Illegal centerboards?

[Guest]

I recently purchased a new centerboard from Cape Code Shipbuilding for my '84 Spindrift DS1. The board is what is called "the Lyndsey board" which was designed by SLI when they took over DS1 production, and the mold is what is used on all DS1's since. When I went to install the board in my boat, it wouldn't fully retract because the trailing edge of the board would start to hit the inside top of the centerboard trunk as it came up. A comparision to my old centerboard immediately showed the problem. The square hole is drilled about 1/2" closer to the leading edge than my old board. Dismayed, I started talking to some folks and became aware that the DSA rules call for the pivot point to be 6" back of the leading edge...exactly where my OLD centerboards placement is... Wendy at Cape Code Shipbuilding is contacting the DSA class measurer to discuss the apparent discrepency, but until told to do so, they cannont alter the centerboard molds which are owned by the DSA. The hole, BTW, is set in the mold, so all centerboards produced from this mold are this way.

Has anyone ever experienced this problem? Apparently, either the handle hole in O'Days is drilled slightly lower than my Spindrifts, or the trunk is slightly taller since this centerboard has been sold as a replacement for these boats w/o a problem.. For now, my solution will be to grind down about 3/8" of the trailing edge on the portion above the waterline, and then reapply the gelcoat. A pain, but my original centerboard is waterlogged and weighs 34 lbs so I can't use it, and there are no other sources for these boards...

Any thoughts are appreciated, and I'll post any updates from Wendy at CCS...

Kevin Clark (clarkr-at-aud.alcatel.com)

[Guest]

Kevin,

DON'T TOUCH YOU BOARD (yet)! Especially a Linsay board. This is a matter for the class measurer, Steve Braese. Email him at DS2869@aol.com or write him with your concerns. But don't hack up your new board until you/we find out if there is a problem and how it will be resolved. The class may end up amending the measurement drawings or grandfathering boards already in boats.

Does the board fit up in the trunk entirely without the handle in the pivot hole? If so it may just be a matter of moving the hole (a much less radical fix then removing 3/8" of the trailing edge)


Keith A. Bay (kabay-at-execpc.com)

[Guest]

Keith,

My old board was 14" wide from top to bottom, hole was 6" back and 6 3/8" from top. The new board is 14" wide on the 39" below the waterline, but 14 1/2" wide on the part above. The hole is 5 9/16" back and 6 3/8" from the top. The extra 1/2" in width is above the water line and added on the trailing edge. It allows a smooth fairing back to the hull at the bottom of the boat. It's this extra 1/2" that causes me problems, although it would not be a problem if the square hole were placed at 6" back from the leading edge.

As for moving the hole in my centerboard trunk, this would require that I also move the 3 glassed-in, threaded inserts that hold the handle in. Not an easy task! I think that grinding down the new centerboard should really be pretty easy. I'd actually use a belt sander w/ 40-60 grit paper, and I'm sure it would only take a few minutes. Brush on some gelcoat, and I'm finished... I'd lose the nice fairing that Mr. Lindsay (or whoever) added, but at least it would fit.... I will wait until the class measurer has addressed all this just to be safe, but this sure seems like the kind of problem you should NOT have when building a one-design boat, and I'm surprised they ever allowed this type of centerboard fairing in the first place.

Kevin Clark (clark-at-aud.alcatel.com)

[Guest]

Kevin,

You didn't say that you couldn't get the board in the boat when the board was 'down' so I assume the position of the hole relative to the top of the board is OK.

If you were to move the hole 'back' to 6" that would seem to compensate for the additional 1/2" width in the board. It would lower the board in the trunk by 1/2" while it is in the up position without affecting its position (length) when in the down position.

I think the measurement drawings give no tolerances on the positioning of the pivot hole because the 6" measurement is advisory, not definitive. The placement of the hole is irrelevant as long as the board does not present an underwater profile of more than 14-1/2" width and 39" length.

If you sand off the back edge of the board you will probably remove any fiberglass there. I don't know if the board has a foam or wood core. If the board has a foam core you willl need to replace the glass to preserve the strength in the area. If the board has a wood core the strength will not be compromised as much but you should replace the glass to preserve the water-resistant layer that it provides.

Keith A. Bay (kabay-at-execpc.com)

[Guest]

Keith,

You are correct, the position of the hole relative to the top is the same, and this new board will ride 7/16" higher now when retracted. The overall length when down will be unchanged, but the centerboard will now be 7/16" further aft with respect to the boat. I have no idea if this will change the pointing characteristics and balance of the boat. I'm sure it would slighty, and maybe it is trivial, but maybe not? This is why I find it hard to believe that this 6" measurement which is marked "Ref" is not a fixed requirement. Moving a centerboard fore or aft would have to be an advantage for some particular set of conditions. Maybe moving it forward helps going windward in light air, but hurts in moderate winds? I don't know, but for a one-design class, this should be a fixed measurement.

I talked to Wendy at Cape Code Shipbuilding today. She said the reason the hole was moved to 5 9/16" (horizontally) is that when the molds were built for the SLI boat, they apparently messed up on the placement of the trunk handle hole and associated inserts. They got them 7/16' too low. This meant that the board hung down slighly when fully retracted. Not good when you put your boat on a trailer and all the weight is on the centerboard as it passes over the rollers! Also, not good on downwind reaches where you want the entire board out of the water. Well rather than change the mold for the boat, they just moved the hole in the centerboard. Of course this also causes the board to be 7/16' aft of the original placement when down, but I guess they thought that was negligible, and as for replacements, apparently, the O'Days had enough clearance to still use the new centerboard...but they probably never looked at Rebel and Spindrift boats.

As for the glassing, I'm told it's not neceesary. All the grinding will be done on the portion that is above the waterline. It will need to be sealed to keep out water, but Cape Code is sending me instructions outlining the steps and materials to use. That's all for now.

Kevin Clark (clarkr-at-aud.alcatel.com)

[Guest]

Kevin,

The 7/16" difference in fore/aft placement of the centerboard will have (effectively) no noticeable affect on the handling of the boat. The trim of the boat is a function of balancing the center of effort [CE] (in the sails) over top of the the center of lateral resistance [CLR] (in the centerboard). Because the DS centerboard is effectively locked in the down position by the centerboard pawl you achieve that balance in the Day Sailer more by adjusting the position of CE fore & aft with the outhaul, downhaul, cunningham and mast bend in general. You can release the pawl and swing the board (and the CLR) aft as you 'raise' the board affect a change in this balance. Actually that is what I do on reaches and runs because the 'balance'/trim of the boat moves aft the further off the wind and/or faster you go. In these cases I am moving the tip of the board (and the CLR) multiple inches.

Good luck with the fitting.

Keith A. Bay (kabay-at-execpc.com)

[Guest]

Every Lindsey CB I have measured since Sunfish/Laser made the DS mold, has failed to comply with our class rules. The problem is with the curve at the tip of board. Either you have to add about 1/4 " of putty to the tip or grind down the offending edge (lead or trailing I can't remember). Cape Cod has been aware of this since 1997.

Phill Root (phillrt-at-msn.com)