Chine Log Material

[Frank R]

I have plans for a small boat that uses the older style plywood construction using 3/4 stock for the chine logs and keelson.

I recently came across some pre-primed trim stock at the home center store. It is the kind that is solid pine without knots. It comes in lengths up to 14-16 feet. The only downside is it is made up of shorter sections of wood that are finger-jointed together to make the long lengths. Would this be okay to use for chine logs and a keelson? It seems like a good choice since it will be painted anyway.

[JimD]

Don't use it, Frank. The joints will come apart and the wood is likely too soft anyway. Is the boat going to be glued?

[Frank R]

Don't use it, Frank. The joints will come apart and the wood is likely too soft anyway. Is the boat going to be glued?

Epoxy will be used to glue the plywood to the chine logs. Screws or nails will be used to reinforce it. Fiberglass tape and epoxy over the outside edge.

Thanks for the warning about the glue. I will need to check that.

Is the pine really too soft? All the old plans I have seen call for fir or cedar for a lot of these parts.

[JimD]

Fir is much harder and stronger than big box trim stock. And there are a lot of varieties of cedars with quite different properties. But another really big problem is pre primed. You definitely don't want that. You will have no epoxy to wood bond. Only an epoxy to primer bond. Under any stress at all the epoxy will simply pull the primer off the wood. So at the very least you should be using un primed, un jointed stock for logs and clamps.

[Thorne]

That Big Box pre-scarfed/joined stuff is junk as far as I know. Probably hemlock rather than any sort of real pine, but they often label any softwood "pine".

Much better to buy some decent Doug Fir and rip 'em out yourself, then use good epoxy to set them in place.

[Greno]

I bet alot of the pre-primed stuff is magnolia or someother worthless tree.

[SMARTINSEN]

If this is a "budget" boat, you are much better off just picking through their stock of 2" x 4"'s and cutting your own chine stock. It's mostly Hemlock, not Doug Fir, so anticipate it rotting rapidly if you don't soak it in something nasty.

It varies regionally. Around here framing lumber is either green doug fir, or KD spruce. The fir is generally heavy, wet, full of knots and has very wide growth rings. Occasionally if you are lucky you will find a stray piece that is pretty good. The spruce is better, usually with small knots, and if you are lucky will find a nice straight almost clear piece. Usually these better finds are in the larger and longer dimensions, like 2 x 10. Maybe you could find one and rip out and mill a suitable chine log. The Doug fir would be acceptable, but I do not know how good the spruce would be though in terms of rot resistance, and I do not know what is available in your area.

I used a built up chine log of two layers of 9mm marine ply, which made the bending fairly easy. Glued and screwed with epoxy.

[Paul Girouard]

Most of the pre-primed stock out here is low grade Spruce. If it's finger jointed , I would NOT use it on a boat.

In fact I wouldn't use the Pre-prime non - finger jointed material on a boat either.

[Frank R]

I have problems with the finger-jointed baseboards failing in the hallway of my HOUSE!

Now that is a good example!:)

[spirit]

I am using cambara (erisma uncinatum) "mahogany," which is available as decking from many local lumber yards at about $5/board foot. It comes 5/4" (planed to one inch thick), 5.5" wide, and at lengths up to 18 feet. The grain is smooth, there are no knots, it glues very well with epoxy, and it bends sufficiently for gunnels. It is slightly denser than douglas fir, and comparably rot-resistant. I buy 12' lengths and cut 5 1x1" chine pieces (with bevels as necessary from 0-17 degrees), using a Festool saw and a 12 foot guide. The cut edges are smooth and ready for glue.

[Frank R]

Thanks for the info spirit. I will keep cambera in mind.