DS II Centerboard Cable

[mikeval]

New DS II owner and I have a couple of questions on the centerboard which I've removed and one of the chainplates for the stays. The CB tip hung down a few inches from the hull so I assumed the rope was stretched as it's older. The cabling is also looking rough so I want to replace both.
Centerboard:
1) On the wire cabling, I count 7 wires made up of 7 strands each but not sure if that is the original or what was used as a replacement. The ratings for this are more than enough but I'd like to have what should be there.
2) I noticed the SS tang \ wire connection to raise the board is forward of the pivot point. This would lead to less leverage and wondering if I can move that connection back so it's over the centerline or perhaps even an inch or so behind it?
Chain Plate:
Being 1974, I'm not comfortable with the small stainless (1" or so) backing plate. I'd like to spread the load of this high-stress area over several more inches. It's maybe more for my own peace of mind but it seems like a very very small area of support and I'm aware of a similar setup on the Sunbird I believe being a weak point with disastrous results. I'd like to head this off before it's an issue. I was considering G-10 as it's sandable to fit the underside curved surface and could be lightly fiberglassed in as well. The backing plate would again be used to sandwich if in with slightly longer bolts now spreading load over 5 or so inches. Wondering if anyone else a) had a problem with the orginal setup and b) what was done about it.

Thanks
Mike

 

[Sunbird22358]

Mike, the lifting cable attachment should work fine as originally installed, If you move it it may cause problems with the cable slipping off to one side and jamming the CB, especially if you were to sail into shallow water and the CB were to be forced up as you hit bottom. The other problem is that moving it further back may result in not being able to lower the CB all the way unless you make that cable longer, which would basically defeat your reason for moving it in the first place. <GRIN> The "lever-arm" created by the distance from the pivot to the cable attachment point is what is critical, the cable attachment can be "forward" of the pivot yet still have plenty of mechanical advantage to pull the board up. It is "normal" for the tip of the CB to not fully retract into the hull, and the routing of that cable actually works better with it attached closer to the forward edge of the CB. I'll add another diagram here that I don't think I showed you before (Didn't we discuss this on Facebook?) It shows a later model year than yours, but the lifting cable is pretty much same setup as yours. The original setup is not "perfect", but moving that attachment point will make a built-in problem worse, that of the cable not feeding straight out of the hole in hte forward end of hte CB trunk, which actually resulted in the cable starting to break where it rubbed on the edge of the hole on my boat a few years ago, luckily I had a spare cable on hand and could replace with minimal delay in my launch schedule. By the way, my drawing of the CB top shows the tang attached further back than it should, I need to correct that! Picture of my CB is correct location.

As to the chainplates, they are a lot stronger than they look. they are bolted through the hull-deck joint and that is a very strong area. You could add longer (extending further forward and aft) backing plates, but that isn't really needed as that area is pretty thick (see the sketch below of a typical O'DAY small boat hull-deck joint, that is basically what the area around the chainplates looks like). I would suggest if you are concerned (and I was more concerned by the chainplates themselves, as the holes for the clevis pins seemed too close to the top edge), it is worth ordering a new set of the 2 chainplates and backing plates, with bolts and nuts, from D&R Marine (www.drmarine.com 508-644-3001) just for piece of mind. I did that last year and it has increased my comfort a lot. The holes are more centered on the fittings and with 1/4-20 bolts instead of the original 10-32 ones........... well, much stronger! While you are at it (the most expensive words ever said!) if your boat still had the original standing rigging, which was 3/32" cable, it is well worth it to upgrade that to 1/8" cable, not cheap (around #240.00 for the set of 2 side stays and forestay) but good piece of mind, as "experts" tell us to replace the rigging every 10 years, however.. mine was still in good condition 36 years after the previous owner had upgraded to the 1/8" rigging.

 

[mikeval]

Really appreciate the thorough reply.
I've got a couple more questions if you don't mind...

I've got my board out now and want to get things right as it wasn't easy to get out having to keep her on the trailer, well slightly raised off and yeah I asked on FB as well.

1) what is the purpose of the 90 degree twist in the SS Tang? Seems it just raises the pull point and puts more stress on the forward screw which in fact caused mine to lift a bit. Can I not just keep if flat, a much less slight bend upward which would still provide clearance?

2) On your pics, my CB also has the lower rope at the bottom just forward of the pivot point which I just replaced with new before thinking this through. It seems this could slip off to either side and cause issues when retracted, the rope follows the curve of the board up towards an exit at the top of the bunk which I would need to as as there is none. Also seems the rope and SS rope will 'interact' or rub. I thought of adding a channel on the CB for the rope to sit in but more trouble than it's worth and probably not work anyway. My thoughts about changing this.... I noticed my Trunk has the below two pics and in the 'parts bag' were pic number three. I'm assuming this was arranged per my drawing (Proposed). Could I add a small hump type bracket atop the SS Tang to attach the downhaul or... is there really not enough clearance under the bunk. This obviously doesn't need to be large \ heavy duty and I figure I could keep it all very low profile? No tangling, nothing getting stuck, etc, and no new holes to make as I would need for the current rope attachment on the CB to exit through the top of the bunk. Of course I thought all this, after I replaced the previous rope with new, resined in place, etc, etc.

The other side of the trunk does have a cleat in place for the CB Uphaul line and it looks like there was one on the pic side that was removed along with the pully system up top which is now just a hole. Prev owner said they use that hole to push the board down if it gets stuck from seaweed or whatever else.

I really appreciate your time and thoughts. This is basically the last piece to sort out to give me piece of mind before the first splash
Mike