dimensions for hollow oars

[davebrown]

can anyone give me dimensions for hollow oars? sounds like a fun project, and i thought it might be good to do before i jump in and do a hollow mast.

the oars will be 8 ft spruce. is birdsmouth the way to go, or are there alternatives that are easier?

[Steve Lansdowne]

For masts one generally enlarges the diameter by 10% as compared with a solid spar, thus I assume the same would be true for oars, though these would seem to be a bit more complicated than masts and the relative weight savings rather small. I have a computer copy of an article by Joel Herzel that I can send you that discusses building hollow shaft spoon blade oars. PM me for a copy. There is a useful article and dimension calculator at http://www.duckworksmagazine.com/04/s/articles/birdsmouth/index.cfm you should look at also.

[davebrown]

thanks steve. the article was really good, although funnily, written by someone who had not built oars or mast.

i don't know how to pm for your other article.

[Peerie Maa]

I'd delete that or you will have every fruitcake in the world emailing you. If you left click on Steve's name it will open a drop down menu with the send a PM option.

[davebrown]

done

[mike1]

hi all, I am intending making a pair of hollow wooden spoon oars, I have some quite nice oregon ,
I have an old hollow scull blade about 60 years old , the original was cut down to be used as a trophy,, I have taken dimension off this , and have a general idea of what's involved.
The workmanship is quite outstanding.
Cant figure the glue used,
Any input would be appreciated
Ragrds to all,
Mike

[Peerie Maa]

The 60 yo glue is probably aerolite, if there is a purple glue line it will be resourcinol, or it might have been caesin. However I would not worry about 60yo technology. Epoxy will do the job.

[Terry Haines]

The answer to the original question depends on wall thickness. Increasing the diameter by 10% gives same strength for wall thickness 18% of OD; weight saving 27%. The weight saving may not justify the extra work.

Wall OD x Weight Reduction
10% 1.27 42%
18% 1.1 27%
20% 1.08 25%
25% 1.05 18%