resistant.
UPS Ground Shipping
Minimum of $300 in the US with protective packaging.
Installation Labor and Materials
Considerable time and cost should be anticipated, depending on new/existing pool or dock configuration. Specialty hardware, blocking, concrete work, etc. will likely be needed. May require other contractor and extended timeline prior to install.
Top Planks: (3) 93" x 3/4" x ~5-1/2" --> edge join with epoxy w/ spline or biscuits(?)
Middle Planks: (2) ~89" x 3/4" x ~5-1/2" --> edge join with epoxy w/ spline or biscuits(?)
Support Stack A: (3) ~30" x 3/4" x 3" --> epoxy and screw Stack A to Stack B parts
Support Stack B: (3) ~30" x 3/4" x 3" with 30-deg beveled nose
End Caps on Top Plank: (2) 18" x 3/4" x 1-1/4" --> Epoxy and screw to end grain
Roundover top plank edges w/ 3/8" radius bit.
Round nose of the top plank along a fair arc. Route several 3/16" groves in parallel arcs across the nose; use a template. Alternatively, wrap sailing cord or add silica sand to finish for traction. This takes some real skill to get right. Additional cost. Consider routing a grove across the board near the nose to identify jump-off zone. Fill with tinted epoxy. Sand flush.
Q: "What's the best method for joining ipe using West System epoxy?"
A: "For prepping to bond, wipe down with acetone to remove the oil on the surface then sand with 60 or 80 grit sandpaper to open up the wood pores wipe with acetone then put on the G/flex on both surfaces. Put together with light clamp pressure just to hold it in place."
- Greg Bull, Gougeon Brothers, Inc. (June 2016 via email)
Bond most of the hardware in the countersunk holes in wood with epoxy - See West System pamphlet for instructions - or just put G/flex epoxy in the holes, wait a few minutes, then add hardware.