Your thoughts on a dangling centerboard?

TomY · Apr 17, 2009

Hi Dave, I found the drawing for that article. It doesn't sound like yours is in the same jammed spot though, it would be stuck in the upper end of it's lift. At any rate, when the toggle is inverted and pushed up, it can jam as the linkage is un able to clear the top of the centerboard trunk when pushed, as opposed to pulled.
I proved this beyond a shadow of a doubt years ago.

If it is jammed, it would be holding the board up.

If your board is down, your linkage is raised, maybe the bronze pin and or link plates failed at the centerboard? I'm assuming the pivot pin did not fail and the board is out of the trunk?

Are you hauled out now and anticipating repairs pre launch?

TomY · Apr 21, 2009

I don't remember any pin or such in my arrangement on my bronze trunk. My only thought is IF the board was pushed up from the bottom, the very linkage that jammed on my boat is what's stuck just below the table on yours. Keep in mind Dave, I had to drive that linkage out of the centerboard trunk with a 5 pound sledge and rod.

For safety sake, keep an eye on the boat during tidal changes. If the linkage is bound in the bronze trunk, when the boat rests on the bottom, there's a chance the board will put enough leverage upward to lift the centerboard housing off the keel. It sounds like your mud is good and soft but I'd still keep an eye on it.

Hope you get a good tide to get out soon Dave. Keep us posted.

southport · Apr 21, 2009

Dave_

I actually posted last Sat. but my computer (or I) had a numb spell and it never posted- some how the date today on the forum was the 18th and just tonight I caught up with the rest of the world...

The drawings I have show a truloc eye swaged to 1/4" s.s. wire as the pennant. This is connected to the lifting bar by 1/8" thick plates that sandwich the eye and bar. There are two 1/2" bolts to make the connection- recessed in one plate and threaded into the other. The drawing says "to be locked into place". hmmmmmmmmmm. This is the same way the lifting bar is attached to the board at the lower end.

The locking pin I referred to is actually in not there unless you want to "lock" the board in the up position. To do so you put a 1/2" bolt through a hole in the lifting bar ( when the board is totally up) which "trigs" it on the top of the galley table when you release the pennant holding the board up. Maybe if you can get the board all the way up you could do this as a "preventer".

I have a drawing labelled "centerboard details" if this might help- Provided there is not another numb spell I can now scan/email/mail details thereof. My ability to post such is still tech. challenging ( I still think time warner cable is holding out info on how to do this

)

Let me know if I can send any thing and good luck!!- This is a great way for us in New England to pass the winter but not good that you are having these troubles!!

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TomY · Apr 21, 2009

Dave and Jon, if your servers make it too difficult, send any photos or scans to me, maybe I can figure out a way to get them on here. I've never seen the drawings for this detail. My lifting bar was attached at the centerboard and the SS lifting cable with the bronze plates and rivets about 1/4" in diameter. There may have been an extra hole in the lifting bar to capture the board raised above the joint at the table but I don't recall. That joint between the bronze trunk and lower pipe is now brazed so both the trunk and lower pipe are one piece. I unscrew the top pipe from the turning block on the ceiling to change the pennant.

Dave, I have my SS cable made up long(measure and add a few feet)fitted with a swagged fitting on one end before I lift. When the boat is lifted, I attach the swagged fitting to the lifting gear and thread the loose end down the pipes. ( I've done this twice before the boat is hoisted before launch)

Once the boat is in the slings, we drop the board, block to fully down, cut the old cable (leaving the board at it's lowest setting), unbolt the old, thread the new pennant down the tubes, put the new one through a thimble, pull it through a nicro press fitting till taught, and clamp. It's fast this way, the yard would take quite a bit of time doing the cable work in the slings.

southport · Apr 22, 2009

Tom- I'm emailing you some drawings shortly that might help. I think you can post them here easier than I can.

Dave look at the bright side--you still have over a year to get her all set before you need to be up here for the 50th!

TomY · Apr 22, 2009

Thanks Jon, these are really helpful.

southport · Apr 23, 2009

Boy the pcture you posted baffles me- That looks like the square head that one could put a wrench on to turn the shaft. Looks like it has been "tack welded" on the top to prevent it from turning on its own. I'd be tempted to release that weld and try it.- But what it would do is perplexing!

It would be great to keep raising the board little by little- by taking a strain on the strap under the board can you wiggle the pennat any more than before?

A tru-lok is a fancy name for a swaged eye on the end of a wire.

TomY · Jun 9, 2009

Centerboard pivot bolt replacment.

As long as this has become the centerboard thread, I'll post a photo of replacing my pin. As I've never pulled it, I took the cover plates off. The bronze nuts were corroded to the point they easily split off with a cold chisel. The pin took a bit of pounding with a punch to come out. I found it had a pretty good bend in it from my infamous grounding years ago. However, it was in good shape as were the visible holes through the lead keel and bronze board. The pin did have two scores around the area outside of the CB. I wonder if it once had some spacers which simple wore away?

I thought I had seen the original on the drawings was a bronze 3/4" bolt(in reviewing the drawings now, I don't see a specific bolt detail???)
so I had them put one together at the local yard. They threaded on a nut, brazed it on, ground the head and left me with the same length replacment and nut. It went in easily of course being straight.

The real reason I did this was to put some spaces between the CB and the lead keel. From the drawings, I see some spaces of some kind. In probing the slot, I was running into an "edge" that may be those spaces set into the lead? Does anyone know exactly what's going on in there?

At any rate, with a small pry bar, I was able to move the CB back and forth on the pin. I slid a 3/4" copper washer between the two. It's 1/8" thick. I had to tape the washer to a carpenters square which allowed me to slowing get it into the hole. When it was partially up, I was able to move it into the center with a punch. I slid the bolt through it and into the CB. Then with the same process, I eventually got the other washer centered and slid the bronze bolt through the remaining other side, and tightened the nut on.

There are two screws threaded into the lead keel at an angle inside recess in the lead keel on each side. These capture the bolt head and nut.

Whether the addition of these spacers will improve the CB clunking at fully dropped remains to be seen. With the spacer block on the CB and inside the lead keel, and now the pin area tightened, it should help.

But now, I'm not sure if I should have gone with a new monel bolt. Anyone know what Alden speced? They were pretty adamant about not having SS and bronze below the waterline when I talked to them several years ago. The monel bolt looked fine though, if not for the bend, I may have re used it. It's not a hard area to inspect and I may try to improve it further with broader spacers and keep an eye on the bronze pivot pin.

It's all very robust and I'm now confident in all the parts.

TomY · Jul 24, 2009

Centerboard mystery.

Sailing with my centerboard newly pinned and bushed above, I have noticed some subtle changes. The clunk that I hear on the mooring or drifting with the board fully lowered, has diminished but by no means gone. I'm still not certain if the area that I was able to push the two large bronze washers into (washers in the photo above) is play that has been worn from the 5/16" bushings shown in the original drawing above, or that the bushings actually wore away completely. Not likely as the play was snug.

And while I can't prove this I feel sailing performance may have improved a bit. Specifically, on some very light air sailing this past week, 6 to 11 knots, I was able to sail a fairly nice gait to windward at about 3+ knots in the lighter early morning breeze (5-6kt) as few other boats were sailing. This seemed improved as I brought the boat closer to the wind (obviously to increase apparent wind over the sails) as I lowered the board. As the boat got into more of a groove in the light air, the board and pendant (I have only a SS cable now, no bronze bar) began a slightly different subtle vibration than past experience. Raising the board a few inches stops the vibration (presumably as more board contacts the spacer plates) but it felt in the light air, that the lowest depth of the blade was delivering a bit more lift. The slight hummmm is not objectionable either.

Modern design critique says our boards operate in a difficult turbulent water area just below the keel, however, the lowest areas are in the smooth flow well below the boat hull. When you think about it, properly set, even a non shaped slab like a bronze board will provide some lift as water flows over it.

Lift will "pin" the board, even with some play (they all must have some) against the side of the trunk when the lifting force is present. But in an optimum setting, lift may cause some "flutter" as it builds and diminishes due to angle. You can feel this in a dinghy dagger board and in tiller steered rudders, I suspect the same would happen with a centerboard achieving lift(my opinion, but doesn't that make some sense?)

This sail last weekend of 27 NM also had the other extreme as winds increased to gusts of 20+ knots, much of which I needed to sail to windward. Sailing a familiar and often windward stretch of water on the western end of the Fox Island Thoroughfare, I seemed to be pointing higher. I know, alot to assume from merely stiffening up a sloppy board! And I was carrying more sail than usual in the building winds, which may have simply given me better drive, and current, etc, etc.

At any rate, I've often and heard some don't use their centerboard much. I've even been told by a few keel centerboard owners they can't tell the difference. This always surprises me. Then again, I once heard Bob Perry say he couldn't tell the difference between sailing a Beetle Cat with the centerboard up or down. Having sailed many dagger board, centerboard boats, this statement really surprises me.

So, there's my centerboard experience. I believe it may be worthwhile to get these boards as snug as possible so I'll continue to improve that aspect.

A few photos from that sail last week. Sailing a beam reach through the Fox Island Thoroughfare in flat water and ample wind, CHRISTMAS was at times roaring.

Once outside of the protection of the surrounding islands, winds were stronger and a bit too much sail up.

Then squirting home at gps speeds often holding 8 knots off the waves, the centerboard was up. It was a very good sail of all conditions. Off the wind, the stern wave kept me company.

TomY · Jul 25, 2009

You're right Dave, our boards are not quite so obvious as say a dinghy with a daggerboard. With the daggerboard down sailing to windward, suddenly pulled, the dinghy simply slides off to leeward. It may still appear to be still sailing the same course (heading), but is immediately powerless to make actual way to windward.

It's certainly not as dramatic on our Challengers or other large keel centerboarders but the most basic principle of the centerboard is to cut down that leeward slipping. The full keel and rudder alone on our boats will achieve a windward direction, the centerboard should simply eliminate more of the leeway slide. How much is a difficult question and reliant on many factors.

Actual lift would be more mysterious but as these boats and even more basic non keeled boats like typical Maine schooners of ancient design attest, it must be there as they will sail to windward.

My son has often taken cast off lobster buoys on the shore, split them in half, stuck a stick in the flat "topside", laced a piece of plastic onto the stick for a sail, and built a small sailboat for amusement on a Maine island. He can launch them all day long and they won't do a thing but drift, in irons, to leeward even though the sails fill and it looks like it's sailing.

Then he'll take his knife, cut a slot in the bottom, find a suitable shard of rock, stick this in the slot (no rudder), and viola. Some of these little buoy boats, if only in a slightly windward direction, will sail merrily away.

TomY · Aug 3, 2009

That's funny! And not too uncommon. I've been experimenting sailing lately with the centerboard. Using the ap to steer a relatively consistent heading, and pinching up to a good combination of speed and heading, I've sailed with the board up and down. It's not immediately apparent but comparing headings with; compass and gps-direction over the ground, i'm able to get some interesting results.

For one, the gps, a digital image of a compass dial, will generally begin to show a higher direction with the board down (as you would expect). With the little experimenting I've done, I've seen some swinging and a general settling on something like 10 degrees. This, btw, would not be readily apparent to the helmsmen as this is simply cutting down on leeway slippage. Little change has actually occured to the angle of the sails and boat to the apparent wind.

But on the more subtle level (and this may be personal, hopeful?), I can somewhat feel, and I believe, see an increase in speed to windward with the board down. This may also require a slight sail adjustment as the apparent wind changes it's angle to sails slightly. If this is indeed so, it could be the result of some added lift from the board.

On another note just playing around with this stuff, I also sailed jib and jigger for some comparison. It was harder to tell (board up-board down) and the reason may be from the lack of drive this combo gives to windward. We all know that of course, but swinging compass reciprocals, I was amazed at how little windward distance was made. I'd dare say in the conditions (about 12 knots of wind, some current running against the boat as the tide ebbed from Penobscot bay), we were at best swinging 160 degrees. You may make more windward miles job and jigger by cracking off for better speed and not much lost in windward heading.

With the main up and close hauled but cracked off a bit for better speed, the reciprocal course was about 100 degrees.

Your thoughts on a dangling centerboard?

Dave Richardson

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TomY

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