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Report on Swing Keel Haul System Mod.

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britinusa
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Initially Posted - 06/01/2008 : 18:40:51

First time (getting away from the dock) with the new keel haul system installed, WOW!

Here's a sketch of the system.

a) Removed the old hauling setup but kept all the bits.
b) Cut the exhaust tube down to about 5"
c) Made a PVC 3" tube with adapter to mate with the cut down exhaust tube.
d) Moved the turning wheel and SS metal hanger aft of original position.
e) Put together a new block and tackle setup with these features.
<ul><li>The hauling line is now on the moving (lower block)</li><li>The dead end of the tackle is secured to the original top fixed block eye strap</li><li>The tackle uses smaller line</li></ul>

The result is JOY! I can raise the keel with ease! Maybe 10lb of pull on the line (perhaps I should try it with a scale).

The lower moving block fits inside the 3" tubing! This setup has dramatically reduced the dead ends and the force is applied to the moving block instead of via multiple unneeded turning blocks.

I'll put up some pics later. I was so pleased with the outcome, I wanted to share it soonest.

A great sailing weekend! New engine, New Sail, and new keel haul. Bliss!

Paul

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - on

Tom Potter
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Response Posted - 06/01/2008 : 18:49:59

Thats great news Paul, I recall you having a hard time pulling that keel up.
I got no sailing in this weekend, spent yesterday with a chain saw cutting a path on my lot to the water. Today was spent hooking up shore power. Can't complain too much I got 30 miles in last weekend and did get to spend the today "on" the boat.

Edited by - Tom Potter on 06/01/2008 18:52:56

essen48183
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Response Posted - 04/23/2009 : 13:49:10

Any pics of this hanging around on your camera Paul? I am working on and have mine apart right now.... sounds like I should just put it together your way.

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Arlyn Stewart
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Response Posted - 04/23/2009 : 19:39:52

I'd also be interested in the drawing as I'm not following the narration.

Lets discuss this a bit. It is important to stay with the correct angle of pull on the cable coming up the tube because to move off that angle any appreciable amount will in time see the fiberglass section of the tube above the turning ball sawed by the cable and that wouldn't be a fun repair and could sink the boat at the slip as at first the leak would be small and probably go unnoticed. The second issue is that if the tube is shortened any amount, there is risk of getting greater amounts of water backflushing the tube. I don't know the exact reason for this phenomena and all don't seem to suffer it. I've experienced it a couple of times and the C25 people suffer it.

It seems to happen as a result of motoring a little too fast in reverse with the board up. Perhaps the shape of the board is forcing water to jet up the tube or an air chamber is forced in the keel trunk and then it collapses to a rush of water, who knows. I've never seen this happen because I'm always in the cockpit handling my boat, but a nephew who crewed with me once and was stowing his things in the aft berth while we were getting away from the ramp told me his things got pretty wet when water came rushing from the tube. I've also found the after berth wet after launching a couple of other times. I guess I'm saying that I wouldn't want to go any shorter on the tube.

My experience with the system found it worked fairly well when new but got increasingly difficult until it was almost impossible to deal with. Found were two issues.

1. The wire block at the top eye strap was bad. The shoulders of the block had stretched and drawn very tight to the nickel plated brass block. Nickel is a worthy coating to prevent oxidation of the brass block but nickel has very very poor self lubrication qualities and the block had a great deal of drag where the sheave rubbed against the blocks side straps. I salvaged the block by adding nylon washers to each side of the sheave keeping the sheave from rubbing on the side straps.

2. The pendant line was not feeding correctly onto the triple block and was inducing twist knots onto the line between the two blocks. Looking at the drawing, one can easily see that the pendant line comes off at an angle that was causing the line to twist and induce the twist knots. My line between the two blocks was a mass of twist knots that would not roll over the sheaves of the blocks smoothly and in fact made the line so large as to resist going through the blocks.

The fixes were to add the nylon washers to the upper wire block and install a twist shackle at the triple block where it is made to the lower eye strap. Rotating the lower block 90 degrees makes the entry of the pendant onto the block fair. There was in fact a twist shackle at the upper eye strap that I deemed had no reason to be there so it was used at the lower eye strap.

Edited by - Arlyn Stewart on 04/23/2009 20:08:42

essen48183
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Response Posted - 04/23/2009 : 20:08:26

Wow... I never really looked at this system closely until you posted that picture. The dacron line passes three pulleys (the third one is not even fairly led) before increasing advantage... then after the next several turns (which do contribute to mechanical advantage) the wire makes a 180 degree sharp turn adding more drag without adding additional advantage. What an odd and overly complex system.

I am guessing that Paul examined this and removed (by flipping it upside down) the first wasted turn on the dacron, and the last one on the wire. I'd really love a picture or diagram.

Edited by - on

essen48183
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Response Posted - 04/23/2009 : 21:00:32

I found a better description from his thoughts prior to the mod:

"It's official, the admiral has commanded me to improve the centerboard raising system so that she can manage it.

For those of you that don't know, the C250 WB has a centerboard that is raised by brute force pulling on the line from a 6:1 block and tackle system. If you look at the online manual you'll see the setup.

I took a long hard look at the whole thing, sadly I'm missing one piece of info: what is the distance between the blocks when the keel is fully lowered?

Besides that, here's my review of the keel hauling system (has a certain ring to it 'keel haulin'

Observations:
There are too many useless turning points: The Pull from the cockpit first turns via a Garhauer Block which does nothing more than direct the line down to the bottom block. The angle of turn is about 120degrees. Angles outside a straight line increases friction.
The line next turns around a useless wheel in the lower block, I say useless because it does not increase the purchase, it simply increases friction.
The Vectran line turns 180 degrees at the underide of the cabin entrance, again this does nothing for the purchase, but again increases friction

Here's my concept:
Shorten the vectran line so that when the keel is fully down, it just extends up out of the 'tube'
Shift the lower block to the end of the vectran line
fix the top block to the current turning point of the vectran line

This setup would expand the turn angle of the line from the cockpit, reducing friction, makes the most of the mechanical advantage of the 6:1 block and tackle, eliminating the friction of the top vectran turning point, eliminating the friction of the lower block turn.

This all depends upon the distance between the blocks when the keel is in the fully down position. JD is on the trailer right now so I can't make that measurement.. anyone got it handy?

Paul"

Edited by - on

essen48183
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Response Posted - 04/23/2009 : 21:12:24

Is it like this?

how do you get the dacron line from the cockpit to the new upper three part block attached to the eye that used to hold the 5/32 wire turning block? Do you still route it through block 1 or did you cut some kind of hole around 2?

Edited by - essen48183 on 04/23/2009 21:14:32

britinusa
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Response Posted - 04/24/2009 : 05:02:28

Close Essen,

the top block is fixed to the underside of the step.
as you show in your drawing, the original single block under the step has been moved aft, so the raising line still exits through the original hole in the bulkhead aft of the step.

I'll make up a nice drawing and take some pics and post them when I get back from this weekend sailing (yep, actually taking the boat our for a sail!)

Paul

Edited by - on

Arlyn Stewart
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Response Posted - 04/24/2009 : 15:57:15

For some clarity, here are some terms that might be helpful to the discussion. We can also assume that wire line and vectron line are interchangeable.

Also a couple of measurements. The distance between the upper and lower eye straps is 42". The travel of the wire or vectron line needed to raise the board is less than 20".

Edited by - Arlyn Stewart on 04/24/2009 16:33:36

essen48183
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Response Posted - 04/27/2009 : 20:09:07

O.K. A bow shackle I had laying around to drop the height of the upper triple block and a very very slight bend (with a pair of channel locks) to the upper turning block for a nice fair lead and therefore a workable system with less friction and more advantage.

Thanks Paul... I'm glad you looked at that system and thought "Hmm, I bet I can improve that" I just looked at it and thought "Hmm, that looks overly complex"

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britinusa
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Response Posted - 04/28/2009 : 06:40:44

That's really a close diagram Essen,

I drilled a 1.5" (approx) hole in the underside of the tunnel and two new screw holes in the bridge deck in order to relocate the wheel that turns the line from the tunnel down to the blocks. So now the line goes from the cockpit through the bulkhead at the aft end of the bridge deck over the relocated wheel and then down to the lower block.

I replaced the original haul line with a new 3/16" line.

Works a treat.

The lower end of the large diameter pvc pipe is reduced using a standard pipe reducer. I cut the 'exhaust' down so that it just fits fully inside the reducer.

I'm very pleased with the setup.

Paul

Edited by - on

Arlyn Stewart
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Response Posted - 04/28/2009 : 08:59:49

The Catalina 250 manual claims that the system is a six to one purchase but I only count 5:1 but I'm not that versed on block n tackles.

At any rate, Paul's system seems to me to increase the purchase by one because it employs a moving entry block. I think he now has a 6:1. He has also eliminated the wire block and lowered slightly the turning angle of the upper turning block both eliminated drag. Also one block that was an idler is converted to providing purchase. So he has certainly gained power and reduced drag.

I do see one possible negative and wish to be careful to say I don't know if it would be or not. If the tunnel serves as a water damn for rainwater migrating into the tunnel via the pendant line, drilling the bottom would invite that water into the boat.

Does the footwell end of the tunnel drain flush with the bottom of the tunnel and does the tunnel slope aft slightly? I've never examined the tunnel much to note. Alternatively if drilling into the tunnel to provide a line chase, a piece of pvc could be inserted into the hole protruding vertically far enough to eliminate any rain water entry issue.

Edited by - Arlyn Stewart on 04/28/2009 15:17:05

britinusa
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Response Posted - 04/29/2009 : 13:02:01

Rain water is not an issue as far as I can see.

My greatest concerns were
a) the joint between the exhaust and the PVC reducer. if that separated then ... glug glug glug .. however the exhaust fits so tight that I had to put it in a vice to push it into the reducer, then I sealed it.

b) the upper block would hit the underside of the bridge deck before the keel was fully hauled. There's about 1/4" to spare!

I had thought of making a solid connection from the top of the large dia pvc pipe to the underside of the bridge deck to make movement even less likely.

We have pounded the boat to bimini in heavy seas, so the system seem capable of taking a beating.

Paul

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