Accessing chainplates

[Della and Dave]

Thanks Pete and Dale.  I was able to find both chain plate drawings and download them, but ironically, not using my main windows 7 based computer.  It doesn't show any attached file.  On my iPhone however, I could see both attachments and downloaded them to Dropbox and could read them using an autocad reader app. 

Both drawings are quite similar, but Dale's holes are just a touch larger, 25/64 instead of 3/8. Most interested in the mizzen at the moment. 

Our local steel supplier cheesed out on us,  when I went to pick up the steel today, they had subbed 304 for 316.  I noticed it and they were good about a refund, but it looks like I will be going to online metals and it will be a bit longer before I am can start drilling.   

[Della and Dave]

Does anyone have a drawing or the dimensions for the tang at the upper end of the mizzen upper/cap shroud?   I realized with the zeal of upgrading our mizzen chain plates that it won't do much good if we don't do the same to the upper end.  All we would have done is move the weak link to where we can't see it.  

We got the first batch out and they don't look too bad.  A little chaffing where the stay clevis fits and some light surface corrosion.  It looks like the holes in the original didn't line up quite perfect.   We also noted that most of the bolts were installed with the nut against the steel.  I would have done it opposite so the threads don't ride in the steel plate.  That way all the bolts take the load more evenly.  

[Dale Tanski]

Before you commit to using 1/4" bar stock, check the width of the jaw at the bottom of the mizzen turnbuckles.  Will they fit over the 1/4" thick bar? 

Dale

[Della and Dave]

Well, I have been busy on this project.  I have now made new mizzen chain plates.  I also  have the main lowers drilled up, except for the full sizing on the top hole that attaches to the stay.    Still some finish work to do on the main lowers.  Dale:  We followed your suggestion, and only went to 3/16 instead of 1/4.  It is still not the weak link by any means, even with upsizing the wire and turnbuckles.  Still need to sort out the upper end. 

WARNING:  To anyone using Dale or Pete's drawings, on Polaris at least, the bolt spacing is not the same as it was on their boats.  The mizzen was pretty close, only about .010 off when I measured with calipers, but the main lower were off the drawing spacing by about .245 from the top bolt hole to the bottom.  I haven't installed them yet, so we will see what trouble I can get into there.  They were very consistent between all four chain plates on the boat. 

Even with lots of oil, I had to resharpen my new 3/8 cobalt drill bit.  Usually I would just get a new one, but working in the evenings, none of the stores are open and I want to get this done ASAP. 

I think I need a new grinder......   

[Jim S]

I pulled and inspected the starboard and port shroud chainplates on November 25th.  Two of the six plates had serious cracks and are being replaced.  All chainplates have pitting and corrosion.  I am having the new chainplates constructed by Chainplates Express in Texas, http://chainplatesexpress.com/.  I will post again after I see their product.  The samples at the shop were of very good quality and finish.

Phantom is 1981 production and this is probably the first chainplate inspection.

[Della and Dave]

Jim: Good luck on the chain plate project.  Once I got it all done, I was glad I did it.  Once I read Dale's comment, I decided that 1/4 inch on the mizzen was overkill, so I went with 3/16. I polished the plates after sanding them with a buffing wheel.   

I ran into a little bit of corrosion on the main chainplates, but nothing really severe in my case.  Polaris spent a lot of her life in Seattle where she got a fresh water rinse frequently and Seward Alaska is also somewhat rainy, so not as severe an environment with respect to corrosion as the tropics.  Installation was fairly straight forward, except access behind the vanity in the head.  I had to take that apart and the back panel now needs to be replaced.

Be prepared to replace some of the ground wire terminals.  I also replaced all the bolts washers and nuts, and they are a mixture of different lengths.  I personally can't stand threads in bearing, so I addresses that as a few of the originals were not quite long enough so the threads took the load instead of the shank of the bolt.  Where possible, I made sure the bolt head was next to the chain plate.  Sometimes I forgot the ground wire, and had to take it apart  again to put it on.  Buy extra nuts, you might drop one or two.

The chain plate covers were also a bit of a struggle.  All the ones I could find for the main had the wrong hole pattern, so I cleaned mine up and reused them. The hole pattern were not all the same, so I tried to put them back where they came from.   I bedded them in butyl tape.   Someone had used something really strong to bond them to the deck, probably 3M 5200 it took a razor blade and lots of time to remove them.  The deck core was fine but a little round file work was necessary to accommodate the thicker mizzen chain plates.  Also on the chain plate cover.   A Dremmel tool helped until I broke it.  A selection of small files were useful. 

A bit of a chamfer on the deck to give the butyl somewhere to live is recommended by the books I read, so I did that too. Compass marine has a good write up on butyl.  On balance, I am glad I did it and it might have saved a little money, but if I had it to do over, I think buying them from a reputable supplier would save a lot of time.  Online Metals was great and I got certs so it really is good German 314 SS, not Chinese crap, so I think they will last a long time, but it was quite a bit of work.  It feel good to have confidence in the rig. 

[Jim S]

The new chainplates from Chainplates Express were installed on November 28th.  The quality was very good with very little adjustment.  I  bedded them with Ace Rope Caulk (butyl tape) and the original chainplate covers.  The only access difficulty was behind the shower.  I inspect all chainplates yearly visually in place.  I plan to remove them for inspection every three to four years.