Oar length and other questions - Mountain Buzz
 



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Old 04-26-2013   #1
 
Redmond, Oregon
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Oar length and other questions

Is there, should there be a different formula or fudging of math in determining oar length/set up between Cats and Rafts?
All other things like height above water, tower angle, locks, tube size, boat loading and crew being equal.

I'm thinking that part of the reason the smooth bottom boats do so well with really long oars is because of their limited turbulence compared with a self bailer. That its not just that they expect greater performance.
But that shouldn't be the case with Catarafts.

Is there a general rule that one can go with different sized oars on a Cat?

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Old 04-26-2013   #2
 
Redmond, Oregon
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Ths formula doesn't work for whitewater

.
.



The Oar Length Formula Step-by-Step

1) Measure pin-to-pin span for the rowing station

2) Divide span by 2 and add 2" to compensate for freeboard

3) Divide by 7.

4) Multiply by 25 to get oar length in inches.

5) Divide by 12" to get oar length in feet and tenths of inch.

6) Round to nearest whole inch.

Oars & Rowing by Clint Chase
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Old 04-26-2013   #3
 
Redmond, Oregon
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This one does for some:

Formula: Distance between the Oar Locks X 3 - 6", Divided by 2, Divide by 12 to get feet.

Example: 72" X 3 = 216 - 6" = 210 divide by 2 =105, divide by 12 = 8.75 ft oars.

==========

This general guide from river connections at:
Riverconnection.com - Articles - Boating Gear - Choosing the correct Oar size for you.
on oar sizing

===============

Quote:
Oar length is largely a matter of personal preference; we can help you wade through some of the specifications you should consider.
Important specifications include boat type and size, gear and passenger load, water classification, skill, and your preferences as the oars person.
Frames are measured by various manufactures differently. So the outside edge of the frame may have a different measurement for one company to another. This can also change with double railed frames. It is best to use the inside width of the Raft, Cataraft or pontoon Boat plus one tube size. Always round up the nearest ( 9.3 would be 9.5). Drift boats are measured by the widest width at the bottom (from chine to chine).
----------

Quote:
FRAME WIDTH

RECOMMENDED OAR LENGTH
54" 7.5 feet
60" 8 - 9 feet
66" 9 - 10 feet
72" 10 feet
(Wait a minute; They're formula for 72 inches says 8.75 feet)

Their contact number has been disconnected.
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Old 04-26-2013   #4
 
Redmond, Oregon
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So the formula used by smooth bottom boaters in post 2 says 11.3 foot oars.
The formula by River Connections says 8.75 foot.
The general rule table by River Connections says 10 foot.

= = = = = =

What works for you?

Your oarlock with and oar length and why you think that is.

Thanks
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Old 04-26-2013   #5
 
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Quoted from the other thread:
Quote:
Originally Posted by cataraftgirl View Post
To BilloutWest .... there is no one answer, and you will blow a blood vessel in your head by trying to figure it out. Get a boat, get a frame, get some oars, and spend all winter with it in your garage (or living room) trying to make it all work to your liking. Then put it all in the river, and start tweaking it yet again. This is the life of a river rat.
Pretty much!


I saw another table that compared boat length to oar length, but in general, boat length/boat width/frame width end up being somewhat proportional.

There have been numerous threads on the topic and no clear consensus. Generally, ~8' for 12' boats, 8.5-9' for 13' boats, 9-10' for 14-15' boats and 10-11' for 16-18' oats. Longer for exceptionally wide frames or large tubes.

Personal preference overrides all "rules".
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Old 04-26-2013   #6
 
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Here is my oar story, starting with my cataraft. No I don't think it matters if you have a cat or a raft. Frame size, raft or cat size (length, width, tube size), seat height, tower height, rower size (legs, arms, torso, gender), rivers run (big water, small & technical) are just some of the variables that determine oar length.

Back to my Cat story. I was happy with my oar set-up for many years, until I added a second dry box to my frame, and put a AAA flip seat bracket over one of the dry boxes, thus raising my rowing position. Oars felt short. Longer oars purchased, taller oar towers purchased to lean outward, giving more width, and allowing for a balanced oar position. Happy Cataraftgirl.

Got my new small Hyside raft - 12 ft. X 6 ft. X 19 inch tubes. 54 inch NRS frame which fits this raft perfectly.I looked at the NRS oar sizing guide, and decided the recommended 7.5 ft. oars sounded too short. Got 8 ft. oars. Got them set up, and they didn't feel right. To enter the water and get a power stroke would mean the oars would come up rather high. Not a good power position for rowing. Bad for the shoulders. Many years ago, a long time rafting guide told me that your oars should allow you to push at the same level as a boxer throwing a solid jab punch. I also noticed that most of the Hyside Mini-Max folks were running 8 ft. oars with a 48 inch frame on that smaller boat. That, combined with my gut feeling, combined with my "too short oar" experience with my cat, led me to return the 8 ft. oars, and get 8.5 ft. oars. With taller towers, wider spacing of the oar locks, and longer oars, it now feels right. Happy cataraftgirl.

And there you have it. The oar gospel according to cataraftgirl. Amen. Your mileage may very. Row your own rig. Go with the flow.
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Old 04-26-2013   #7
 
Redmond, Oregon
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I'll get beat up for this.

Rather than seat placement dictated by drybox height and oar specifics following. It should be the oar lock placement, oar length, balance, fulcrum and all that should be optimally placed for a given rower.
They dictate the seat height.
THEN the drybox height etc follows.

Should follow .............

Some compensation can be gained by having higher oarlocks ....... sure

= = = = = = = =

I think there is a lot of difference between raft and cat, with regard to degree of difficulty. Even a bucket boat has issues with turbulence.

Contrast a scull to a row boat to a cat to a self-bailer.
At some point all that resistance will affect what oar 'system' is practical.
Especially when looking at rowing all day into the wind on a SW River.
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Old 04-26-2013   #8
 
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Quote:
Originally Posted by BilloutWest View Post
I'll get beat up for this.

Rather than seat placement dictated by drybox height and oar specifics following. It should be the oar lock placement, oar length, balance, fulcrum and all that should be optimally placed for a given rower.
They dictate the seat height.
THEN the drybox height etc follows.

Should follow .............

Some compensation can be gained by having higher oarlocks ....... sure

= = = = = = = =

I think there is a lot of difference between raft and cat, with regard to degree of difficulty. Even a bucket boat has issues with turbulence.

Contrast a scull to a row boat to a cat to a self-bailer.
At some point all that resistance will affect what oar 'system' is practical.
Especially when looking at rowing all day into the wind on a SW River.
That's all fine and all but if i wanted to row crew i would live next to the Charles

Practical considerations usually dictate how your seat height is created

Like you got this killer drybox from a friend for $150. Or you want to go on weeklong trips and you have to sit on your cooler

Its usually easier to swap out your towers and change your oar towers than to try and find that perfect setup that you nailed after three years of careful contemplation

That's why I row with friends and check out their boats. Mine feels pretty comfortable but I'm never know if I'm there yet unless i keep trying something different
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Old 04-27-2013   #9
 
Redmond, Oregon
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Reinventing the wheel has its merits.

Learning from others the same.

========

My wife pointed out that its not called rowing.
Its floating.
Mostly its people that can't or don't want to backpack because of the work.
That applies to me at this point in my life.

The river does the work.
Rowing is a side issue.

=========

However. If one can cut back that nasty work even more its not a bad thing.

The people from the crew world have a lot more knowledge about rowing than we.
They use their thighs.

Using legs with a sliding seat allows not just a stringer stroke but also a wider arc for the oars.

At a minimum one should not spend more money on a fixed rigid back seat that stops leg movement. That is not a killer deal.
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Old 04-27-2013   #10
 
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Rowing a raft in whitewater and rowing crew are two totally different animals. Crew is about moving a streamlined craft down a river in a straight line as fast and efficiently as possible. Whitewater rafting is about moving a less than streamlined craft, that's loaded with gear, adults, dogs, kids down a river in a semi zig-zag fashion, avoiding rocks, holes, and huge waves. Speed and efficiency aren't always the goal in whitewater. Mostly it's about control, which may correlate with power, or may correlate with well timed & placed oar strokes.

As for the frame, and positioning your oar towers for maximum efficiency.... there are often too many variables to consider that make that difficult. As Avatard pointed out, often gear acquisition is done by spur of the moment purchases, not always well thought out plans. Like a killer deal on something that you find at a gear swap. Some folks who are just getting started in whitewater rafting pick up a used boat and frame, and must live with the hand they are dealt with the frame. In the case of my small raft. I got it mainly for easy float & fishing weekends, but I'm taking it on a week long whitewater trip next week. So the frame configuration is different than it would be for fishing. Cross bars and oar towers are moved around. Having the ability to reconfigure the frame suits me, but not everyone would like that.
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