View Full Version : DF counter timbers

11-12-2003, 07:37 AM
I'm rebuilding (among other jobs)the long counter and raked, curved transom on a 35-foot former smack. For the framing including stern chock and fashion pieces (running from the last frame up the quarter to the chock) I'm considering Douglas Fir, because I don't trust the affordable oak I've seen here in the Netherlands, especially for the fairly massive chock which will be laminated to a substantial curve(possible gluing and stability problems). Surprisingly good DF is available - 14 rings to the inch, good reddish colour, right smell, affordable. Helpful wood merchant here agrees with choice. I know the stuff from a few years framing buildings in California many moons ago.
I'm consulting you across the water, after doing a search on the site, because I understand DF is quite often used in the U.S. for structural boat timbers, takes glue well, and is very strong (90% of oak for weight?) These timbers shoudn't ever get particularly wet, but will be in a somewhat humid atmosphere up in the counter, however well I work out the ventilation. They'll be innaccessible, and should be there a long time!

I gather DF likes epoxy - does it also like resorcinol, of the Aerodux 500 slightly gap-filling variety? I've just re-read Larry Pardey on adhesives, and got scared. Engine exhaust runs up there, too - too much long-term warmth for an epoxy-laminated beam?

Would you carve the massive fashion pieces, which run fairly straight up the quarters, from solid, or laminate for stability?
Would resorcinol allow me to use thicker laminations, and traditional red-lead type sealing afterwards?

All advice very gratefully accepted...

Ken Hutchins
11-12-2003, 08:29 AM
I agree with Larry's opinion. Use resorcinol.

Bob Smalser
11-12-2003, 06:03 PM
DF a good choice. The latest USDA Wood Handbook has it measuring between 42 and 107 pct the strength of White Oak depending on individual test...with an average somewhere around 90pct as you state. The weakest values compared to oak are in parallel sheer and forces perpendicular to grain. Tight-ringed sticks like you describe have survived in exposed footbridges on my place since the 1930's...so it's reasonably durable.

Two points:

1) The tests were done with run-of-the-mill plantation DF meant for construction, and your material sounds significantly better than that.

2) Laminations properly done are stronger.

Epoxy begins to weaken at much above 100 degrees, so resorcinol sounds like a good choice next to the exhaust...not to mention that heat also making a solid timber there more prone to checking and eventual deterioration than it's mates.

Resorcinol requires perfect joints, hard and uniform clamping and above 70 degrees F, however. And I'd make double sure only pink heartwood went into those sticks and I'd Cuprinol or Penta the heck out of them after glueup and before and after they go into place.

[ 11-13-2003, 01:28 AM: Message edited by: Bob Smalser ]

11-13-2003, 07:00 AM
Many thanks for responses - plus your added extras, Bob. I've ordered technical information sheets from the Aerodux people in the UK, and will start setting up a massive clamping jig at home, where the workbench stands in front of a large radiator!
Got to rush off now for some money-earning work (no prizes for guessing where the stuff will go!) but will post again later with more on the beautiful boat herself, as I'm sure I'll be back with more queries over the coming weeks/months....


Bob Smalser
11-13-2003, 01:50 PM
Guess I'm out of date...maybe your shipyard can get it, but I went looking this morning and can't find Penta anymore...even on a commercial account...the strongest antimildew I can find is Jasco 25pct Copper Napthenate....trade name "Termin-8".

[ 11-13-2003, 02:53 PM: Message edited by: Bob Smalser ]

11-13-2003, 03:18 PM
Luckily, Bob, I've still got half a gallon of the strongest, real Cuprinol, bought in the UK, which I gather is not being sold anymore. Once that's gone, I'm told the best option will be a cocktail of the chemicals used for anti-bug and anti-fungus in the garden - copper and so on. Don''t know if he was pulling my leg, though.........
There's nothing very strong allowed here in the Netherlands any more.