#1449: RotatOar

Today’s invention is an oar for a rowing machine. This is intended to give a more realistic rowing action, during training, than the usual handlebar arrangement.

An oar-like arm is attached to the chain which is joined to the flywheel/air damper. The other end of the oar fits into a spring-loaded vertical axle which is, in turn, bolted onto the front stand of the rowing machine.

This allows an oarsman/woman to experience the asymmetry of pulling on an oar and provides an extra source of resistance via the (variable) spring rate.

A further version would allow the axle to be placed on either (or both) sides of the machine. It might also contain a cam within the axle in order to rotate the shaft of the oar according to the current degree of pull-back (thus helping rowers practice turning the blade into and out of the water).

2 Comments:

  1. My Tupenth worth,I think autohelms are ok but wodlun’t take one for the following reasons:Extra power drain need more solar panels, more weight.They encourage a lack of consentration. By that I mean at night when you’re knackered and trying to keep awake (falling asleep at the oars is not unheard of!) being in charge of holding the course is a great way of keeping your mind active. We had times when we fell asleep rowing but it was always the guy who was on stroke (aft rowing postion) who nodded off. The guy on the footsteering in the bow then had to shout and try and get a nonsense conversation going .. Anyhow, with a decent GPS with a rolling road screen holding course is a piece of cake.Now onto rudders. All of the boats we made or worked on had foil profiled rudder blades. This makes the rudder cut through the water far more effectively than any other shape, making sure there is a laminer flow around it (not turbulant). As much as I hate dissing other people’s work or opinions, a big plank of plywood with the leading and trailing edges rounded off is the wrong way to go about it. After the first race crews were coming back with the opinion that the rudders needed to be bigger as they weren’t working effectively. This is certainly not the case. What ever size rudder you have doesn’t make a difference if the forward edge is an inch wide as it goes through the water. It’s best described by looking at a rock in a river, watching how the water breaks away from it each side, diagonally. The faster the river flows the wider the angle becomes. It’s exactly the same with boat rudders. The faster you go (especially surfing) the more you will have to steer to make it have any effect, untill it gets to the point of not having enough movement to have any steering at all.The trailing edge is equally as important, but I could go on and on trying to discribe it so I’ll leave it there.Having a small amount of area forward of the pivot point of the rudder actualy balances the rudder giving a neutral feel on your foot, or hands depending on what you have. Off the top of my head I think you can go up to about 20% of the total area forward of the pivot before it starts having the opposite effect, but don’t quote me on that one. We had about 10% forward of ours.Anyway to conclude, if you have a decently profiled rudder there is no need to any bigger than a sailing dinghy’s. Something like the size of an RS400 rudder would probably be good enough. Then, if you take any big hits there isn’t the large surface area to get slammed into.We always anchored from the stern during the storms and our rudder stayed there quite happily throughout. Even when one of the shackles snapped when a big goffer hits us the rudder just banged aroung for a bit until it woke us up and we went out and lashed back firm again.Going back to the orginal post, we had Concept2 footplates and straps and we each had our own pair of shoes.In Ocean rowing everybody makes the best of what they have and you’ll get a different take on most things, but I fully recommend foot steering. If you need to kick the stern round to square off to a breaking wave nothing else will be as quick. Also avoid morse cables, they break and are a pain to maintain. It’s easy to take spare rope. I would say whatever you do, keep it simple so it can be repaired.CheersJustin

  2. That seems like a lot more than tuppence worth.
    Thanks
    P

Comments are closed