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Carbon Mast base is loose after unstepping


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My J/88 has a deck stepped carbon mast which is set onto a metal plate on the deck fitting to a metal plate bolted into a socket in the bottom of the mast. This year after will pulled the stick I reached over and pulled on the base plate and it moved in the mast. I will go back and try to sort out what is going on but am wondering if this is normal. 

Certainly I can see that there is no particular stress or weight on this joint if the mast is up and stayed but it is intended to be hinged down on one of the bolts through the plate if not using a crane to pull the mast up and off the boat. 

Anyone with experience here? 

Dan 

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The tan coloured base is likely part of a socket up into the base of the mast then cross bolted...I guess! 

When you are unstepping with a crane there is a time when the bolts are still in and the shrouds are coming off that I can see there being lots of 'twist' or stress on the base so perhaps the socket is deliberately loose but I have never noticed the thing being at all loose before. 

J88MastBase.jpg

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Tan thing most likely is a plate of G-10, electrically insulates carbon from ss. Should be bolted to ss plate underneath. Interior plug looks like it extends up to thru bolts. no other reason for bolt there. There should be NO rotation of mast on plate.

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Would you Guys think the cross bolt is the only thing retaining the socket in there or is it bonded with adhesive somehow? There are lots of flush set sockets going up from the base plate into what is likely the socket. 

I have to get back to the boat to see if the cross bolt is loose and can be tightened. Movement was very slight but completely unexpected.

Dan 

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Bolt just holds mast to base. Above the visible plate (inside the mast) should be a 1/2-3/4" plug of G-10 that fits the inside mast contour tightly. Your plug may be a sloppy fit (or worst case, mast is splitting). Examine carefully. Plug fit can be fixed by epoxy w/hi density filler (& tons of wax on the spar)

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Dan, see photo for what this plug looked like on my J/88 before I first launched it. After this, whenever I pulled the mast I always left the socket attached to the boat and lifted it off the plug. The cross bolt goes through the U-bracket and its purpose is to prevent the mast from accidentally popping off (according to the manual). The fit was fairly snug and I never noticed any rotational movement. - John

EM163966.JPG

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19 hours ago, JJK said:

Dan, see photo for what this plug looked like on my J/88 before I first launched it. After this, whenever I pulled the mast I always left the socket attached to the boat and lifted it off the plug. The cross bolt goes through the U-bracket and its purpose is to prevent the mast from accidentally popping off (according to the manual). The fit was fairly snug and I never noticed any rotational movement. - John

EM163966.JPG

Fantastic John, 

This is very helpful. I will go down and check to see if any of the fasteners or the cross bolt are at all loose and check for any cracks in the tube. If all the above is fine I will relax and watch with interest next year when we get her going and in the water again. 

Dan

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11 hours ago, il1395 said:

Do the 88’s use gin poles to raise/lower the mast, or do you rely on Marina cranes?

That base is set up so that you can undo the forward bolt (once supported by a gin pole) and hinge the mast aft using a support from above. I have only used a crane so far but would like to use the gin pole method as the crane method is pretty hectic as a crew of Guys are taking down 10-15 masts in a short time and I like to take my time with dangerous things! 

The reason I haven't done this is the distance from the gin pole to the storage yard and the difficulty moving the mast between them. 

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Sure wish JBoats would provide the complete solution when they design these things. Look at that robust fitting for the vang. Why not wrap it around the base if the mast with an attachment for the boom on the other side?

When it comes time to raise or lower the mast, attach the boom to the front of the mast with the spinnaker halyard and tack line secured to the other end. Run the tail of tack line back to a winch and grind it up, or ease it down. If the sprit is not up for the task, run the tack through a large block attached to the bow instead.

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So I went down and had a second look at this after putting the winter cover on the boat. The mast base is not able to rotate any significant amount but the bottom plate/socket is loose vertically and will move 1/2" or so up and down. This is obviously no problem when the shrouds are tightened so I am happy now that this is a non-issue. 

JJK's photo was a real help in understanding the situation and I may adopt the same strategy he outlines when I pull the stick next year. 

Thanks Everyone,

Dan 

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Glad to hear it worked out Dan. Just be sure and run a messenger line attached to the electrical lines when you pull the mast. Tie it off to the U-bracket while the mast is down and you'll be able to pull things through when reinstalling. 

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