rusting metal plate under foredeck

[Warren Moore]

On my CD28 '79, I noticed the metal plate in the anchor well is showing considerable rust. It still seems strong, but concerned about the amount of rust. It looks like a big job to replace the plate. Any suggestion? Thanks,
Warren



wmoore@peconic.net

[Matt Cawthorne]

Warren, Those of us with other CD models might be able to make suggestions if we had some more detail. For instance where is the plate? Is it a backing plate for a cleat or is it acting like a chainplate? If it is a backing plate some rust is not too important because the plate is there to spread the load out and would normally be designed for stiffness. If it is loaded in tension and designed for strength (like a chainplate for an inner forestay) it is worthy of a good hard look, because corrosion can degrade the fatigue strength by a factor of two or three.
As a minimum the rust suggests that it may be time to do some re-bedding of whatever is on deck in the area. The re-bedding is particularly important if the deck is cored in this area. The folks at Cape dory tended not to spoil away the core and re-fill with epoxy filler prior to bedding down deck hardware. As a consequence the core stays dry only when the bedding is good. When it starts to leak the core gets wet and an eventually rots.

I can't tell without more info, but sometimes the preventative maintenance now can save a whole lot of work later.

Matt

On my CD28 '79, I noticed the metal plate in the anchor well is showing considerable rust. It still seems strong, but concerned about the amount of rust. It looks like a big job to replace the plate. Any suggestion? Thanks,
Warren

mcawthor@bellatlantic.net

[warren moore]

thanks Matt, It appears to be a backing plate for the bow cleat. I agree that re bedding is probably the first thing to check into
Warren

Warren, Those of us with other CD models might be able to make suggestions if we had some more detail. For instance where is the plate? Is it a backing plate for a cleat or is it acting like a chainplate? If it is a backing plate some rust is not too important because the plate is there to spread the load out and would normally be designed for stiffness. If it is loaded in tension and designed for strength (like a chainplate for an inner forestay) it is worthy of a good hard look, because corrosion can degrade the fatigue strength by a factor of two or three.
As a minimum the rust suggests that it may be time to do some re-bedding of whatever is on deck in the area. The re-bedding is particularly important if the deck is cored in this area. The folks at Cape dory tended not to spoil away the core and re-fill with epoxy filler prior to bedding down deck hardware. As a consequence the core stays dry only when the bedding is good. When it starts to leak the core gets wet and an eventually rots.

I can't tell without more info, but sometimes the preventative maintenance now can save a whole lot of work later.

Matt

On my CD28 '79, I noticed the metal plate in the anchor well is showing considerable rust. It still seems strong, but concerned about the amount of rust. It looks like a big job to replace the plate. Any suggestion? Thanks,
Warren

wmoore@peconic.net

[Jim Jones]

I just had a 1977 CD28 surveyed and there is some slight rusting of the metal backing plate in the forepeak. The manual contains a drawing of this plate and it would be a substantial operation to replace it. The plate is not only under the foredeck, but bends at the stemhead and runs part way down the stem.

Aside from any possible leaks causing the rusting, this is also a very moist area caused by wet chain and rode after hauling the anchor. You could still get rusting even with no leaks.

You probably need to clear out your cockpit lockers and crawl in and check the back stay backing plate as well. It is also an angled plate. On my boat there was more rust here then on the bow backing plate.

The surveyor suggested that all the loose rust and scale should be cleaned as throughly as possible, painted with rust convertor and then with a good primer.

Hope this helps.

Jim Jones <jjones@intergate.com>



jjones@intergate.com

[Mike Thompson]

Yes, mine is rusting too.

What is a 'rust converter'?



miket@truesoft.com

[Richard Gelfand]

In considering the purchase of a CD27, I have found the problem in the stern locker at the chain plate area. There is a bar that runs from the deck, rear back stay chain plate to the transom. The bitter end of the stern anchor rode is tied off to the "bar". The bar and the chain plate itself have a fair amount of rust on them. A closer look at this is ceratainly on my list. Resealing of the chain plate probably inorder, and yes an inspection of the deck itself for rot. Scraping of the area and use of one of the products that "changes" rust to primer, and painting with rustolium product part of the solution. My greater concern is to find out if there is any structural probelm i.e weakening and rot in the deck.



Aldajon@aol.com

[Jim Jones]

Mike,

I will quote from the 1998 West Marine catalog on pg# 332:

Phosphoric-acid-based compound that converts rust to a chemically
inert form to seal it for painting and prevent new rust from
forming. Provides an excellent base for subsequent paint.

A quart costs $9.19. Before applying, you need to clean off all loose scale really well using a wire brush. After that if you can hit it a few licks with some emery paper, so much the better. Wipe down with thinner and then apply the converter.

WARNING: Be sure to wear protective gloves when you use this stuff and provide good forced ventilation (small fan) and wear a fume filter mask.


Richard,

When I said mine was rusty I didn't mean rusty to the point of failure. This is a fairly substantial chunk of metal and there is surface rusting, but still more then enough meat to preform it's job.

The rebar which is welded in and glassed to the transom does not appear to be structual. Welding the rebar to the plate provided two functions 1) maintains the correct angle of the plate to the deck and transom and 2) a means of holding the plate in position before and during attaching the deck to the hull. If you look closely there is only one layer of glass which is pretty sloppy in it's application and the rebar is only tack welded - this is not structual.

Replacement is totally dependent on how far the rusting has progressed. You need to be the judge of this or get a good surveyor to give an opinion. The price you were quoted by the yard is probably not too bad considering the work involved. If you elect to have this done, insist that they use 316 stainless rather then 304.


Jim Jones <jjones@intergate.com>




jjones@intergate.com

[Jerry]

Yes, mine is rusting too.

What is a 'rust converter'?

A rust converter is a milk-like liquid you apply to rust to stop the rusting. It also converts the existing rust to a paint-like primer. I've used the brand "X-Tend" on my boat stands with good results. "X-Tend" is usually available in hardware stores.

[Larry DeMers]

I have an '83 CD30C, and it is a freshwater boat. This weekend, I noticed that the backing plate (the 12 in. x 12 in. plate) in the anchor locker (forepeak locker) has large sheets of paint peeling off of it. The metal appears to have surface rust on it. The boat has no leaks, but that area is wet from the anchor rode, so this is probably the cause of the paint failure and subsequent rusting. I will try the rust conversion ideas that others have provided and then paint with rustoleum or some equivalent paint.
This plate is really Stainless? The color is all wrong it seems. I was thinking that it was a piece of steel plate with zinc chromate on it.



demers@cray.com

[Matthew Atkinson]

On my CD28 '79, I noticed the metal plate in the anchor well is showing considerable rust. It still seems strong, but concerned about the amount of rust. It looks like a big job to replace the plate. Any suggestion? Thanks,
Warren

I have a 1978 CD 30 Cutter and I elected to remove the backing plate in the bow due to serious corrosion. My situation was somewhat more radical since I am also replacing the bowsprit which has longitudinal splits as well as checking.
Removal of the backing plate itself is not a huge job, the problems are in what is concealed. The backing plate is set on an epoxy base and then the forward support is glassed into the bow - easily removed with a grinder. I now have many holes in the foredeck which appear to be the remains of hollow bits, hawse pipes, reattachments of the old repaired bowsprit, and the lord knows what. The balsa core appears to end just forward of where the pumpout and water intake deck plates are located. I found this fact when I moved these deck plates aft so to clear the chain locker area. Consequently most of the foredeck repair can be accomplished by some grinding and reglassing without affecting the balsa core. I intend to complete the glass repairs after I install the new blacking plate, using an epoxy base, so as to have a surface to glass against. I shall then install the bowsprit, again in a thin epoxy base to provide a solid seat. Note that the underside of the new bowsprit is curved to conform to the curve of the deck anyway. As for the backing plate, I am generally rigging the boat for offshore cruising, so the new plate is longer to pick up the inner forestay which is substantially beefed up for a storm jib. This way I have in total strengthened the forestays by providing a heavier bowsprit on a reglassed foredeck with a continuous backing plate, incuding tabs aft to glass against the hull. As I consequence, I can also use two anchor rollers that are seated on stainless plates let into the teak with stainless backing plates without much concern for the strength of the bowsprit.
In any event, I do not recommend doing more than necessary. In my case, the metal rot was severe and replacement was advisable considering my purposes. Nonetheless, mere removal of the blacking plate is not horrendous, but it does require removing the bolts that connect it to the bowsprit and you may have a reseating problem.

Good lock with whatever course you take.



matkinson@genesis.law.pace.edu