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Thread: How to apply glass to oars ?
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28th November 2010, 06:37 PM #1GOLD MEMBER
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How to apply glass to oars ?
Hi. These are some oars (I think I should call them sculls, really) that I am making. What I would like to do is apply a layer of epoxy/glass - just to the actual blade, and preferably just to one side. The objective is just to make them more robust. I'd like to know if this is this sensible, and should the front or the back of the blade be glassed ?
More info that might be useful: the blades are about 9mm thick on average (except near the central spine). The blades are about 570mm long. They flex very little in use, due to the strong central spine. I have some 3oz glass and some BoteCoat epoxy which I would like to use. The glue-up was done with epoxy. Ultimately I'll put a coat of marine varnish over the lot.
cheers and thanks
Arron
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28th November 2010, 07:13 PM #2
Howdy Arron,
Most timbers will be fine without the glass. The ones that might need some protection all over would be cedar or paulownia, if you used them for the blades. In that case I would glass the lot.
If it is a pine, or fir/oregon or other medium density timber the vulnerable area are the tips only.
The glass has the nice function of preventing the timber from splitting to - even if they get a big hit on the end, you will get a dent but the glass will prevent the timber from splitting.
The light glass you have will finish very transparent so you don't need to worry about that side - if you put it around both sides of the tip it will make it much stronger.
I would read the section on this page about glassing small complex areas. It talks about cutting the glass on the bias so it wraps around the end more neatly.
FAQ - Boat Building and Repair Methods - Plywood Epoxy Fibreglass Cedar Strip - Michael Storer Wooden Boat Plans
Ends of the oars should have all hard edges rounded over to a 4mm radius or more.
I would tend to do two layers of that glass. First layer over the tip and down both sides by about 25mm. Then a second layer that comes down about double that amount.
Best wishes
Michael Storer
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28th November 2010, 07:52 PM #3GOLD MEMBER
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Thanks Michael,
I should have mentioned that the oars are made from clear pine (I was feeling cheap) with brush box edges. I read somewhere that brush box was formerly used in boatbuilding because it was the timber least likely to splinter. Not sure if thats true or not. Anyway, it makes the edges of the blade very tough and abrasion resistant, so my main concern is the blades splitting, especially after a good whack around something that I've run into. This is an ever present problem in the shallow, narrow waterway where I use my boats.
Reading your response, you seem to be suggesting putting the glass over just the tips, presumably wrapped right round once or twice. Is that correct ?
I guess the other possibility is to put a metal band over the tip, which I have seen done on older oars. I wonder how this would compare to the epoxy/glass aternative ?
cheers
Arron
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28th November 2010, 11:44 PM #4
I too wouldn't recommend a 'glass sheathing, but if you want to really protect the blade, then embed an epoxy soaked length of single braid line, along the perimeter of the blade edges. A shallow groove makes this very easy. On that blade a 6 mm line would work well, tack at one and lay into the groove and tack at the other end to hold it until the goo cures. I soak the line in very slow cure goo for several minutes, then apply the line wet. It's a messy job, but I've been using this technique on daggerboards, centerboards and rudder blades for years, without a single issue, in spite of testing the technique on rocks, stumps, engine blocks, trailer cross members, etc. repeatably. The worst that happens is the thickened epoxy, used to attach the line chips or cracks locally. It's easily repaired and the wood is rarely damaged. If you use a brightly colored line, you can be stylish too.
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29th November 2010, 06:37 PM #5Novice
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very nice, can I ask how you made the blades? Adze or CNC router?
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29th November 2010, 08:09 PM #6GOLD MEMBER
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Closer to the adze, really
they are just glued up as a thumping big bit of wood, then rough shaped with an arbortech on an angle grinder. Then fine shaped with a fishtail gouge (hand carving tool) which is the only bit of the process that I actually enjoy, then coarse sanded with a sanding disk on an angle grinder, and finally fine sanded with an ROS. Easy, especially as I had an old scull to copy.
To Michael and PAR, thanks for the input. I think I'm on the right track now.
cheers
Arron
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29th November 2010, 11:28 PM #7
An old trick I use on oars, sweeps and paddles is to cut the tip off the blade when it's done, then glue it back on with epoxy. This forms a natural break in case moisture tries to climb up the blade from tip damage. Water can't get past the epoxy glue line, so the worst that will happen is the tip will rot, the remaining blade is fine.
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