Builders' Forum Archives
Re: Dynel vs. Brass?
Posted by terry on Jul 5, 2005
Ok, folks, I pasted in my notes on installing brass rub strips.
John: feel free to include all or some parts of these notes in Shop Tips.
Lazlo: I most respectfully beg to differ on the corrosion problem with brass. The strips have been installed for five years on two of our boats, used extensively in rocky, salt water and stored for the last two winters in an unheated garage 120 feet from the Atlantic Ocean. They're a bit green, but the green can be easily polished or sanded off if one cares to bother. The strips are still near their installed thickness, are otherwise sound and have been zero maintenance. For the few bucks and hour it takes to install them, I belive they are much less trouble and more durable than any combination of epoxy, addtives and fabric.
Happy stripping, folks!
INSTALLING BRASS RUB STRIPS
I use a method to reinforce my keel ends that has been used in wooden canoe and boat-building for over a hundred years. I use 3/8" brass half-oval strips, available by the foot from jamestowndistributors.com. I cut two pieces about 18" each for the stem and stern. I then drill each piece every two inches to accept ½" brass #6 oval-head wood screws. I then rough up the flat side with 60 grit and file or sand the ends to a flat taper. Lastly I bend one end of each piece to curve up the stem and stern an inch or so (do this carefully, as the strips can break at the drilled holes).
Next I slightly pre-drill the holes along the keel, stem and stern to accept the screws. Then I rough-sand the keel with 60 grit where the strip will be mounted, sanding through the paint along a 1/2" wide section the length of the rubstrip. I do not plane or sand out a flattened notch to accommodate the brass (too lazy). Then I apply some very-thickened epoxy to the strip and screw it on. I then flip the boat over and wipe off any excess epoxy with a vinegar soaked paper towel. I find it important to using a very thick (stiff, actually) epoxy mix to glue on the strips, then when you invert the boat, the goo settles and widens just a bit to make a support platform for the brass that is as wide as the brass. Too thin a mix, and the stuff just runs on the floor and leaves a gap between the edges of the brass and the keel/stem. If this happens, go back the next day and add some more thick goo to the brass/keel joint. Total prep and installation time for two strips: about an hour.
These strips last a LONG time, even in the very rocky waters up in Maine and Canada where we use some of our boats.. I actually think they add less weight than repeated applications of multiple layers of cloth, dynel, graphite or whatever, last far longer and look pretty good. They will eventually tarnish, but if you're very fastidious (I'm not), you could polish or sand off the tarnish.
One builder even suggested using the brass strips for rubrails. Certainly easier to install/maintain than a wooden rubrail. Maybe lighter also. I'm also considering installing them along about 8' of each chine on a few of my boats, as this is another area that meets the rocks more than I'd like.
Any other questions, e-mail me at email@example.com
And from an old e-mail I wrote on this topic:
"I have seen several canoes with the brass installed with screw spacing that appeared to be 4 or 5" or thereabouts. I've never discussed my penchant for 2" hole spacing with an engineer, or even a very experienced professional builder, due to my chronic and abject laziness. Sorry. My rationale, however is that the critical attachment is the thickened epoxy I apply on the rough-sanded keel and brass. The screws merely serve as clamps in this hard-to-clamp area until the epoxy cures. The screws are so short (so they don't pierce the hull completely) and made of very soft brass, that they just wouldn't hold the brass on for very long without the epoxy. The close spacing merely improves the clamping of the brass onto the boat.
Of all the boats I've installed the brass on, none, save for a MC 16.5, had a keel/stem edge at the ends wide enough to eliminate a slight overhang of the brass edge on each side. Hasn't been a problem yet, and some of the brass has been on for five years and used in Maine, Canada and other strange places with granite that's harder than a pig's head and sharper than a kind barber's razor. I credit the epoxy for keeping the brass in place. But now I think that it makes sense to apply the brass with a very thick, stiff epoxy mix, to fill in this gap on the upper edge of the brass. "
Generally, a canoe keel is wider to start with, with a much larger radius in the curve of the keel up into the stem, so wider spacing of the screws may be all that's needed. "
In Response to: Re: Dynel vs. Brass? by CLC on Jul 5, 2005
- Re: Dynel vs. Brass? by LeeG on Jul 5, 2005
- Re: Dynel vs. Brass? by terry on Jul 5, 2005
- Re: Dynel vs. Brass? by Laszlo on Jul 6, 2005