Advice on corroded bow eye backing plate

[cantabrian]

Hi, all. Took possession of my 16, and it's great. I've been looking over some things to get it ready for the water. Looking at the bow eye, which connects the bobstay to the bowsprit and also is used to winch the boat on the trailer, I was thinking about how it carries a lot of load and should have a solid plate on the other side of the fiberglass (boy eye backing plate). So I crawled to the front and looked, and it's really really corroded. Like, metal coming off in chunks. How urgent is this? Assuming I should replace this sooner rather than later, what should i use as a backing plate? The bow eye in the link below (3/8, right? not 1/2?) says it comes with a backing plate, but I assume I need something contoured to match that corner of the bow? What kind of sealant should I use/how should I apply it? (Photos are of the inside and outside.) Thank you for your help!

https://www.westmarine.com/buy/west-marine--stainless-steel-bow-eyes--P002_060_008_501

[Cpy23ecl]

I would replace ASAP with either a piece of aluminum or stainless around 1/4" thick.  Your bow eye may be fine once you clean it up.  If the threads show any corrosion I would replace the eye too.

Fred

[Bob23]

Hey canta and welcome to the center of the Compac universe!!
I used a piece of hardwood shaped to fit the contour of the inside of the bow,  sealed in epoxy and with a flat stainless plate, then lock washers and finally the nuts.
I would caution about using this to winch the boat onto the trailer however, not sure that's what it's designed for. It's a good place to secure the boat on the trailer but I wouldn't put tons of pulling force on this. Of course, I could be wrong, just my 2 cents- keep the change!
Bob23

[bruce]

I'm sure originally there was blocking as Bob describes, I'd guess plywood. The backing plate distributes the load on the block. It should be stiff enough so it doesn't deflect under load, I'd use 3/16" SS. Clearly there's been work done to the bow eye before, and it doesn't look well-sealed now. You'll need to replace the blocking if it's rotted.

If you can get the nuts off, remove the mild steel backing plate and see what's going on. You may need to cut the bow eye on the outside and drive it through. Com-Pac lists a bow eye block and bow eye (yes, 3/8" dia.) on their CP16 parts list.
https://www.dropbox.com/sh/xtfxq40jvl9esw9/AADHttjwMACdw5Voo2NYBoLVa?oref=e&preview=CP+16+2021.pdf

Here's a shot down the hawse pipe on my PC, it looks like you have better access than I would! My blocking wasn't glassed in place, it looks like they just smeared caulking in there. It is under compression, so that would work, but I'd probably glass it in. I'd also use G-10 for the blocking, to avoid rot in the future. For a sealant, I'd use Sikaflex 291. 3M 4200 would also be a popular choice

[Bristol14]

I replaced my bow eye a few years ago on my 1987 23 MK 2. I bought the replacement from Hutchiins. Biggest issue was access inside the bow. I wound up carefully cutting an inspection hole after conferring with Gerry at Hutchins. Wanted to make sure the access wasn?t going to create a structural issue.

My boat has a teak block shaped to fit the curve of the bow and a stainless steel backing plate. I used butyl tape to create a watertight seal and I check it periodically for leakage. None to date. 

The fiberglass at the bow is pretty thick and I?ve used the bow eye as a backup to my mooring set up during storms. The bow eye is also used to secure the boat on my trailer with no issues.

[cantabrian]

Thanks for all of this! Really helpful. Yes, as you all guessed, there's old wood blocking behind that corroded plate, and it's basically mush now. And the bolts basically come off in pieces if you squeeze them with a wrench. So I'll clean all that out today.

As for what to put in its place, I was thinking about Marine-Tex epoxy puddy. Seems like it's basically bondo. Thinking I could put some in there, make a flat surface for a metal plate (I couldn't find a SS sheet that works, but found an aluminum plate; might work?), let it cure. Then take off the bow eye, drill holes through, put sealant in the holes, put the bow eye in, put sealant behind the plate, seal it all up. That sound reasonable? Basically using Marine-Tex instead of blocking. From their site, it seems like it should carry the load fine on the trailer. I do use that bow eye to winch it up, but it's mostly floating when I winch it, except for the last turn or two of the winch. Thanks again!

[bruce]

Aluminum is OK, you'll have corrosion with the SS fasteners as always. Isolate as possible.

Epoxy putties work great for fairing and filleting, but can be brittle and lack tensile strength when used as a gap filler, possibly cracking under stress. Fiberglass gets it's strength from the matrix of glass fibers bonded by the resin. The Marine-Tex is bulked with a variety of fillers, including calcium carbonate, aka chalk. It will thicken the mixture, but not add any strength. I don't see any fibers listed on the Safety Data Sheet. Marine-Tex might be fine, but I'd go with an epoxy, like West System, bulked with chopped or coarsely-milled glass fibers, and silica, if I wanted to go this way. Both of these make the putty much harder to sand, not a desirable feature for a product like Marine-Tex, which tries to cover all the bases.

You don't need to sand, just smoosh a flat surface into the putty (with a suitable release layer!), brace it in place while the epoxy sets up, pop it off and continue.

[cantabrian]

An overdue update: I ended up basically doing what Bruce suggested. I made a putty with west epoxy and chopped fiberglass plus west 407 (the high density one). Put it in, and smashed it down with a backing plate (aluminum, cause that's what I had). So far so good!

[crazycarl]

That will work!

[bruce]

Good for another 40 years!

[K3v1n]

https://youtu.be/tdl0U5VzsFc

Here is a video on how I repaired mine(CP23) for future vistors.