Prindle 15 mast Step hinge plate
nohuhu wrote: JB welded the old holes and redrilled for larger stainless rivets. Added stainless washers as internal backing plates.
Is the "mast hinge plate" the plate that is attached onto the front cross beam via rivets? If so, it sounds like you're saying you JB welded the old holes in the cross beam, then re-drilled the holes to a larger size, then "added stainless washers as internal backing plates before applying the new, larger rivets" to hold the plate onto the beam?
If so, how did you get stainless washers inside the beam to serve as "internal backing plates" for the new rivets? Or maybe I'm misunderstanding something?
Reason I'm asking is because I may want to do the same with regard to the rivet holes and rivets holding my traveler adjuster onto my rear cross beam. But I don't know I'd get "washers as internal backing plates" inside the cross beam, because they won't fit through the holes. Or maybe I'm misunderstanding something here...?

on the front beam you can remove the dolphin striker and access the mast ball area
on a rear beam - in the center you are not able to access that area unless you use an extension (think wad of gum on a stick holding your screw/bolt in place, or a wrench on a 4' extension)
It's tricky but can be done
i have gotten wrenches on side stay chainplate bolts via access ports in my front bows before - it was not fun nor easy
MN3
spags wrote: Hello fellow prindle 15 or 18 sailors. Just wondering if you ever had the rivets in your mast hinge plate get loose or pop out after raising your mast. If so, any suggestions to fix this problem?Edited by spags on May 24, 2019 - 01:24 AM.
yes. Rivets can work themselves loose. Drill out the rivets. If the hole in the beam is a sloppy 3/16", I would recommend upgrading to 1/4". Otherwise, it will be best to thru-bolt the plate back on.
Catfan, I’m referring only to the stainless bracket attached to the port side of the mast (on the P18). This can separate after a few bad mast raises. The hinge pins usually bend first, indicating you were doing something wrong.
You need to remove the lower mast casting to access the mast internals. There is usually a ton of corrosion and crud in there on an older boat. This needs to be cleaned up. It’s the perfect time to flush the whole inside with salt away and check for corrosion or leaks (on the nearby limiter and mast hound hardware).
Consider whether you would like to add a drain plug or pressure valve before closing it up. Goop everything.
If the larger rivets don’t hold, I’ll be using bolts, as Scott mentioned.
nohuhu wrote: Catfan, I’m referring only to the stainless bracket attached to the port side of the mast (on the P18).
Ok thanks nohuhu, now I understand what plate you & spags are talking about (and it's not what I was thinking).
FYI for spags if you decide to replace the existing rivets with larger, 1/4" diameter rivets: I found out a couple weeks ago my standard rivet squeezer would not accommodate the large, 1/4" diameter rivets, so I had to buy a heavy duty rivet squeezer. However, Harbor Freight had them on sale for only $15.99 - it's amazing how inexpensive tools from China are these days. Also found out 1/4" dia stainless rivets were not to be found in Home Depot/Lowes, local hardware stores, or even my local marine supply stores - had to get them from a sailing supplier.
MN3, thanks for the tip on using a long stick and chewing gum to get something to the center of the rear cross beam. I was thinking of that, but sorry to say I didn't know what needs to be done to get the cross beam end cap off; was afraid to just start pounding w/ a hammer. Can anyone let me know if there's anything in particular that needs to be done to get the end caps off of Prindle cross beams without bending/damaging something?
PS, hope spags doesn't feel I'm jumping his thread, sounds like at this point his question's been answered.
This is the part Frank is referring to.
https://www.murrays.com/product/56-6516/

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