tabernacle plate bending

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tabernacle plate bending

Postby dpatrick » Fri Oct 27, 2017 12:43 am

So... the bottom plate of my mast hinge is pretty deformed. Wondering if anybody else has had this issue? I’ve tuned the rig to the North sails guide and it’s pretty snug. I don’t know if the plate is fatigued( I did bend it back up flat) and it bent right back after the next time sailing. Maybe it happened before I got the shrouds tuned properly? Or maybe after? I’m stumped and need to replace the bottom plate. I’m just hoping for some insight before I replace with a new one. I’ll get a picture of it as soon as I can.
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Re: tabernacle plate bending

Postby GreenLake » Fri Oct 27, 2017 12:53 pm

A picture would help.

For something to be deformed it would mean that any opposing forces are not lined up. Normally, the idea about the hinge is that when folded shut, it just holds the mast in place so that compression loads can be borne by the compression post. If the compression post is yielding and some of the plate rests on the deck, then I could see the plate being deformed. But that would mean the deck is being loaded, which should not be.

Assuming your tabernacle does rest directly on the deck, check the support for your compression post below the cuddy floor (you may need to cut an inspection port.

Alternatively, if everything is solid, but the rig tension is changing geometry on you, there may be a need to add a bit to the length of the compression post.
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Re: tabernacle plate bending

Postby dpatrick » Thu Apr 12, 2018 10:55 pm

I almost forgot I had this little problem. Getting the boat together for this Spring reminded me...
The mast step may not be set in the proper place, when I got the boat it had a rotten piece of wood under the aluminum step.I replaced it and tried as hard as I could to place the new block and step exactly where it was originally. The only reference I can find was in a tuning guide as to where to locate it, I think it said mast base 11' from transom? Well I'm off by 1 1/2". That might be for a Daysailer 1 and maybe different on a 2?
I feel like the mast may be rigged so it leans forward a little. I did have some issues when I ordered a new forestay the proper length (Rudy) a few years ago. I also remember the tuning measurement from transom to top of the mast being a couple of inches over too.
Does anyone know or possibly measure their mast base to the transom on a Daysailer 2?
Currently I am replacing the trailer axle, springs, and hubs, and oh yeah my tires since I'm hoping to take it longer distances this year! As soon as its mobile again I'm setting the rig up and trying my hardest to square it away once and for all!

Also Finally getting some photos of the bent plate
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Re: tabernacle plate bending

Postby dpatrick » Thu Apr 12, 2018 11:26 pm

I suppose there's also the possibility that the plates just get fatigued after many years?
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Re: tabernacle plate bending

Postby GreenLake » Fri Apr 13, 2018 4:06 am

I was in the middle of writing a very nice reply when FF crashed on me. A really rare occurrence. Anyway.

North Sails has a DS tuning guide with measurements.

Assuming your mast wasn't shortened by a PO, the numbers should work (for both DS1 and Ds2 - rig is the same).

If your mast leans forward, you should have lee-helm. What you want instead is weather helm that's moderate. Less than 5 degree rudder deflection and no sense that you have to fight or work hard until you are close to or beyond the point where you might think of reefing when you are not racing.

Rig her up, take her out in 8-10. Observe, measure tiller angle.
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Re: tabernacle plate bending

Postby dpatrick » Fri Apr 13, 2018 9:26 am

Yes, I'm using the North sails tuning guide. Problem is I'm not sure the measurements apply to DS2.
It's highly possible the mast isn't exactly the right height as the p.o. told me it was dismasted and that's when the tabernacle was added. They added a new lower mast extrusion, and did some sort of welding on the upper mast section.

Honestly the boat has been sailing great with moderate weather helm in moderate breeze, not excessive anyway.
I just want to make sure the rig is tuned properly. If the measurements are the same for the DS1 and DS2 , which North sails says 11' from the mast base to transom edge, mine measures about 10' 10 1/2" ,I'm short about an inch and a half. That seems pretty substantial and would indicate the mast step should go forward
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Re: tabernacle plate bending

Postby GreenLake » Fri Apr 13, 2018 1:01 pm

Honestly the boat has been sailing great with moderate weather helm in moderate breeze, not excessive anyway.


Well, that's the answer, then. Except that if you suspect that the mast is raked too far forward, you'd be looking for evidence of too little weather helm, not too much.

Anyway, the goal should be to get the boat to sail right, not to hit some numbers.

I don't think the nominal numbers are different for DS1 / DS2 because the rig is the same. However, the measurement of the mast base location might be affected because of the cuddy floor.
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Re: tabernacle plate bending

Postby dpatrick » Tue Apr 24, 2018 8:20 am

After getting everything rigged for the season, I noticed when the rig is tensioned, the mast lowers maybe 1/4” or so. It would seem the compression post has a little give. Took a pic of the post under the floor and can’t really tell if it needs repair or not. Should it really compress or is it supposed to be completely solid?
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Re: tabernacle plate bending

Postby Alan » Tue Apr 24, 2018 1:24 pm

There shouldn't be any give. If the top of the compression post were free to slide up and down in the bottom, the base of the mast would be supported only by the cuddy floor. Since a properly tightened rig is very tight (there are threads about rig tension elsewhere on the forum), this would put a pretty big load on a sheet of fiberglass.

The easiest way to check would be to pull the mast up and out of the cuddy, climb partway in, and push on the cuddy floor directly above the compression post, where the mast rests. If it flexes, there's your answer.

Another possibility, that's happened to a couple of people, is that the compression post is misaligned with the bottom of the mast, so the downward pressure of the mast is not directly on top of the compression post.
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Re: tabernacle plate bending

Postby dpatrick » Tue Apr 24, 2018 2:47 pm

After reading some other posts about this, I am guessing the plywood under the glass floor is rotten, or gone. When I bought the boat five years ago there was an oak plate under the cast aluminum step. I replaced it(unfortunately with 5200). I never considered there would be any more wood under the floor. So yeah, when I attach the forestay under full tension I can see the tabernacle go down probably at least a quarter inch maybe more.
To clarify... the compression post is pvc pipes? if so that seems silly! then plywood backer, glass floor, then I’ve got an oak plate, then the aluminum step. Looks like my oak plate is doing a good job of hiding problems underneath.
And I have my rig tensioned pretty high, not as high as the north tubing guide ,but close!
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Re: tabernacle plate bending

Postby dpatrick » Wed Apr 25, 2018 12:09 am

What I found
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Re: tabernacle plate bending

Postby dpatrick » Wed Apr 25, 2018 12:10 am

All cleaned up and ready for repairs
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Re: tabernacle plate bending

Postby GreenLake » Wed Apr 25, 2018 12:52 am

Waiting to see the next step in your saga.
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Re: tabernacle plate bending

Postby Alan » Wed Apr 25, 2018 12:38 pm

Interesting. I didn't suspect there would be plywood under the floor; I figured the flange at the top of the compression post was all there was. Maybe I need to take a closer look at my boat.

That's a nice setup, by the way, with the battery box firmly secured and the wood reinforcement for the centerboard line attachment.

How much fun was it to undo the 5200?
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Re: tabernacle plate bending

Postby dpatrick » Wed Apr 25, 2018 2:14 pm

Thanks!
Surprisingly the wood came off pretty easy.
The plywood has me puzzled as well, maybe it’s to give something to fasten the step to, and the centerboard hardware. Or maybe as some have suggested to cover in discrepancies in placement of the compression tube.
I’m considering filling the void where the plywood was with chopped mat and filling it all with glass.
On a side note, the comp. post is accurately at the 11’ mark from transom to post. My mast was clearly not or just barely touching the the back of the post. There is enough movement to set the mast on the post now, I’m just not sure if I should try moving the mast base forward or not. Obviously that will change rig measurements if I do. I know my mast also is 24’ 2 1/2”, oday brochure says mast height is 24’ 11”. Now that is the Ds1, which doesn’t have the second floor, so it’s all a little confusing as to what the height should be. In any case I want to set the rig to have proper mast rake, which it didn’t have at all before all of this, so i’m inclined to nudge the mast step forward a little and see how it all works out, I can always move it back if I need to( but I’d really like the step to be supported on the compression post).
To backtrack a little, When I replaced the oak under the step, I made sure to measure everything and put the mast exactly where it was, knowing what I know now, I couldn’t be sure the p.o. who put the wood in there actually put it in the right place. It would be really helpful if there was a consensus on the measurement from transom/deck edge to the back of the mast step. My friend’s DS1 is 11’ exactly. Sorry if I’m rambling on too long!
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