sc 20 righting pole ?

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andrew
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sc 20 righting pole ?

Post by andrew »

does any body know about or had any luck with installing a righting pole on a sc 20. I sail alone 175 lbs, just thinking about one. I assume on a 20 it would attach to the fwd cross beam maybe 6 to 8 feet loa. ??
Kevin Keller
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Boat Make/Model: SC-20, ARC22
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Post by Kevin Keller »

Did you ever get any info on doing this? I am curious also.
Matt Haberman
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Post by Matt Haberman »

Kevin,

I don't know why a righting pole or water bag wouldn't work, but don't forget about the shroud extender/righting system that was standard feature on the SuperCat 20. At 175 lbs there is a good chance you might get the boat back up using just the shroud extender. But if not, it will get you a lot closer then without it.
Matt Haberman
Aquarius Sail Inc.
http://www.aquarius-sail.com
andrew
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Location: quincy,mass

Post by andrew »

I eventually built my own righting pole; mount's under fw'd cross beam pln's in place. the two times iv'e gone over in 10 to 20 kt's I had the boat back up with allmost zero effort.I tried the shroud extender's a couple of times with not a lot of success. Im sure they would work with two on board but a lot of the time I sail alone currently down to 165 lb's so it's what ever work's for you.
Kevin Keller
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Boat Make/Model: SC-20, ARC22
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Post by Kevin Keller »

Matt,

I did flip my SC20 in >15 knot winds one time and with the upper shroud extended and the wind helping blow us over it did take a good effort with three of us (about 480#'s) to get the boat back up. We had the sheets released and I am pretty sure that the mast did not leak. The three of us were standing on the daggerboard and hanging out to get as much leverage as possible.

I will say I was surprised how fast the boat was sailing from the trampoline only.


Andrew,

If you get the opportunity can you take some pictures of your setup? I am sure a few of us would be interested in seeing it.
davefarmer
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Post by davefarmer »

I installed a righting pole on an H18 using a section of windsurfing mast for the pole, and using the rubber universal joint to attach the pole to the dolphin striker just below the main beam. Will require a bit of engineering to attach to the floating compression post. The pole extended aft to just ahead of the rear crossbeam, and was held in place by a bit of shock cord. Worked well.

Dave
efinley
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Post by efinley »

You guys make me wonder. I flipped my SC20 at least once this summer and I righted it nearly by myself with no special effort short of using the shroud extender. I weigh 200 lbs and had a little help from a ~100 lb helper (I was solo when I flipped). With me leaning back on the righting line, standing on the hull (I'm too chicken to stand on the dagger!) and my helper leaning back a little on the righting line the boat came right back up. I wonder what we are doing different...

-Eric
SC20 #113
Kevin Keller
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Post by Kevin Keller »

I am wondering myself. How is your righting line set up? Does it come from inside the hull or is it over the hull when you are righting?

I had mine com from the inside corner of the hull.

How long did it take to get it up?
efinley
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Post by efinley »

Mathematically speaking it doesn't matter where you righting line comes from, you will get the same leverage. But realistically speaking the higher it is the easier it is to hold on to. However the difference in over the hull vs under the hull probably makes very little difference in the ability to hold on. what I typically do is put of wrap of line around my trap harness and hike back with it. The friction of the line around the trap hook makes it easy to lie nearly all the way back and not pull your arms off.

My righting line is pretty cheesy. I had a coil of line tied to the front cross bar with the coil sitting in the tramp bag. When I flip I climb up and pull it through the hole in the corner of the tramp. So to answer the question I have my righting line under the hull because it is easier than getting it over the hull.

The longest part of the deal was climbing up and undoing the shroud extender and waiting for the boat to turn into the wind. I suspect it took 5-10 mins tops. I don't really recall, I was having too much fun. I'm a twisted guy in that I enjoy flipping my boats. I don't flip the 20 on purpose very often but I flip my H16 almost every time I go out. :)

-Eric
pworthington
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righting and leverage

Post by pworthington »

Leverage is all about creating distance between the pivot point and the applied force and/or increasing the force. The equation for leverage or torque is Torque = Force x Distance. Therefore, tossing the righting line up and over the airborne hull and releasing the righting system will increase the distance from the pivot point (hull in water) to the applied force (you). This will substantially increase your righting moment or force. If you draw a picture or force diagram this will be quite evident. I have a righting line tucked in my trampoline at the forward cross beam and I put a 6 inch long x 2 inch thick dowel at the end of the line so there is something substantial to hang on. I'll have to try the method of moving aft on the submerged hull to turn the boat around.
What did I get myself into now?
Matt Haberman
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Post by Matt Haberman »

Guys,

Here are a couple of things to keep in mind.

When the 20 was first introduced with the Righting System in 1979, Bill Roberts could get the boat back up by himself (33' mast). If any of you have ever met Bill you will know that he isn't a real big guy, probably close to 175 lbs at the time.

Where you tie the rope DOES make a difference. If you don't throw the rope OVER the top of the upper hull, you are loosing close to 15-20% of your leverage when you go to right the boat.

Lift yourself up and get your feet off the hull or daggerboard. If your feet are touching, your loosing leverage. We did a test several years ago where we put a scale on the righting line and I would hang from it. I weighed 175-180 lbs at the time and if I leaned back and left my feet on the hull, the scale would NEVER go over 100 lbs. By having my feet on the hull I was essentially looseing 45% of my righting moment. Combine that loss in righting moment with a loss in leverage by not throwing the rope over the top side of the hull and you probably won't get the boat back up.

If the mast leaks it will get a lot of water in it very quickly. If the mast has water in it, you will have a tough time getting the boat back up. Check the mast, make sure it doesn't leak!

Get the boat facing head to wind before you climb up and undo the righting system lever. Remember that the righting system is not just a function of opening the lever, you also need to remove the upper pin so the shroud can extend out to the end of the jumper wire.

I have been over on both the ARC-21 & ARC-22 several times. In either case we did not have too much trouble getting the boat back up. Usually one person rigged the righting line while the other climbed up and undid the righting system. The guy who rigged the righting line usually leaned out and got his weight off the hull. If that wasn't enough weight to bring the boat back up, the other guy leaned out against him (feet still on hull) and that was enough to bring the boat back up.
Matt Haberman
Aquarius Sail Inc.
http://www.aquarius-sail.com
efinley
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Post by efinley »

Well I am not convinced that where you tie the line makes a big difference but tomorrow I will try to draw some free body diagrams and prove it to myself one way or another. Either way I think I recall this discussion on the beachcats list and nobody ever convinces the others. :)

However you point of hanging from the line is interesting and I had never thought about it before. Since with the shroud extender the hull comes over center I think you are correct that the most effective righting moment would be to hang from the line. On a hobie (or other boat without the shroud extender) this would only serve to turtle the boat...

-Eric (who hasn't worked on statics problems in quite a while.... ) :)
Peter Kirschhoffer
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Post by Peter Kirschhoffer »

Matt,

If the mast has developed a leak, what do you recommend for sealing it back up?

-Peter
SC 15
Matt Haberman
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Post by Matt Haberman »

Eric,

Just like doing the test with the hanging scale, we have tried righting the boat with the rope over and under the hull. We have proven that going over the top does make a difference.

Peter,
We typically use 3M 5200 to seal all fittings. We normally glue a 2" thick plug into the top of the mast using the 5200 and then coat the entire exposed face of the plug with 5200 (like frosting a cake) to ensure that it doesn't absorb water.
Matt Haberman
Aquarius Sail Inc.
http://www.aquarius-sail.com
efinley
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Post by efinley »

Well I just wanted to say that yesterday I deliberately flipped my boat to try this out. I climbed up top, lengthened side shroud and flipped the righting line over the hull. Then I hooked the line to my trap harness and hung there and nothing happened.

So I thought what happens if I kick off the tramp and swing out a little. Well the boat started to right and as I swung in I did it again and I righted the boat. I can tell you that I really impressed my friends on the beach that I can solo right a SC 20! :)

So I now humbly admit I was wrong and Matt and Tom were right. I love this boat. :)

BTW I should add that I am 205 lbs and there was basically no wind when I righted it, obviously if there was wind it would make things even easier.
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