Oars too long?

[county]

I have a Marblehead gunning dory with a beam of 4'7". In Gardner's dory book he says to use 8' oars, but Shaw & Tenney's formula gives me a length of 8'8". My current oars are 8'10" which seem to be a good length except for the fact that they are banging my knees mid-stroke.

I'm 6'3" and my feet are all the way to the frame and my back is at the c.b. trunk.

Will shorter oars help and how do I figure out the proper length?

[Gib Etheridge]

Are your legs fully extended when your feet are at the frame? If not do the oars still hit your knees on the back stroke when your legs are fully extended? You may be able to install "stretchers" (foot braces) at the proper and comfortable distance somewhere past the frame, thereby lowering your knees.

If that doesn't work you may be able to raise the oarlocks some by changing or adding oarlock socket pads.

Another alternative would be to lower the thwart.

Changing the oar length won't have any effect regarding your knees, but I think that 8" oars would be exactly right for 55" of beam. I just tried some 9" oars on a boat with similar beam and they are definitely too long, by about a foot, I think. You could try cutting off 5" and try them out, after you solve the knee thing, then more if it seems necessary.

I have found that I like oval shaped grips, on a plane perpendicular to the plane of the blade, more than I like the typical round cross section. Telling you that in case you shorten the looms and need to reshape the grips. If you find you don't prefer the oval cross section you can just make them round, nothing lost.

Can we see a photo or two of your boat? Please?

[David G]

Shaw & Tenney's formula consistently offers up longer prescriptions than any other, in my experience. This may be because the believe in rowing cross-handed, and are convinced of their leverage ratios. It might also have something to do with the fact that they sell their product by length?

[johngsandusky]

Shorter oars will help, as the blade dips closer to the hull, the handle rises. I've always used oars 8' or shorter in small boats. The beam on my dinghy is 4'5", 7'6" oars are fine. Try holding the grips crossed while the afloat to judge how much shorter they shoud be. When the blade is submerged and your knees are clear, mark them and measure.

[county]

My legs are not fully extended when my feet are at the frame but when I extend my legs past the frame my legs rest on the frame (due to not having floor boards made yet) and that's not so comfortable. Maybe I should get some floor boards together to get my legs past the frame. Would you install "stretchers" to the floor boards or where?

[Gib Etheridge]

I'm assuming that you're talking about the looms hitting your legs on the return stroke. When you're pulling the looms are up, on the return stroke they are down near your legs. Is that correct?

There's a thread about stretchers here somewhere.

[county]

There she is.

[Gib Etheridge]

Here are a few ideas.

http://www.google.ca/search?tbm=isch...w=1024&bih=596

[Gib Etheridge]

Looks to me like it's just foot placement. You would naturally want to place them against the frames, but they may be too close.

That sure is a pretty boat.

[county]

Thanks for all quick replies and information!
I will makeup some quick and dirty stretchers and try to figure out the oar length before I try to do everything proper.

[Hunky Dory]

I like the idea of floorboards with foot braces set up adjustable to find the most comfortable rowing position and to allow a shorter person to row. I prefer a set of oars a little long as opposed to short as a short set of oars requires more up and down motion and you end up making big circles with your arms instead of back and forth motion.

[Eric Hvalsoe]

8' oars on my boats of 4'6+"inch beam, moderate depth. I do not overlap the grip. My feet rest lighty on heel blocks, knees slightly raised. Oarlocks app 6.5 inches above thwart surface app 12" aft of thwart (aft edge). The oarlocks are set in pads above the gunwales. All of these numbers will vary with every boat - but just to give you some of the variables and a basis of comparison. IF all I rowed was flat water, longer oars might be nice. However, 8' gives me satisfactory power and adequate blade clearance in lumpy water. I tend to sit on one those standard sort of boat cushions.

[Bob Cleek]

Sorry... I couldn't resist...

[Ian McColgin]

I used 8', 9', and 10' oars on my Chamberlain gunning dory with no problems. Most of the time it helped with the 10' to cross. The 9' were my favorite. With none of these, of course, did I have knee banging and I join those who don't see how length of the oar makes any difference.

I like it when the oars balance, which for me means I can keep the oar out of the water totally relaxing so that the weight of my forearms is enough, no muscle up or down, and with the oar in the water the blade floats immersed with the shaft to blade spot just in the water and since that's a gentle slope some of the top of the blade on the upper half is out of the water. I don't like to dip the whole blade under water since I believe with almost no evidence that the conventional symetrical blade with a spine down the middle on each side - no spoon or cup - is most efficient if it's stirring the surface just a little.

[Ian McColgin]

I love #13.

[NickW]

Sorry... I couldn't resist...

I trust they do good business!

[dredbob]

As others have said, if you are banging your knees on the return stroke, it's not the length of the oars. Either your seat is too high (or locks are too low), or the footrests are not properly positioned. Also, the locks could be too far or (more likely) too close to the rowing thwart.
Pete Culler wrote that oarlocks (the base) should be about 7 inches above the level of the rowing thwart (seat) and about 11 inches abaft the nearest (after) edge of the thwart, for an average sized guy. Since you are a bit taller than average, you'll want those dimensions increased by a bit. And your footrests should be such that your knees don't stick up any higher than your thighs, ie, your upper leg should be essentially level. You don't want them too far away either, because you want to be able to really push against them when you are rowing hard.

Bob

[Canoeyawl]

You are a big fella, there is no hard and fast "one size fits all" rule. As mentioned there are basic parameters for a guide, but a good rowing craft will be fitted out for the person that rows it.
Consider raising the oarlocks on "pads" or "blocks", a very traditional way to "tune" the boat. Small amounts here and there will make a big difference. The oar length sounds about right, I certainly wouldn't want them any shorter (or, do not cut them).

[Bob Smalser]

This kid's rowing a Chamberlain Gunning Dory hard from the forward locks using Shaw and Tenney formula oars in a seaway. And without a stretcher or banging his knees. They were designed more for leverage and efficiency than convenience. The thwarts have to be the correct height and you have to learn to row with an overlap.

[Ben Fuller]

Another thing on which to focus is technique. Oars don't have to be any higher on the recovery than needed to clear what ever sea is running. In most conditions the oars need to be no more than level on the return a few inches above your thighs. I try to minimize the height of the path that the handles take, Think very flat oval. If you are rigged so that you have clearance when the oars are crossed on the boat the height of seat and pads is probably OK. Stretchers are critical; effective rowing using your lower back efficiently is impossible unless your feet are well braced. I usually build foot braces into the floorboards. Nice if you can get a full foot or ball of the foot brace but even heel braces work.

[CapnJ2ds]

I'll go with those who advise not to shorten the oars but to adjust the stretcher, rowlock blocks and positioning etc. My Bolger Gypsy is a metre 37 across the rowlocks, so my oars are two metres 90 long, following the traditional formula of: beam x 2 + 15cm. (That's 4'6", 9'6" and 6" respectively, for those still using 19th century measurements. ) Remember, but, this is a "rule of thumb" - you don't have to be exactly to the millimetre. These oars are longer than the light spoons I brought to the boat when I first got her - they came out of a narrower boat - and once I readjusted to the longer and heavier pair, they gave better rowing.

The spoons have oval grips, and I liked them, but not enough to start thinking of ways to alter the round ones on the new oars.

I also agree with posts above regarding technique. Keep the return stroke low and flat, feather the oars. While it is sometimes necessary to raise the blades high on the return in rough water, "windmilling" is generally to be avoided. In (reasonably) smooth water I feather and skim - the latter is really just showing off, but I learned the technique copying older kids 60+ years ago, and have never broken the habit.

[dredbob]

Another thing on which to focus is technique.....

Here is a nice graphic by the British Coastal Rowing folks illustrating what Ben is describing.

http://www.britishrowing.org/upload/...quePoster2.pdf

And here is another with tons of information that is pertinent to both fixed and sliding seat rowing.

http://www.welshsearowing.org.uk/doc...nd-Rigging.pdf

[Gerarddm]

Bump.

The varying formulae have me a bit confused. Using the formula in post #21' I come up with an oar length of 9'-4" for my 15' Lincolnville Salmon Wherry, with a designed beam of 4'-5". Yet using Shaw and Tenney's calcs, they would have the oars at 8'-6", a significant differential. Another Internet formula had me at 9'-6".

I'd like to make my oars from spruce. But just priced it at Martin Lumber here in Everett and they want $15 per board foot, eek eek. That's for clear stock, 6/4 x6.

I suppose I could make them the longer length and reduce in length later if I had to, but would rather they were alright the first time.

BTW, anybody have strong feelings about laminated versus solid stock?

[Oldad]

Go to your local big box and sort through the pile of construction grade spruce and find a 2 x 6 that is clear and straight grained. Shouldn't cost more than a few bucks and you can get two oars out of a ten footer. There is a great thread somewhere here on building a pair of oars. I made a pair a few years ago and they are holding up just fine. If I were to build another pair I would laminate the spoons (is that the right word for the wet end?) and cut the shafts from a clear construction grade spruce 2 x 4. I guess it depends on what your purpose is and the level of finish you desire. Something to get out to the mooring is what I strive for.

[Upshur]

Longer better, unless you have narrow channels to navigate. more balance more power, and I find I can use the oars as sails. Raising the oar lock blocks can help as well and will give you more wave clearance in higher seas

[Ben Fuller]

Check in with Walt Simmons; he is pretty experienced. I suspect that 9 footers would need a little cross hand technique which is pretty efficient if you are comfortable with it. My experience is that the S&T formula errs a little on the short side.

[lincolns1st]

Speaking of oars and oar construction...may I ask a question somewhat off topic? Is there a formula for oar-blade to shaft/handle that I can apply? I took up the project of a scullling oar to break up the project focus a little on my 33' cutter repair. I used Pardy's plan in one of his books for the 16'er, but as I was laying out the blade it didn't look right, i.e. propertionally starting looking like a fly-swatter. So before I got too far along I dug up the "golden rule" of 1.186 or some specific number I don't have in front of me, and tried applying it to Pardy's basic dimesions which was missing the taper portion in his sketch. The start of taper given is 4'10" from the overall length of 15'9". That worked out proportionally very close using the "golden rule" I came accross, but still didn't look right. Any suggestions?
I get addicted to reading this Forum,

Trying to Carry on!

[Ben Fuller]

Sculling oars are different. Blades are related to the size of the loads being moved. Weight of the blade is not a problem, you want it blade heavy. With a big blade you can adjust what you have according to the load, resistance etc. As an example I have a 4 foot blade on a 12 foot oar. For a look at dimensions for a big oar, find Roger Taylor's book on the elements of seamanship. He used a two piece oar that could easily be stowed and assembled. Consider the long tapering Chinese/ Bahamanian solution.

Ben

Speaking of oars and oar construction...may I ask a question somewhat off topic? Is there a formula for oar-blade to shaft/handle that I can apply? I took up the project of a scullling oar to break up the project focus a little on my 33' cutter repair. m,

Trying to Carry on!

[lincolns1st]

Thank you Ben, I will look for that referance, much appreciated. I definitely want big and beefy 18000lbs. is a lot of boat plus forces.

[Lazy Jack]

I use 9 foot oars on my chamberlain gunning dory and that feels about right. The 8s were a little bit short, the boat tended to out run them. I'm used to rowing Adirondack guide boats so hand crossing is not a problem for me. I use a long leather collar on the oars so I can slide them more inboard or outboard against the thole pins depending on the conditions.

[neilm]

I don't think the oar length is the problem but the oarlock height. I added a block of wood under my oarlocks on my CLC Skerry and it helped a lot. Of course when you go up you need longer oars but yours are not too long.

Neil