Wednesday, November 27, 2013

‘Minnow’s’ Yuloh

On measuring ‘Minnow’s’ yuloh I discovered it was about a foot too long, and the extra length was in the blade. Not only was the blade too long, but it was too wide by 55 millimetres. The less width a blade has, the faster must be the action for thrusting a boat forward at a required speed.

Matt Layden, the designer of Paradox’s yuloh, would appear to prefer low geared yulohs, i.e., those with narrow blades and long shafts - presumably because less effort is required to move them through the water, but paradoxically, more strokes are required to advance the boat the same distance a boat powered by a higher geared yuloh would travel. If a higher geared yuloh is stroked at the same rate as a lower geared one, the vessel driven by the higher geared yuloh will arrive at a destination first.

I’ll keep the existing width of the blade at 148 millimetres for a higher geared yuloh than Matt advocates. The plan shows a maximum width of 94 millimetres. If I find that working the yuloh is too much hard work, I can always reduce the width of the blade. Initially, I will not cap the tip of the blade with fibreglass, because I may have to decrease the width.

If my memory serves me correctly, some people who made standard Paradox yulohs discovered they worked better if the pivot cup was moved up the shaft by about 70 millimetres. A better balance was obtained, and the yuloh sat more happily on the pivot pin. In light of this, I shall place the pivot cup on my yuloh 70 millimetres higher up the shaft than shown on the plan.

The yuloh I have inherited has a straight shaft, whereas the plan shows a curved one. The blade itself has been set at an angle to the shaft - rather more than depicted on the plan. In view of this, I think I shall cut and remove a thin wedge from the shaft, and rejoin the parts by epoxying them together.

I am giving thought as to how to make a stowage rail for the yuloh on the starboard side deck. The plan shows a ¼ inch brass pipe in the form of a loop. There is also a semicircular strap from the same pipe bolted to the foredeck for securing the end of the yuloh’s shaft. I may modify a rowlock for securing the shaft to the deck.

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