Making a pair of oars - measurements ?

sarabande

sarabande

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I have a little sculling dinghy a shade under 9ft OA and am making up a pair of oars.

The crutches are at max beam and placed prezackly 4ft apart.

It's tempting to think that I should make the loom of each oar about 22 inches long, with the leather about 6 inches long. That would allow me to row without bashing my thumbs together mid-stroke.

Do those figures seem reasonable please ? And what overall length would be sensible ?

TIA
 
Having rowed a dinghy many times with rather short oars, I'd suggest something around 7 foot. Actually, for best efficiency the looms should overlap so each stroke is completed with one hand above the other - otherwise the shorter loom doesn't allow as much energy to be put into the stroke, after all they are the equivalent of a fools purchase (the input is to the shorter lever so the longer outboard robs you of power).

If you're feeling really enthusiastic, you could carve out spoon blades - I could let you have the PBO article on how to do it...

Rob.
 
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sarabande said:
I have a little sculling dinghy a shade under 9ft OA and am making up a pair of oars.

The crutches are at max beam and placed prezackly 4ft apart.

It's tempting to think that I should make the loom of each oar about 22 inches long, with the leather about 6 inches long. That would allow me to row without bashing my thumbs together mid-stroke.

Do those figures seem reasonable please ? And what overall length would be sensible ?

TIA
Click to expand...

My little dinghy is about the same beam. Its oars are 5'6"

I used the 6ft long mirror dinghy oars for a while but found the slightly shorter ones better


These, and the Mirror oars in relation to the Mirror, are appreciably shorter than the above formula gives
 
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I would suggest you go for slightly shorter oars than Lady in bed's diagram indicates. Note that the illustration is of a fairly long and narrow skiff. Experimentation with my own 10 foot dinghy (maybe not as beamy as yours, though) shows six foot oars to be the longest that are comfortable to use and in practice I prefer the 5foot 6inch ones. Their slightly shorter length makes them more convenient around other boats and I also think they are easier to use when the dinghy is heavily loaded. I agree with you about non-overlapping looms. I think the blades should be about 4 inches wide, too. Rowing is good! I have seven outboard motors in the shed and never use any of them!
 
The problem with short(ish) oars is that the higher the freeboard the higher will the handles need to go if one is to get a good grip on the water by fully immersing the blades. Murphy has practically the same beam and I don't think that the oars are slightly less than 2 metres. (Murphy is 2.03 metres long). I can measure them when I go down to the boat if you wish.

IMG_0113_zpsu34uk54z.jpg
 
sarabande said:
I have a little sculling dinghy a shade under 9ft OA and am making up a pair of oars.

The crutches are at max beam and placed prezackly 4ft apart.
Click to expand...

I would suggest whatever maximum length you can fit in the boat for transport. Two feet is not much leverage - I'd go for overlapping hand, so about 2'6' or so of each oar inboard. I overlap on my dinghy and it works fine. No thumbs have ever been caught, I think because the overlap is big. Having oars with a 1/2" gap between them is just asking for painful trouble.
 
I don't think there is a single 'right' answer.
Longer oars will let you row faster for a given stroke rate.
Loom/length ratio dictates the leverage.
Are you looking for a quick workout or gentle exercise over a longer period?
Do you like to row with quick light strokes or put your back into it?
Will the boat be heavily loaded? The drag of an immersed transom can seem vast.
The tippier the boat, the more your thumbs can clash IMHO.
Personally I am not looking for max efficiency and I don't like bashed thumbs so I would aim to have the looms a couple of inches short of touching.
But 22" is quite short, the boat is narrow....
 
I recently bought a pair via the internet. They are beautiful straight grained spruce and German made. I am extremely pleased with them I think they were about £28 for the pair including delivery. 7' long.
 
neil_s said:
I would suggest you go for slightly shorter oars than Lady in bed's diagram indicates. Note that the illustration is of a fairly long and narrow skiff. Experimentation with my own 10 foot dinghy (maybe not as beamy as yours, though) shows six foot oars to be the longest that are comfortable to use and in practice I prefer the 5foot 6inch ones. Their slightly shorter length makes them more convenient around other boats and I also think they are easier to use when the dinghy is heavily loaded. I agree with you about non-overlapping looms. I think the blades should be about 4 inches wide, too. Rowing is good! I have seven outboard motors in the shed and never use any of them!
Click to expand...

I too prefer to row out to my mooring as its only 150m from the shore.
 
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