4.0m 90x45 solid ash/Western Red Cedar oar

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4.0m 90x45 solid ash/Western Red Cedar oar

Post by topherdawson on Sun Mar 26, 2017 7:02 pm

This oar was made by Topher Dawson. It is 4.0m long to be used at stroke, and has a solid ash inboard 90mm wide and 45mm deep. It has a rectangular section twice as wide as it is deep, tapering as it gets further out. The outboard is scarphed on to the inboard with a 6:1 scarph joint, and the oar has a 4mm plywood spoon blade.

The Unbalanced Handle Force (UHF) @ gearing of 3.0 = 2.60kg. @ 2.8 = 2.22kg @ 2.6 = 1.86kg.

Total weight = 5.5kg and deflection at 10kg at 2.5m = 61mm which is good and stiff.

This oar was tested with too much negative pitch, i.e. it dug in too much, but this is now remedied.

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Re: 4.0m 90x45 solid ash/Western Red Cedar oar

Post by topherdawson on Sun Mar 26, 2017 9:41 pm

Design 2B Stroke 4.0m 90x45 solid ash/Western Red Cedar oar
It is 4.0m long to be used at stroke, and has a solid ash inboard 90mm wide and 45mm deep. It has a rectangular section twice as wide as it is deep, tapering as it gets further out. The cedar outboard is scarphed on to the inboard with a 6:1 scarph joint, and the oar has a 4mm plywood spoon blade.

The Unbalanced Handle Force (UHF) @ gearing of 3.0 = 2.60kg. @ 2.8 = 2.22kg @ 2.6 = 1.86kg.

Total weight = 5.5kg and deflection at 10kg at 2.5m = 61mm which is good and stiff.

Build time 10 hours. Cost of timber about £100.

A 4.3m version would have similar numbers but would be about 6kg total weight.

This oar was tested with too much negative pitch, i.e. it dug in too much, but this is now remedied.

topherdawson
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Posts : 211
Join date : 2016-11-24

http://sasoo.forumotion.co.uk

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